Sensitive detection of Golgi protein 73 by magnetic separation combined with a dual nanozyme MOF-818 and magnetic nucleus@bifunctional shell (FeO@PB-Au) cascade reaction catalytic amplification strategy.

Metal-organic framework (MOF-818) and nanocomposite (FeO@PB-Au) dual nanozymes for enhanced cascade signal amplification were designed. MOF-818 has excellent catechol oxidase mimetic activity and catalyzes the production of color and generation of hydrogen peroxide from the substrate 3,5-di--butylcatechol (3,5-DTBC). Subsequently, FeO@PB-Au with peroxidase-like activity catalyzes the generation of reactive oxygen species from hydrogen peroxide, which oxidizes 3,3',5,5'-tetramethylbenzidine (TMB) to generate the oxidized state of oxTMB, resulting in a signal-enhancing effect. The prepared dual nanozymes can be combined with aptamers with specific recognition ability, thus developing a colorimetric aptamer sensor with high sensitivity and selectivity for detecting Golgi protein 73, which provides a feasible assay for clinical detection of GP73 protein. Detection of GP73 was accomplished by measuring the UV absorption peak at 415 nm. Under the optimal conditions, the concentration of GP73 was linearly correlated with the absorbance in the range of 10.0-100.0 ng mL with a detection limit of 1.83 ng mL. The proposed colorimetric biosensor was successfully applied to the determination of GP73 in spiked human serum samples with recoveries of 96.15-100.95% and RSDs of 1.52-6.85%, which demonstrated the great potential of the highly sensitive GP73 assay in clinical detection.