Dual-channel ratiometric colorimetric sensor array for quantification and discrimination of o-, m- and p-phenols

Abstract The determination of trace o-, m- and p-phenols in food samples was of great significance, but it is still very challenging due to the low concertation and complex matrix. In comparison to traditional sensors based on “Lock-and-key” strategy, the sensor arrays that mimicked human olfactory system exhibited excellent universality and efficiency in assays of structural analogues. Herein, we described a costless and robust colorimetric sensor array for ratiometric quantification and discrimination of o-, m- and p-phenols. The obtained Cu2(OH)3Cl with peroxidase-like (POD) activity was served as nanozyme to accelerate oxidation of 3,3’,5,5’ -tetramethylbenzidine (TMB) with H2O2. UV-vis absorbance spectroscopy displayed remarkable enhancements both at 652 nm and 450 nm, individually attributable to formation of single and dual electron-oxidized TMB (TMBox) substances. Then varied phenols regulated the absorbance via specific electron transfer processes. With the two peaks as dual signals, a ratiometric colorimetric sensor was designed to monitor different phenols. The ratio (I652/I450) was recorded to quantify phenols sensitively, where internal reference ruled out interferences from environment and equipment. Moreover, a ratiometric colorimetric sensor array was also explored for simultaneous discrimination of o-, m- and p-phenols. By integrating with colorimetric fingerprints and principal component analysis (PCA), each phenol was distinctly discriminated even at a very low concentration. This work demonstrated the reliability of a ratiometric colorimetric sensor array for identification of multiple phenols.