Antibacterial Electrospun Wound Dressing with Flame-Made Ag/SiO₂ Nanoparticles

Wound healing is a multifaceted biological phenomenon that encompasses tissue repair and the restoration of functionality. The healing process can be significantly impeded by wound infections, which occur when microbes infiltrate the wound. These infections can cause severe health issues, including prolonged healing, septicemia, and deep tissue and bone infections, leading to reduced mobility, financial burden, and potential limb amputation [1]. To mitigate this, antibacterial dressings have been developed to decrease bacterial colonization in wounds. Many of these dressings contain antibiotics, but with the increasing prevalence of antibiotic resistance, there is a growing need for antibiotic-free alternatives [2].<br/><br/>One potential solution is the use of antimicrobial nanomaterials, such as nanosilver, in wound dressings [3]. However, commercially available silver-based dressings often fail to demonstrate clear clinical effectiveness due to the uncontrolled release of silver ions (Ag⁺) at sub-lethal concentrations, which could unintentionally foster resistance. To ensure the successful integration of nanoparticles, it is crucial to employ a scalable and reproducible method that allows for precise control over the size and shape of the nanoparticles while minimizing product development costs. In response to this challenge, we propose a solution that combines two industrial manufacturing processes: flame spray pyrolysis [4] and electrospinning.<br/><br/>In our research, we present antibacterial wound dressings composed of electrospun nanofibrous membranes made from polyvinyl alcohol (PVA) and chitosan, which are infused with Ag/SiO₂ nanoparticles produced via flame spray pyrolysis. Four different membranes were used with varying ratios of PVA and chitosan – 100:0, 95:5, 90:10 and 80:20, to examine the influence of the membrane composition on their antibacterial activity. Notably, the dressings with PVA: chitosan ratios of 90:10 and 80:20 demonstrated robust antibacterial activity against gram-positive Methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) and gram-negative <i>Pseudomonas aeruginosa</i>, both of which are common pathogens responsible for wound infections.<br/><br/>To further validate their effectiveness, these dressings were tested using an ex-vivo model with porcine skin. Additionally, biocompatibility tests were conducted on fresh human skin obtained from surgical procedures. Moreover, we carried out comprehensive mechanistic investigations, which revealed that the composition of the fibers and the manufacturing process significantly influence the sustained release of Ag⁺ ions from a minimal amount of Ag/SiO₂ nanoparticles. This results in potent antibacterial properties while reducing the risk of Ag⁺ ion resistance and nanosilver toxicity, thereby representing a promising strategy for the development of effective, antibiotic-free wound dressings.<br/><br/><b>References</b><br/>[1] Carter, M. J. et al. <i>Journal of Medical Economics</i> 26, 894–901 (2023).<br/>[2] Wang, C. et al. <i>Nat Rev Mater</i> (2024).<br/>[3] Chen Xu et al<i>. </i><i>Bioconjugate Chemistry</i> 31, 1708-1723 (2020).<br/>[4] GA Sotiriou, SE Pratsinis <i>Environmental Science & Technology</i> 44, 5649-5654 (2010).