Bifunctional aptasensor based on novel two-dimensional nanocomposite of MoS2 quantum dots and g-C3N4 nanosheets decorated with chitosan-stabilized Au nanoparticles for selectively detecting prostate specific antigen.

A novel nanostructured biosensing platform was designed based on two-dimensional (2D) nanocomposite of graphitic carbon nitride (g-C3N4) nanosheets and MoS2 quantum dots (MoS2 QDs), followed by decoration with chitosan-stabilized Au nanoparticles (CS-AuNPs) (denoted as MoS2QDs@g-C3N4@CS-AuNPs), of which CS-AuNPs were prepared by plasma enhanced-chemical vapor deposition. Owning to the good surface plasmon performance of the CS-AuNPs and excellent electrochemical activity of MoS2QDs@g-C3N4 nanosheets, the as-obtained 2D MoS2QDs@g-C3N4@CS-AuNPs nanocomposite was simultaneously explored to construct both surface plasmon resonance spectroscopy (SPR) sensor and electrochemical aptasensor. The MoS2QDs@g-C3N4@CS-AuNPs-based aptasensor shows strong bio-binding affinity toward the prostate specific antigen (PSA) targeted aptamer strands as compared to the individual component, including MoS2 QDs, g-C3N4, and CS-AuNPs. When detecting PSA, the low limit of detection (LOD) of 0.71 pg mL-1 deduced by electrochemical aptasensor is three orders of magnitude lower than that deduced by SPR sensor (0.77 ng mL-1). As expected, both SPR sensor and electrochemical aptasensor demonstrate good selectivity, highly stability, acceptable reproducibility, and well consistent applicability in human serum. The satisfactory results suggest potential application of the MoS2QDs@g-C3N4@CS-AuNPs in bifunctional biosensing fields and clinical monitoring of cancer markers.