Myelin basic protein immunosensor for multiple sclerosis detection based upon label-free electrochemical impedance spectroscopy
By Derkus, Burak; Emregul, Emel; Yucesan, Canan & Emregul, Kaan Cebesoy
Published in Biosensors and Bioelectronics
2013
Abstract
A novel highly sensitive impedimetric Myelin Basic Protein (MBP) immunosensor for the determination of a Multiple Sclerosis (MS) autoantibody, Anti-Myelin Basic Protein (Anti-MBP) was developed by immobilization of MBP on Gelatin and Gelatin–Titanium Dioxide (TiO2) modified platinium electrode. Cyclic voltammetric (CV) and Electrochemical Impedance Spectroscopic (EIS) methods were employed in determination of the electrode responses and applicability. Gelatin-MBP and gelatin–TiO2-MBP electrodes were prepared by chemical immobilization of the substrates onto the platinium electrodes. The formal potentials of MBP confined on gelatin-MBP and gelatin–TiO2-MBP surfaces are estimated to be 195 and 205 mV, respectively. Thus, a little more reversible electron transfer reaction occurs on the gelatin–TiO2-MBP immunosensor surface. The peak separations of MBP (150 mV and 110 mV s-1 at 100 mV s-1) and the asymmetric anodic and cathodic peak currents indicate that the electron transfer between Anti-MBP and gelatin-MBP/gelatin–TiO2-MBP immunosensor is quasireversible. Control samples containing a nonspecific human immunoglobulin G (hIgG) antibody were also studied, and calibration curves were obtained by subtraction of the responses for specific and nonspecific antibody-based sensors. Gelatin-MBP and gelatin–TiO2-MBP immunosensors have detection limit of 0.1528 ng ml-1 and 0.1495 ng ml-1 respectively. This immunosensor exhibits high sensitivity and low response times (58 s for gelatin-MBP and 46 s for gelatin–TiO2-MBP immunosensor). The developed label-free impedimetric immunosensors also provide a simple and sensitive detection method for the specific determination of Anti-MBP in human cerebrospinal fluid (CSF) and serum samples.