The effect of silver nanoparticle shape on the physicochemical properties of a poly(n-isopropylacrylamide) hydrogel nanocomposites

Abstract

Hydrogels have unique properties and many potential applications, particularly in medicine and biotechnology. Gel porosity and swelling properties, stability, and biocompatibility are characteristics that are widely variable and easily adjusted. Stimuli-responsive or intelligent hydrogels are a class of these materials that shows a significant response to small changes in the surrounding environment. Poly(N-isopropylacrylamide) (PNiPAAm) is the best-known thermosensitive polymer with a well-defined volume phase transition temperature (VPTT) around 32°C. On the other hand, silver nanoparticles (AgNPs) have been the subject of intense interest due to their size-dependent optical, catalytic, and electronic properties as well as remarkable antimicrobial potential. Within the last decade, scientists have demonstrated that anisotropic AgNPs can be synthesized in a controlled manner and that these materials exhibit distinctively different physicochemical properties from their spherical counterparts. A significant challenge that scientists face is establishing how these nanoparticles can be used in a wider spectrum of practical applications. Therefore, we present a simple, straightforward two-step synthesis of AgNPs/PNiPAAm hydrogel nanocomposites that includes the chemical formation of both spherical and triangular AgNPs, followed by gamma irradiation-induced PNiPAAm crosslinking in the presence of nanoparticles. The gamma irradiation technique merges sterilization and synthesis in a single technological step, optimizing the process and opening up a wide range of innovative biomedical applications. The formation of stable and uniformly distributed AgNPs in the polymer was confirmed by UV-VIS spectroscopy, while the network porous sponge-like structure was observed by SEM analysis. Physicochemical characterization was performed by examining the swelling and deswelling processes in water at 25°C and 48°C, respectively. In addition, AgNPs were shown to have an effect on VPTT values. Our main goal is to investigate how different morphologies of AgNPs affect the physicochemical properties of nanocomposite samples, considering the potential applications and the ongoing need for the widespread use of biocompatible materials.