We have developed a turn-on photoluminescence protocol to detect hydrogen peroxide (H2O2) utilizing a supramolecular hydrogel as a sensing platform. Hydrogen peroxide is widely used in formulations, starting from healthcare products to explosives. It is also known to induce deleterious health effects at its irregular physiological concentration and considered as a biomarker in various disease conditions. We designed molecule 2, which releases the Tb3+ sensitizer biphenyl-4-carboxylic acid (1) upon unmasking by hydrogen peroxide. This chemistry led us to develop a sensitive photoluminescence assay for H2O2 through the 1-induced photoluminescence of terbium (Tb3+) in a hydrogel matrix. Paper discs (0.45 cm) were coated with the soft hydrogel to make the sensing process simple and cost-effective. The green luminescence from the paper discs, observed under a UV lamp, allowed naked-eye detection of H2O2 in the micromolar level without any sophisticated instrumentation. Image processing software or a plate reader can be used for the accurate quantification of the analyte in micromolar and nanomolar ranges. Several commercial hand sanitizers containing hydrogen peroxide were tested by this method. The results indicated that this low-cost system could be practically adopted, especially in resource-limited areas, to quantify/detect H2O2 for quality control purposes or other applications.
Keywords: hand sanitizers; hydrogel; hydrogen peroxide; lanthanide; naked-eye detection; paper discs; paper-based sensors; photoluminescence; terbium.