Magnetic nanoparticle-linked colorimetric aptasensor for the detection of thrombin

Employed as a peroxidase mimic, chitosan modified Fe3O4 magnetic nanoparticles (MNPs) were synthesized via solvotherrnal method. This alternative model evidenced a remarkable catalytic activity in presence of hydrogen peroxide/3,3',5,5'-tetramethylbenzidine (TMB) solution. Fe3O4 peroxidase mimic has the merits of stability, magnetic separation and enrichment. Enzyme-linked immunosorbent assay (ELISA) was used to detect thrombin by employing the catalytic properties of the as-synthesized chitosan modified Fe3O4 MNPs. The results showed that the absorption values at 652 nm increased with the thrombin concentrations, a linear range from 1 to 100 nM and 1 nM thrombin (S/N = 3) could be detected. The proposed approach confirmed that the Fe3O4 MNPs not only possessed peroxidase activity but also showed potential application in varieties of simple, robust, and cost-effective analytical methods in the future. (C) 2010 Elsevier B.V. All rights reserved.