Ultra pH-sensitive detection of total and free prostate-specific antigen using electrochemical aptasensor based on reduced graphene oxide/gold nanoparticles emphasis on TiO/carbon quantum dots as a redox probe.

The development of a rapid, sensitive, and straightforward detection method of prostate-specific antigen (PSA) is indispensable for the early diagnosis of prostate cancer (PCa). This work relates an electrochemical method using functionalized single-stranded DNA aptamer to diagnose PCa and benign prostate hyperplasia. The sensing platform relies on PSA recognition by aptamer/Au/GO-nanohybrid-modified glassy carbon electrode. Besides ferrocyanide TiO/carbon quantum dots (CQDs) probe is used to investigate the effect of nanoparticle-containing electrolyte. Optimization of incubation time of aptamer/Au/GO-nanohybrid and volume fraction of nafion were done using Design Expert 10 software reporting 42.4 h and 0.095% V/V, respectively. In ferrocyanide medium, PSA detection as low as 3, 2.96, and 0.85 ng mL was achieved with a dynamic range from 0.5 to 7 ng ml, in accord with clinical values, using cyclic voltammetry, square wave voltammetry, and electrochemical impedance spectroscopy, respectively. Moreover, this sensor exhibited conspicuous performance in TiO/CQDs-containing medium with different pH values of 5.4 and 8 to distinguish total PSA and free PSA, resulting in very low limit of detections, 0.028, and 0.007 ng ml, respectively. The results manifested the proposed system as a forthcoming sensor in a clinical and point of care analysis of PSA.