Phenolphthalein-Conjugated Hydrogel Formation under Visible-Light Irradiation for Reducing Variability of Colorimetric Biodetection.

Polymerization-based signal amplification (PBA) is a colorimetric biodetection method for use in resource-limited settings. It uses phenolphthalein as a colorimetric reagent, but leaching of the dye from a resultant hydrogel can lead to variability in PBA results. In this work, we use polymerizable phenolphthalein in PBA to produce a phenolphthalein-conjugated hydrogel. Considering the photoinitiation mechanism of eosin Y and triethanolamine in air with an aqueous monomer solution, we determine reaction conditions for modified PBA that maintain a rapid polymerization response. Using the optimized conditions, we demonstrate that modified PBA can detect malaria antigen, Pf HRP2, with reduced variability.