A portable and quantitative enzyme immunoassay of neuron-specific enolase with a glucometer readout

Abstract

A portable and quantitative enzyme immunoassay with a glucometer readout was developed for the sensitive monitoring of neuron-specific enolase (NSE, as a model analyte) in a high-binding polystyrene 96-well microtiter plate (MTP), conjugated with monoclonal mouse anti-human NSE antibody (mAb₁). Gold nanoparticles heavily functionalized with glucoamylase and polyclonal rabbit anti-human NSE antibody (pAb₂) were utilized as the trace tag. A sandwich-type immunoassay format was adopted for the quantitative detection of NSE in the mAb₁-functionalized MTP. Accompanying the gold nanoparticles, the carried glucoamylase could hydrolyze amylopectin in glucose. The produced glucose could be quantitatively monitored using a portable personal glucose meter (PGM). Under optimal conditions, the PGM-based immunoassay exhibited good analytical properties for the determination of the target NSE, and allowed the detection of NSE at concentrations as low as 0.05 ng mL⁻¹. The intra- and inter-assay coefficients of variation (CVs) were below 10% and 11%, respectively. The methodology was also evaluated by assaying 15 clinical serum samples, and showed good accordance between results obtained by the developed immunoassay and the referenced values.