AuNPs/PpPD/PEDOT:PSS-Fc modified screen-printed carbon electrode label-free immunosensor for sensitive and selective determination of human serum albumin

A novel, label-free immunosensor was fabricated for human serum albumin (HSA) detection in urine and human serum. A screen-printed carbon electrode (SPCE) was modified with a poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate) and ferrocene nanocomposite (PEDOT: PSS-Fc) which was first coated with poly(para-phenylenediamine) (PpPD) and then functionalized with gold nanoparticles (AuNPs). Anti-human serum albumin (anti-HSA) was immobilized on the AuNPs/PpPD layer by direct chemisorption. HSA sample concentration was determined from the change in the Fc oxidation peak current caused by the formation of HSA/anti-HSA immunocomplex. Under optimal conditions, the sensor's output was linear from 1.0 x 10(-9) to 1.0 x 10(-2) mu g mL(-1) with a detection limit of 5.4 x 10(-10) mu g mL(-1). Modification with AuNPs increased the amount of anti-HSA that could be immobilized on the surface of the electrode and as a result, sensitivity increased 10.1 times. The developed immunosensor exhibited good reusability (sensitivity >90% after 8 cycles of binding-rebinding), good stability (90% sensitivity within 30 days), excellent reproducibility (RSD of <7.6%, n = 6) and high specificity. Applied to detect HSA in urine and human serum, the sensor produced results that agreed well with results obtained from the standard immunoturbidimetric method (P > 0.05). The excellent performance of the sensor confirmed its utility in clinical diagnosis.