Small molecule sonosensitizers in cancer therapy: recent advances and clinical prospects

Stable cavitation, also known as non-inertial cavitation, is characterized by the repetitive oscillations of microbubbles around their equilibrium radius without significant changes in volume. Typically, the maximum expansion of a gas microbubble does not exceed twice its equilibrium radius. This type of cavitation generates heat, induces microflow in the surrounding fluid, and creates localized shear forces. These effects can disrupt cell membranes and enhance fluid movement, making stable cavitation useful in applications such as drug delivery and SDT.⁶²

Inertial cavitation is also referred to as transient or collapse cavitation. It involves the unstable expansion and rapid, forceful collapse of bubbles. The collapse generates high-pressure shock waves, extremely high local temperatures, and the release of free radicals (Fig. 3A).⁶³ This type of cavitation can cause mechanical damage to nearby structures and induce chemical reactions. For instance, the high-pressure microjets produced during inertial cavitation can physically damage tumor cells, while the shock waves and thermal stress can lead to molecular pyrolysis, releasing free radicals that react with endogenous substrates to generate ROS.^61,64 Additionally, the light emitted during bubble collapse, known as sonoluminescence, can activate sonosensitizers, which transfer energy to surrounding oxygen, triggering cytotoxic oxidative reactions within tumor cells.⁶⁵

	Fig. 3 (A) Mechanism diagram of sonocatalytic ROS production through the cavitation effect. Upon US irradiation, the cavitation bubbles experienced three steps: nucleation, bubble growth, and implosion. After that, they (i) generate ROS; (ii) undergo sonoluminescence to activate the ROS production by sonosensitizer. (B) Schematic diagram of piezoelectric effect for the generation of ROS. e−–h+: electron–hole pair.

Ultrasonic cavitation plays a crucial role in SDT through both mechanical and chemical mechanisms. Stable cavitation enhances drug transport and delivery by transiently disrupting cell membranes, improving the uptake of sonosensitizers by tumor cells. For example, Forbes et al. demonstrated significant uptake of fluorescein isothiocyanate (FITC)-labeled dextran below the microbubble collapse threshold.⁶⁶ Inertial cavitation, with its ability to generate high-pressure shock waves and extreme temperatures, contributes to the mechanical destruction of tumor cells and the induction of chemical reactions that produce cytotoxic effects.⁶⁷

In the context of ROS generation through sonoluminescence activation, there is a subtle distinction in the mechanism between organic sonosensitizers and their inorganic counterparts. For organic sonosensitizers, upon photon absorption, they are activated to singlet excited state followed by intersystem crossing (ISC) to the triplet excited state. The activated molecules participate in two distinct reaction pathways: type I mechanism involving electron transfer with oxygen and biological substrates to generate free radicals, or type II mechanism through energy transfer with oxygen to produce ¹O₂.^25,70

Further research with clinically relevant parameters and specific ROS probes is needed to clarify the role of sonoluminescence in SDT.⁶¹

In SDT, ROS generation in piezoelectric materials primarily occurs through two mechanisms: mechanical stress-mediated piezo-catalysis and sonoluminescence-mediated photocatalysis. In piezo-catalysis, mechanical stress induces the repositioning of charges, leading to the formation of free charges that react with water to produce reactive species. Sonoluminescence-mediated photocatalysis involves the excitation of electrons from the valence band to the conduction band by sonoluminescence, creating an internal electric field that drives redox reactions and ROS generation.^74,75

Piezoelectric materials with non-centrosymmetric structures can generate dynamically updated built-in electric fields under mechanical force, modulating carrier migration and band bending through the piezoelectronic effect. This allows for the continuous separation and attraction of electrons and holes to opposite surfaces of the material, catalyzing redox reactions. The piezophototronic effect integrates piezoelectricity, photoexcitation, and semiconductor behavior, modulating the transport behavior of excited charge carriers and thereby altering catalytic performance. This phenomenon allows for the regulation of piezoelectric polarization charges on heterostructure band alignments as well as the manipulation of photogenerated carrier conduction.^76–78

In summary, piezoelectric materials provide new avenues for the design of sonosensitizers and the exploration of SDT mechanisms.⁷⁹ They can modulate charge migration behavior through the US-induced piezoelectric field, promoting ROS generation and thereby enhancing SDT effects. Although some piezoelectric semiconductors have been used in SDT, their efficiency remains to be improved. The rapid recombination of US-generated electrons and holes in piezoelectric sonosensitizers limits the generation of ROS, affecting treatment outcomes, which is a key issue that needs to be addressed. Therefore, optimizing the structure and performance of piezoelectric materials to enhance the efficiency and stability of ROS generation is crucial for improving the efficacy of SDT.⁸⁰

ICD induction is intrinsically linked to cellular stress responses and can be triggered by diverse stimuli, including viral infections, chemotherapy, radiotherapy, PDT and SDT.^87,88 Among these, SDT, a non-invasive therapeutic approach, employs US to selectively activate sonosensitizers within tumors, generating cytotoxic ROS. Beyond direct tumor cell killing, these ROS induce ER stress to trigger DAMPs release, thereby initiating anti-tumor immune responses.^89,90 SDT offers unique advantages such as deep tissue penetration and minimal off-target effects, while demonstrating synergistic potential with immune checkpoint inhibitors to amplify anti-tumor immunity.⁹¹

The efficacy of SDT-induced ICD is governed by multiple factors, including sonosensitizer properties such as ROS generation types and efficiency, US parameters (frequency, intensity and duration) and tumor heterogeneity such as cell types and TME features, etc.⁹¹ Given its dual mechanism of local tumor eradication and systemic anti-tumor immunity activation, SDT-induced ICD holds significant promise for treating refractory and metastatic tumors, offering an innovative solution for cancer immunotherapy.

SDT, as an emerging non-invasive anti-tumor strategy, not only directly kills tumor cells through ROS bursts mediated by sonosensitizers, but also reprograms the functions of immune cells within the TME, particularly the polarization of TAMs.⁹⁶ SDT promotes the transition of TAMs from the immunosuppressive M2 phenotype to the pro-inflammatory M1 phenotype via ROS-dependent or -independent pathways.^97,98 This transition is characterized by the upregulation of M1-type markers, such as inducible nitric oxide synthase (iNOS), CD86 and major histocompatibility complex II (MHC-II), and the downregulation of M2-type markers, such as CD206, CD163 and arginase-1 (Arg-1).⁹⁹ The reprogrammed M1-like TAMs exhibit enhanced immune-activating capabilities. Specifically, they display increased phagocytic activity, which facilitates the efficient clearance of tumor cell debris and subsequent CD8⁺ T cell activation through antigen cross-presentation. Additionally, these M1-like TAMs secrete elevated levels of pro-inflammatory cytokines, including TNF-α, IL-12 and IL-6, which promote Th1-type immune responses while recruiting natural killer cells and DCs.¹⁰⁰

Furthermore, the metabolic state of macrophages directly influences their polarization.¹⁰¹ SDT exerts anti-tumor immunotherapeutic effects by reprogramming TAMs metabolism, such as through enhancing glycolytic activity while inhibiting oxidative phosphorylation, thereby sustaining their anti-tumor M1 phenotype.¹⁰² Notably, ICD induced by SDT releases DAMPs, which activate TAMs via receptors like TLR4 and P2X7, further promoting M1 polarization. The reprogrammed M1 TAMs, in turn, amplify the immune effects of ICD, establishing a positive feedback loop for anti-tumor immunity.^103,104

Although SDT is an emerging cancer treatment that uses US to stimulate a sonosensitizer to produce cytotoxic ROS with excellent tissue penetration, the sonosensitizer may spread to surrounding healthy tissues, causing unwanted side effects under US stimulation. To address this issue, prodrugs that are specifically activated by factors in the TME can be designed to minimize damage to healthy tissues. Glutathione (GSH), which is overexpressed in the TME, serves as an effective trigger for activating prodrugs at the tumor site. In 2023, An et al. developed a GSH-activatable sonosensitizer prodrug (pro-THPC, Fig. 6) by attaching a quencher (2,4-dinitrobenzenesulfonyl) to tetrahydroxy porphyrin. Under US irradiation, this prodrug shows weak fluorescence and low ROS yields, but GSH-mediated activation enables tumor-specific enhancement of both fluorescence and ROS generation (Fig. 6B and 7A). To facilitate in vivo use, the prodrug was formulated into NPs using DSPE-PEG₅₀₀₀. After intravenous injection into mice at 24 h, the prodrug NPs achieved a significantly higher tumor-to-background ratio (T/N = 8.9) compared to drug NPs (T/N = 2.3) or prodrug NPs combined with a GSH inhibitor (L-buthionine sulfoximine, BSO, T/N = 3.4) (Fig. 7C). This high ratio enables precise US targeting during SDT. Furthermore, the prodrug effectively inhibited tumor growth under US irradiation (Fig. 7D).¹¹⁴ In the following year, An et al. further utilized this prodrug (pro-THPC) as both a photosensitizer and a sonosensitizer. Upon activation by GSH, pro-THPC releases the dual-sensitizer THPC, enabling simultaneous fluorescence imaging and combined PDT-SDT. A significantly higher tumor-to-normal tissue ratio was observed for pro-THPC NPs in in vivo fluorescence imaging, compared with both THPC NPs and the pro-THPC NPs group treated with the GSH inhibitor BSO. Additionally, ROS generation from the dual-sensitizer was effectively confined within the tumor tissues. In vivo studies demonstrated that pro-THPC NPs eradicated tumors through PDT and SDT while reducing skin phototoxicity.¹¹⁵

	Fig. 6 Chemical structures of pro-THPC and TPP-Ce6.

	Fig. 7 (A) Conceptual illustration showing GSH-triggered activation of prodrug NPs, resulting in simultaneous fluorescence emission and ROS generation. (B) Fluorescence emission spectra of the prodrug after 1 and 60 min of incubation with GSH, respectively. (C) Tumor-to-normal muscle (T/N) fluorescence intensity ratios at various time points in the drug NPs, prodrug NPs, and BSO with prodrug NPs group. (D) Tumor volume curves of tumor-bearing mice across different treatment groups. Statistical significance was determined using two-way ANOVA with GraphPad (p < 0.01). Groups 1, 2, 3, and 4 refer to control, prodrug NPs, US, and prodrug NPs + US, respectively. Reproduced with permission.114 Copyright 2023, Wiley-VCH. (E) Schematic illustration of the combined chemo-sonodynamic therapy (chemo-SDT) employing biocompatible EVs loaded with mitochondria-targeting TPP-Ce6 and pro-oxidant piperlongumine (PL). Reproduced with permission.116 Copyright 2023, Elsevier.

To address the limitations of sonosensitizers, including inefficient intracellular delivery, low cancer specificity, poor aqueous stability, and suboptimal pharmacokinetics, nanoplatform-assisted delivery has emerged as a promising strategy. Nanoplatforms enhance cellular uptake and bioavailability of sonosensitizers and can passively accumulate in tumor sites through the enhanced permeability and retention (EPR) effect. Among various nanocarriers, extracellular vesicles (EVs) have garnered significant attention. These natural nanoscale sacs, derived from cells, offer low systemic toxicity and serve as highly biocompatible nanovehicles for delivering therapeutic agents. EVs protect bioactive molecules from degradation in the bloodstream and selectively accumulate in tumors via the EPR effect. In 2023, Shim et al. developed EV-based nanosonosensitizers for combined mitochondria-targeted SDT and pro-oxidant chemotherapy (Fig. 7E). Ce6 was modified with lipophilic positively charged triphenylphosphonium (TPP) moieties to form TPP-Ce6 (Fig. 6), which efficiently accumulates in mitochondria. TPP-Ce6 was loaded into EVs along with piperlongumine (PL), a pro-oxidant and cancer-specific chemotherapeutic agent. This combination enhanced cellular internalization of TPP-Ce6 in MCF-7 breast cancer cells, leading to increased ROS generation under US exposure. The EVs effectively disrupted mitochondria under US irradiation, enhancing anticancer activity. The co-encapsulation of PL further amplified SDT efficacy through excessive ROS generation and triggered cancer-selective apoptosis. In vivo studies using MCF-7 tumor-xenograft mice showed that EVs accumulated in tumors after intravenous injection, significantly inhibiting tumor growth without causing systemic toxicity.¹¹⁶

Recently, Tang et al. developed a novel SDT platform to overcome other limitations of traditional porphyrin derivatives, such as poor water solubility, tendency to aggregate, and low ROS production. This platform is based on a unimolecular porphyrin derivative called OPV-C₃-TPP (Fig. 8), synthesized by covalently linking a water-soluble cationic conjugated oligo-(phenylenevinylene) (OPV, donor) with 5,10,15,20-tetra(4-aminophenyl)porphyrin (TAPP, acceptor). The covalent connection between OPV and TAPP enhances the water solubility of the porphyrin while reducing its self-aggregation tendency. Additionally, the emission spectrum of OPV overlaps well with the absorption spectrum of TAPP, facilitating efficient intramolecular energy transfer from OPV to TAPP. As a result, OPV-C₃-TPP shows significantly increased ROS production under US activation, leading to apoptosis and necrosis of tumor cells and significantly inhibiting in vivo tumor growth.¹¹⁷

	Fig. 8 Chemical structures of OPV-C3-TPP, P4CO-0P, P4CO-2P and P4CO-4P.

CO is a therapeutic gas with anti-tumor properties, and its precise delivery and controlled release in tumor tissues are critical for effective cancer treatment. However, efficiently generating CO in situ from metal-free CO-releasing molecules (CORMs) is challenging. US combined with GT can enhance the US cavitation effect, promoting damage to tumor organelles and facilitating the diffusion of drugs into the tumor tissues. In 2024, Zheng et al. reported two meso-carboxyl porphyrin derivatives, P4CO-0P and P4CO-2P (Fig. 8), which can decompose and release CO under US irradiation. The spatiotemporal control of CO release, including the release rate and self-decomposition products, was carefully evaluated. These US-driven CO-releasing molecules (US-CORMs) also function as sonosensitizers, generating ROS under US treatment to achieve SDT. Both in vitro and in vivo studies demonstrated the potential of these porphyrin-based US-CORMs as metal-free CO precursors for synergistic gas-sonodynamic anti-cancer treatment. This approach combines the benefits of GT and SDT, offering a promising strategy for cancer treatment.¹¹⁸

SDT can non-invasively eliminate localized solid tumors but struggles to combat metastasis due to its limited systemic anti-tumor response. To address this challenge, Zhao et al. developed DYSP-C34 (C34), a biocompatible and multifunctional molecular machine, by modifying Chenghai chlorin (CHC) with 32-aryl and 15-aspartyl substituents (Fig. 9A). The unique structure of C34 enhances its tumor localization, US-triggered cytotoxicity, and intrinsic immune-boosting effects. Its high binding affinity with plasma proteins and its amphiphilic nature, balanced by an aromatic group and an amino acid residue, facilitate selective tumor delivery and accumulation. Additionally, the positive charges on C34's carboxyl groups promote preferential uptake in cancer cells, which have higher membrane potentials than normal cells. C34 can directly stimulate DCs to trigger anti-tumor immunity, generating CD8⁺ cytotoxic T lymphocyte responses. This effect is significantly amplified during SDT, likely due to increased tumor antigen exposure. The 32-aryl substituent in C34's structure, which is absent in Npe6, contributes to its distinct immunogenic properties, possibly through the π-extension system in its macrocyclic structure. In summary, C34 functions as both a tumor-killing agent and an immune booster under US activation. Its sono/immune synergistic anti-tumor effects were demonstrated in breast cancer models with lung metastasis and colon cancer with liver metastasis, highlighting its potential for simultaneous primary tumor regression and metastasis inhibition (Fig. 9B–D).¹¹⁹ Building on this work, the same research team recently explored the combination of phytochlorin-based sonosensitizers and free-field US for effective immune-sonodynamic therapy. Free-field US offers significant advantages over standing waves, which can cause mechanical damage and thermal effects. Free-field US minimizes additional cell injury, ensuring that sonodynamic effects arise solely from the interaction between US and phytochlorin. This approach optimizes SDT for better treatment outcomes. Free-field US maintains stable acoustic pressure, with 0.121 MPa being sufficient to activate phytochlorin to produce ROS, triggering ICD in vitro. This stable activation is crucial for minimizing unintended damage and maximizing therapeutic efficacy. The amphiphilic nature of C34, one of the phytochlorin-based sonosensitizers, further enhances SDT efficiency by reducing interfacial tension. In an orthotopic murine breast cancer model, intravenously injected C34 combined with free-field US effectively inhibited tumor growth and elicited immune responses (Fig. 9E). Additionally, this treatment significantly prevented tumor lung metastasis, highlighting its potential as a powerful therapeutic strategy for cancer management.¹²⁰

	Fig. 9 (A) Schematic illustration of the preparation process of C34. (B) Illustration of workflow for SDT in vivo. (C) Tumor volume curves of various treatment groups. (D) Average numbers of lung metastasis nodules in different treatment groups. Data are presented as mean ± SD (n = 4 per group; four independent replicates). Student's t test was used for statistical analysis. *p < 0.05, **p < 0.01, and ***p < 0.001. Reproduced with permission.119 Copyright 2021, AAAS. (E) Representative immunohistochemistry staining of IFN-γ in tumor sections (scale bar = 500 μm, enlarged image scale bar = 50 μm). Reproduced with permission.120 Copyright 2025, Wiley-VCH.

The unique structure of metalloporphyrins, which resembles that of natural enzymes such as heme and chlorophyll, allows them to effectively mimic natural catalytic functions. This structural similarity, combined with their diverse chemical properties, makes metalloporphyrins highly versatile in the biomedical field, with applications spanning biomimetic catalysis and theranostics. In therapeutic applications, zinc and iron porphyrins are widely used in PDT because of their favorable light absorption properties and biocompatibility.^121,122 In the realm of imaging, metalloporphyrins, such as manganese porphyrins, have demonstrated exceptional performance in magnetic resonance imaging for high-resolution tumor imaging due to their ability to enhance contrast and provide detailed anatomical information.^122,123

US is non-invasive and can penetrate deep tissues, making it effective for treating deep-seated tumors, such as gliomas. It can also focus on small brain regions to precisely target tumors. However, efficiently activating sonosensitizers accumulated in gliomas for SDT remains a significant challenge. Image-guided therapy addresses this challenge by providing detailed tumor information and identifying the optimal therapeutic window. In 2018, Yan et al. developed a manganese-protoporphyrin complex DVDMS-Mn (Fig. 10) and constructed a multifunctional agent, DVDMS-Mn-LPs, for image-guided SDT. DVDMS-Mn-LPs consist of DVDMS chelated with manganese ions in nanoliposomes. These liposomes are stable and biocompatible, and they can generate ¹O₂ to kill cancer cells upon US irradiation. Additionally, they support magnetic resonance and fluorescence imaging. In vitro and in vivo experiments have shown that DVDMS-Mn-LPs significantly enhance anti-tumor efficacy, even in the presence of the skull.¹²⁴

	Fig. 10 Chemical structures of metalloporphyrin-based small molecule sonosensitizers.

Although the metalloporphyrins have shown the therapeutic potential for cancer treatment, their clinical application has been hindered by poor aqueous solubility, rapid metabolism, and risk of phototoxicity. To address these challenges, NPs have been developed as effective drug delivery systems to enhance drug accumulation in tumors. Human serum albumin (HSA) has emerged as an ideal nanocarrier due to its biocompatibility and targeting ability. Additionally, deep-tissue imaging-guided SDT using well-defined metalloporphyrin nanocomplexes has become a promising approach for precise treatment of malignant tumors. In 2018, Cai and colleagues developed three metalloporphyrin complexes (MnTTP, ZnTTP, and TiOTTP, Fig. 10) based on 4-methylphenylporphyrin (TTP), and formulated them into nanocomplexes with HSA. These nanosonosensitizers efficiently generate ¹O₂ under US irradiation and exhibit excellent US-activatable properties, with deep-tissue penetration depths up to 11 cm. Among them, MnTTP-HSA showed the strongest ROS-activatable behavior due to its smallest energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), as determined by density functional theory (DFT). Furthermore, MnTTP-HSA allows for dual-modal photoacoustic and magnetic resonance imaging, leveraging the paramagnetism of Mn(II) and the photoacoustic properties of porphyrins. This enables real-time tracking of nanoparticle accumulation in tumors for precise SDT. Notably, MnTTP-HSA achieves high SDT efficiency by suppressing the growth of both local and distant tumors in mice, demonstrating its effectiveness across different tissue depths.¹²⁵

Activating the immune system is a powerful strategy for suppressing tumor growth, recurrence and metastasis. Inspired by immunogenic chemotherapy and PDT, the same research group developed a manganese-protoporphyrin complex (MnP, Fig. 10) and constructed a multifunctional nanosonosensitizer (FA-MnPs) to treat deep-seated and metastatic tumors by enhancing drug accumulation and uptake by tumor cells, enabling synergistic SDT and immunotherapy (Fig. 11). FA-MnPs are constructed by encapsulating MnP into folate-liposomes. Liposomes, a leading drug delivery platform in cancer treatment, can entrap hydrophobic agents within their bilayer structure. Since FA receptors are overexpressed in many cancers, FA was incorporated into the liposome bilayer to enhance tumor targeting. DFT calculations showed that metal coordination in MnP enhances its responsiveness to US. Under US irradiation, FA-MnPs demonstrated high acoustic intensity in mimicked tissue (up to 8 cm depth) and generated abundant ¹O₂. Notably, SDT mediated by FA-MnPs promoted M2-to-M1 macrophage polarization and induced ICD. These effects collectively stimulated natural killer cells, DCs, and T lymphocytes, generating a robust anti-tumor immunity. In a triple-negative breast cancer mouse model, FA-MnPs effectively suppressed the growth of both superficial and deep-seated tumors.¹²⁶

	Fig. 11 The process of FA-MnPs-mediated noninvasive deep SDT and immune activation, leading to tumor growth inhibition. Reproduced with permission.126 Copyright 2021, Elsevier.

To overcome the poor water solubility of traditional metalloporphyrin derivatives, Zhang et al. developed a water-soluble sulfonated Ir(III)–porphyrin sonosensitizer (IrTMPPS) for SDT. This sonosensitizer can generate abundant ¹O₂ under US irradiation and sonocatalytically oxidize intracellular nicotinamide adenine dinucleotide (NADH), thereby disrupting the redox balance in cancer cells. This dual-action mechanism enhances the efficiency of SDT and provides a novel pathway for sonotherapy. The efficacy of IrTMPPS was demonstrated by its low IC₅₀ values (less than 10 μM) for all tested cancer cells under US irradiation, indicating its high potency as a sonosensitizer. Moreover, in vivo studies showed that IrTMPPS under US irradiation significantly suppressed tumor growth and proliferation, with tissue penetration depths reaching up to 10 cm. Furthermore, this treatment also effectively inhibited tumor lung metastasis, highlighting its potential as a powerful therapeutic agent in SDT.¹²⁷ Similarly, in 2023, Das et al. explored the sonodynamic potential of two water-soluble glycosylated porphyrin derivatives (free base porphyrin and zinc porphyrin) in vitro in a triple-negative breast cancer cell line. The glycosylation of these porphyrins enhances their water solubility and cellular uptake. At a concentration of 15 μM, the porphyrin derivatives demonstrated the ability to generate ROS. Under specific US irradiation, the free base porphyrin derivative achieved higher cell death rates (60–70%) compared to the zinc porphyrin derivative (50% viability).¹²⁸

In 2021, Erdoğmuş et al. synthesized di-axially substituted silicon phthalocyanines (SiPc) with distinct linker heteroatoms (O or S), namely Pc-1 and Pc-2, as well as their quaternized derivatives, Pc-3 and Pc-4 (Fig. 13). They tested the effects of sonodynamic, photodynamic, and sonophotodynamic therapies on these sensitizers using PC-3 prostate cancer cells. The synthesized complexes exhibited significantly higher ¹O₂ quantum yields than unsubstituted SiPc across all solvents, with DMSO yielding the highest efficiency. The axial groups also influenced quantum yields, with Pc-1 and Pc-3 outperforming Pc-2 and Pc-4 due to the sulfur atom's heavy atom effect. These findings highlight the importance of substituents, solvents, and axial groups in determining the complexes’ quantum yields. The MTT assay showed that the sensitizers significantly reduced cell viability compared to the control group. Apoptosis measurements indicated that combining SDT and PDT enhanced the sensitization effects, with Pc-1 and Pc-3 showing superior performance. Notably, Pc-2 achieved a 95% apoptotic cell rate after SPDT.¹³¹

	Fig. 13 Chemical structures of Pc-1, Pc-2, Pc-3 and Pc-4.

In 2023, Liu et al. synthesized a novel phthalocyanine–iron complex, FeS₂@PcD, by loading PcD (Pc-5, Fig. 14A) onto FeS₂. The DPA-modified Pc-5 exhibits initially suppressed fluorescence (Φ_F = 0.05) and sonosensitivity due to photoinduced electron transfer (PET) effect. However, when Pc-5 was incorporated into the FeS₂@PcD nanoreactor system, this quenching becomes dynamically reversible in response to TME conditions. The activation mechanism involves FeS₂@PcD reacting with H⁺ to release Fe²⁺, which is subsequently oxidized by H₂O₂ to form Fe³⁺. Fe³⁺ chelation by DPA's nitrogen atoms inhibits PET effect, resulting in restored fluorescence emission (Fig. 14A). Notably, FeS₂@PcD demonstrates exceptional tumor fluorescence imaging capabilities, with a 52.21-fold increase in fluorescence signal in response to the TME, which is significantly higher than that achieved by single-factor stimulation (Fig. 14B). Notably, the MR signal and sonosensitive activity of FeS₂@PcD switch from “OFF” to “ON” under the regulation of H⁺ and H₂O₂. FeS₂@PcD is specifically activated in tumor cells, but not in normal liver cells. Under US irradiation, FeS₂@PcD does not induce the death of LO2 cells (Fig. 14C). However, under the same conditions, FeS₂@PcD-mediated SDT and chemodynamic therapy (CDT) effectively kill HepG2 cells, with an IC₅₀ value of 0.53 ± 0.08 μM (Fig. 14D). The complex catalyzes the conversion of H₂O₂ to reactive •OH and exhibits enhanced sonosensitivity under US irradiation, thereby facilitating effective SDT/CDT.¹³²

	Fig. 14 (A) Simplified illustration of the Fe3+-induced activation of PcD (Pc-5). (B) Intracellular fluorescence emissions of HepG2 cells and LO2 cells incubated with PcD and FeS2@PcD ([PcD] = 0.5 μM) for 12 h, analyzed by flow cytometry. Cytotoxicity of FeS2@PcD against (C) LO2 cells and (D) HepG2 cells with and without US irradiation, respectively. Reproduced with permission.132 Copyright 2023, Elsevier.

Due to the sonodynamic activity of artemisinin derivatives, in 2022, Huang et al. introduced artesunate (ARS) on ZnPcs to fabricate covalent phthalocyanine–artesunate conjugates (ZnPcTAs), expecting to obtain novel efficient organic sonosensitizers via the combination of ZnPcs and ARS (Fig. 15). To maximize the ARS effect, ZnPc was combined with four ARS units to produce ZnPcT₄A (Pc-6). For comparison, ZnPc was also linked to one and two ARS units, resulting in ZnPcT₁A (Pc-7) and ZnPcT₂A (Pc-8), respectively. These conjugates showed significantly higher sonodynamic ROS generation in aggregation form than disaggregation form (Fig. 16A). For the increasing levels of aggregation-enhanced ROS, these sonosensitizers followed the trend, Pc-6 (60-fold) > Pc-8 (44-fold) > Pc-7 (35-fold) > ZnPcT₄ (17-fold) > Ce6 (10-fold) > PpIX (4-fold). Remarkably, Pc-6 demonstrated a ROS generation capacity in water approximately 60 times greater than that observed in water supplemented with 2% cremophor EL (Fig. 16B). Biological assessments revealed that Pc-6 exhibited high biocompatibility, robust SDT anticancer activity, and an amplified SPDT effect, effectively inhibiting tumor growth (Fig. 16C).¹³⁶

	Fig. 15 Chemical structures of zinc phthalocyanine–artesunate conjugates (ZnPcTAs).

	Fig. 16 (A) Conceptual illustration of aggregation-enhanced sonodynamic activity of phthalocyanine–artesunate conjugates. (B) Fluorescence intensity changes of DCFH at 524 nm in the presence of ZnPcT4A in different aqueous solutions under sonication. (C) Tumor volume curves of mice after different treatments over 14 days. n = 5, ***p < 0.001. Reproduced with permission.136 Copyright 2021, Wiley-VCH.

In 2023, Nyokong and colleagues investigated the impact of ultrasonic frequency and power on variously substituted ionic Pcs in SDT. Their chemical structures are shown in Fig. 17. Their key findings include that Pcs with a tertiary nitrogen on an aliphatic moiety (Pc-9, Pc-10) degrade more easily compared to those with a tertiary nitrogen on an aromatic moiety (Pc-13) under US irradiation. Additionally, zwitterionic Pcs (Pc-11, Pc-12) exhibit lower stability than their cationic counterparts (Pc-9, Pc-10). Furthermore, ethylated Pc-14 demonstrates increased susceptibility to US when compared to methylated Pc-13. Moreover, TPP-labeled Pcs (Pc-15, Pc-16) show reduced stability relative to their methylated counterparts, with the mitochondria-targeting ability of the TPP moiety potentially enhancing their anticancer effects. In the context of SPDT, cationic Pcs (Pc-9, Pc-10) produce more ROS than zwitterionic Pcs (Pc-11, Pc-12) due to their stronger binding affinity to cancer cells and bovine serum albumin (BSA) protein. The combination of light and US treatments significantly enhances ROS generation and cytotoxicity in vitro. The study concludes that a lower US parameter of 1.0 MHz and 1.0 W cm⁻² is more effective for Pcs in both SDT and SPDT than higher settings.¹³³

	Fig. 17 Chemical structures of zinc phthalocyanines.

In 2023, the same research team synthesized quaternized methylated and ethylated cations Pc-17 and Pc-18 to create cationic Pcs (Fig. 17). They observed increased ROS generation when these Pcs were conjugated to AuGSH and AgGSH NPs, leading to enhanced in vitro therapeutic efficacy on MCF-7 cells. The ethyl-substituted Pc-18 exhibited higher cytotoxicity compared to its methylated counterpart Pc-17, correlating with its superior ROS generation observed in ESR studies. This performance difference likely stems from the bulkier ethyl substituents. Combination US and light irradiation treatments boosted ROS generation for both ¹O₂ and •OH. Using MCF-7 cancer cell lines, the team found decreased cell survival with increasing concentrations of Pcs, NPs, and conjugates in SDT and SPDT. This study highlights the potential of cationic Pcs in improving cancer therapy efficacy.¹³⁷

In 2023, Sobotta et al. explored solitaire- and trans-zinc(II) porphyrazine/phthalocyanine hybrid complexes (Pc-19 and Pc-20) for photodynamic and sonodynamic therapy. Both complexes were stable under light irradiation and sonication. They demonstrated high photodynamic antibacterial activity against MRSA and Staphylococcus epidermidis, achieving >5 log reduction, but had negligible sonodynamic antibacterial effects. In vitro, Pc-20 showed no photodynamic activity against squamous cell carcinoma (SCC-25) or hypopharyngeal tumor (FaDu) but reduced the viability of MRC-5 fibroblasts and exhibited slight sonodynamic activity against FaDu cells. Additionally, Pc-20 inhibited protease-activated protein C by up to 38% at 1 μM, platelet-activated factor acetylhydrolase by 52% at 0.1 μM, and aldehyde dehydrogenase by 29% at 0.5 μM. These hybrid complexes hold promise for photodynamic and sonodynamic treatments of cancers and diabetes mellitus.¹³⁸

	Fig. 18 Chemical structures of Pc-21, Pc-22, Pc-23, Pc-24, Pc-25, Pc-26 and Pc-27.

In 2024, Emre Güzel et al. investigated the water-soluble sulfonated gallium(III) phthalocyanine Pc-27, exploring its photochemical, sonophotochemical, and DNA-binding properties for potential SDT and SPDT applications. Given that gallium is heavier than aluminum, silicon, and zinc, it is hypothesized that gallium phthalocyanines (GaPcs) have higher triplet quantum yields than their counterparts. The results showed that the ¹O₂ quantum yield of Pc-27 was 0.94 in sonophotochemical studies, higher than that in photochemical studies (Φ_Δ = 0.72). In MCF-7 breast cancer cells, GaPc-mediated SPDT induced cell death via ROS generation. Molecular docking simulations revealed that Pc-27 exhibits effective binding affinity for EGFR and VEGFR2, with stronger interaction toward VEGFR2 than EGFR. This water-soluble phthalocyanine-based sensitizer shows great potential for applications in PDT, SDT, and SPDT. These findings highlight Pc-27 as a promising water-soluble sensitizer for PDT, SDT, and SPDT applications.¹⁴¹

Iridium complexes, like other precious metals, are widely used as catalysts. In 2023, Yang et al. synthesized an Ir(III) phthalocyanine complex (IrPc, Pc-28) with an octabutoxyphthalocyanine ligand and encapsulated it with BSA to form IrPc NPs (Fig. 19A). This aimed to leverage the catalase-like activity and sonosensitizing properties of IrPc. The complex crystallized in a monoclinic P2₁/n space group, with the iridium ion coordinated to four pyrrole nitrogen atoms and two axial chloride anions in an octahedral geometry. BSA enhanced the biocompatibility and aqueous dispersion of IrPc-NPs. These NPs demonstrate dual catalytic and sonosensitizing capabilities, decomposing H₂O₂ to generate O₂ while producing cytotoxic ¹O₂ both in vitro and in vivo. This bifunctionality enhances SDT by alleviating tumor hypoxia and amplifying ROS generation. Additionally, the NPs enhance photoacoustic imaging, enabling real-time monitoring of tumor accumulation to guide optimal US irradiation timing. The SDT-induced ICD further contributes to anti-tumor immunotherapy. With excellent biocompatibility, minimal systemic toxicity in 4T1 tumor-bearing mice, and precise US-triggered controllability, IrPc-NPs exhibit strong potential for clinical translation in immunogenic sonodynamic therapy (iSDT). Both in vitro and in vivo studies demonstrated the anti-tumor efficacy of IrPc-NPs (Fig. 19B and C).¹⁴²

	Fig. 19 (A) Synthetic process of iridium-based sonosensitizer IrPc-NPs and its application in sonodynamic tumor therapy. (B) Variation of 4T1 cell viability with IrPc-NPs concentration under different conditions for 3 h. (C) The changes in relative tumor volume over time under various conditions. Reproduced with permission.142 Copyright 2022, Wiley-VCH.

Mn compounds with high activity can trigger CDT, while the US has been demonstrated to markedly promote the process. In 2024, the same research team developed a multimodal cancer therapy using MnClPc complexes (Pc-29, Fig. 20) with HSA for CDT, SDT, and α-PD-L1 immunotherapy. They synthesized MnClPc@HSA NPs, which generated ¹O₂ under US and converted H₂O₂ into superoxide anion (O₂˙⁻) and ¹O₂, ensuring ROS production across different oxygen levels. Under hypoxia, MnClPc@HSA NPs showed minimal toxicity. However, when combined with H₂O₂, they reduced 4T1 cell viability by 47.1%, compared to 36.6% decrease in normoxia. The therapeutic effect was further enhanced by US irradiation through combined SDT and CDT, showing the viability of 27.5% and 18.6% in hypoxia and normoxia, respectively. This differential efficacy correlated with distinct patterns of ¹O₂ and O₂˙⁻ generation. Beyond direct cytotoxicity, the NPs overcame tumor hypoxia limitations while inducing ICD and promoting T cell infiltration. In bilateral 4T1 tumor models, combination with immune checkpoint inhibitor α-PD-L1 simultaneously eradicated primary tumors and suppressed distal/metastatic growth, demonstrating potent systemic anti-tumor immunity.¹⁴³

	Fig. 20 Chemical structures of Pc-28, Pc-29, Pc-30 and Pc-31.

In 2022, Cheng et al. developed a nanoplatform based on iron(II) phthalocyanine nanodots (FePc-NDs) originating from FePc (Pc-30, Fig. 20) by the high-temperature pyrolysis for enhanced SDT. The Fe in Pc-30 acts as a Fenton reagent, generating •OH with H₂O₂. After modification with polyethylene glycol (PEG), FePc-PEG NDs show good biocompatibility, stability, and tumor accumulation. FePc-PEG NDs exhibited efficient US-activated ROS generation enabled by their conjugated porphyrin ring system. Additionally, the central Fe ions facilitate •OH production through Fenton reaction, demonstrating dual therapeutic mechanisms. More importantly, FePc-PEG NDs have good biological safety and do not cause any adverse effects on mice.¹⁴⁴

In 2024, Lin et al. synthesized CuPc-Fe@BSA NPs that aggregate in acidic conditions, enhancing SDT/CDT and imaging. They activated CuPc (Pc-31, Fig. 20) with H₂SO₄, improving aggregation-induced emission (AIE) property and ROS generation. The NPs, linked by Fe³⁺, dissociate in acidic environments, releasing Fe³⁺. This acid-sensitive aggregation is crucial for tumor-specific accumulation and enhanced SDT efficacy. The researchers evaluated ICD in vitro by assessing HMGB1 translocation and CRT exposure. Post-treatment with CuPc-Fe@BSA + US, HMGB1 was significantly released. Compared to the control group (0.54%) and US alone group (1.49%), CRT exposure increased in CuPc-Fe@BSA-treated group (24.3%). The combined CuPc-Fe@BSA + US treatment achieved synergistic efficacy, further elevating CRT exposure to 34.0%. This indicates high ICD induction, likely due to CDT and SDT synergies, stimulating an immune response and leading to mitochondrial damage and ferroptosis.¹⁴⁵

	Fig. 22 Chemical structures of BDP1–BDP4 and C-BDP.

Since the heavy atom substitution in BODIPY chromophore could increase the photodynamic therapeutic effect, iodine-substituted BODIPY has considerable sonosensitivity. Besides, the hydrophilic groups such as carboxyl and glycol groups can be introduced to construct amphiphilic BODIPY derivatives to improve the hydrophilicity. Further advancements included the development of a negatively charged amphiphilic BODIPY derivative, C-BDP (Fig. 22), which incorporated a p-carboxyphenyl group at the meso-position, iodine at the 2, 6-positions, and triethylene glycol at the 3, 5-positions. C-BDP demonstrated strong sonophotosensitivity and self-assembled with the positively charged A-BDP (a NO probe) to form CANPs. Upon exposure to US and light, these CANPs exerted dual sonophototherapeutic effects via C-BDP while simultaneously triggering an inflammatory TME. Moreover, due to the A-BDP component, CANPs emitted intense fluorescence, enabling real-time monitoring of TAM repolarization through NO release (Fig. 23A). In cellular studies, CANPs efficiently entered cancer cells, where they generated ROS to trigger apoptosis and promoted M1-type macrophage polarization by regulating TGF-β1 secretion (Fig. 23B and C). In vivo experiments using 4T1 breast tumor-bearing mice further validated their therapeutic potential. Notably, mice treated with CANPs showed stable body weight, confirming the biosafety of both CANPs and C-BDP. Tumor volume measurements revealed significant suppression in groups receiving C-BDP + U + L, CANPs + U, CANPs + L, and CANPs + U + L compared to the control group (Fig. 23D and E). Collectively, these findings demonstrate that CANPs not only enable effective sonophototherapy but also allow real-time imaging of TME reprogramming through M1 macrophage polarization tracking.¹⁵⁰

	Fig. 23 (A) Schematic illustration of the preparation of self-assembled CANPs and the theranostic mechanisms. (B) Concentrations of TGF-β1 in culture media of 4T1 cells treated with C-BDP, A-BDP, and CANPs (equivalent to 1.25 μM C-BDP and 0.625 μM A-BDP) with or without US/laser irradiation. (C) The percentages of M1-polarized (CD11b+/CD80+) RAW 264.7 cells treated with different 4T1 culture media were calculated from the upper-right quadrant (Q2) of the scatter plots using flow cytometry. *p < 0.05, **p < 0.01 compared with the control group. ##p < 0.01, compared with the CANPs + U + L group. (D) Tumor growth curves of 4T1 tumor-bearing mice after different treatments. (E) Tumor images of 4T1 tumor-bearing mice after treatment with saline, C-BDP + U + L, CANPs, CANPs + U, CANPs + L and CANPs + U + L. U: US irradiation, L: laser irradiation. Reproduced with permission.150 Copyright 2024, American Chemical Society.

In 2022, Xiang et al. reported an intelligent therapeutic nanoplatform, Aza-BDY NPs, which incorporated an acrylic ester group at the 3-position. The co-addition of Cys with the acrylic ester moiety of Aza-BDY promotes the formation of thioethers, effectively depleting intracellular GSH, causing redox imbalance and inducing ferroptosis (Fig. 24A). Aza-BDY NPs can function as both a ferroptosis inducer and a sonosensitizer upon internalization by tumor cells (Fig. 24A). Notably, under US irradiation, Aza-BDY NPs exhibited markedly elevated cytotoxicity against 4T1 cells, which was not observed when Aza-BDY NPs were used alone under the same conditions (Fig. 24B). Intriguingly, when co-administered with Fer-1, Cys, or GSH, the cytotoxic effects of Aza-BDY NPs were substantially attenuated, as evidenced by recovered cell viability (Fig. 24C). In vivo studies conducted on 4T1 tumor-bearing mice confirmed the synergistic anti-tumor efficacy of ferroptosis-enhanced SDT.⁴⁵

	Fig. 24 (A) Aza-BDY NPs serve as ferroptosis inducing agent and sonosensitizer. (B) Cell viability of 4T1 cells following treatment with various concentrations of Aza-BDY NPs, with or without US exposure. Data are shown as mean ± SD (n = 5). p value was determined by two-tailed unpaired Student's t test. ns: not significant. **p < 0.01, ***p < 0.001. (C) Relative survival rate of 4T1 cells subjected to various treatments. Error bars are mean ± SD (n = 5). p value was determined by one-way ANOVA test. ***p < 0.001. Reproduced with permission.45 Copyright 2022, Wiley-VCH. (D) H2S generation by Aza-BD@PC NPs for GT in the presence of Cys and 1O2 production of Aza-BD@PC NPs + US stimulation for SDT. (E) In vivo anti-tumor efficacy of Aza-BD@PC NPs + US irradiation, represented by tumor volume changes, (F) tumor-growth inhibition study. G1: control, G2: US, G3: Aza-BD NPs, G4: Aza-BD NPs + US, G5: Aza-BD@PC NPs, and G6: Aza-BD@PC NPs + US. Data are expressed as mean ± SD. *p < 0.05, **p < 0.01, and ***p < 0.001. Reproduced with permission.151 Copyright 2024, Wiley-VCH.

Similarly, Wu et al. in 2024 developed a specific Cys-triggered intelligent nanoplatform (Aza-BD@PC NPs) based on Aza-BODIPY dyes and phenyl chlorothiocarbonate-modified DSPE-PEG molecules. By introducing hydrophilic aniline groups at the 3- and 5-positions, the aqueous solubility and biocompatibility of Aza-BD were enhanced. This platform exhibited excellent capacity for depleting Cys and releasing H₂S, disrupting cellular homeostasis and affecting glioblastoma multiforme (GBM) cell metabolism, thereby inhibiting GBM cell proliferation (Fig. 24D). Under US irradiation, the released Aza-BD generated significant quantities of ¹O₂, facilitating GT and SDT for gliomas (Fig. 24D). To evaluate the therapeutic efficacy of GT and SDT, an in vivo study was conducted using a subcutaneous GL261 glioma mouse model. Tumor volume assessments indicated significant tumor growth in the control, US irradiation alone, and Aza-BD NP groups, suggesting that neither US nor Aza-BD NPs alone effectively inhibited glioma growth (Fig. 24E and F).¹⁵¹

	Fig. 25 Chemical structures of ICG, IR780, IR806 and TFHC.

Despite its potential, ICG's application in biomedical settings is limited by several drawbacks, including rapid elimination by the liver, a short in vivo half-life of approximately 2–3 min, non-specific binding to proteins under physiological conditions, a propensity to aggregate at high concentrations, and susceptibility to light and heat. To overcome these limitations, researchers have been exploring the incorporation or doping of ICG into various NPs.¹⁵⁵ For example, Liu et al. introduced an innovative nanoplatform (CSI) by embedding catalase (CAT) into silica NPs, followed by the incorporation of ICG. To enhance its functionality, the constructed CSI was subsequently coated with AS1411 aptamer-conjugated macrophage exosomes, yielding CSI@Ex-A (Fig. 26A). This design endowed CSI@Ex-A with efficient blood–brain barrier (BBB) permeability and good cancer-cell-targeting capability. Moreover, highly expressed GSH in the TME triggered the biodegradation of CSI@Ex-A, releasing CAT, which in turn catalyzed H₂O₂ to produce O₂ to relieve intracellular hypoxia. In vitro experiments, U87 cells treated with CSI@Ex-A (100 μg mL⁻¹) and unfocused US (1.0 MHz, 1.5 W cm⁻², 40% duty cycle, 5 min) showed markedly reduced viability (10.1%) compared to CSI-treated (35.2%) and free ICG-treated (68.9%) cells under the same US exposure. In U87 tumor-bearing mice, CSI@Ex-A + US markedly suppressed tumor growth, whereas CSI@Ex + US had limited effects, and the other five control groups (PBS, PBS + US, free ICG + US, CSI@Ex, CSI@Ex-A) showed negligible inhibition. Notably, spinal metastasis of tumor occurred in PBS-, PBS + US-, and free ICG + US-treated mice but was negligible in CSI@Ex-A-treated mice. Survival analysis revealed that CSI@Ex-A + US extended median survival of mice over 35 days, surpassing all other groups (CSI@Ex-A: 27 days; CSI@Ex + US: 31 days; CSI@Ex: 29 days; free ICG + US: 24 days; US: 24 days; PBS: 23 days). These results demonstrate that GSH depletion and O₂ self-supply effectively enhance SDT efficacy in both cellular and animal models (Fig. 26B).¹⁵⁶ In 2023, Cao et al. developed macrophage-cancer hybrid membrane-camouflaged nanoplatforms for target gene silencing-enhanced SDT of GBM. The ZIF-8 NPs were synthesized to simultaneously encapsulate ICG and HIF-1α siRNA (ICG-siRNA@ZIF-8, ISZ). This nanoplatform utilized its pH sensitivity to accumulate effectively within the TME, achieving precise release of ICG and HIF-1α siRNA. HIF-1α siRNA significantly inhibited HIF-1α expression, thereby enhancing the SDT efficiency under hypoxic conditions.¹⁵⁷ Cheng et al. developed ICG-loaded nanobubbles (ICG-NBs) and explored their potential in enhancing cancer treatment. By combining ICG-NBs-mediated SDT with shikonin, they observed a significant increase in necroptosis, a form of programmed cell death. This approach not only overcame drug resistance often associated with tumor cell apoptosis resistance but also markedly improved the anti-tumor effects against hepatocellular carcinoma (HCC) in both in vivo and in vitro studies.¹⁵⁸

	Fig. 26 (A) Diagram depicting the preparation process of CSI@Ex-A. (B) Conceptual representation of biodegradable CSI@Ex-A for improved SDT of glioblastoma treatment. Reproduced with permission.156 Copyright 2022, Wiley-VCH.

IR780 iodide (Fig. 25) is a lipophilic cationic heptamethine cyanine dye exhibiting peak absorption at 780 nm. Owing to its intense fluorescence emission and stability, it is widely recognized as a valuable probe for fluorescent imaging in vivo. Beyond imaging applications, this compound also demonstrates efficacy as a therapeutic agent for both PTT and PDT.¹⁵⁹ In 2016, Li et al. explored IR780 as a sonosensitizer in SDT, finding significantly reduced cell viability and increased necrotic/apoptotic cells in cancer cells treated with IR780 under US irradiation. This SDT approach significantly inhibited tumor growth in vivo in xenografts of 4T1 cancer cells.¹⁶⁰ Building on the potential of IR780, researchers have made modifications to expand its applications, particularly in combination with nanoplatforms that leverage their synergy with various reagents. In 2017, Liu et al. developed an oxygen-self-produced SDT nanoplatform, integrating a fluorocarbon (FC) chain-mediated oxygen delivery strategy. This nanoplatform leverages FHMON-based nanosystems, featuring a well-defined mesoporous structure for high IR780 loading and in situ FC chain modification for ample oxygen binding sites (Fig. 27A). In vitro, extracellular, intracellular, and in vivo studies show that US enhances the accumulation of this biocompatible nanoplatform in hypoxic tumors, accelerates oxygen release, and alleviates hypoxia permanently (Fig. 27B). Importantly, reversing hypoxia reduces resistance to SDT, leading to highly efficient therapy against hypoxic PANC-1 pancreatic cancer.¹⁶¹

	Fig. 27 (A) Schematic of IR780@O2-FHMON. (B) Principle of intensified SDT using IR780@O2-FHMON. Reproduced with permission.161 Copyright 2017, American Chemical Society. (C) Conceptual illustration of CSR NPs activated by both US and light, enabling trimodal SDT, PTT and PDT in localized prostate cancer. Reproduced with permission.162 Copyright 2021, Wiley-VCH.

Researchers have also explored the synergistic use of SDT with phototherapy to enhance tumor treatment efficacy. In a study by Qian et al., IR780 was chemically modified to produce the carboxyl derivative IR806 (Fig. 25), which was then covalently linked to chondroitin sulfate (CS) through disulfide bonds to create amphiphilic CS-ss-IR806 (CSR) conjugates. These conjugates self-assemble into CSR NPs that possess improved endocytosis, redox/hyaluronidase responsiveness, and the ability to target mitochondria. When subjected to combined sono/photoirradiation, the CSR NPs efficiently induce hyperthermia and generate ROS (Fig. 27C). In a mouse model bearing prostate cancer tumors, the application of CSR NPs with dual-irradiation demonstrated significantly enhanced trimodal anticancer effects compared to single-irradiation approaches.¹⁶² Qin et al. developed a NIR trifluoromethyl-heptamethine cyanine dye (TFHC, Fig. 25) that serves dual roles as a mitochondria-targeting sonosensitizer for SDT and a photothermal therapy agent for PTT. The addition of trifluoromethyl significantly enhances the biocompatibility of TFHC. TFHC demonstrates high efficacy in killing cancer cells (80%) under NIR and US without significant side effects.¹⁶³

CO exhibits therapeutic potential in cytoprotection, anticancer activity, and anti-inflammation.¹⁶⁴ Moderate CO doses induce cell death by impairing mitochondrial function and generating ROS, with a more pronounced effect in cancer cells.^165,166 Zhang et al. synthesized a tricarbonyl Re(I) complex (Re-Cy) functionalized with cyanine moieties, which can be triggered by US to provide a synergistic combination of CO GT and SDT against cancers. The chemical structures of Re-Cy are shown in Fig. 28. The cyanine components augment the complex's responsiveness to US, thereby facilitating the release of CO upon sonication. Upon US activation, Re-Cy induces ferroptosis in 4T1 cancer cells, characterized by the depletion of GSH, downregulation of glutathione peroxidase 4 (GPX4), and the accumulation of lipid peroxides.¹⁶⁷

	Fig. 28 Chemical structures of metal–cyanine conjugates (Re-Cy, Pt-Cy and IRCur-Pt).

In light of the extensive use of platinum-based anti-tumor drugs, researchers have developed platinum-cyanine complexes for SDT to potentially reduce side effects and chemotherapy resistance. In 2022, Zhang et al. developed a Pt(II)–cyanine complex (Pt-Cy, Fig. 28) that generates ¹O₂ under US or light irradiation. Pt-Cy induces ferroptosis in 4T1 cells by reducing cellular GSH and GPX4 under US irradiation, and metabolomics analysis confirmed the dysregulation of glutathione metabolism leading to ferroptosis. In vitro studies showed that Pt-Cy exhibited strong sono-toxicity toward 4T1 cells under US irradiation (3.0 MHz, 0.3 mW cm⁻², 20 min), with an IC₅₀(US) value of 6.94 μM. Similarly, under 465 nm light irradiation (10 mW cm⁻², 30 min), Pt-Cy displayed phototoxicity, yielding an IC₅₀(light) value of 15.01 μM. In vivo studies showed that Pt-Cy + US treatment obviously inhibited tumor growth in 4T1-bearing mice compared to the other groups (untreated, Pt-Cy alone, US alone (3.0 MHz, 0.3 W cm⁻², 20 min), light alone (465 nm, 10 mW cm⁻², 30 min), and Pt-Cy + light). On day 14, tumors were excised and analyzed, revealing that the Pt-Cy + US group had the lowest average tumor weight among all treatment groups, confirming its superior SDT efficacy compared to PDT.¹⁶⁸

Building on this, in 2024, Lu et al. synthesized IRCur-Pt (Fig. 28), an organometallic sonosensitizer that combines an IR775 derivative with curcumin through platinum atoms. IRCur-Pt has a lower system energy gap, enhancing ROS generation and mitochondria targeting, while reducing cellular toxicity and increasing sonodynamic effects compared to curcumin. US activation of IRCur-Pt triggers ROS release, mitochondrial dysfunction, GSH depletion, GPX4 reduction, and lipid peroxidation, leading to ferroptosis. Proteomics and biological analyses identified factors contributing to ferroptosis, and both in vitro and in vivo experiments confirmed IRCur-Pt's direct cytotoxicity and immune response activation. IRCur-Pt targets primary tumors through SDT and suppresses distant tumors due to its immune-stimulating effects.¹⁶⁹

In 2023, Zhu et al. developed cyaninplatin (Fig. 29), an US-activatable Pt(IV) prodrug integrating IR780 for on-demand delivery of Pt(II) chemotherapeutics. Focused ultrasound (FUS) enhances the reduction of mitochondria-targeted Pt(IV) to release carboplatin, overcoming drug resistance by depleting intracellular reductants and intensifying ROS-induced damage (Fig. 29). Cyaninplatin triggers mitochondrial dysfunction, ER stress, and cancer cell death through paraptosis and ICD. It also serves as a multi-modal imaging contrast agent, enabling high-resolution US, NIR optical and photoacoustic imaging before treatment. The precise activation of cyaninplatin demonstrated exceptional anticancer efficacy in mice, achieving a theranostic strategy known as sonosensitized chemotherapy (SSCT).¹⁷⁰

	Fig. 29 Diagram illustrating the working mechanism of cyaninplatin. Upon activation by FUS, cyaninplatin facilitates cancer cell killing and enables multimodal imaging guided SSCT. Reproduced with permission.170 Copyright 2023, AAAS.

Additionally, multifunctional intelligent nanosystems involved sonosensitizers and Cu ions have also received widespread attention. In 2024, Zhu et al. reported for the first time the construction of intelligent nanoassemblies (Cu-IR783 NPs) that activates IR783 selectively in tumors in response to the TME, enabling visualized in situ SDT (Fig. 30). The release of copper ions in tumor tissues amplifies ROS generation through a Fenton-like reaction and initiates cuproptosis via dihydrolipoamide S-acetyltransferase (DLAT) oligomerization and mitochondrial damage. This strategy not only reverses the immunosuppressive TME but also triggers ICD, stimulating systemic immunity to combat both primary and distant tumors.¹⁷¹

	Fig. 30 Diagram depicting the synthesis of Cu-IR783 NPs, with “off/on” switch for sonodynamic activity and NIR imaging capability. Also shown is the mechanism of the visualized in situ SDT/CDT synergized with cuproptosis for cancer theranostic. Reproduced with permission.171 Copyright 2024, Wiley-VCH.

	Fig. 31 Chemical structures of FS, AD-R, EB, and RB.

Erythrosin B (EB), an iodinated fluorescein derivative (Fig. 31), is particularly significant in the biomedical field due to its low toxicity.¹⁷³ It absorbs light effectively in the 500–550 nm range and shows significant photosensitivity, with the iodine in its structure enhancing its ability to generate ¹O₂. This feature is advantageous for EB in PDT and SDT applications.¹⁰ Research has shown EB's potential as a sonosensitizer, with a study by Yumita et al. in 2002 demonstrating that EB induced greater cytotoxic effects on Sarcoma 180 cells under US irradiation compared to FS, attributed to its increased ROS generation.¹⁷⁴

RB, a tetrachlorotetraiodide fluorescein derivative (Fig. 31), is known for its ability to generate ¹O₂ upon light irradiation, making it an effective photosensitizer for PDT applications.¹⁷³ A study by Yumita et al. in 1999 showed that RB significantly enhances US-induced cell damage, highlighting its efficacy in SDT.⁴³ To address the stability, targeting, and biotoxicity issues of sonosensitizers, Liu et al. in 2024 developed RB-encapsulated peptide-nanomicelles (REPNs) with integrin α_vβ₃ targeting. The in vitro cell experiments confirmed their specific tumor targeting capability and ROS generation under US irradiation, leading to tumor cell apoptosis. In vivo studies demonstrated their significant anti-tumor effects and excellent biosafety without major side effects.¹⁷⁵

	Fig. 32 Chemical structures of RBNa and RBD2-RBD6.

Vascular endothelial growth factor (VEGF) and its receptor (VEGFR) serve as critical modulators in cancer progression and angiogenesis. Elevated VEGF signaling is prominently associated with angiogenesis in numerous malignancies. Sunitinib, a highly effective VEGFR tyrosine kinase inhibitor with an inhibitory concentration (IC₅₀) ranging from 4 to 55 nM, has been approved by the FDA for the treatment of various cancers.¹⁷⁷ Kim et al. developed a sunitinib-conjugated rose bengal sonosensitizer, TK-RB (Fig. 33), which enhances anticancer effects through dual mechanisms: VEGFR inhibition-mediated antiangiogenesis and ROS generation under US irradiation. In vitro studies revealed that conjugating rose bengal with sunitinib increased the uptake of TK-RB in VEGFR-positive U87MG cells. Upon US exposure, this led to significant production of ROS and cytotoxicity. Moreover, the VEGFR inhibition by sunitinib in TK-RB further amplified its cytotoxic effect on U87MG cells. In vivo and ex vivo fluorescent imaging, as well as tumor growth studies in U87MG xenografted nude mice, confirmed that TK-RB significantly enhanced anti-tumor efficacy.¹⁷⁸

	Fig. 33 Chemical structures of TK-RB.

In the realm of immunotherapy, pyroptosis is emerging as a strategy to boost tumor immune responses and inhibit tumor growth. In 2024, Kim et al. designed a NIR-II (1000–1700 nm) emitting pyroptosis biotuner, Rd-TTPA, which induces pyroptosis under US irradiation to enhance SDT and ICD (Fig. 34A). Rd-TTPA addresses the limitations of conventional pyroptosis-inducing agents. It exhibits unique advantages of tumor-selective mitochondrial targeting and high-performance NIR-II fluorescence imaging properties (Fig. 34B). In vivo studies demonstrated that NIR-II fluorescence imaging-guided SDT mediated by Rd-TTPA induced potent tumor suppression through pyroptosis activation (Fig. 34C).¹⁷⁹

	Fig. 34 (A) Diagrammatic scheme of molecule engineering strategies for the sonodynamic-biotuner Rd-TTPA. (B) In vivo imaging of tumor-bearing mice after intratumoral injection of Rd-TTPA for 0–48 h. (C) Tumor volume comparison of different groups of 4T1 tumor-bearing mice. Reproduced with permission.179 Copyright 2025, Elsevier.

	Fig. 37 (A) Chemical structure of [Ru(bpy)3]2+. (B) ESR spectra confirming the production of 1O2 from [Ru(bpy)3]2+ under US exposure (0.3 W cm−2, 3.0 MHz, 1 h). The 2,2,6,6-tetramethylpiperidine (TEMP) and 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) served as trapping agents for 1O2 and •OH, respectively. (C) Ultraviolet-visible spectroscopy monitoring the oxidation process of NADH (150 μM) by [Ru(bpy)3]2+ (10 μM) under US irradiation (0–200 min) in PBS solution. Insert: Plots of lnA/A0 at 339 nm as a function of irradiation time. (D) Viability assay of 4T1 cells following exosure to different concentrations of [Ru(bpy)3]2+ with or without US stimulation. (E) Fluorescence imaging illustrating 1O2 production in the presence of [Ru(bpy)3]2+ and SOSG within deep pork tissue (0–10 cm) under US irradiation for 30 minutes. (F) Fluorescence imaging of tumor slices co-stained with DAPI (blue) and DCFH-DA (green), collected from treated mice after various experimental conditions. Ru: [Ru(bpy)3]2+; US: 0.3 W cm−2, 3 MHz. Reproduced with permission.193 Copyright 2021, Springer Nature.

Photoactivation of ruthenium(II) complexes is a powerful strategy for synergistic photodynamic and chemotherapy in cancer treatment, offering reduced nonspecific toxicity. However, its limited deep tissue penetration restricts its efficacy for treating deep-seated tumors. In 2024, Sun et al. developed the sono-responsive ruthenium complex, RuHF, for SDT and sono-activated chemotherapy. RuHF generates O₂˙⁻ via a type I process and undergoes ligand fracture upon US activation. By incorporating hydroxyflavone (HF) as an “electron reservoir” into the octahedral polypyridyl-ruthenium complex, the HOMO–LUMO energy gap and triplet-state metal-to-ligand charge transfer (³MLCT) energy were reduced to 0.89 eV. This modification enhanced O₂˙⁻ generation under US irradiation. The produced O₂˙⁻ rapidly triggered an intramolecular cascade reaction and HF ligand fracture. They further incorporated RuHF into a metallopolymer platform (PolyRuHF), which can be activated by low-power US (1.5 W cm⁻², 1.0 MHz, 50% duty cycle). Under US stimulation, the system demonstrated dual therapeutic effects through simultaneous O₂˙⁻ generation and release of cytotoxic ruthenium species. These synergistic mechanisms triggered programmed cell death through both apoptotic and ferroptotic pathways, mediated by mitochondrial impairment and elevated lipid peroxidation (Fig. 38). In vivo studies demonstrated that PolyRuHF effectively inhibited the growth of subcutaneous and orthotopic breast tumors and prevented lung metastasis by downregulating metastasis-related proteins in mice.¹⁹⁴

	Fig. 38 Schematic illustration of the US induces the decomposition of PolyRuHF to release O2˙− and anticancer Ru species for synergistic SDT and sono-activated chemotherapy. Reproduced with permission.194 Copyright 2024, American Chemical Society.

	Fig. 41 Chemical structures of Tz-Ir and Ir-DPP-Ir.

ROS-induced ER stress in SDT can trigger ICD and elicit robust anti-tumor immunity, thereby enhancing sono-immunotherapy. However, the efficacy of SDT and ICD stimulation is often limited by the suboptimal sonodynamic activity and insufficient ER stress induction of current sonosensitizers. In 2024, Zhao et al. developed an ER-targeted iridium(III) sonosensitizer, Ir-CA, functionalized with cholic acid (CA) (Fig. 42A). To improve stability and tumor targeting, Ir-CA was crosslinked with HSA using a reduction-cleavable crosslinker (NPC-SS-NPC), forming a reduction-responsive nanosonosensitizer, HSA@Ir-CA (Fig. 42A). In cells, the disulfide linkages in HSA@Ir-CA are cleaved by overexpressed GSH, releasing Ir-CA. Guided by the CA moiety, Ir-CA selectively accumulates in the ER. Upon US irradiation, ER-localized Ir-CA generates dual ROS to disrupt the ER, achieving high-efficiency SDT. This process significantly intensifies ER stress, boosting ICD and stimulating systemic anti-tumor immunity. Consequently, it inhibits primary and distant tumor growth, lung metastasis, and tumor recurrence. Moreover, combining this ER-targeted SDT with immune checkpoint inhibitor αPD-L1 further enhances therapeutic outcomes against immunologically “cold” tumors by activating anti-tumor immunity and alleviating immunosuppression.¹⁹⁸

	Fig. 42 (A) Conceptual illustration of the crosslinking self-assembly and reduction-responsive disassembly mechanisms of nanosonosensitizer HSA@Ir-CA. Reproduced with permission.198 Copyright 2024, Wiley-VCH. (B) Illustration of nano-Ir preparation and induced ROS generation upon exposure to US irradiation. (C) Quantification of ROS production in CT26 cells subjected to treatments with PBS, PBS + US, nano-Ir, and nano-Ir + US, respectively, were determined by flow cytometry. (D) Percent of CD80+CD86+ DCs gated on CD11c+ cells in the tumorous tissues. (E) Percent of CD8+ T cells among CD3+ T cells in the tumorous tissues. (F) Average tumor size of OV PDX-bearing BALB/c nude mice treated with PBS, cisplatin, and nano-Ir + US + cisplatin, respectively. Reproduced with permission.199 Copyright 2024, Wiley-VCH.

Light-activatable dinuclear iridium(III) complexes are promising for cancer therapy due to their spatiotemporal control, but their application is limited by poor tissue penetration and off-target effects. NIR wavelengths can address these issues by enabling deeper tissue penetration and reducing biological fluorescence interference. However, the use of NIR dinuclear iridium(III) complexes in iSDT remains largely unexplored. In 2024, Shang et al. developed NIR dinuclear iridium(III) complex Ir-DPP-Ir (Fig. 41) for iSDT. Ir-DPP-Ir features a diketopyrrolopyrrole central core and two iridium(III) entities adorned with phenyl pyridine ligands. To enhance solubility, Ir-DPP-Ir was co-assembled with the commercially available amphiphilic polymer DSPE-PEG₂₀₀₀, forming nano-Ir. Upon US irradiation, nano-Ir generates ¹O₂ and ˙OH (Fig. 42B). Compared to cells treated with nano-Ir alone, a significant increase in ROS production was observed in cells treated with nano-Ir + US (Fig. 42C). Following intravenous injection via the tail vein, nano-Ir accumulates at the tumor site, allowing US irradiation guided by fluorescence imaging. This approach enables nano-Ir + US to effectively kill tumor cells and induce ICD. The dying cells release pro-inflammatory factors, which promote the activation of CD8⁺ T cells, thereby achieving iSDT (Fig. 42D and E). In ovarian cancer patient-derived xenograft mouse models, cisplatin monotherapy showed moderate anti-tumor activity with a tumor inhibition rate of 48.5%, whereas the nanoIr + US + cisplatin combination achieved superior efficacy with a tumor inhibition rate of 96.5% (Fig. 42F). Notably, all cisplatin-treated mice died within 36 days, the nanoIr + US + cisplatin combination group maintained an 80% survival rate at 60 days. These results demonstrate synergistic effects between nanoIr + US and cisplatin.¹⁹⁹

	Fig. 44 Chemical structures of APHB, CTHB, BBR and Rh.

Notably, hypocrellin derivatives with longer absorption wavelengths offer an additional advantage: they effectively alleviate skin phototoxicity triggered by sunlight exposure. This property is particularly relevant when addressing the challenges associated with treating deep intracranial tumors. Sonotheranostic agents derived from these hypocrellin derivatives exhibit substantial promise for SDT applications. Their distinctive optical properties enable enhanced penetration and more efficient utilization within the intricate biological environment of deep tissues, while simultaneously mitigating concerns about potential skin damage due to phototoxicity. Consequently, the development of such sonotheranostic agents represents a highly valuable research direction in tumor therapy. Wang et al. constructed an appropriate assembly by utilizing the biocompatible hypocrellin derivative CTHB (Fig. 44). CTHB NPs not only generate ROS upon US stimulation but also exhibit fluorescence and photoacoustic imaging capabilities, which are crucial for precise tumor localization, a fundamental prerequisite for effective treatment. Through studies using both subcutaneous and intracranial tumor models, CTHB NPs were rigorously validated as effective sonosensitizers. Under US irradiation, they significantly inhibit tumor growth. These findings underscore the promising clinical prospects of CTHB NPs for the non-invasive treatment of GBM. Their dual functionality (ROS generation and imaging capabilities) positions them as a valuable candidate for clinical translation in the fight against GBM.²⁰²

Berberine (BBR, Fig. 44) is a natural dye with strong yellow fluorescence and has been used in traditional Chinese medicine since 3000 B.C. Recent studies show that BBR can suppress tumor cell proliferation by releasing ROS, such as ¹O₂, which is traditionally activated by light. However, US can also activate BBR to release ROS, expanding its potential in cancer therapy. Chen et al. demonstrated that berberine NPs (BBR NPs) are effective sonosensitizers for cancer SDT, showing significant therapeutic effects in both in vitro and in vivo experiments. The mechanism of tumor inhibition by BBR NP-mediated SDT involves two synergistic pathways. First, BBR NPs induce tumor angioembolism, blocking the local supply of oxygen and nutrients and triggering early-stage apoptosis in HeLa cells. Second, US activates BBR NPs, causing cavitation and ROS release, which damages tumor vasculature and induces HeLa cell apoptosis, ultimately leading to tumor shrinkage. These dual pathways work together to suppress HeLa xenograft tumor growth, highlighting BBR NPs as a promising SDT agent for cancer treatment.²⁰³

Chondroitin sulfate (CS) is a non-immunogenic polysaccharide known for its excellent biocompatibility and ability to target tumor tissues via CD44 receptors on cancer cells. Rhein (Rh, Fig. 44), a sonosensitizer, spontaneously generates ROS in cancer cells, suppressing tumor growth by activating the JNK/Jun/caspase-3 signalling pathway. US treatment further amplifies Rh-mediated tumor suppression by enhancing ROS production. Rh-based nanoplatforms enable sustained ROS generation in tumor tissues post-intravenous injection, addressing the limitation of transient ROS production during US treatment. Additionally, Rh's inherent anti-tumor and anti-metastasis properties significantly enhance the therapeutic efficacy of SDT. To further improve anti-tumor outcomes, docetaxel (DTX), a cell cycle inhibitor, was integrated into NPs to achieve combined therapeutic effects. Zhai et al. developed an innovative CD44 receptor-targeted, redox/US-responsive, oxygen-carrying nanoplatform using CS, Rh, and perfluorocarbon (PFC). The perfluoroalkyl groups in PFC facilitated enhanced oxygen delivery to B16F10 melanoma cells, thereby improving SDT efficiency. In contrast, control NPs lacking PFC produced lower ROS levels under US treatment and demonstrated weaker tumor inhibition both in vitro and in vivo. Furthermore, SDT utilizing CS-Rh-PFC NPs promoted ICD by inducing the exposure of CRT on tumor cells. When combined with DTX-loaded NPs, SDT treatment not only enhanced immune activation but also increased the secretion of key cytokines (IFN-γ, TNF-α, IL-2, IL-6) and boosted the infiltration of CD4⁺ and CD8⁺ T cells into tumor tissues. This synergistic approach underscores the potential of combining targeted drug delivery with SDT to achieve robust anti-tumor and immunomodulatory effects.²⁰⁴

Resveratrol (3,5,4′-trihydroxystilbene), a natural compound renowned for its anti-inflammatory properties, has been widely investigated as a chemopreventive agent in the context of carcinogenesis. Building on this foundation, He et al. developed a series of sonosensitizers (TR1, TR2 and TR3, Fig. 45) targeting nuclear factor kappa B (NF-κB) by conjugating resveratrol with a triphenylamine benzothiazole-derived donor–acceptor (D–A) system. Notably, TR2 containing two resveratrol moieties showed superior NF-κB pathway suppression compared to that of TR1 and TR3. This dual-functional agent TR2 combined strong sonodynamic activity with effective NF-κB suppression, yielding potent US-induced cytotoxicity against MCF-7 cells. Under US treatment (0.8 W cm⁻², 1.0 MHz, 30 s), TR1, TR2, and TR3 all showed higher sonocytotoxicity than known sonosensitizers such as curcumin and protoporphyrin IX, with IC₅₀ values of 4.2 ± 0.7 μM (TR1), 1.6 ± 0.4 μM (TR2), and 3.5 ± 0.5 μM (TR3), respectively. Extending the US duration to 2 min further improved their antiproliferative performance, reducing the IC₅₀ of TR2 and TR3 to the submicromolar range (0.55 ± 0.08 μM for TR2 and 0.83 ± 0.12 μM for TR3, respectively). This therapeutic potential was further validated in xenograft mouse models, where TR2 demonstrated potent anticancer activity alongside favorable biosafety. These findings highlight the promise of TR2 as a novel sonosensitizer for targeted cancer therapy.²⁰⁵

	Fig. 45 Chemical structures of TR1–TR3.

	Fig. 46 Chemical structures of AIEgen-based sonosensitizers.

In 2024, Liu et al. proposed an acceptor engineering strategy for AIE sonosensitizers (TPA-Tpy, Fig. 46) with an acceptor–donor–acceptor (A–D–A) structure, enhancing US sensitivity through increased cationization. Under US stimulation, enhanced cationization in TPA-Tpy promotes intramolecular charge transfer and charge separation, significantly increasing type I ROS production. Liu et al. further developed weakly acidic pH-activated NPs (TPA-Tpy NPs) with a charge-converting layer (DMMA-PAH-PEG) for controlled release of the sensitizer. In vivo experiments demonstrated that TPA-Tpy-mediated SDT induces CRT exposure, DCs maturation, and CD8⁺ T cell infiltration, effectively suppressing primary and metastatic tumors.²⁰⁷

Tang et al. designed US-excitable AIE-active organic molecules proficient in generating reactive ROS for enhanced tumor inhibition in SDT. They replaced benzothiadiazole's (BT) acceptor moiety with a dithiafulvalene-fused benzothiadiazole (BSM) structure. This led to the sonosensitizer TPE-BSM (Fig. 46) having a twisted conformation and a reduced energy gap. Meanwhile, the ortho-positioned alkyl chains on the thiophene moiety also contributed to its twisted structure, granting it notable AIE activity. Thanks to the reduced energy gap and AIE traits, the sonosensitizer showed enhanced ROS production and emission in the aggregate state.²⁰⁸

Tetrakis(4-carboxystyryl) pyridinium salt (TCSVP, Fig. 46) is a classic AIE molecule with unique structural and functional properties. It contains multiple freely rotatable benzene rings that contribute to its AIE characteristics. Additionally, TCSVP has a D–A structure, with triphenylamine as the strong electron-donating group and pyridinium salt as the effective electron-accepting group. The presence of double bonds further enhances its conjugation degree. These features collectively enable TCSVP to efficiently generate ROS and exhibit NIR emission in the aggregated state. As a result, TCSVP shows great promise as both a photosensitizer and a sonosensitizer for tumor treatment. Moreover, the pyridinium salt group endows TCSVP with the ability to target mitochondria, further enhancing its therapeutic potential. Recently, Chen et al. utilized TCSVP as a sonosensitizer, leveraging its AIE effect and mitochondrial targeting capacity. TCSVP not only promotes the accumulation and visualization of mitochondria but also facilitates efficient ROS generation under low-frequency US irradiation. Through careful optimization of experimental conditions, the ROS produced by TCSVP induce non-lethal mitochondrial oxidative stress rather than direct cellular damage. Importantly, this stress efficiently enhances tumor sensitivity to radiotherapy. In vitro experiments, H460 cells treated with radiation or US (without TCSVP) showed no significant damage, whereas TCSVP + US treatment enhanced subsequent radiotherapy efficacy across multiple radiation doses. In H460 tumor-bearing mice, the mice in “TCSVP + US + RT” group exhibited noticeable tumor growth suppression after two treatment sessions. Notably, all mice in this group survived beyond 14 days, while control groups experienced mortality between days 6–10. Notably, this study represents the first attempt to use a sonosensitizer to trigger non-lethal mitochondrial stress to improve tumor radiosensitivity. The effectiveness of enhancing tumor radiosensitivity using TCSVP and US was demonstrated in both H460 cells and H460 and 4T1 tumor-bearing mice.²⁰⁹