Bioorthogonal nanozymes: an emerging strategy for disease therapy.

Transition metal catalysts (TMCs), capable of performing bioorthogonal reactions, have been engineered to trigger the formation of bioactive molecules in a controlled manner for biomedical applications. However, the widespread use of TMCs based biorthogonal reactions in vivo is still largely limited owing to their toxicity, poor stability, and insufficient targeting properties. The emergence of nanozymes (nanomaterials with enzyme-like activity), especially bioorthogonal nanozymes that combine the bioorthogonal catalytic activity of TMCs, the physicochemical properties of nanomaterials, and the enzymatic properties of classical nanozymes potentially provide opportunities to address these challenges. Thus, they can be used as multifunctional catalytic platforms for disease treatment and will be far-reaching. In this review, we first briefly recall the classical TMC-based bioorthogonal reactions. Furthermore, this review highlights the diverse strategies for manufacturing bioorthogonal nanozymes and their potential for therapeutic applications, with the goal of facilitating bioorthogonal catalysis in the clinic. Finally, we present challenges and the prospects of bioorthogonal nanozymes in bioorthogonal chemistry.

Nanozymes for Regenerative Medicine.

Nanozymes refer to nanomaterials that catalyze enzyme substrates into products under relevant physiological conditions following enzyme kinetics. Compared to natural enzymes, nanozymes possess the characteristics of higher stability, easier preparation, and lower cost. Importantly, nanozymes possess the magnetic, fluorescent, and electrical properties of nanomaterials, making them promising replacements for natural enzymes in industrial, biological, and medical fields. On account of the rapid development of nanozymes recently, their application potentials in regeneration medicine are gradually being explored. To highlight the achievements in the regeneration medicine field, this review summarizes the catalytic mechanism of four types of representative nanozymes. Then, the strategies to improve the biocompatibility of nanozymes are discussed. Importantly, this review covers the recent advances in nanozymes in tissue regeneration medicine including wound healing, nerve defect repair, bone regeneration, and cardiovascular disease treatment. In addition, challenges and prospects of nanozyme researches in regeneration medicine are summarized.

Development and Evaluation of a PSMA-Targeted Nanosystem Co-Packaging Docetaxel and Androgen Receptor siRNA for Castration-Resistant Prostate Cancer Treatment.

Primary prostate cancer (PC) progresses to castration-resistant PC (CRPC) during androgen deprivation therapy (ADR) in early stages of prostate cancer. Thus, rather than blocking the androgen-related pathway further, docetaxel (DTX)-based therapy has become the most effective and standard first-line chemotherapy for CRPC. Although the therapy is successful in prolonging the survival of patients with CRPC, chemotherapy resistance develops due to the abnormal activation of the androgen receptor (AR) signaling pathway. Thus, to optimize DTX efficacy, continued maximum suppression of androgen levels and AR signaling is required. Here, we designed a prostate-specific membrane antigen (PSMA)-targeted nanosystem to carry both DTX and AR siRNA (Di-PP/AR-siRNA/DTX) for CRPC treatment. Specifically, DTX was encapsulated into the hydrophobic inner layer, and the AR siRNA was then condensed with the cationic PEI block in the hydrophilic outer layer of the PEI-PLGA polymeric micelles. The micelles were further coated with PSMA-targeted anionic polyethylene glycol-polyaspartic acid (Di-PEG-PLD). In vitro and in vivo results demonstrated that the resulting Di-PP/AR-siRNA/DTX exhibited prolonged blood circulation, selective targeting, and enhanced antitumor effects. Consequently, Di-PP/AR-siRNA/DTX holds great potential for efficient CRPC treatment by combining chemotherapy and siRNA silencing of androgen-related signaling pathways.

Sequential Delivery of Quercetin and Paclitaxel for the Fibrotic Tumor Microenvironment Remodeling and Chemotherapy Potentiation via a Dual-Targeting Hybrid Micelle-in-Liposome System.

Cancer-associated fibroblasts (CAFs), an important type of stromal cells in the tumor microenvironment (TME), are responsible for creating physical barriers to drug delivery and penetration in tumor tissues. Thus, effectively downregulating CAFs to destroy the physical barrier may allow enhanced penetration and accumulation of therapeutic drugs, thereby improving therapeutic outcomes. Herein, a matrix metalloproteinase (MMP)-triggered dual-targeting hybrid micelle-in-liposome system (RPM@NLQ) was constructed to sequentially deliver quercetin (Que) and paclitaxel (PTX) for fibrotic TME remodeling and chemotherapy potentiation. Specifically, antifibrotic Que and small-sized RGD-modified micelles containing PTX (RPM) were co-encapsulated into MMP-sensitive liposomes, and the liposomes were further adorned with the NGR peptide (NL) as the targeting moiety. The resulting RPM@NLQ first specifically accumulated at the tumor site under the guidance of the NGR peptide after intravenous administration and then released Que and RPM in response to the extensive expression of MMP in the TME. Subsequently, Que was retained in the stroma to remarkably downregulate fibrosis and decrease the stromal barrier by downregulating Wnt16 expression in CAFs, which further resulted in a significant increase of RPM for deeper tumor. Thus, RPM could precisely target and kill breast cancer cells locally. Consequently, prolonged blood circulation, selective cascade targeting of tumor tissue and tumor cells, enhanced penetration, and excellent antitumor efficacy have been demonstrated in vitro and in vivo. In conclusion, as-designed sequential delivery systems for fibrotic TME remodeling and chemotherapy potentiation may provide a promising adjuvant therapeutic strategy for breast and other CAF-rich tumors.

Novel brain-targeted nanomicelles for anti-glioma therapy mediated by the ApoE-enriched protein corona in vivo.

BACKGROUND: The interactions between nanoparticles (NPs) and plasma proteins form a protein corona around NPs after entering the biological environment, which provides new biological properties to NPs and mediates their interactions with cells and biological barriers. Given the inevitable interactions, we regard nanoparticle‒protein interactions as a tool for designing protein corona-mediated drug delivery systems. Herein, we demonstrate the successful application of protein corona-mediated brain-targeted nanomicelles in the treatment of glioma, loading them with paclitaxel (PTX), and decorating them with amyloid ß-protein (Aß)-CN peptide (PTX/Aß-CN-PMs). Aß-CN peptide, like the Aß1-42 peptide, specifically binds to the lipid-binding domain of apolipoprotein E (ApoE) in vivo to form the ApoE-enriched protein corona surrounding Aß-CN-PMs (ApoE/PTX/Aß-CN-PMs). The receptor-binding domain of the ApoE then combines with low-density lipoprotein receptor (LDLr) and LDLr-related protein 1 receptor (LRP1r) expressed in the blood-brain barrier and glioma, effectively mediating brain-targeted delivery. METHODS: PTX/Aß-CN-PMs were prepared using a film hydration method with sonication, which was simple and feasible. The specific formation of the ApoE-enriched protein corona around nanoparticles was characterized by Western blotting analysis and LC-MS/MS. The in vitro physicochemical properties and in vivo anti-glioma effects of PTX/Aß-CN-PMs were also well studied. RESULTS: The average size and zeta potential of PTX/Aß-CN-PMs and ApoE/PTX/Aß-CN-PMs were 103.1 nm, 172.3 nm, 7.23 mV, and 0.715 mV, respectively. PTX was efficiently loaded into PTX/Aß-CN-PMs, and the PTX release from rhApoE/PTX/Aß-CN-PMs exhibited a sustained-release pattern in vitro. The formation of the ApoE-enriched protein corona significantly improved the cellular uptake of Aß-CN-PMs on C6 cells and human umbilical vein endothelial cells (HUVECs) and enhanced permeability to the blood-brain tumor barrier in vitro. Meanwhile, PTX/Aß-CN-PMs with ApoE-enriched protein corona had a greater ability to inhibit cell proliferation and induce cell apoptosis than taxol. Importantly, PTX/Aß-CN-PMs exhibited better anti-glioma effects and tissue distribution profile with rapid accumulation in glioma tissues in vivo and prolonged median survival of glioma-bearing mice compared to those associated with PMs without the ApoE protein corona. CONCLUSIONS: The designed PTX/Aß-CN-PMs exhibited significantly enhanced anti-glioma efficacy. Importantly, this study provided a strategy for the rational design of a protein corona-based brain-targeted drug delivery system. More crucially, we utilized the unfavorable side of the protein corona and converted it into an advantage to achieve brain-targeted drug delivery.

Development of Mitomycin C-Loaded Nanoparticles Prepared Using the Micellar Assembly Driven by the Combined Effect of Hydrogen Bonding and π-π Stacking and Its Therapeutic Application in Bladder Cancer.

Micelle is mainly used for drug delivery and is prepared from amphiphilic block copolymers. It can be formed into an obvious core-shell structure that can incorporate liposoluble drugs. However, micelles are not suitable for the encapsulation of water-soluble drugs, and it is also difficult to maintain stability in the systemic circulation. To solve these problems, a type of polymer material, Fmoc-Lys-PEG and Fmoc-Lys-PEG-RGD, was designed and synthesized. These copolymers could self-assemble into micelles driven by π-π stacking and the hydrophobic interaction of 9-fluorenylmethoxycarbony (Fmoc) and, at the same time, form a framework for a hydrogen-bonding environment in the core. Mitomycin C (MMC), as a water-soluble drug, can be encapsulated into micelles by hydrogen-bonding interactions. The interaction force between MMC and the polymers was analyzed by molecular docking simulation and Fourier transform infrared (FTIR). It was concluded that the optimal binding conformation can be obtained, and that the main force between the MMC and polymers is hydrogen bonding. Different types of MMC nanoparticles (NPs) were prepared and the physicochemical properties of them were systematically evaluated. The pharmacodynamics of the MMC NPs in vitro and in vivo were also studied. The results show that MMC NPs had a high uptake efficiency, could promote cell apoptosis, and had a strong inhibitory effect on cell proliferation. More importantly, the as-prepared NPs could effectively induce tumor cell apoptosis and inhibit tumor growth and metastasis in vivo.

Efficient Anti-Glioma Therapy Through the Brain-Targeted RVG15-Modified Liposomes Loading Paclitaxel-Cholesterol Complex.

BACKGROUND: Glioma is the most common primary malignant brain tumor with a dreadful overall survival and high mortality. One of the most difficult challenges in clinical treatment is that most drugs hardly pass through the blood-brain barrier (BBB) and achieve efficient accumulation at tumor sites. Thus, to circumvent this hurdle, developing an effectively traversing BBB drug delivery nanovehicle is of significant clinical importance. Rabies virus glycoprotein (RVG) is a derivative peptide that can specifically bind to nicotinic acetylcholine receptor (nAChR) widely overexpressed on BBB and glioma cells for the invasion of rabies virus into the brain. Inspired by this, RVG has been demonstrated to potentiate drugs across the BBB, promote the permeability, and further enhance drug tumor-specific selectivity and penetration. METHODS: Here, we used the RVG15, rescreened from the well-known RVG29, to develop a brain-targeted liposome (RVG15-Lipo) for enhanced BBB permeability and tumor-specific delivery of paclitaxel (PTX). The paclitaxel-cholesterol complex (PTX-CHO) was prepared and then actively loaded into liposomes to acquire high entrapment efficiency (EE) and fine stability. Meanwhile, physicochemical properties, in vitro and in vivo delivery efficiency and therapeutic effect were investigated thoroughly. RESULTS: The particle size and zeta potential of PTX-CHO-RVG15-Lipo were 128.15 ± 1.63 nm and -15.55 ± 0.78 mV, respectively. Compared with free PTX, PTX-CHO-RVG15-Lipo exhibited excellent targeting efficiency and safety in HBMEC and C6 cells, and better transport efficiency across the BBB in vitro model. Furthermore, PTX-CHO-RVG15-Lipo could noticeably improve the accumulation of PTX in the brain, and then promote the chemotherapeutic drugs penetration in C6luc orthotopic glioma based on in vivo imaging assays. The in vivo antitumor results indicated that PTX-CHO-RVG15-Lipo significantly inhibited glioma growth and metabasis, therefore improved survival rate of tumor-bearing mice with little adverse effect. CONCLUSION: Our study demonstrated that the RVG15 was a promising brain-targeted specific ligands owing to the superior BBB penetration and tumor targeting ability. Based on the outstanding therapeutic effect both in vitro and in vivo, PTX-CHO-RVG15-Lipo was proved to be a potential delivery system for PTX to treat glioma in clinic.