An electrochemical aptasensor for detection of prostate-specific antigen-based on carbon quantum dots-gold...

In this work, an electrochemical aptasensor was described for the determination of prostate-specific antigen (PSA). Aptamer chains were decorated on the surface of a glassy carbon electrode (GCE) via carbon quantum dots/Au nanoparticles (Au/CQD). Structural analysis that was used to characterize the prepared materials shows that Au/CQD nanoparticles synthesized in a spherical shape with an average size of 70 nm. Furthermore, the combination of Au nanoparticles with CQD resulted in formation of crystalline the structure of the Au/CQD composite. To study the electrochemical performance of the prepared aptasensor, cyclic voltammetry, square wave voltammetry, and electrochemical impedance spectroscopy were used. The results show that the aptasensor has a good selectivity to PSA over other biomaterials with the time optimized about 30 min. K₄ [Fe(CN)₆ ] was used as an electrochemical probe with the limit of detection about 2 fg⋅mL^-1 . To avoid the hazardous nature of K₄ [Fe(CN)₆ ], a label-based aptasensor was prepared using methylene blue as an electrochemical signal producer. They provide the capability of electrochemical detection in buffer phosphate solution with high sensitivity.