Rapid detection of neuron specific enolase by chemiluminescence immunoassay using bio-functionlized magnetic nanocomposites

To detect a biomarker for small cell lung carcinoma (SCLC), neuron specific enolase (NSE), a chemiluminescent immunoassay combined with immunomagnetic separation was proposed, in which bio-functionalized magnetic nanocomposites (BFMNs) were used as mobile substrate for capturing and isolating the NSE proteins. The BFMNs coated with anti-NSE antibody would connect with NSE and horseradish peroxidase labeled anti-NSE antibody in a sandwich-type detection manner. After fast magnetic collection, the sandwich immunocomplex is separated from excess antiboby or non-specific proteins. The immunocomplex further reacts with chemiluminescent substrate to produce chemiluminescence. A home-made three-channel luminometer was used to detect the chemiluminescence so as to improve the detection speed. There is a good linear response between the chemiluminescence intensity and the NSE concentration in the range from 2 to 200 ng/mL. The proposed immunoassay also shows good reproducibility and excellent selectivity for NSE against other proteins. The whole detection process including incubation, washing and detection could be performed within 40 min. The proposed method offers a simple, noninvasive and reliable tool for detecting SCLC and has potential application for clinical testing.