Nanozymology: An Overview

Abstract

The concept of nanozyme in this book refers to a class of nanomaterials that possess intrinsic enzyme-like properties. Typically, nanozyme has the following features: First, it is made of a nanomaterial (inorganic or organic) with specific nanostructure which endows distinct physicochemical properties and catalyzes biochemical reactions of the substrates for natural enzymes under physiological conditions including mild temperature and physiological pH. It follows the same enzymatic kinetics (e.g., Michaelis-Menten equation) and catalytic mechanism (e.g., ping-pong, ordered, or random reaction) as a natural enzyme (Fig. 1.1). It also has inhibitors and activators to regulate its activity. The catalytic activity is from the nanozyme itself without modifying additional natural enzymes or chemical catalysts. In other words, the catalysis is an intrinsic enzyme-like activity. Second, typical nanoscale factors, such as size, morphology, and surface remarkably affect the activity of nanozymes, which provides a superior strategy for adjusting its activity. A nanozyme often has active centers or electron-transport structures which is similar to natural enzymes. The active site endows nanozyme with enzymatic or catalytic activity. For instance, carbon nanozymes doped with nitrogen mimic natural enzyme-like activity by having a similar structure as porphyrin in the active center of HPR. Third, nanozyme can be used as an enzyme substitute for human health and surpasses natural enzymes in many aspects such as stability, low cost, and ease of production. The first evidence of nanozyme was reported in 2007, discovering that iron oxide nanoparticles possessed intrinsic peroxidase-like activity. Interestingly, this discovery comes from an unexpected result. While our team was working on precision cancer treatment through interdisciplinary collaboration by labeling our antibody