Zinc oxide nanoparticle-enhanced ultrasensitive chemiluminescence immunoassay for the carcinoma embryonic antigen

An ultrasensitive enzyme-linked immunosorbent assay (ELISA) is reported for the determination of carcinoma embryonic antigen (CEA) in human serum. It was realized using a microplate reader using a 384-well plate. Monoclonal antibody (Ab) against CEA (1A degrees Ab) acting as the capture probe was immobilized on zinc oxide nanoparticles (ZnO-NPs) in the form of self-assembled monolayers (SAMs). CEA captured by 1A degrees Ab was quantified using a sandwich ELISA wherein a polyclonal second antibody against CEA (2A degrees Ab) was used for detection and quantified using an HRP-labeled secondary antibody (3A degrees Ab). The ZnO-NPs-CEA capture probe was deposited on the bottom of the wells in order to enhance capture of CEA. A 3-fold enhancement in the chemiluminescence (CL) signal of luminol is found (compared to a conventional ELISA). CEA can be quantified by this method in concentrations as low as 1 pg A center dot mL(-1). The upper limit of detection is 20 ng A center dot mL(-1). The use of ZnO-NPs also imparts improved thermal stability. When stored at 4 A degrees C in phosphate-buffered saline of pH 7.4, the probe displays stability of up to 30 days.