Regulating immobilization performance of metal-organic coordination polymers through pre-coordination for biosensing

Abstract

We propose a method for regulating biomolecules immobilization performance of metal-organic coordination polymers (MOCPs) through pre-coordination for highly sensitive biosensing. 2,5-dimercapto-1,3,4-thiadiazole (DMcT) was used as organic monomers. Firstly, using CuCl2 as the source of metal ions to form short oligomers with DMcT (MOCPsCu), which can regulate the length of ligands through pre-coordination. Then exploiting NaAuCl4 as the source of Au ions to coordinate both short oligomers and biomolecules (MOCPsCu+Au), since Au ions can coordinate with both N and S atoms. Through controlling the concentration of CuCl2, oligomers with desired length could be readily obtained to prepare MOCPsCu+Au framework with controllable porosity and enzyme entrapment efficiency. Thus MOCPsCu+Au offers several advantages including improved mass transfer efficiency and biocatalytic sensitivity than conventional MOCPs using single metal ions. Glucose oxidase (GOx) was used as the representative biomolecule, the entrapment ratio of enzyme in MOCPsCu+Au case reached an extreme value of 100%. These MOCPsCu+Au biocomposites modified electrode also showed greatly enhanced biocatalytic sensitivity (127 μA cm−2 mM−1) and very low detection limit (58 nM), compared with those reported analogues. The new materials/strategy may create new avenue to regulate the performance of ligand-constructed polymers and their composites for entrapment-based applications.