Multifunctional quaternized 4-vinylpyridine-based cryogels: A synthetic cationic platform for dye adsorption and antibacterial performance

Abstract

Macroporous hydrogels, known as cryogels, have emerged as versatile polymeric materials with significant potential across diverse applications. However, despite their promise, limited research has focused on the development of multifunctional cryogels capable of addressing both dye removal and bacterial growth inhibition. This study aims to design chemically tailored cationic cryogels via quaternization to prepare polymeric networks that integrate adsorption and antibacterial functionalities within a single material platform. The non-quaternized cryogels were synthesized using 4-vinylpyridine and oligo(ethylene glycol) methyl ether methacrylate monomers, with N,N '-methylenebisacrylamide as a crosslinker. These cryogels were quaternized to produce quaternized cryogels, and a secondary crosslinked variant was prepared using bifunctional quaternization agent. The cryogels were characterized using FTIR, SEM, swelling, mechanical, dye adsorption, and antibacterial activity tests. The resulting cryogels exhibited macroporous structure with pore diameters of 50-90 mu m, rapid swelling, and robust mechanical properties. These attributes, along with their positive charge, enable their efficient anionic dye adsorption and bacterial growth inhibition. Dye adsorption studies demonstrated that the cationic cryogels excelled in removing anionic dyes through electrostatic interactions. Indeed, the Congo Red removal efficiency reached 99 % within 96 h for all cryogels tested, while the adsorption rates during the first 2 h followed the trend: non-quaternized < quaternized < secondary crosslinked cryogels. Moreover, while nonquaternized cryogels lacked antibacterial activity, both quaternized and secondary crosslinked cryogels exhibited notable antibacterial efficacy against S. aureus and E. coli. Overall, the developed quaternized cationic cryogels represent a versatile platform for next-generation multifunctional materials, uniting efficient dye adsorption and antibacterial properties.