Integrated microfluidic systems with an immunosensor modified with carbon nanotubes for detection of prostate specific antigen (PSA) in human serum samples

This paper describes the development of an immunosensor coupled to glassy carbon electrode (GCE) modified with multiwall carbon nanotubes (MWCNT) (CNT-GCE) integrated with microfluidic systems for rapid and sensitive quantification of prostate specific antigen (PSA) in human serum samples. Mouse monoclonal (5G6) to PSA antibodies were immobilized on a rotating disk. PSA in the serum sample are allowed to react immunologically with the immobilized anti-tPSA and horseradish peroxidase (HRP) enzyme-labeled second antibodies specific to PSA. HRP, in the presence of hydrogen peroxide (H(2)O(2)) catalyzes the oxidation of 4-tert-butylcatechol (4-TBC), whose back electrochemical reduction was detected on CNT-GCE at -0.15 V. The electrochemical detection can be done within 1 min and total assay time was 30 min. The calculated detection limits for electrochemical detection and the ELISA procedure are 0.08 and 0.5 microg L(-1), respectively and the intra- and inter-assay coefficients of variation were below 4.5%. The electrochemical immunosensor showed higher sensitivity and lower time consumed than the standard spectrophotometric detection ELISA method, which shows potential for detecting PSA in clinical diagnosis.