Effect of nano-metal oxides (TiO2, MgO, CaO, and ZnO) on antibacterial property of (PEO/PEC-co-AAm) hydrogel synthesized by gamma irradiation

Abstract

The global threat of infectious diseases and antibiotic resistance calls for the development of potent antimicrobial agents integrated with hydrogel for effective control and treatment. Hydrogel is advanced biomaterials compounds. Hydrogel is an advanced biomaterial compound that offers tunable physical and chemical properties, which can be tailored to specific biomedical applications. This study investigates the antibacterial properties of pectin/polyethylene oxide (PEC/PEO)-based poly acrylamide hydrogels containing 5 wt% nano-metal oxides (TiO2, CaO, MgO, and ZnO) synthesized through gamma irradiation at a dose of 30 kGy. This technique allows for sterilization and effectively incorporating the metal oxide nanoparticles within the hydrogel matrix. Characterization of the nanocomposites is performed using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Incorporating metal oxide nanoparticles induces noticeable changes in the FTIR spectra, confirming interactions between the nanoparticles and the hydrogel matrix. The antibacterial activity of the nanocomposites is evaluated against different bacteria, and the results demonstrate significant inhibitory effects, especially for MgO- and ZnO-hydrogel nanocomposites against P. mirabilis, S. aureus, P. aeruginosa, and C. albicans, highlighting their potential as antimicrobial agents. The 5 wt% of MgO, ZnO, TiO2 and CaO inside PEO/PEC-co-AAm hydrogel nanocomposites exhibited significant inhibitory effects, with a respective optical density at λ = 600 nm (OD600) values of 0.896 nm, 0.986 nm, 1.250 nm, and 1.980 nm compared to the control and hydrogel alone (OD600 values of 2.88 nm and 2.72 nm, respectively). The antibacterial activity of the (MgO-, ZnO-, TiO2-, and CaO-hydrogel) was enhanced, resulting in the inhibition of S. aureus growth by approximately 68.89 %, 65.86 %, 56.25 %, and 31.94 %, respectively. Incorporating nanoparticles into a hydrogel matrix introduces novelty by preventing their aggregation and synergistically enhancing the antibacterial activity. The hydrogel's porous structure and water content facilitate the physical entrapment of bacteria and promote proximity to the metal oxide nanoparticles, resulting in improved interaction and antimicrobial effectiveness. Moreover, the hydrogel ability to absorb and entrap resistance compounds released by bacteria, coupled with its ability to supply water for the generation of reactive oxygen species, further contributes to its antimicrobial properties.