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 charac-teristics that are widely variable and easily adjusted. Stimuli-responsive or intelligent hydrogels are a class of thesematerials 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 theother 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 thesenanoparticles can be used in a wider spectrum of practical applications. Therefore, we pre-sent 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 irradia-tion technique merges sterilization and synthesis in a single technological step, optimizing the pro-cess 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 characteri-zation 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 physicochemicalproperties of nanocomposite samples, considering the potential applications and the ongoing need for the wide-spread use of biocompatible materials

Hidrogelovi su materijali koji poseduju specifičnu poroznost, stabilnost, biokompatibilnost i sposobnost apsorpcije okolne tečnosti, kao i svojstva koja su promenljiva i lako podesiva širokom spektru primena, naročito u oblasti medicine i biotehnologije. Posebno je interesantna oblast “inteligentnih“ hidrogelova, odnosno materijala koji reaguju na spoljašnje stimulanse i pokazuju značajanu fizičku ili hemijsku promenu pri malim promenama u okruženju. Poli(N-izopropilakrilamid) (PNiPAAm) je najpoznatiji termosenzitivni polimer sa jasno definisanom temperaturom faznog prelaza (VPTT) od oko 32°C. S druge strane, nanočestice srebra (AgNPs) poseduju optička, katalitička i električna svojstva koja se mogu modifikovati promenom njihove veličine i oblika a imaju i izražen antibakterijski potencijal, pa su stoga, poslednjih decenija intenzivno proučavane. Pokazano je da se anizotropne nanočestice srebra mogu kontrolisano sintetisati sa fizičkohemijskim svojstvima različitim od sfernih analoga, pri čemu su značajna istraživanja usmerena na njihovu praktičnu primenu. Zbog svega navedenog, u okviru ovog istraživanja biće izvedena jednostavna dvostepena sinteza AgNPs/PNiPAAm hidrogel nanokompozita koja uključuje hemijsko formiranje sfernih i trouglastih AgNPs u prvom koraku, a zatim gama-indukovano umrežavanje NiPAAm-a u prisustvu ovih AgNPs. Tehnika gama zračenja objedinjuje sterilizaciju i sintezu u jednom tehnološkom koraku čime se proces optimizuje i otvara širok spektar inovativnih biomedicinskih primena. Formiranje stabilnih i uniformno distribuiranih AgNPs unutar matrice hidrogela potvrđeno je UV-Vis spektroskopijom, a porozna sunđerasta struktura polimerne mreže SEM analizom. Fizičkohemijska karakterizacija izvršena je i ispitivanjem procesa bubrenja i kontrahovanja u vodi na 25°C i 48°C, redom. Pored toga, pokazano je da prisustvo AgNPs utiče na vrednosti temperature faznog prelaza polimera. Osnovni cilj ovog istraživanja je ispitivanje uticaja različite morfologije AgNPs na fizičkohemijska svojstva sintetisanih nanokompozita, imajući u vidu njihovu potencijalnu primenu i stalnu potrebu za širokom upotrebom biokompatibilnih materijala.