An ultrasensitive label-free electrochemical aptasensing platform for Golgi protein-73 detection based on RGO-Fc-Mn3O4 nanocomposites

Golgi protein-73(GP73) is one of the most common biomarkers with outstanding sensitivity and specificity in the diagnosis of hepatocellular carcinoma. Herein an ultrasensitive label-free electrochemical aptasensing platform was constructed for GP73 detection based on reduced graphene oxide-ferrocene formic acid-tripterythrine tetroxide nanocomposites (RGO-Fc-Mn3O4) and GP73 aptamer (GP73Apt). Gold@poly-o-phenylenediamine (Au@PoPD) was electrodeposited on the surface of screen-printed electrode (SPE) as the conductive substrate. RGO-Fc-Mn3O4 was then drop-coated on Au@PoPD/SPE as a signal probe to generate measurable redox peaks due to the electroactivity of Fc in RGO-Fc-Mn3O4. GP73Apt was anchored on the surface of RGO-Fc-Mn3O4 NPs/Au@PoPD/SPE to constitute an electrochemical aptasensing biosensor. When GP73 was captured via the specific affinity of GP73Apt and formed GP73-GP73Apt complex onto the aptasensing platform, the formation GP73-GP73Apt complex impeded the electron transfer on the electrode interface, resulting in a decrease in the peak current recorded by differential pulse voltammetry method. Thus, GP73 can be detected by measuring the change of Fc redox peak current in RGO-Fc-Mn3O4. Log-linear calibration curve for GP73 concentration (0.01–1000 ng/mL) was obtained with good correlation coefficients of 0.99485 and a lower limit of detection of 0.01 ng/mL. The human serum samples were tested by direct detection method, and the relative error and relative standard deviation are 4.21–9.87% and 3.28–9.40%, respectively. All these results demonstrate that the proposed aptasensor would be a promising tool for clinical analysis of GP73 in the diagnosis of hepatocellular carcinoma.