Ensuring high selectivity for preconcentration & detection of ultra-trace cadmium by phage-functionalized metal-organic framework
Metal-organic frameworks functionalized with Cd(Ⅱ) binding phage were for the first time fabricated for the isolation and preconcentration of ultra-trace cadmium. Highly specific Cd(Ⅱ) binding phages were screened through biological panning from phage display peptide library. Thereafter, chloroauric acid (HAuCl) was reduced by the phages to provide phage-stabilized gold nanoparticles (AuNPs). The phage-AuNPs networks were then assembled onto the metal-organic frameworks UiO66-NH2 to serve as affinity probe for the selective recognition and isolation of ultra-trace cadmium. 2.0 μg L-1 Cd2+ was selectively captured by the derived UiO66-NH2@phage composite with an adsorption efficiency of 100%. UiO66-NH2@phage exhibits favorable anti-interference capability against the coexisting species. It ensures highly selective and sensitive quantification of ultra-trace cadmium with detection by graphite furnace atomic absorption spectrometry (GFAAS). An enrichment factor of 17.4 was obtained along with a limit of detection (LOD) of 3.9 ng L-1 within a linear range of 0.01-0.35 μg L-1. The procedure was further validated by analyzing cadmium content in a certified reference material (CRM, simulate water, GBW08608) and a series of environmental water samples. In general, the present study provides a new protocol for the development of novel adsorbents toward the target by biopanning to regulate the selectivity.