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

NANCI V. PANINI; GERMÁN ALEJANDRO MESSINA; ELOY SALINAS; HÉCTOR FERNÁNDEZ; JULIO RABA

BIOSENSORS & BIOELECTRONICS

Año: 2008 vol. 23 p. 1145 - 1151

0956-5663

Abstract 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 immobilised 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 (H2O2) 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 µg 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.