ABSTRACT
BACKGROUND: Based on enhanced permeability and retention effect of nanoscale drug delivery systems in tumors, intelligent design of anti-tumor drug delivery vehicles has recently become a major direction in the development of tumor treatment strategies. Among them, the enzyme-responsive nano-delivery system has played a relatively important role, taking tumor-specific and highly expressed enzymes as precise targets so as to greatly improve targeting performance. OBJECTIVE: To summarize researches on the protocol, targeting efficiency and anti-tumor effects of enzyme-responsive nanoparticles in cancer treatment in recent years. METHODS: PubMed, Web of Science, CNKI and Wanfang databases were searched for the articles concerning the enzyme-responsive nanoparticles related to tumor treatment, with the search terms of “nanoparticles; neoplasms; enzymes; drug carriers; responsive” in English and Chinese, respectively. After initial screening of all articles according to inclusion and exclusion criteria, those with higher relevance were retained for the successive review. RESULTS AND CONCLUSION: Currently, enzyme-responsive nanoparticles are classified into two basic types in the article: drug-releasing type and functional type. Both are further divided into several sub-categories. Different designs target at corresponding tumors and their microenvironment characteristics. Among them, drug-releasing enzyme-responsive nanoparticles are designed to achieve controlled release of drugs at specific sites in tumors by enzyme response, while functional enzyme-responsive nanoparticles focus on improving the targeting efficiency and accumulation of nanoparticles in tumors. Both main types achieved specific release of drugs in tumors due to corresponding enzyme response, thereby reducing systemic toxicity and improving anti-tumor effects. According to current research trends, enzyme responsiveness is gradually turning into a part of the design of multiple responsive nanoparticle antitumor drugs in coming years. More tumor-specific enzymes and response mechanisms will be discovered to cope with complex tumor types and their microenvironment as well.