Advances and perspectives in phototherapy-based combination therapy for cancer treatment

Phototherapy, including photothermal therapy (PTT) and photodynamic therapy (PDT), has the advantages of spatiotemporal selectivity, non-invasiveness, and negligible drug resistance. Phototherapy has been approved for treating superficial epidermal tumors. However, its therapeutic efficacy is limited by the hypoxic tumor microenvironment and the highly expressed heat shock protein. Moreover, poor tissue penetration and focused irradiation laser region in phototherapy make treating deep tissues and metastatic tumors challenging. Combination therapy strategies, which integrate the advantages of each treatment and overcome their disadvantages, can significantly improve the therapeutic efficacy. Recently, many combination therapy strategies have been reported. Our study summarizes the strategies used for combining phototherapy with other cancer treatments such as chemotherapy, immunotherapy, sonodynamic therapy, gas therapy, starvation therapy, and chemodynamic therapy. Some research cases were selected to analyze the combination therapy effect, delivery platform feature, and synergetic anticancer mechanisms. Moreover, additional research cases are summarized in the tables. This review provides strong evidence that phototherapy-based combination strategies can enhance the anticancer effect compared with phototherapy alone. Additionally, the challenges and future perspectives associated with these combinational therapies are discussed.

RSS and ROS Sequentially Activated Carbon Monoxide Release for Boosting NIR Imaging-Guided On-Demand Photodynamic Therapy

Carbon monoxide shows great therapeutic potential in anti-cancer. In particular, the construction of multifunctional CO delivery systems can promote the precise delivery of CO and achieve ideal therapeutic effects, but there are still great challenges in design. In this work, a RSS and ROS sequentially activated CO delivery system is developed for boosting NIR imaging-guided on-demand photodynamic therapy. This designed system is composed of a CO releaser (BOD-CO) and a photosensitizer (BOD-I). BOD-CO can be specifically activated by hydrogen sulfide with simultaneous release of CO donor and NIR fluorescence that can identify H2S-rich tumors and guide light therapy, also depleting H2S in the process. Moreover, BOD-I generates 1O2 under long-wavelength light irradiation, enabling both PDT and precise local release of CO via a photooxidation mechanism. Such sequential activation of CO release by RSS and ROS ensured the safety and controllability of CO delivery, and effectively avoided leakage during delivery. Importantly, cytotoxicity and in vivo studies reveal that the release of CO combined with the depletion of endogenous H2S amplified PDT, achieving ideal anticancer results. It is believed that such theranostic nanoplatform can provide a novel strategy for the precise CO delivery and combined therapy involved in gas therapy and PDT.

Nanoplatform-based strategies for enhancing the lethality of current antitumor PDT

Photodynamic therapy (PDT) exhibits great application prospects in future clinical oncology due to its spatiotemporal controllability and good biosafety. However, the antitumor efficacy of PDT is seriously hindered by many factors, including tumor hypoxia, limited light penetration ability, and strong defense mechanisms of tumors. Considering that it is difficult to completely solve the first two problems, enhancing the lethality of antitumor PDT has become a good idea to extend its clinical application. Herein, we summarize the nanoplatform-involved strategies to effectively amplify the tumoricidal capability of current PDT and then discuss the present bottlenecks and prospects of the nanoplatform-based PDT sensitization strategies in tumor therapy. We hope this review will provide some references for others to design high-performance PDT nanoplatforms for tumor therapy.

Albumin-manganese dioxide nanocomposites: a potent inhibitor and ROS scavenger against Alzheimer's β-amyloid fibrillogenesis and neuroinflammation

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease pathologically caused by amyloid-β protein (Aβ) aggregation, oxidative stress, and neuroinflammation. The pathogenesis of AD is still uncertain and intricate, and helpful therapy has rarely been recorded. So, discovering amyloid modulators is deemed a promising avenue for preventing and treating AD. In this study, human serum albumin (HSA), a protein-based Aβ inhibitor, was utilized as a template to guide the synthesis of HSA-manganese dioxide nanocomposites (HMn NCs) through biomineralization. The in situ formed MnO2 in HSA endows this nano-platform with outstanding reactive oxygen species (ROS) scavenging capability, including superoxide dismutase-mimetic and catalase-mimetic activities, which could scavenge the plethora of superoxide anion radicals and hydrogen peroxide. More importantly, the HMn NCs show enhanced potency in suppressing Aβ fibrillization compared with HSA, which further alleviates Aβ-mediated SH-SY5Y neurotoxicity by scavenging excessive ROS. Moreover, it is demonstrated that HMn NCs reduce Aβ-related inflammation in BV-2 cells by lowering tumor necrosis factor-α and interleukin-6. Furthermore, transgenic C. elegans studies showed that HMn NCs could remove Aβ plaques, reduce ROS in CL2006 worms, and promote the lifespan extension of worms. Thus, HMn NCs provide a promising tactic to facilitate the application of multifunctional nanocomposites in AD treatment.

A CO-mediated photothermal therapy to kill drug-resistant bacteria and minimize thermal injury for infected diabetic wound healing

With an increasing proportion of drug-resistant bacteria, photothermal therapy (PTT) is a promising alternative to antibiotic treatment for infected diabetic skin ulcers. However, the inevitable thermal damage to the tissues restricts its clinical practice. Carbon monoxide (CO), as a bioactive gas molecule, can selectively inhibit bacterial growth and promote tissue regeneration, which may be coordinated with PTT for drug-resistant bacteria killing and tissue protection. Herein, a CO-mediated PTT agent (CO@mPDA) was engineered by loading manganese carbonyl groups into mesoporous polydopamine (mPDA) nanoparticles via coordination interactions between the metal center and a catechol group. Compared to the traditional PTT, the CO-mediated PTT increases the inhibition ratio of the drug-resistant bacteria both in vitro and in diabetic wound beds by selectively inhibiting the co-chaperone of the heat shock protein 90 kDa (Hsp90), and lowers the heat resistance of the bacteria rather than the mammalian tissues. Meanwhile, the tissue-protective proteins, such as Hsp90 and vimentin (Vim), are upregulated via the WNT and PI3K-Akt pathways to reduce thermal injury, especially with a laser with a high-power density. The CO-mediated PTT unified the bacterial killing with tissue protection, which offers a promising concept to improve PTT efficiency and minimize the side-effects of PTT when treating infected skin wounds.

Bioactive inorganic nanomaterials for cancer theranostics

Bioactive materials are a special class of biomaterials that can react in vivo to induce a biological response or regulate biological functions, thus achieving a better curative effect than traditional inert biomaterials. For cancer theranostics, compared with organic or polymer nanomaterials, inorganic nanomaterials possess unique physical and chemical properties, have stronger mechanical stability on the basis of maintaining certain bioactivity, and are easy to be compounded with various carriers (polymer carriers, biological carriers, etc.), so as to achieve specific antitumor efficacy. After entering the nanoscale, due to the nano-size effect, high specific surface area and special nanostructures, inorganic nanomaterials exhibit unique biological effects, which significantly influence the interaction with biological organisms. Therefore, the research and applications of bioactive inorganic nanomaterials in cancer theranostics have attracted wide attention. In this review, we mainly summarize the recent progress of bioactive inorganic nanomaterials in cancer theranostics, and also introduce the definition, synthesis and modification strategies of bioactive inorganic nanomaterials. Thereafter, the applications of bioactive inorganic nanomaterials in tumor imaging and antitumor therapy, including tumor microenvironment (TME) regulation, catalytic therapy, gas therapy, regulatory cell death and immunotherapy, are discussed. Finally, the biosafety and challenges of bioactive inorganic nanomaterials are also mentioned, and their future development opportunities are prospected. This review highlights the bioapplication of bioactive inorganic nanomaterials.

Carbon monoxide therapy: a promising strategy for cancer

Cancer is one of the acute life-threatening diseases endangering the whole of humanity. The treatment modalities for cancer are various. However, in most cases, a single treatment choice provides multiple side effects, poor targeting, and ineffective treatment. In recent years, the physiological regulatory function of carbon monoxide (CO) in the cancer process has been reported gradually, and CO-related nano-drugs have been explored. It shows better application prospects in cancer treatment and provides new ideas for treatment. The present review introduces the pathophysiological role of CO. The recent advances in cancer therapy, such as CO-mediated gas therapy, combined application of CO chemotherapy, photodynamic therapy (PDT), photothermal therapy (PTT), and immunotherapy, are described. Current challenges and future developments in CO-based treatment are also discussed. This review provides comprehensive information on recent advances in CO therapy and also some valuable guidance for promoting the progress of gas therapy nanomedicine.

Approaches to Improve EPR-Based Drug Delivery for Cancer Therapy and Diagnosis

The innovative development of nanomedicine has promised effective treatment options compared to the standard therapeutics for cancer therapy. However, the efficiency of EPR-targeted nanodrugs is not always pleasing as it is strongly prejudiced by the heterogeneity of the enhanced permeability and retention effect (EPR). Targeting the dynamics of the EPR effect and improvement of the therapeutic effects of nanotherapeutics by using EPR enhancers is a vital approach to developing cancer therapy. Inadequate data on the efficacy of EPR in humans hampers the clinical translation of cancer drugs. Molecular targeting, physical amendment, or physiological renovation of the tumor microenvironment (TME) are crucial approaches for improving the EPR effect. Advanced imaging technologies for the visualization of EPR-induced nanomedicine distribution in tumors, and the use of better animal models, are necessary to enhance the EPR effect. This review discusses strategies to enhance EPR effect-based drug delivery approaches for cancer therapy and imaging technologies for the diagnosis of EPR effects. The effort of studying the EPR effect is beneficial, as some of the advanced nanomedicine-based EPR-enhancing approaches are currently undergoing clinical trials, which may be helpful to improve EPR-induced drug delivery and translation to clinics.

Gasotransmitter-Induced Therapeutic Angiogenesis: A Biomaterial Prospective

Gasotransmitters such as NO, H₂S, and CO have emerged as key players in the regulation of various pathophysiological functions, prompting the development of gas therapy for various pathogeneses. Deficient production of gasotransmitters has been linked to various diseases such as hypertension, endothelial dysfunction, myocardial infarction, ischemia, and impaired wound healing, as they are involved in the regulatory action of angiogenesis. A better understanding of the regulatory mechanisms has given new hope to address the vascular impairment caused by the breakthroughs in gasotransmitters as therapeutics. However, the unstable nature and poor target specificity of gas donors limit the full efficacy of drugs. In this regard, biomaterials that possess excellent biocompatibility and porosity are ideal drug carriers to deliver the gas transmitters in a tunable manner for therapeutic angiogenesis. This review article provides a comprehensive discussion of biomaterial-based gasotransmitter delivery approaches for therapeutic angiogenesis. The critical role of gasotransmitters in modulating angiogenesis during tissue repair as well as their challenges and future directions are demonstrated.

A multifunctional nanoplatform delivering carbon monoxide and a cysteine protease inhibitor to mitochondria under NIR light shows enhanced synergistic anticancer efficacy

Photoactivated chemotherapy has attracted widespread attention due to its ability to circumvent the shortcomings of hypoxia in tumor tissues compared with traditional photodynamic therapy. In this work, novel multifunctional nanoplatform (1), Ru-inhibitor@TPPMnCO@N-GQDs, was designed and prepared, which was capable of mitochondria-targeted co-delivery of the cysteine protease inhibitor and carbon monoxide (CO) stimulated with an 808 nm near infrared (NIR) laser. Nanoplatform (1) was prepared by covalent attachment of a mitochondria-targeted CO donor (TPPMnCO) and a Ru(II)-caged cysteine protease inhibitor (Ru-inhibitor) on the surface of fluorescent N-doped graphene quantum dots (N-GQDs). Nanoplatform (1) preferentially accumulated in the mitochondria of cancer cells and instantly delivered CO and the cysteine protease inhibitor upon 808 nm NIR light irradiation, thus damaging mitochondria and leading to significant in vitro and in vivo anticancer efficacy. In addition, nanoplatform (1) has good biocompatibility and did not exert any toxic side effects on mice during the period of treatment. The targeted subcellular mitochondrial co-delivery of CO and the cysteine protease inhibitor may provide new insights into CO and enzyme inhibitor combined therapies for cancer treatment.

Therapeutic implication of carbon monoxide in drug resistant cancers

Drug resistance is the major obstacle that undermines effective cancer treatment. Recently, the application of gas signaling molecules, e.g., carbon monoxide (CO), in overcoming drug resistance has gained significant attention. Growing evidence showed that CO could inhibit mitochondria respiratory effect and glycolysis, two major ATP production pathways in cancer cells, and suppress angiogenesis and inhibit the activity of cystathionine β-synthase that is important in regulating cancer cells homeostasis, leading to synergistic effects when combined with cisplatin, doxorubicin, or phototherapy, etc. in certain resistant cancer cells. In the current review, we attempted to have a summary of these research conducted in the past decade using CO in treating drug resistant cancers, and have a detailed interpretation of the underlying mechanisms. The critical challenges will be discussed and potential solutions will also be provided. The information collected in this work will hopefully evoke more effects in using CO for the treatment of drug resistant cancers.

A calcium phosphate drug carrier loading with 5-fluorouracil achieving a synergistic effect for pancreatic cancer therapy

Calcium based biomaterials were widely used for drug delivery application due to their biodegradability, biocompatibility, and high drug loading capacity. Herein, amino-capped polyamidoamine (PAMAM) dendrimer was applied as a macromolecular template to form amino-modified calcium phosphate hollow sphere (CaPO-NH2). After loading with 5-fluorouracil (5Fu), this system performed synergistic cancer chemotherapy. In this study, the 5Fu/CaPO-NH2 particles could be efficiently uptaken by cancer cells, and then decompose into Ca2+ and release 5Fu drug in the cytoplasm; therefore calcium overload and reactive oxygen species (ROS) accumulation were found in PSN1 cells that could induce cell membrane damage and elicit cell apoptosis through a series of biochemical reactions including endoplasmic reticulum stress, lipid peroxidation and mitochondrial apoptosis. In the PSN1 pancreatic cancer xenograft model, the 5Fu/CaPO-NH2 system performed high tumor inhibition via chemotherapy and calcium overload induced apoptosis. Comparingly, the normal cells and organs were insensitive to this synergistic therapy, which indicated the well biocompatibility of delivery system. Thus, this study provided a promising CaPO-NH2 drug delivery platform for enhanced 5Fu chemotherapeutic effect.

HSA-MnO2-131I Combined Imaging and Treatment of Anaplastic Thyroid Carcinoma

Purpose Compelling evidence suggests that nanoparticles (NPs) play a crucial role in cancer therapy. NPs templated with human serum albumin (HSA) has good retention in tumors. Manganese dioxide (MnO₂) has been used to enhance the effect of radiotherapy. In this study, synthesized NPs using HSA-MnO₂ labeled ¹³¹I to perform both imaging and therapy for anaplastic thyroid carcinoma (ATC). Method HSA-MnO₂ was synthesized via HSA using a simple biomineralization method, and then labeled with Na¹³¹I by the chloramine T method. The cytotoxicity and biosafety of HSA-MnO₂ were evaluated by the MTT test. The proliferation-inhibiting effect of HSA-MnO₂-¹³¹I was evaluated in papillary thyroid cancer cell lines (K1, BCPAP, and KTC) and anaplastic thyroid carcinoma cell lines (Cal62, THJ16T, and ARO). For further translational application in medicine, we established a model of transplantable subcutaneously tumors in BALB\c-nu mice to assess the anti-tumor effect of HSA-MnO₂-¹³¹I. The imaging effects of NPs were evaluated by MRI and SPECT/CT. Results The MTT test proved that the HSA-MnO₂ had low toxicity. HSA-MnO₂-¹³¹I significantly inhibited the proliferation of PTC and ATC cell lines. In addition, the results unveiled that HSA-MnO₂-¹³¹I exhibited dual-modality MR/SPECT imaging for thyroid cancer visualization. In particular, HSA-MnO₂-¹³¹I had an enhanced T1 signal in MR. Using SPECT/CT, we observed that HSA-MnO₂-¹³¹I had good retention in tumor tissue, which was helpful for the diagnosis and treatment of tumor. In vivo assays indicated that the NPs led to a reduction in radioresistance in the tumor hypoxic microenvironment. Conclusion The nanomaterial had a simple synthesis method, good water solubility and biosafety, and good retention in tumor tissue. Hence, it could be used for SPECT/CT and MR dual mode imaging and therapy with radioiodine of tumor cells. The experimental results provided a feasible solution for combining radiotherapy and dual-model imaging by NPs for cancer diagnosis and treatment.

NIR as a "trigger switch" for rapid phase change, on-demand release, and photothermal synergistic antibacterial treatment with chitosan-based temperature-sensitive hydrogel

Temperature-sensitive hydrogels have shown good performances as wound dressing owing to their ability to fill wounds in the liquid state and to release drugs in a solid state. However, their treatment efficiency is restricted by the phase transition time. In this study, we developed a photothermal synergistic chitosan-based temperature-sensitive hydrogel, h-EGF-CS/β-GP-MPDA@Cip, with the unique properties of rapid phase transition and drug release under near-infrared light (NIR). High antibacterial efficiency was achieved when we covered infected mice wounds with hydrogels. The local high temperature produced under NIR illumination not only accelerated the formation of a porous gel to release the loaded drug on-demand, but also dissolved bacteria, achieving synergistic anti-bacterial treatment. In addition, the healing cycle of wounds could be significantly shortened by adding human epidermal growth factor (h-EGF) in the hydrogel. Overall, the developed temperature-sensitive hydrogel could utilise NIR as a "trigger switch" for on-demand drug release and photothermal-enhanced antibacterial treatment during the rapid phase change process.

Mitochondria-targeted accumulation of oxygen-irrelevant free radicals for enhanced synergistic low-temperature photothermal and thermodynamic therapy

BACKGROUND

Although lower temperature (< 45 °C) photothermal therapy (LPTT) have attracted enormous attention in cancer therapy, the therapeutic effect is still unsatisfying when applying LPTT alone. Therefore, combining with other therapies is urgently needed to improve the therapeutic effect of LPTT. Recently reported oxygen-irrelevant free radicals based thermodynamic therapy (TDT) exhibit promising potential for hypoxic tumor treatment. However, overexpression of glutathione (GSH) in cancer cells would potently scavenge the free radicals before their arrival to the specific site and dramatically diminish the therapeutic efficacy.

METHODS AND RESULTS

In this work, a core-shell nanoplatform with an appropriate size composed of arginine-glycine-aspartate (RGD) functioned polydopamine (PDA) as a shell and a triphenylphosphonium (TPP) modified hollow mesoporous manganese dioxide (H-mMnO2) as a core was designed and fabricated for the first time. This nanostructure endows a size-controllable hollow cavity mMnO2 and thickness-tunable PDA layers, which effectively prevented the pre-matured release of encapsulated azo initiator 2,2'-azobis[2-(2-imidazolin-2-yl) propane] dihydrochloride (AIBI) and revealed pH/NIR dual-responsive release performance. With the mitochondria-targeting ability of TPP, the smart nanocomposites (AIBI@H-mMnO2-TPP@PDA-RGD, AHTPR) could efficiently induce mitochondrial associated apoptosis in cancer cells at relatively low temperatures (< 45 °C) via selectively releasing oxygen-irrelevant free radicals in mitochondria and facilitating the depletion of intracellular GSH, exhibiting the advantages of mitochondria-targeted LPTT/TDT. More importantly, remarkable inhibition of tumor growth was observed in a subcutaneous xenograft model of osteosarcoma (OS) with negligible side effects.

CONCLUSIONS

The synergistic therapy efficacy was confirmed by effectively inducing cancer cell death in vitro and completely eradicating the tumors in vivo. Additionally, the excellent biosafety and biocompatibility of the nanoplatforms were confirmed both in vitro and in vivo. Taken together, the current study provides a novel paradigm toward oxygen-independent free-radical-based cancer therapy, especially for the treatment of hypoxic solid tumors.

NIR light-controlled mitochondria-targeted delivery of carbon monoxide combined with histone deacetylase inhibition for synergistic anticancer therapy

A multifunctional nanoplatform APIPB-MnCO@TPP@N,P-GQDs (APIPB = N-(2-aminophen-yl)-4-(1H-imidazo[4,5-f] [1, 10] phenanthrolin-2-yl) benzamide, TPP = triphenylphosphine, Mn = manganese, CO = carbon monoxide, and GQDs = graphene quantum dots), nanoplatform (1), was synthesized, which consists of a fluorescent N, P-doped GQDs carrier with its surface covalently functionalized by an CO donor APIPB-MnCO with histone deacetylases (HDAC) inhibitory property and a TPP derivative directing group. Nanoplatform (1) selectively localized in the mitochondria of HeLa cells to inhibit HDAC activity, and released CO upon 808 nm near-infrared light irradiation, destroying the mitochondria and thus inducing cancer cells apoptosis. The targeted subcellular mitochondrial CO delivery combined with inhibitory HDAC activity maximized the cytotoxicity of the nanoplatform which may provide new insights for CO-mediated multimodal therapies for cancer treatment.

Selectively down-regulated PD-L1 by albumin-phenformin nanoparticles mediated mitochondrial dysfunction to stimulate tumor-specific immunological response for enhanced mild-temperature photothermal efficacy

Background

Mild-temperature photothermal therapy (mild-PTT) has emerged as a highly promising antitumor strategy by triggering immunogenic cell death (ICD) to elicit both innate and adaptive immune responses for tumor control. However, mild-PTT still leads to the risk of tumor recurrence or metastasis because it could hardly completely eradicate tumors due to its impaired immunological efficacy owing to the enhanced PD-L1 expression in tumor cells after treatment.

Results

In this study, we described a hydrogen peroxide (H₂O₂) responsive manganese dioxide mineralized albumin nanocomposite loading with mitochondria function inhibitor phenformin (PM) and near-infrared photothermal dye indocyanine green (ICG) by modified two-step biomineralization method. In combination with ICG induced mild-PTT and PM mediated mitochondria dysfunction, PD-L1 expression was obviously down-regulated and the generated immunological responses was able to effectively attack the remaining tumor cells. Meanwhile, the risk of tumor metastasis was effectively inhibited by reducing the expression of tumor invasion-related signal molecules (TGF-β and vimentin) after combining treatment.

Conclusion

Such a strategy offers novel insight into the development of nanomedicine for mild-PTT as well as cancer immunotherapy, which can provide protection against tumor relapse post elimination of their initial and metastatic tumors.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01124-8.

Over-expression of PD-L1 after mild-photothermal therapy significantly limited its efficacy.

Phenformin could effectively downregulate PD-L1 expression and inhibit tumor metastasis through AMPK activation.

Hydrogen peroxide responsive manganese dioxide mineralized albumin nanocomplex co-loading with phenformin and ICG named ICG@PM@NP was constructed by modified two-step biomineralization method.

ICG@PM@NP could enhance T cell infiltration and antitumor metastasis in vivo.

ICG@PM@NP mediated mild-photothermal therapy could make up the defects of conventional mild-photothermal therapy in lacking the anti-metastasis ability and inducing enhanced PD-L1 expression.

Mitochondria-targeted carbon monoxide delivery combined with singlet oxygen production from a single nanoplatform under 808 nm light irradiation for synergistic anticancer therapy

A multifunctional nanoplatform (1), MnCO@TPP@C-TiO2, which consists of a carrier of carbon-doped TiO2 nanoparticles with surface covalent functionalization of manganese carbonyls and a directing group of triphenylphosphine, was prepared for mitochondria-targeted carbon monoxide (CO) delivery combined with photodynamic therapy (PDT). MnCO@TPP@C-TiO2 selectively localized in the mitochondria of HeLa cells where the overexpressed-H2O2 triggered CO release resulting in mitochondrial damage. And singlet oxygen species generated upon 808 nm near infrared light irradiation further destroyed the mitochondria and induced cancer cells apoptosis. Cytotoxicity assays revealed that the nanoplatform with mitochondria-targeted CO delivery and PDT exhibited the highest lethality against cancer cells in comparison with all the other control samples tested, and it showed good dark biocompatibility with normal cells that express low H2O2 levels. This work may provide new insights into combining CO-based gas therapy with traditional PDT for efficient cancer treatment.

Cascade targeting tumor mitochondria with CuS nanoparticles for enhanced photothermal therapy in the second near-infrared window

Photothermal therapy, assisted by local heat generation using photothermal nanoparticles (NPs), is an emerging strategy to treat tumors noninvasively. To improve treatment outcomes and to alleviate potential side effects on normal tissue cells, utilizing the optically transparent second near-infrared (NIR-II) window and actively targeting tumors are critical. Considering that mitochondria are heat sensitive and play an important role in the up-regulation of metabolic activity in tumor cells, herein we report a cascade targeting scheme that enables active photothermal ablation of tumor mitochondria. First, NIR-II absorbing CuS NPs were surface modified with the mitochondria targeting moiety (3-carboxypropyl) triphenylphosphonium bromide (TPP) and then shielded with CD44 targeting hyaluronic acid, which will only expose TPP upon reaching the tumor sites. This allowed over 90% CuS NP enrichment at tumor mitochondria, and as a result, significantly improved tumor cell photothermal ablation was observed at the cellular level. An in vivo study demonstrated enhanced tumor uptake and improved tumor growth suppression by using these cascade targeting CuS NPs as NIR-II photothermal agents.