A rapid and highly sensitive immunoassay format for human lipocalin-2 using multiwalled carbon nanotubes

A sensitive and rapid sandwich immunoassay (IA) was developed for human lipocalin-2 (LCN2) by functionalizing a KOH-treated polystyrene microtiter plate with multiwalled carbon nanotubes (MWCNTs) dispersed in 3-aminoproyltriethoxysilane (APTES). The significantly increased surface area due to the presence of MWCNTs led to a high immobilization density of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) activated anti-LCN2 capture antibodies (Ab). The anti-LCN2 Ab-bound MTPs were stable for 6 weeks when stored in 0.1 M PBS, pH 7.4 at 4 °C. The IA detects LCN2 from 0.6 to 5120 pg mL⁻¹ with a limit of detection (LOD) and limit of quantification (LOQ) of 0.9 pg mL⁻¹ and 6 pg mL⁻¹, respectively. The assay offered a ~50-fold lower LOD and ~3-fold faster IA, compared to a commercial sandwich enzyme-linked immunosorbent assay kit.