Engineering Quantum Dots with Ionic Liquid: A Multifunctional White Light Emitting Hydrogel for Enzyme Packaging

Herein, a new and straightforward approach for the fabrication of a stable and multifunctional white light emitting (WLE) hydrogel is reported. For the first time, the utility of such hydrogels for protein packaging with enhanced activity and stability is presented. Initially, a WLE composite with color chromaticity of (0.33, 0.27) is fabricated by engineering the surface of an orange light emitting Mn²⁺-doped ZnS quantum dot (QD) using a blue-emitting choline-tosylate ionic liquid (IL). The color chromaticity can be tuned by altering the concentration of the IL and excitation wavelengths. The WLE hydrogel is constructed through the conjugation of the WLE QD-IL composite with an alginate biopolymer. Remarkably, the WLE QD-IL composite and WLE hydrogel show preservation of their structural and luminescence properties for an extended time and thus indicate a potential for storage applications. When cytochrome c (Cyt C) is caged within the WLE hydrogel matrix, the peroxidase activity increases by more than 1.7-times compared with native Cyt C and a Cyt C-loaded QD hydrogel at room temperature. Also, Cyt C-immobilized WLE hydrogel shows a 3.5-fold increase in activity (compared with native Cyt C) at a higher temperature (120 °C) and in the presence of a denaturation agent.