Novel redox species polyaniline derivative-Au/Pt as sensing platform for label-free electrochemical immunoassay of carbohydrate antigen 199

• A novel electrochemical redox composite PPPD-Au/Pt was synthesized by one-pot method.
• PPPD-Au/Pt was used as sensing substrate for label-free electrochemical immunosensor.
• The immunosensor showed wide detection range and ultralow detection limit for the detection of CA199.

A novel electrochemical redox-active nanocomposite was synthesized by a one-pot method using N,N′-diphenyl-p-phenylediamine as monomer, and HAuCl4 and K2PtCl4 as co-oxidizing agents. The as-prepared poly(N,N′-diphenyl-p-phenylediamine)-Au/Pt exhibited admirable electrochemical redox activity at 0.15 V, excellent H2O2 electrocatalytic ability and favorable electron transfer ability. Based on these, the evaluation of the composite as sensing substrate for label-free electrochemical immunosensing to the sensitive detection of carbohydrate antigen 199 was described. This technique proved to be a prospective detection tool with a wide liner range from 0.001 U mL−1 to 40 U mL−1, and a low detection limit of 2.3 × 10−4 U mL−1 (S/N = 3). In addition, this method was used for the analysis of human serum sample, and good agreement was obtained between the values and those of enzyme-linked immunosorbent assay, implying the potential application in clinical research. Importantly, the strategy of the present substrate could be extended to other polymer-based nanocomposites such as polypyrrole derivatives or polythiophene derivatives, and this could be of great significance for the electrochemical immunoassay.

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