Remodeling of Tumor Microenvironment by Nanozyme Combined cGAS-STING Signaling Pathway Agonist for Enhancing Cancer Immunotherapy

Transition-Metal-Based Nanozymes: Synthesis, Mechanisms of Therapeutic Action, and Applications in Cancer Treatment

Cancer, as one of the leading causes of death worldwide, drives the advancement of cutting-edge technologies for cancer treatment. Transition-metal-based nanozymes emerge as promising therapeutic nanodrugs that provide a reference for cancer therapy. In this review, we present recent breakthrough nanozymes for cancer treatment. First, we comprehensively outline the preparation strategies involved in creating transition-metal-based nanozymes, including hydrothermal method, solvothermal method, chemical reduction method, biomimetic mineralization method, and sol-gel method. Subsequently, we elucidate the catalytic mechanisms (catalase (CAT)-like activities), peroxidase (POD)-like activities), oxidase (OXD)-like activities) and superoxide dismutase (SOD)-like activities) of transition-metal-based nanozymes along with their activity regulation strategies such as morphology control, size manipulation, modulation, composition adjustment and surface modification under environmental stimulation. Furthermore, we elaborate on the diverse applications of transition-metal-based nanozymes in anticancer therapies encompassing radiotherapy (RT), chemodynamic therapy (CDT), photodynamic therapy (PDT), photothermal therapy (PTT), sonodynamic therapy (SDT), immunotherapy, and synergistic therapy. Finally, the challenges faced by transition-metal-based nanozymes are discussed alongside future research directions. The purpose of this review is to offer scientific guidance that will enhance the clinical applications of nanozymes based on transition metals.

Nanozymes with biomimetically designed properties for cancer treatment

Nanozymes, as a type of nanomaterials with enzymatic catalytic activity, have demonstrated tremendous potential in cancer treatment owing to their unique biomedical properties. However, the heterogeneity of tumors and the complex tumor microenvironment pose significant challenges to the in vivo catalytic efficacy of traditional nanozymes. Drawing inspiration from natural enzymes, scientists are now using biomimetic design to build nanozymes from the ground up. This approach aims to replicate the key characteristics of natural enzymes, including active structures, catalytic processes, and the ability to adapt to the tumor environment. This achieves selective optimization of nanozyme catalytic performance and therapeutic effects. This review takes a deep dive into the use of these biomimetically designed nanozymes in cancer treatment. It explores a range of biomimetic design strategies, from structural and process mimicry to advanced functional biomimicry. A significant focus is on tweaking the nanozyme structures to boost their catalytic performance, integrating them into complex enzyme networks similar to those in biological systems, and adjusting functions like altering tumor metabolism, reshaping the tumor environment, and enhancing drug delivery. The review also covers the applications of specially designed nanozymes in pan-cancer treatment, from catalytic therapy to improved traditional methods like chemotherapy, radiotherapy, and sonodynamic therapy, specifically analyzing the anti-tumor mechanisms of different therapeutic combination systems. Through rational design, these biomimetically designed nanozymes not only deepen the understanding of the regulatory mechanisms of nanozyme structure and performance but also adapt profoundly to tumor physiology, optimizing therapeutic effects and paving new pathways for innovative cancer treatment.

Co-, N-doped carbon dot nanozymes based on an untriggered ROS generation approach for anti-biofilm activities and in vivo anti-bacterial treatment

Bacterial infections originating from food, water, and soil are widely recognized as significant global public health concerns. Biofilms are implicated in approximately two-thirds of bacterial infections. In recent times, nanomaterials have emerged as potential agents for combating biofilms and bacteria, with many of them being activated by light and H2O2 to generate reactive oxygen species (ROS). However, this energy-consuming and extrinsic substrate pattern poses many challenges for practical application. Consequently, there is a pressing need to develop methods for the untriggered generation of ROS to effectively address biofilm and bacterial infections. In this study, we investigated the oxidase-like activity of the Co,N-doped carbon dot (CoNCD) nanozyme, which facilitated the oxidation of ambient O2 to generate 1O2 in the absence of light and H2O2 supplementation; this resulted in effective biofilm cleavage and enhanced bactericidal effects. CoNCDs could become a potential candidate for wound healing and treatment of acute peritonitis in vivo, which can be primarily attributed to the spontaneous production of ROS. This study presents a convenient ROS generator that does not necessitate any specific triggering conditions. The nanozyme properties of CoNCDs exhibit significant promise as a potential remedy for diseases, specifically as an anti-biofilm and anti-bacterial agent.

A novel self-assembled nucleobase-nanofiber platform of CDN to activate the STING pathway for synergistic cancer immunotherapy

2', 3'-cGAMP (CDN) as cGAS-STING pathway agonist is extensively used in tumor treatment. However, due to its negatively charged nature (containing two phosphate groups) and high hydrophilicity, CDN faces challenges in crossing cell membranes, resulting in reduced efficiency of its use. Additionally, CDN is susceptible to inactivation through phosphodiesterase hydrolysis. Therefore, the development of a new drug delivery system for CDN is necessary to prevent hydrolysis and enhance targeted accumulation in tumors, as well as improve cellular uptake for STING activation. In this study, we have developed peptide-polymer nanofibers (PEG-Q11) that incorporate thymine (T) and arginine (R) residues to facilitate complexation with CDN through the principles of Watson-Crick base pairing with thymine and favorable electrostatic interactions and bidentate hydrogen bonding with arginine side chains. The entrapment efficiency (EE) of PEG-Q11T3R4@CDN was found to be 51% higher than that of PEG-Q11@CDN. Due to its favorable biocompatibility, PEG-Q11T3R4@CDN was employed for immunotherapy in mouse CT26 tumors. In local tumor treatment, the administration of PEG-Q11T3R4@CDN at a low dose and through a single injection exhibited inhibitory effects. Furthermore, the local injection of PEG-Q11T3R4@CDN resulted in systemic therapeutic responses, effectively suppressing tumor metastasis by activating CD8 + T cells to target distant tumors. This research not only underscores the potential of PEG-Q11T3R4@CDN as an efficient therapeutic agent but also highlights its ability to achieve long-lasting systemic therapeutic outcomes following local treatment. Consequently, PEG-Q11T3R4@CDN represents a promising strategy for immunization.