(260k) Antibody-Conjugated Nanoscale Enzyme Reactors for Highly Sensitive Immunoassay

A highly sensitive immunoassay method was developed by using antibody conjugated nanoscale enzyme reactors (NERs), termed as NER-linked immunosorbent assay (NER-LISA). Glucose oxidase (GO) was simply adsorbed into amine-functionalized spherical mesoporous silica (ADS-GO), and further treated with glutaraldehyde to crosslink adsorbed GO molecues in spherical mesoporous silica (NER-GO). The activity of NER-GO was 2.5 and 1.5 times higher than ADS-GO and covalently attached GO (CA-GO), respectively. NER-GO was highly stable by maintaining 98% of initial activity under shaking at 200 rpm for 26 days while ADS-GO and CA-GO retained 20% and 4% in the same condition, respectively. For the detection of human IgG (hIgG), highly stable NER-GO with high enzyme loading was conjugated with anti-human IgG. NER-LISA was performed and it was observed that the sensitivity and dynamic range was drastically improved in case of NER-LISA compare to conventional enzyme-linked immunosorbent assay (ELISA). The limit of detection (LOD) in case of NER-LISA was ~0.5 ng/mL hIgG (~3.3 pM), which was 20 times more sensitive than conventional ELISA. The higher sensitivity in case of NER-LISA was due to higher ratio of enzyme/antibody than conventional ELISA with one-to-one ratio of enzyme/antibody.