Vitamin B6 Cofactor‐Conjugated Polyethyleneimine‐Passivated Silver Nanoclusters for Fluorescent Sensing of Zn2+ and Cd2+ Using Chemically Modified Cellulose Strips

Abstract

AbstractThis work presents the fluorescent turn‐on sensing of Zn2+ and Cd2+ by using a nano‐assembly designed by the surface modification of the blue fluorescent polyethyleneimine (PEI) passivated silver nanoclusters (PEI‐AgNCs) with the vitamin B6 cofactor pyridoxal 5‘‐phosphate (PLP) in aqueous medium. The cofactor PLP was conjugated through the Schiff base condensation between the ‐CHO group of PLP and the free –NH2 present in PEI‐AgNCs. The formation of nano‐assembly PLP_PEI‐AgNCs was ascertained from various characterization along with the fluorescent color change from blue to yellow. Upon addition of Zn2+ and Cd2+, the yellow fluorescent of PLP_PEI‐AgNCs instantaneously and selectively changed to bluish‐green with a significant fluorescence enhancement at 475 nm. The developed nanoprobe shows the detection limit down to 50.5 x 10−8 M for Zn2+ and 59.0 x 10−8 M for Cd2+ without any interference from other tested metal ions and was applied for the recognition of Zn2+ and Cd2+ in various environmental and biological fluids with good recovery %. Also, the PLP conjugated PEI‐AgNCs was covalently anchored over the cellulose paper strips, characterized and then applied for the detection of Zn2+ and Cd2+. In addition, the developed system has been employed for the qualitative detection of intracellular Zn2+ in live HeLa cells by fluorescence imaging.