Dual-signal sandwich-type aptasensor based on H-rGO-Mn3O4 nanozymes for ultrasensitive Golgi protein 73 determination

Golgi protein 73 (GP73) is a new type of marker that can specifically detect hepatocellular carcinoma (HCC). Herein, a dual-signal sandwich-type electrochemical aptasensor for GP73 determination was constructed on the basis of hemin-reduced graphene oxide-manganese oxide (H-rGO-Mn3O4) nanozymes. Gold@poly(o-phenylenediamine) (Au@POPD) nanohybrids with a large specific surface area and conductance were co-electro-deposited onto a screen-printed electrode (SPE) surface to immobilize GP73 capture aptamer 2 (Apt2). H-rGO-Mn3O4 nanozymes were used not only to immobilize amino functionalised GP73 aptamer 1 (Apt1) as the detection probe, but also to serve as an in-situ redox signal indicator because of the redox reaction of Hemin (Fe(Ш)/Hemin(Fe(II)). In addition, given their excellent peroxidase-like activity, H-rGO-Mn3O4 nanozymes can catalyse the decomposition of H2O2 and oxidation of substrate (3,3',5,5'-tetramethylbenzidine, TMB) to oxTMB, which is used as another redox signal. In the presence of the target GP73, the two aptamers specifically bind to the target, thereby affecting two electrochemical signals. Under optimal conditions, the dual-signal sandwich-type electrochemical aptasensor had a salient analytical performance. The two electrochemical redox signals linearly increase with the logarithm of the GP73 concentration in the range of 0.01-100.0 ng/mL with the limit of detection (LOD) of 0.0071 ng/mL and sensitivity of 2.441 μA/μM/cm2. Moreover, the recovery of human serum samples ranged from 98.66% to 121.11%. Furthermore, the two redox signals can simultaneously corroborate each other, thereby preventing missed diagnosis and misdiagnosis. All the results can provide new insights into the clinically effective determination of HCC.