A cascaded enzyme-loaded Fe-hemoporfin framework for synergistic sonodynamic-starvation therapy of tumors

Dressing and undressing MOF nanophotosensitizers to manipulate phototoxicity for precise therapy of tumors

Photodynamic therapy (PDT) is a clinically approved treatment for tumors, and it relies on the phototoxicity of photosensitizers by producing reactive oxygen species (ROS) to destroy cancer cells under light irradiation. However, such phototoxicity is a double-edged sword, which is also harmful to normal tissues. To manipulate phototoxicity and improve the therapy effect, herein we have proposed a dressing-undressing strategy for de-activating and re-activating therapy functions of photosensitizer nanoparticles. One kind of metal organic framework (PCN-224), which is composed of Zr(IV) cation and tetrakis (4-carboxyphenyl) porphyrin (TCPP), has been prepared as a model of photosensitizer, and it has size of ∼70 nm. These PCN-224 nanoparticles are subsequently coated with a mesoporous organic silica (MOS) shell containing tetrasulfide bonds (-S-S-S-S-), realizing the dressing of PCN-224. MOS shell has the thickness of ∼20 nm and thus can block 1O2 (diffusion distance: <10 nm), deactivating the phototoxicity and preventing the damage to skin and eyes. Furthermore, PCN-224@MOS can be used to load chemotherapy drug (DOX·HCl). When PCN-224@MOS-DOX are mixed with glutathione (GSH), MOS shell with -S-S-S-S- bonds can be reduced by GSH and then be decomposed, which results in the undressing and then confers the exposure of PCN-224 with good PDT function as well as the release of DOX. When PCN-224@MOS-DOX dispersion is injected into the mice and accumulated in the tumor, endogenous GSH also confers the undressing of PCN-224@MOS-DOX, realizing the in-situ activation of PDT and chemotherapy for tumor. Therefore, the present study not only demonstrates a general dressing-undressing strategy for manipulating phototoxicity of photosensitizers, but also provide some insights for precise therapy of tumors without side-effects. STATEMENT OF SIGNIFICANCE: Photosensitizers can generate reactive oxygen species (ROS) under light radiation to destroy cancer cells. However, this phototoxicity is a double-edged sword and also harmful to normal tissues such as the skin and eyes. To control phototoxicity and improve therapeutic efficacy, we prepared a PCN-224@MOS-DOX nanoplatform and proposed a dressing and undressing strategy to deactivate and reactivate the therapeutic function of the photosensitizer nanoparticles. The MOS shell can block the diffusion of 1O2, eliminate phototoxicity, and prevent damage to the skin and eyes. When injected into mice and accumulated in tumors, PCN-224@MOS-DOX dispersions are endowed with an endogenous GSH-driven undressing effect, achieving in situ activation of PDT and tumor chemotherapy.

Cascade strategy for glucose oxidase-based synergistic cancer therapy using nanomaterials

Nanomaterial-based cancer therapy faces significant limitations due to the complex nature of the tumor microenvironment (TME). Starvation therapy is an emerging therapeutic approach that targets tumor cell metabolism using glucose oxidase (GOx). Importantly, it can provide a material or environmental foundation for other diverse therapeutic methods by manipulating the properties of the TME, such as acidity, hydrogen peroxide (H2O2) levels, and hypoxia degree. In recent years, this cascade strategy has been extensively applied in nanoplatforms for ongoing synergetic therapy and still holds undeniable potential. However, only a few review articles comprehensively elucidate the rational designs of nanoplatforms for synergetic therapeutic regimens revolving around the conception of the cascade strategy. Therefore, this review focuses on innovative cascade strategies for GOx-based synergetic therapy from representative paradigms to state-of-the-art reports to provide an instructive, comprehensive, and insightful reference for readers. Thereafter, we discuss the remaining challenges and offer a critical perspective on the further advancement of GOx-facilitated cancer treatment toward clinical translation.

Recent advances in glucose oxidase-based nanocarriers for tumor targeting therapy

Glucose oxidase (GOx) can specifically catalyze the conversion of β-d-glucose into gluconic acid and hydrogen peroxide (H2O2) in the presence of oxygen, making it promising for tumor starvation therapy and oxidative therapy. However, GOx's immunogenicity, poor in vivo stability, short half-life, and potential systemic toxicity, limit its application in cancer therapy. Nanocarriers are capable of improving the pharmacological properties of therapeutic drugs (e.g. stability, circulating half-life, and tumor accumulation) and lower toxicity, hence resolving GOx issues and enhancing its efficacy. Although the application of targeted nanocarriers based on GOx has recently flourished, this field has not yet been reviewed and evaluated. Herein, we initially examined the mechanism of GOx-based nanocarriers for enhanced tumor therapy. Also, we present a comprehensive and up-to-date review that highlights GOx-based nanocarriers for tumor targeting therapy. This review expands on GOx-based nano-targeted combination therapies from both passive and active targeting perspectives, meanwhile, active targeting is further classified into ligand-mediated targeting and physical-mediated targeting. Furthermore, this review also emphasizes the present challenges and promising advancements.

Design and synthesis of cancer-cell-membrane-camouflaged hemoporfin-Cu9S8 nanoagents for homotypic tumor-targeted photothermal-sonodynamic therapy

Multimodal therapies have aroused great interest in tumor therapy due to their highly effective antitumor effect. However, immune clearance limits the practical application of nanoagents-based multimodal therapies. To solve this problem, we have designed hemoporfin-Cu₉S₈ hollow nanospheres camouflaged with the CT26 cell membrane (CCM) as a model of multifunctional agents, achieving homologous-targeted synergistic photothermal therapy (PTT) and sonodynamic therapy (SDT). Hollow Cu₉S₈ as photothermal agents and carriers have been obtained through sulfurizing cuprous oxide (Cu₂O) nanoparticles through "Kirkendall effect", and they exhibit hollow nanospheres structure with a size of ∼200 nm. Then, Cu₉S₈ nanospheres could be used to load with hemoporfin sonosensitizers, and then hemoporfin-Cu₉S₈ nanospheres (abbreviated as H-Cu₉S₈) can be further surface-camouflaged with CCM. H-Cu₉S₈@CCM nanospheres exhibit a broad photoabsorption in the range of 700-1100 nm and high photothermal conversion efficiency of 39.8% under 1064 nm laser irradiation for subsequent PTT. In addition, under the excitation of ultrasound, the loaded hemoporfin could generate ¹O₂ for subsequent SDT. Especially, H-Cu₉S₈@CCM NPs are featured with biocompatibility and homologous targeting capacity. When intravenously (i.v.) injected into mice, H-Cu₉S₈@CCM NPs display a higher blood circulation half-life (3.17 h, 6.47 times) and tumor accumulation amount (18.75% ID/g, 1.94 times), compared to H-Cu₉S₈ NPs (0.49 h, 9.68% ID/g) without CCM. In addition, upon 1064 nm laser and ultrasound irradiation, H-Cu₉S₈@CCM NPs can inhibit tumor growth more efficiently due to high accumulation efficiency and synergistic PTT-SDT functions. Therefore, the present study provides some insight into the design of multifunctional efficient agents for homotypic tumor-targeted therapy.

Efficient sonodynamic ablation of deep-seated tumors via cancer-cell-membrane camouflaged biocompatible nanosonosensitizers

Ultrasound (US)-triggered therapies are promising in cancer treatments, and their effectiveness can be enhanced through the proper camouflage of sonosensitizers. Herein, we have constructed cancer cell membrane (CCM)-camouflaged sonosensitizers for homotypic tumor-targeted sonodynamic therapy (SDT). The camouflaged sonosensitizers have been prepared by encapsulating hemoporfin molecules in poly(lactic acid) polymers (H@PLA) and extruding with CCM from Colon Tumor 26 (CT26) cells, forming the H@PLA@CCM. Under excitation with US, the hemoporfin encapsulated in H@PLA@CCM can convert O₂ into cytotoxic ¹O₂, which exerts an efficient sonodynamic effect. The H@PLA@CCM nanoparticles show enhanced cellular internalization to CT26 cells compared to H@PLA, and they also can be more efficiently engulfed by CT26 cells than by mouse breast cancer cells, due to the homologous targeting ability of CT26 CCM. After the intravenous injection, the blood circulation half-life of H@PLA@CCM is determined to be 3.23 h which is 4.3-time that of H@PLA. With high biosafety, homogeneous targeting ability, and sonodynamic effect, the combination of H@PLA@CCM and US irradiation has induced significant apoptosis and necrosis of tumor cells through the efficient SDT, achieving the strongest inhibition rate of tumors among other groups. This study provides insights into designing efficient and targeted cancer therapies using CCM-camouflaged sonosensitizers.

Newly developed gas-assisted sonodynamic therapy in cancer treatment

Sonodynamic therapy (SDT) is an emerging noninvasive treatment modality that utilizes low-frequency and low-intensity ultrasound (US) to trigger sensitizers to kill tumor cells with reactive oxygen species (ROS). Although SDT has attracted much attention for its properties including high tumor specificity and deep tissue penetration, its anticancer efficacy is still far from satisfactory. As a result, new strategies such as gas-assisted therapy have been proposed to further promote the effectiveness of SDT. In this review, the mechanisms of SDT and gas-assisted SDT are first summarized. Then, the applications of gas-assisted SDT for cancer therapy are introduced and categorized by gas types. Next, therapeutic systems for SDT that can realize real-time imaging are further presented. Finally, the challenges and perspectives of gas-assisted SDT for future clinical applications are discussed.

Glucose Metabolism Intervention-Facilitated Nanomedicine Therapy

Ordinarily, cancer cells possess features of abnormally increased nutrient intake and metabolic pathways. The disorder of glucose metabolism is the most important among them. Therefore, starvation therapy targeting glucose metabolism specifically, which results in metabolic disorders, restricted synthesis, and inhibition of tumor growth, has been developed for cancer therapy. However, issues such as inadequate targeting effectiveness and drug tolerance impede their clinical transformation. In recent years, nanomaterial-assisted starvation treatment has made significant progress in addressing these challenges, whether as a monotherapy or in combination with other medications. Herein, representative researches on the construction of nanosystems conducting starvation therapy are introduced. Elaborate designs and interactions between different treatment mechanisms are meticulously mentioned. Not only are traditional treatments based on glucose oxidase involved, but also newly sprung small molecule agents targeting glucose metabolism. The obstacles and potential for advancing these anticancer therapies were also highlighted in this review.

Explaining chemical clues of metal organic framework-nanozyme nano-/micro-motors in targeted treatment of cancers: benchmarks and challenges

Nowadays, nano-/micro-motors are considered as powerful tools in different areas ranging from cleaning all types of contaminants, to development of Targeted drug delivery systems and diagnostic activities. Therefore, the development and application of nano-/micro-motors based on metal–organic frameworks with nanozyme activity (abbreviated as: MOF-NZs) in biomedical activities have received much interest recently. Therefore, after investigating the catalytic properties and applications of MOF-NZs in the treatment of cancer, this study intends to point out their key role in the production of biocompatible nano-/micro-motors. Since reducing the toxicity of MOF-NZ nano-/micro-motors can pave the way for medical activities, this article examines the methods of making biocompatible nanomotors to address the benefits and drawbacks of the required propellants. In the following, an analysis of the amplified directional motion of MOF-NZ nano-/micro-motors under physiological conditions is presented, which can improve the motor behaviors in the propulsion function, conductivity, targeting, drug release, and possible elimination. Meanwhile, by explaining the use of MOF-NZ nano-/micro-motors in the treatment of cancer through the possible synergy of nanomotors with different therapies, it was revealed that MOF-NZ nano-/micro-motors can be effective in the treatment of cancer. Ultimately, by analyzing the potential challenges of MOF-NZ nano-/micro-motors in the treatment of cancers, we hope to encourage researchers to develop MOF-NZs-based nanomotors, in addition to opening up new ideas to address ongoing problems.

On-demand assembly of polymeric nanoparticles for longer-blood-circulation and disassembly in tumor for boosting sonodynamic therapy

Sonodynamic therapy (SDT) is one of the promising strategies for tumor therapy, but its application is usually hindered by fast clearance in blood-circulation, abnormal tumor microenvironment, and inefficient generation of reactive oxygen species. To solve these problems, we proposed an on-demand assembly-disassembly strategy, where the assembly is favorable for longer-blood-circulation and then the disassembly in tumor is favorable for boosting SDT. Hematoporphyrin monomethyl ether (HMME) as the model of organic sonosensitizers were conjugated with hyaluronic acid (HA). Then HA-HMME was mixed with catalase (CAT) and assembled into polymeric nanoparticles (CAT@HA-HMME NPs) with size of ∼80 nm. CAT@HA-HMME NPs exhibit good biocompatibility and a longer blood half-time (t_1/2 = 4.17 h) which is obviously longer than that (∼0.82 h) of HMME molecules. After HA receptor-mediated endocytosis of cancer cells, CAT@HA-HMME NPs can be cleaved by endogenous hyaluronidase, resulting in the on-demand disassembly in tumor to release HA-HMME molecules and CAT. The CAT catalyzes the endogenous H₂O₂ into O₂ to relieve the hypoxic microenvironment, and the released HA-HMME exhibits a higher ROS generation ability, greatly boosting SDT for the inhibition of tumor growth. Therefore, the on-demand assembly-disassembly strategy may provide some insight in the design and development of nanoagents for tumor therapy.

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On-demand assembly from molecules to nanoparticles for longer-blood-circulation.

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On-demand disassembly in presence of hyaluronidase (in tumor) for boosting sonodynamic effects.

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Efficient damage on cancer cells in-vitro and Significant inhibition of the tumor growth due to the enhanced SDT.