Enhanced competitive immunomagnetic beads assay with Gold Nanoparticles and Carbon Nanotube-Assisted Multiple enzyme probes

Various nanoparticles provide new nanoscaffolds for enzymes to immobilize and develop a series of multienzyme probes for sensitive assays. In this experiment, gold nanoparticles (AuNPs) and multi-well carbon nanotubes (MWCNTs) were adopted as solid support and different conjugation methods with horseradish peroxidase (HRP) were explored. Kanamycin (KAN), one of amino glycoside antibiotics, was adopted as the target to develop the enhanced MPs-based competitive immunoassays. Three multi-enzyme probes, Au/KAN-HRP/HRP, MWCNTs/KAN-HRP/HRP-p and MWCNTs/KAN-HRP/HRP-c, were synthesized. MWCNTs/KAN-HRP/HRP-p showed highest catalytic efficiency, following MWCNTs/KAN-HRP/HRP-c, and Au/KAN-HRP/HRP lowest. With the optimal condition, enhanced competitive MPs immunoassays with these multi-enzyme probes were established to detect KAN. The value of LOD were 128 pg/mL, 17 pg/mL and 6.99 pg/mL based on Au/KAN-HRP/HRP, MWCNTs/KAN-HRP/HRP-c and MWCNTs/KAN-HRP/HRP-p respectively, which improved 2-fold, 15-fold and 37-fold respectively compared with that of conventional IMBs assay. With the aid of mull-enzyme probes based on nanoparticles, it is promising for sensitive detection and screening of molecules from biological samples.