A highly sensitive and label-free electrochemiluminescence immunosensor for beta 2-microglobulin
A highly sensitive and label-free electrochemiluminescence (ECL) immunosensor was fabricated for the detection of β-2-Microglobulin (β2M) based on gold nanoparticles-doped@carbon nano-onions chitosan nanocomposite modified cadmium selenide quantum dots screen-printed electrode (QDs-SPE/AuNPs@CNOs-CS) for the first time. The electrode was biocompatible, with increased effective surface area for capture and binding of a large number of anti-β2M antibodies. Moreover, it afforded high stability, greatly improved the electronic transmission rate and enhanced the capture of photon emitted from the luminophore Tris(bipyridine)ruthenium(II) chloride ([Ru(bpy)3]2+Cl), which held great promise for the fabrication of highly sensitive ECL immunosensors. The fabrication process involved immobilization of anti-β2M onto QDs-SPE/AuNPs@CNOs-CS pre-blocked by BSA (QDs-SPE/AuNPs@CNOs-CS/anti-β2M/BSA). The principle of ECL detection was based on the increase in the electrostatic attraction between the β2M and [Ru(bpy)3]2+ at a pH above the isoelectric point. The ECL intensity was linearly elevated with the increase in log concentration of β2M from 1 fg/mL to 100 ng/mL and a detection limit of 1fg/mL. The immunosensor demonstrated a huge potential to detect β2M in real serum and urine sample for clinical diagnosis. This work showcased QDs-SPE/AuNPs@CNOs-CS as an ideal interface to fabricate highly sensitive label-free ECL immunosensor to detect other biomarkers of clinical significance.