Chitosan-based fluorescent inverse opal particles for Cr(VI) sensing

Chitosan (CS) is a natural polymer widely used in many fields. However, there are seldom studies that focus on its inherent fluorescence properties. In this work, based on the inherent fluorescence of chitosan (CS) and the mechanism that it can be quenched by hexavalent chromium (Cr(VI)), we developed novel CS-based inverse opal particles (IOPs) for Cr(VI) detection. The CS IOPs were obtained by replicating the silica colloidal crystal beads using CS, which displayed uniform shape and size, as well as enhanced fluorescence-emission capability resulted from the unique microstructure. Under the optimized conditions, the CS IOPs responded to Cr(VI) in a range of 0-10,000 mu M with high sensitivity and specificity and demonstrated a LOD of 0.055 mu M at the linear range of 0-30 mu M. Furthermore, they displayed good detection ability in practical applications with recoveries of 86-106% for tap water and 99.7-107.3% for pond water, respectively. With these features, the developed CS IOPs are promising to be a simple, low-cost, and fast platform for detecting Cr(VI).