Fabrication of a novel and ultrasensitive label-free electrochemical aptasensor for detection of biomarker prostate specific antigen.

In this study, a novel and efficient aptasensor based on immobilization of thiol terminated prostate specific antigen (PSA) binding DNA aptamer onto Au nanoparticles/fullerene C-chitosan-ionic liquid/multiwalled carbon nanotubes/screen printed carbon electrode has been fabricated for ultrasensitive aptasensing of biomarker PSA. Formation of PSA-aptamer complex caused a variation in electrochemical impedance spectroscopic (EIS) and differential pulse voltammetric (DPV) responses of the aptasensor which enabled us to aptasensing of the PSA by EIS and DPV methods. Morphology and electrochemical properties of the fabricated aptasensor were examined by scanning electron microscopy (SEM), cyclic voltammetry (CV) and EIS. The aptasensor was successfully applied to the determination of PSA by EIS and DPV in the range of 1-200 pg mL with a limit of detection (LOD) of 0.5 pg mL and 2.5-90 ng mL with a LOD of 1.5 ng mL, respectively. This aptasensor exhibited outstanding anti-interference ability towards co-existing molecules with good stability, sensitivity, repeatability and reproducibility. Practical application of the aptasensor was examined with analysis of the PSA levels in serum samples obtained from patients with prostate cancer using both the aptasensor and a reference method. The results revealed the proposed system to be a promising candidate for clinical analysis of PSA.