A three-dimensional CoNi-MOF nanosheet array-based immunosensor for sensitive monitoring of human chorionic gonadotropin with core–shell ZnNi-MOF@Nile Blue nanotags?

Analyst Pub Date: 2020-09-22 DOI: 10.1039/D0AN01648A

Abstract

A CoNi-based metal–organic framework (CoNi-MOF) nanosheet array is synthesized by the treatment of a CoNi layered double hydroxide nanosheet array on Ni foam with 3,5-diaminobenzoic acid. The CoNi-MOF nanosheet array with amino and carboxyl groups can be used to capture the human chorionic gonadotropin (HCG) primary antibody (HCG Ab1). Nile Blue decorated ZnNi-MOF (NB@ZnNi-MOF) spheres immobilized with HCG secondary antibodies (HCG Ab2) are used for signal amplification. When HCG exists in an analytical sample, a sandwich structure is formed and an electrochemical signal is produced. The analytical signal generated during the detection is caused by the conversion of Co(II) and Co(III) in the CoNi-MOF nanosheet array. The Nile Blue of the NB@ZnNi-MOF sphere, as a kind of redox-active species, is responsible for the electrochemical signal amplification in the immunosensor. On the basis of the above advantages, the HCG immunosensor exhibits a lower limit of detection (1.85 × 10?3 mIU mL?1) and a wide linear range from 0.005 mIU mL?1 to 250 mIU mL?1. Additionally, this immunosensor is used to quantitatively detect HCG in human blood serum and shows good correlations with the standard enzyme-linked immunosorbent assay (ELISA), providing a high value on clinical diagnosis.

Graphical abstract: A three-dimensional CoNi-MOF nanosheet array-based immunosensor for sensitive monitoring of human chorionic gonadotropin with core–shell ZnNi-MOF@Nile Blue nanotags
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