Rhodamine-Anchored Polyacrylamide Hydrogel for Fluorescent Naked-Eye Sensing of Fe3+

A fluorescent and colorimetric poly (acrylamide)-based copolymer probeP(AAm-co-RBNCH)has been designed via free radical polymerization of a commercial acrylamide monomer with a rhodamine-functionalized monomerRBNCH. Metal ion selectivity ofRBNCHwas investigated by fluorescence and colorimetric spectrophotometry. Upon addition of Fe3+, a visual color change from colorless to red and a large fluorescence enhancement were observed for the ring-opening of the rhodamine spirolactam mechanism. The monomer gives a sensitive method for quantitatively detecting Fe3+in the linear range of 100–200 μM, with a limit of detection as low as 27 nM and exhibiting high selectivity for Fe3+over 12 other metal ions. The hydrogel sensor was characterized by FTIR, and the effects ofRBNCHamount on gel content and swelling properties were explored. According to the recipe of 1.0 mol%RBNCHto the total monomers, the fabricated hydrogel sensor displayed a good swelling property and reversibility performance and has potential for application in the imaging of Fe3+level in industrial wastewater.Keywords:hydrogel sensor;rhodamine;selectivity;naked-eye detection;free radical polymerization