Mild-Temperature Photothermal Effect Enhanced by Functional Conjugated Polymer Nanoparticles through Enzyme-Mediated Starvation

Opportunities for nanomaterials in enzyme therapy

In recent years, enzyme therapy strategies have rapidly evolved to catalyze essential biochemical reactions with therapeutic potential. These approaches hold particular promise in addressing rare genetic disorders, cancer treatment, neurodegenerative conditions, wound healing, inflammation management, and infectious disease control, among others. There are several primary reasons for the utilization of enzymes as therapeutics: their substrate specificity, their biological compatibility, and their ability to generate a high number of product molecules per enzyme unit. These features have encouraged their application in enzyme replacement therapy where the enzyme serves as the therapeutic agent to rectify abnormal metabolic and physiological processes, enzyme prodrug therapy where the enzyme initiates a clinical effect by activating prodrugs, and enzyme dynamic or starving therapy where the enzyme acts upon host substrate molecules. Currently, there are >20 commercialized products based on therapeutic enzymes, but approval rates are considerably lower than other biologicals. This has stimulated nanobiotechnology in the last years to develop nanoparticle-based solutions that integrate therapeutic enzymes. This approach aims to enhance stability, prevent rapid clearance, reduce immunogenicity, and even enable spatio-temporal activation of the therapeutic catalyst. This comprehensive review delves into emerging trends in the application of therapeutic enzymes, with a particular emphasis on the synergistic opportunities presented by incorporating enzymes into nanomaterials. Such integration holds the promise of enhancing existing therapies or even paving the way for innovative nanotherapeutic approaches.

Functionalized Nanomaterials for Inhibiting ATP-Dependent Heat Shock Proteins in Cancer Photothermal/Photodynamic Therapy and Combination Therapy

Phototherapies induced by photoactive nanomaterials have inspired and accentuated the importance of nanomedicine in cancer therapy in recent years. During these light-activated cancer therapies, a nanoagent can produce heat and cytotoxic reactive oxygen species by absorption of light energy for photothermal therapy (PTT) and photodynamic therapy (PDT). However, PTT is limited by the self-protective nature of cells, with upregulated production of heat shock proteins (HSP) under mild hyperthermia, which also influences PDT. To reduce HSP production in cancer cells and to enhance PTT/PDT, small HSP inhibitors that can competitively bind at the ATP-binding site of an HSP could be employed. Alternatively, reducing intracellular glucose concentration can also decrease ATP production from the metabolic pathways and downregulate HSP production from glucose deprivation. Other than reversing the thermal resistance of cancer cells for mild-temperature PTT, an HSP inhibitor can also be integrated into functionalized nanomaterials to alleviate tumor hypoxia and enhance the efficacy of PDT. Furthermore, the co-delivery of a small-molecule drug for direct HSP inhibition and a chemotherapeutic drug can integrate enhanced PTT/PDT with chemotherapy (CT). On the other hand, delivering a glucose-deprivation agent like glucose oxidase (GOx) can indirectly inhibit HSP and boost the efficacy of PTT/PDT while combining these therapies with cancer starvation therapy (ST). In this review, we intend to discuss different nanomaterial-based approaches that can inhibit HSP production via ATP regulation and their uses in PTT/PDT and cancer combination therapy such as CT and ST.

Near-Infrared Triggered Self-Accelerating Nanozyme Camouflaged with a Cancer Cell Membrane for Precise Targeted Imaging and Enhanced Cancer Immunotherapy

Although cancer immunotherapy has made encouraging progress, clinical therapeutic efficiency is often modest due to inadequate immunogenicity and immune resistance. Developing promising nanoagents for simultaneously activating tumor-specific immunity and suppressing immune resistance to achieve efficient immunotherapy is still challenging. Herein, we developed a biomimetic nanozyme consisting of a gold nanorod@mesoporous ceria core-shell scaffold with gold nanoparticle deposition and cancer cell membrane camouflage. The nanozyme exhibited near-infrared (NIR)-enhanced GOx-mimicking activity at high temperatures and performed well under hypoxic environments due to an increased in situ oxygen supply. In cancer cells, the nanozyme induced and amplified hyperthermia by triggering self-accelerating cascade reactions to deplete glucose and inhibiting the expression of heat shock protein under NIR irradiation, which can cause mitochondrial dysfunction and redox balance disruption to activate pyroptosis and elicit a robust immune response. Additionally, the immune checkpoint blockade caused by encapsulated JQ1-mediated PD-L1 downregulation synergistically contributed to excellent immune therapeutic effects. Besides, we demonstrated that cancer cell membrane coating endows the nanozyme targeting ability to tumor. The proposed nanozyme will broaden the application of GOx and have the potential as the nanoplatform for imaging-guided and O2-consuming combined treatments.

Rhythm Mild-Temperature Photothermal Therapy Enhancing Immunogenic Cell Death Response in Oral Squamous Cell Carcinoma

The low antitumor efficiency and unexpected thermo-tolerance activation of mild-temperature photothermal therapy (mPTT) severely impede the therapeutic efficacy, thereby the implementation of reasonable mPTT procedure to improve antitumor efficiency is of great significance for clinical transformation. Herein, a rhythm mPTT with organic photothermal nanoparticles (PBDB-T NPs) is demonstrated, synergistically increasing tumor elimination and intense immunogenic cancer cell death (ICD) to elicit tumor-specific immune responses for tumor treatment. Specifically, PBDB-T NPs are characterized by favorable biocompatibility, excellent and controllable photothermal properties, exhibit the properties of noninvasive diagnostic imaging, and effective mPTT against oral squamous cell carcinoma (OSCC). Encouragingly, a temperature-dependent release of damage-associated molecular patterns (DAMPs) is discovered during the mPTT-induced ICD. Meanwhile, orchestrated rhythm mPTT referring to radiotherapy procedure amplifies and balances antitumor efficiency and abundant DAMPs generation to gain optimal immune activation within clinical-recommended hyperthermia temperature compared with conventional PTT. The in vitro and in vivo results show that the rhythm mPTT unites the killing effect and ICD induction, generating strong mPTT efficacy and active tumor-specific adaptive immune responses. The study offers a promising strategy and a new opportunity for the clinical application of mPTT.