Guar gum graft polymer-based silver nanocomposite hydrogels: synthesis, characterization and its biomedical applications

We have developed a dual-sensitive composite hydrogel network from guar gum grafted polyacrylamidoglycolic acid (graft polymer) using sodium borohydride, which induces cross-linking and growth of silver nuclei by reduction reaction through a fast and easy route. The cross-linked graft polymer (GGAA) and its silver nanocomposite (GGAA@SNC) hydrogels have been successfully utilized to explore sustained release of 5-fluorouracil (5-FU), an anticancer drug, and antibacterial activity was evaluated. The composite hydrogels exhibit sol-gel behavior due to pH and temperature effect. To identify the functional interactions of pure guar gum (GG), graft polymer, 5-FU loaded GGAA and GGAA@SNC hydrogels, the synthesized materials are characterized by FTIR, DSC, and XRD analysis. In addition, the growth of silver nanoparticles (SNPs), its size, and stability in the hydrogel network were verified by UV-vis spectra, FE-TEM, and TGA-DTA analysis. Additionally, the structural morphology and porosity of polymer structures were observed by FE-SEM analysis. The different polymer network parameters (Mc, χ, 휉 and ϕ) and diffusion constant (D) were calculated by using swelling data and evaluated to assess the drug release profile. The diffusion exponents (n) were determined by studying 5-FU release behavior of the composite hydrogels in phosphate buffer solution (pH = 1.2 & 7.4); in vitro release data indicated that, maximum 5-FU release was significantly achieved in pH 7.4 rather than pH 1.2. The GGAA@SNC hydrogels showed excellent antibacterial activity towards Bacillus subtilis and Salmonella ebony using zone of inhibition test. A versatile strategy has been developed to prepare GGAA@SNC hydrogels to enhance 5-FU release over 16 h for its effective anticancer drug release applications.