Electrochemical immunosensor for the detection of tumor necrosis factor α based on hydrogel prepared from ferrocene modified amino acid

摘要

A novel kind of hydrogel was prepared from ferrocene (Fc) functionalized amino acid phenylalanine (Phe) and applied for the fabrication of electrochemical immunosensor to detect tumor necrosis factor α (TNF-α). The prepared hydrogel displays high redox activity due to the incorporation of a significant number of Fc moieties into the hydrogel. When the hydrogel was reacted with ascorbic acid (AA), the redox activity of the hydrogel was decreased as the Fc moieties in the hydrogel were reduced by AA. Based on this phenomenon, the immunosensor was constructed utilizing the traditional sandwich format using the hydrogel modified electrode as sensing platform and alkaline phosphatase (ALP) modified polystyrene sphere (PS) as label. First, primary anti-TNF-α antibody was immobilized onto the electrode surface via gold nanoparticles (AuNPs), then TNF-α and ALP were sequentially captured onto electrode. The ALP captured onto the electrode will catalyzes the hydrolysis of ascorbic acid 2-phosphate (AA-p) to form AA. The latter, in return, will cause the decrease of the redox current of the electrode. The decrease of the redox current is proportional to the concentration of TNF-α detected in the range from 1 pg/mL to 10 ng/mL. The immunosensor testing results were validated through the detection of clinical serum sample with satisfactory results.