An ascorbic acid-responsive chemo-chromic SERS sensing chip for synergistic dual-modal on-site analysis of alkaline phosphatase

This work designs an ascorbic acid (AA)-responsive chemo-chromic SERS sensing chip (C-SERS chip) for synergistic dual-modal on-site analysis. This chip can be easily prepared by immobilizing a new kind of core-shell nanoparticles named AuNSs-MBN@Ag@PB on flat filter membrane via vacuum filtration. The reduction of Prussian blue (PB) shell by AA can rapidly change the chip color and enhance SERS signal of 4-mercaptobenzonitrile (MBN), which leads to a synergistic dual-modal sensing strategy for rapid colorimetric screening and SERS quantification of AA-related analytes. Under optimal parameters, the C-SERS chip shows rapid colorimetric response and linear SERS response to AA concentration ranging from 0.5 to 100 μM. The limit of detection for AA is 0.24 μM. The good reproducibility, stability and robustness of the chip and its selectivity to AA demonstrate its practical application in food and biomedical analysis. Using alkaline phosphatase (ALP) as a model analyte, the proposed method with the help of 2-phosphate-L-ascorbic acid shows linear SERS response in the range of 0.5–100 U/L ALP. The excellent specificity, high accuracy, satisfactory recovery and convenient operation indicate the potential of the miniaturizable C-SERS chip in high-throughput on-site colorimetric screening and quantitative analysis by combining with a portable Raman spectrometer. [Display omitted] •A chemo-chromic SERS sensing chip is designed for synergistic dual-modal response to ascorbic acid (AA).•The chip can integrate rapid screening and accurate quantification of real samples without pretreatment.•The AA SERS sensing chip can be extended for on-site analysis of AA-related analytes such as alkaline phosphatase.•Simple operations and miniaturized equipment bring great potential in on-site analysis.