Label-free electrochemical immunoassay for detecting CYFRA 21-1 using poly(ε-caprolactone)-b-poly(ethylene oxide) block copolymer

As importance of early diagnosis, prognosis, and clinical monitoring in improving survival rate of lung cancer is increasing, the advance of effective diagnostic method for tumor marker is crucial. Herein, linear poly(?-caprolactone)-b-poly(ethylene oxide) (PCL-PEO) copolymer with hydrophilic property is applied to detect CYFRA 21-1 in label-free electrochemical immunoassay. 4-(2-trimethylsilylethynyl)benzoic acid (TEB) as ?bridge? bond first connects initial antibody to the surface of gold electrode. Then one side of CYFRA 21-1 antigen can recognize with initial antibody of electrode interface, and the other side hybridize specifically secondary antibody grafted PCL-PEO copolymer. So far we have constructed a complete immunoassay for CYFRA 21-1 detection using electrochemical impedance spectroscopy. The sensitivity and selectivity of analytical method depend on ?Au?C? bonding, specific recognition of ?antibody-antigen?antibody sandwich?, and PCL-PEO copolymer. Under optimal conditions, the analytical method for quantitative detection of CYFRA 21-1 manifests a broad linear range (1 pg/mL?10 ng/mL) and a low detection limit (0.125 pg/mL, about 3.47 ? 10-15 M). Furthermore, according to the analysis results in clinical samples, the constructed strategy also shows satisfactory sensitivity and anti-interference. It indicates that the immunoassay has broad promising applications for expecting to be applied in practical clinical prevention and monitoring.

Automated summary

This study developed a label-free electrochemical immunoassay method for detecting CYFRA 21-1 using PCL-PEO copolymer, showing high sensitivity and specificity. The method demonstrated satisfactory results in clinical samples, indicating wide potential applications in clinical prevention and monitoring in the future.