Glucometer-based signal readout for a portable low-cost electrochemical immunoassay using branched platinum nanowires

Abstract

A simple and low-cost electrochemical immunosensing platform with a personal glucometer (PGM)-based signal readout device was developed for the quantitative detection of human carbohydrate antigen 125 (CA 125) using invertase for the hydrolysis of sucrose. To achieve a high sensitivity, branched platinum nanowires (BPtNWs) synthesized by a wet-chemistry method were utilized for the conjugation of invertase and anti-CA 125 secondary antibody. The immuno-reaction was carried out on an anti-CA 125 capture antibody-coated polystyrene microtiter plate with a sandwich-type assay mode, using the biofunctionalized BPtNWs as signal-generation tags. Accompanying the formation of the sandwiched immuno complexes, the carried invertase with the BPtNWs hydrolyzed sucrose into glucose and fructose. The glucose produced could be determined for quantification using a portable personal glucometer. By integrating the secondary antibody and invertase with branched platinum nanowires, this method displayed an excellent sensitivity with a detection limit of 23 mU mL⁻¹ CA 125. The selective experiments revealed that the developed system was specific for the target CA 125, even coexisting with a high concentration of other biomarkers. Finally, analysis of human serum samples was also performed, showing that our strategy was reliable and had great potential application in early clinical diagnostics.