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-C 3 N 4 ) nanosheets and MoS 2 quantum dots (MoS 2 QDs), followed by decoration with chitosan-stabilized Au nanoparticles (CS-AuNPs) (denoted as MoS 2 [email protected] 3 N 4 @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 MoS 2 [email protected] 3 N 4 nanosheets, the as-obtained 2D MoS 2 [email protected] 3 N 4 @CS-AuNPs nanocomposite was simultaneously explored to construct both surface plasmon resonance spectroscopy (SPR) sensor and electrochemical aptasensor . The MoS 2 [email protected] 3 N 4 @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 MoS 2 QDs, g-C 3 N 4 , 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 MoS 2 [email protected] 3 N 4 @CS-AuNPs in bifunctional biosensing fields and clinical monitoring of cancer markers.