Microwave-Assisted Rapid Synthesis of Near-Infrared Light-Responsive Pd Single-Atom Nanozymes for Colorimetric Detection of Acetylcholinesterase Activity

Abstract

Single-atom nanozymes (SAzymes) have been widely utilized as promising sensing platforms for numerous analytical applications. However, the preparation of SAzymes usually needs tedious heating treatment, and their enzyme-mimicking activities are still difficult to modulate in a simple way to meet the requirement under special conditions, both of which restrict their practical applications. To overcome these issues, we herein successfully prepared one kind of typical SAzyme, Pd–N–C, in as short as 4 min via facile and efficient microwave-assisted pyrolysis. Pd–N–C showcased excellent oxidase-like activity under near-infrared (NIR) light irradiation, which can also be regulated by light switching. The activation of dissolved oxygen into reactive oxygen species (O₂^•– and ¹O₂) by Pd–N–C subsequently enabled the oxidation of the colorless substrate o-phenylenediamine to yellow product 2,3-diaminophenazine (DAP). Taking advantage of the NIR light-responsive oxidase-like activity of Pd–N–C, sensitive colorimetric assays were developed for the detection of acetylcholinesterase (AChE) activity and its inhibitor based on the cascade catalytic system by combining Pd–N–C with AChE. The green synthesis approach and intelligent modulation of the catalytic activity of SAzymes presented here is thus believed to provide a novel perspective for rational synthesis and manipulation of nanozymes for broader analytical applications.