Novel Colorimetric Aptasensor for the Detection of Golgi Protein 73 by Exploiting the Peroxidase-Like Activity of the H-rGO-Mn3O4 Nanozyme

Golgi protein 73 (GP73) is a novel biomarker for the detection of hepatocellular carcinoma. We prepare a colorimetric aptasensor for GP73 detection based on the catalytic performance of the H-rGO-Mn3O4 nanozyme. The H-rGO-Mn3O4 nanozyme serves as a peroxidase mimetic which can enhance the reaction with the substrate (3, 3,’ 5, 5′-tetramethylbenzidine, TMB) and H2O2. The peroxidase-like activity of H-rGO-Mn3O4 features a 1.78-fold higher binding affinity value (Km) for TMB compared with that of horseradish peroxidase. The H-rGO-Mn3O4 nanozyme not only exhibits admirable peroxidase-like activities due to the synergistic effect of Mn3O4 NPs, rGO and hemin, but also has a large specific surface area to endow the GP73 aptamer with specific recognition capabilities. A sandwich colorimetric aptasensor is formed to realize the visual detection of GP73 through catalyzing the H2O2-mediated oxidation peroxidase substrate TMB to oxidized TMB accompanied by a color change from colorless to blue. Under optimal conditions, the logarithm of the GP73 concentration (0.05–50.0 ng/mL) shows a good linear relationship with the absorbance. The calibration equation is Y =−0.0383 lgC+0.4835, with R2 of 0.9964, and the lowest limit of detection is 36.94 pg/mL. Additionally, the content of GP73 in human serum samples is directly detected, and the relative standard deviation is 0.49–4.91%. Compared with the enzyme-linked immunosorbent assay method, the relative error is 0.23–3.61%. All in all, colorimetric aptasensor is demonstrated to exhibit excellent specificity, stability, and reproducibility.