Antibacterial activity of natural polymer gels and potential applications without synthetic antibiotics

Antibiotics' use has increased, resulting in disadvantages like patients' drug resistance. Consequently, urgent action is required to develop a new generation of antibacterial agents. Most antibacterial platforms still require a modification with further antibacterial agents (e.g., antibiotics) for adequate antibacterial efficiency. Thus, a nonantibiotic methodology is immediately needed. Furthermore, bactericidal agents used for this purpose are usually based on metal nanoparticles, carbon materials, and polymers. Still, chemicals, antibiotics, and biocides lead to environmental damage. Therefore, the help of biocompatible yet durable materials and polymers is highly appreciated. In addition, if a polymer is not biodegradable, it will remain in the environment for more than one hundred years due to its low degradation rate. Moreover, non-biodegradable polymers are harmful to in vivo applications. Hence, the use of biodegradable and non-toxic materials has received many considerations. Over the last few years, the design and synthesis of new polymer gels have gained increasing attention. A polymer gel, also known as a hydrogel, is a three-dimensional and cross-linked network filled with water or other liquid solvents. Besides, the hydrogels supercritical drying method results in aerogels, and the freeze-drying method generates cryogels, where their porous and sponge-like structures are preserved. Additionally, antibacterial polymer gels are a new generation of polymers considered attractive due to their unique properties. The most recent studies and the latest innovations in polymer gels and hybrid polymers with intrinsic antibacterial properties were discussed in the present review. The reviewed studies from 2015 to April 2022 showed a tremendous revival in research about biopolymer hydrogel, aerogel, and cryogel as antibacterial agents.