Label-Free Ratiometric Electrochemiluminescent (ECL) Immunosensor for the Determination of Prostate Specific Antigen (PSA) in Serum

A spatial- and potential-resolved ratiometric electrochemiluminescent (ECL) immunosensor was developed for prostate specific antigen detection in a label-free mode. CdS quantum dots (CdS QDs) and luminol-gold nanoparticles (luminol-Au NPs) were the potential-resolved electrochemiluminescence emitters and H2O2 was used as a co-reactant. The cathodic signal from the CdS QD electrode served as the working signal and the anodic signal from luminol-Au NPs as the reference. For prostate specific antigen detection, several concentrations of prostate specific antigen were immobilized on the CdS QDs modified electrode and a fixed concentration of the prostate specific antigen was modified on the luminol-Au NPs modified electrode. The prostate specific antigen levels were quantified by the electrochemiluminescence signal ratio of the cathodic and anodic (ECLcathodic/ECLanodic). Under the optimized conditions, the ratio of the cathodic and anodic signals (ECLcathodic/ECLanodic) had a linear relationship with the logarithm of (C, g mL(-1)) of prostate specific antigen concentration from 1.0 x 10(-11) to 1.0 x 10(-7) g mL(-1). The detection limit was 5.0 x 10(-12) g mL(-1). Prostate specific antigen was determined in human serum and the recoveries were from 80.0% to 107.0%. The label-free electrochemiluminescence immunosensor offers simplicity and reliability for human serum with potential for clinical application.