Polydopamine-Based Colorimetric Superwettable Biosensor for Highly Sensitive Detection of Hydrogen Peroxide and Glucose

Superwettable surface has broad application prospects in fabricating biosensors due to its significant enrichment effect.Here,we report a polydopamine-based colorimetric superwettable sensor that integrates superhydrophobic-superhydrophilic micropatterns for the determination of hydrogen peroxide(H_(2)O_(2))and glucose.Dopamine can be oxidized into polydopamine with the addition of horseradish peroxidase(HRP)and H_(2)O_(2),leading to the deposited spots color change from colorless to black.The concentration of target can be determined by analyzing RGB value using a smartphone software.The superhydrophobic area on the superwettable surface helps capture droplets by confining them to superhydrophilic microwells.After droplet evaporation,the analytes are concentrated in the small superhydrophilic domain,thus greatly enhancing the sensitivity.The experimental results manifested that superwettable sensor is able to detect H_(2)O_(2)with a broad linear range of 0.25μmol/L-25 mmol/L and a low limit of detection(LOD)of 0.25μmol/L by naked eye.For glucose detection,the linear range of the sensor is from 2μmol/L to 20 mmol/L and LOD is 0.69μmol/L.The superwettable sensor has been successfully applied in practical samples,including cancerous cells,milk,urine,and human serum samples with acceptable results.This superwettable sensor has several merits,such as high sensitivity,rapid response,and low sample volume in a single microdroplet,and shows great potential in manufacturing portable devices for complex biosensing applications.