Biominerized gold-Hemin@MOF composites with peroxidase-like and gold catalysis activities: A high-throughput colorimetric immunoassay for alpha-fetoprotein in blood by ELISA and gold-catalytic silver staining

Catalytic hemin was first remolded with biomineralized gold to form Hemin-Au core and further encapsulated into the Tb metal organic framework (MOF) matrix. The so obtained [email protected] composites could possess high environmental stability and especially double catalysis activities of enhanced peroxidase-like and gold catalysis. Steady state kinetics studies indicate that [email protected] could present much higher intrinsic catalysis and substrate affinity (lower Michaelis constants) than native hemin and even natural peroxidase. Furthermore, the catalytic composites were employed for labeling antibodies towards the sandwiched immunoassays for alpha-fetoprotein (AFP) as a model biomarker of cancers. The results indicate that the [email protected] immunoassays could be conducted by two signal amplification ways of hemin-catalyzed chromogenic reaction and gold-catalyzed silver staining, enabling the detection of AFP in blood with the level down to 0.020 ng mL−1. Importantly, the proposed fabrication protocol combining the gold biomineralization and MOF encapsulation routes may be extended for the fabrication of a variety of enzymes or enzymatic mimics with the improved environmental stability and multiple catalysis activities for the wide catalysis applications.