Tuning Multiple Enzyme-Like Activities By Metal Doping for Identification and Quantitation of Antioxidants in Cosmetics

Inspired by the hydrolysis behaviors of skin cells, we exquisitely designed and synthesized a class of hydrolase mimics to develop an analytical method that can both identify and quantity antioxidant components in skin-whitening cosmetics, including ascorbic acid (AA) and its glycoside and phosphate derivatives. A series of ultra-thin Cu1-xMnxO2 or Fe1-yMnyO2 with rich acid-base pairs were prepared via chemical deposition and in-situ CuI/FeII self-assembly. H218O and D216O isotopic labeling studies and DFT calculations were adopted to analyze the cleaving sites of AAL/AAP and confirm that H2O was involved in the new bonds. In-situ DRIFT NH3-IR and -TPD further confirmed that the Fe- or Cu-substitution could increase the quantity and strength of Brønsted and Lewis acid sites. A cascade catalytic fluorescence sensor was designed for selective recognition or quantification of AA and its derivatives, which presents ultra-high-precision (≤ 2.5%), stability, and selectivity in testing the target ingredients of five cosmetics from the market, with the great potential for point-of-care testing. This work provides a controllable methodology to design hydrolytic nanozymes, which sheds light on biomimetic engineering and paves the way for breakthroughs in cosmetics industrial applications in the future.