Rapid sandwich ELISA-based in vitro diagnostic procedure for the highly-sensitive detection of human fetuin A

A rapid sandwich enzyme-linked immunosorbent assay (ELISA)-based in vitro diagnostic (IVD) procedure has been developed for human fetuin A (HFA), an important disease biomarker for inflammatory diseases as well as malignancies. In this simplified and cost-effective procedure, the EDC-activated anti-HFA antibody (Ab) was admixed with 1% (v/v) 3-aminopropyltriethoxysilane (APTES) in 1:1 (v/v) and dispensed in a KOH-pretreated microtiter plate (MTP). APTES formed a stable complex with the capture antibody that was in turn covalently bonded on the KOH-treated surface in 30min. The resulting immunoassay (IA) format detects HFA with a dynamic range of 0.1-243ngmL^-1, and a limit of detection (LOD) and analytical sensitivity of 0.3ngmL^-1 and 1.0ngmL^-1, respectively. For the determination of HFA spiked in diluted human whole blood and serum, and HFA in ethylenediaminetetraacetic acid (EDTA)-plasma of patients, the obtained analytical precision is similar to that of the conventional sandwich ELISA. The anti-HFA Ab-bound MTPs, stored at 4°C in 0.1M PBS, pH 7.4, retained its biological activity for 8 weeks, thereby demonstrating excellent storage stability. This generic sandwich ELISA procedure can be extended for rapid, simplified and cost-effective detection of other disease biomarkers.