Nanozyme-Based\nMicrofluidic Chip System for pH-Regulated\nPretreatment and Sensitive Sensing

Nanozymes, possessing nanomaterial properties and catalytic\nactivities,\noffer great opportunities to design sensitive analytical detection\nsystems. However, the low interference resistance of nanozymes poses\na significant limitation on the precise detection of target substances.\nHerein, a nanozyme-based microfluidic chip system for pH-regulated\npretreatment and sensitive sensing of cysteine (Cys) is reported.\nThe copper metal–organic framework (Cu MOF) exhibits good cysteine\noxidase-like activity at pH 7.0, while demonstrating excellent laccase-like\nactivity at pH 8.0. Taking advantage of the pH-regulated enzyme-like\nactivity, the integrated microfluidic device involving the immobilization\nof Cu MOF eliminates the interference of dopamine (DA) and accurately\ndetects the target Cys. Compared with the untreated reaction system,\nthe developed nanozyme system shows a significantly improved accuracy\nin detecting Cys, with an <i>R</i><sup>2</sup> value of\n0.9914. This work provides an efficient method to enhance the interference\nresistance of nanozymes and broadens the application in sample pretreatment.