Comparative study of novel in situ decorated porous chitosan-selenium scaffolds and porous chitosan-silver scaffolds towards antimicrobial wound dressing application.

Dermal defects caused by trauma or disease are challenging to treat due to difficult-to-treat infections that impair wound healing. Due to the widespread emergence of drug-resistant bacteria and dwindling discoveries of new antibiotics, there is currently an urgent need to introduce novel antimicrobials effective against antibiotic-resistant bacteria without causing damage to host tissues. As selenium (Se) and silver (Ag) are known for their antimicrobial properties, we investigated the separate loading of these materials into porous chitosan/PVA (CS) scaffolds through a simple in situ deposition method to create two distinct wound dressing materials (CS-Se and CS-Ag). Scaffolds with Se nanostructures and scaffolds containing Ag nanostructures were characterized and their activities against S. aureus - (a Gram-positive bacterium), E. coli - (a Gram-negative bacterium) and Methicillin-Resistant S. aureus (MRSA) - (a multi-drug resistant bacterium) were compared. The release of Ag and Se in vitro was shown to depend strongly on the release medium used (deionised water, mammalian or bacterial culture media). Ag-loaded scaffolds showed a significant reduction in CFUs and cytotoxicity towards fibroblasts while Se-loaded scaffolds showed abilities to damage bacterial cell membrane and non-toxicity to fibroblast. Overall, in this study we have demonstrated simple, in situ immobilization porous CS scaffolds with either Se or Ag nanostructures which could be used to suit different wound healing applications.