*Article* **Antibacterial Hydrogel Sheet Dressings Composed of Poly(vinyl alcohol) and Silver Nanoparticles by Electron Beam Irradiation**

**Rattanakorn Chiangnoon <sup>1</sup> , Pennapa Karawak <sup>1</sup> , Jarurattana Eamsiri <sup>1</sup> , Sasikarn Nuchdang <sup>1</sup> , Nuatawan Thamrongsiripak <sup>2</sup> , Naruemon Neramitmansook <sup>2</sup> , Siwanut Pummarin 3,4, Pimchanok Pimton 3,5 , Kewalee Nilgumhang <sup>6</sup> and Pimpon Uttayarat 1,\***


**Abstract:** Advanced wound dressings that can deliver potent antibacterial action are still much in need, especially for treating wound infections caused by drug-resistant bacteria. In this research, we utilized electron beam (EB) irradiation to develop antibacterial hydrogel sheet dressings from poly(vinyl alcohol) (PVA) and silver nanoparticles (AgNPs) in a two-step processing and evaluated their bactericidal efficacy, as well as the AgNP release. The effect of the irradiation dose on the swelling, gel fraction, network parameters, and mechanical properties of the hydrogels was first determined to establish the optimal doses for the two-step processing. The prototypic hydrogel sheets were then formed in the first EB irradiation and served as a matrix for the AgNP synthesis by the reduction of the silver nitrate precursors during the second EB irradiation. The diffusion assay showed that the minimal inhibition concentration (MIC) of the AgNP-load hydrogels was 0.25 and 0.5 mg/cm<sup>2</sup> against *Escherichia coli* and *Staphylococcus aureus*, respectively. At these MIC levels, the released AgNPs increased sharply before reaching the maximum, ~950 and 1800 ppb, at 24 h as analyzed by atomic absorption. Therefore, we successfully demonstrated that this two-step processing by EB irradiation provides a convenient platform to fabricate AgNP-loaded hydrogel dressings that can be further developed for wound healing.

**Keywords:** hydrogel sheet dressings; poly(vinyl alcohol); silver nanoparticles; electron beam irradiation; antibacterial
