A Sandwich‐Type Electrochemical Immunosensor for Insulin Detection Based on Au‐Adhered Cu₅Zn₈ Hollow Porous Carbon Nanocubes and AuNP Deposited Nitrogen‐Doped Holey Graphene

Abstract

Abstract Rapid, accurate, and sensitive insulin detection is crucial for managing and treating diabetes. A simple sandwich‐type electrochemical immunosensor is engineered using gold nanoparticle (AuNP)‐adhered metal–organic framework‐derived copper–zinc hollow porous carbon nanocubes (Au@Cu 5 Zn 8 /HPCNC) and AuNP‐deposited nitrogen‐doped holey graphene (NHG) are used as a dual functional label and sensing platform. The results show that identical morphology and size of Au@Cu 5 Zn 8 /HPCNC enhance the electrocatalytic active sites, conductivity, and surface area to immobilize the detection antibodies (Ab 2 ). In addition, AuNP/NHG has the requisite biocompatibility and electrical conductivity, which facilitates electron transport and increases the surface area of the capture antibody (Ab 1 ). Significantly, Cu 5 Zn 8 /HPCNC exhibits necessary catalytic activity and sensitivity for the electrochemical reduction of H 2 O 2 using ( i – t ) amperometry and improves the electrochemical response in differential pulse voltammetry. Under optimal conditions, the immunosensor for insulin demonstrates a wide linear range with a low detection limit and viable specificity, stability, and reproducibility. The platform's practicality is evaluated by detecting insulin in human serum samples. All these characteristics indicate that the Cu 5 Zn 8 /HPCNC‐based biosensing strategy may be used for the point‐of‐care assay of diverse biomarkers.