Molybdenum disulfide quantum dot based highly sensitive impedimetric immunoassay for prostate specific antigen

Abstract

This work reports on the synthesis of molybdenum disulfide quantum dots (MoS2-QDs) from preexfoliated MoS2 nanosheets. After a thorough characterization, the MoS2-QDs were assembled onto screenprinted carbon electrodes, followed by the physical adsorption of antibodies against the prostate-specific antigen (PSA) to form a bioelectrode. Because of the hydrophobic nature of the QDs, they are favorable for the hydrophobic interaction with the antibodies. Based on cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques, the bioelectrode was employed for the detection of PSA using hexacyanoferrate as the redox probe. The electrode yielded an optimum CV response of PSA in the range of 0.1 pg.mL(-1) to 10 ng.mL(-1) (scan rate: 0.05 mVs(-1)). The performance improved significantly when EIS was applied (response range: 0.01 pg . mL(-1) to 200 ng . mL(-1); limit of detection: 0.01 pg.mL(- 1)). The feasibility of the immunoassay was demonstrated by successfully analyzing PSA in serum samples based on the standard addition method. A near 100% recovery of PSA from the serum samples supports the possible practical viability of the procedure. The immunoassay highlights a number of advantageous features such as convenient attachment of antibodies over the electrode surface and broad range of PSA detection with the successful demonstration with real serum samples.