By embedding silver oxide nanoparticles on silk fibre, scientists have produced a new material that can be used to make patches to help in healing of wounds and in preventing infection. The patch was able to heal scratch wounds completely in 24 hours and also kill pathogens like S. aureus and M.tuberculosis.
The researchers first tested the mechanical properties of the silk patch. “An ideal wound-dressing material should have good thermal insulation and also allow gaseous and fluid exchange in the wound area. The new material was able to maintain the moisture and had ideal water-holding capacity,” says Dr Punuri Jayasekhar Babu, post-doctoral researcher, IIT Madras, and the first author of the paper published in Colloid and Interface Science.
“We also performed experiments to find the swelling and degradation properties of the silk patch, which are important for wound healing materials. The patch was hydrophilic in nature and its morphology did not change [that is to say] it did not degrade even after 14 days of immersion in phosphate buffer solution (PBS),” he adds. Phosphate buffer solution has a pH of 7.4 which is close to that of human cells.
Anti-bacterial activity of the patch against non-pathogenic E.coli and two pathogens S. aureus and M.tuberculosis was tested. The silk patch was found to be more effective than the commercially used antibiotic, ciprofloxacin.
The exact mechanism behind antimicrobial activity is unknown. Some studies have reported that silver creates ‘pores’ on bacterial cell walls, thereby causing their death.
Wound healing
In vitro wound healing (scratch assay/cell migration) study revealed faster migration of 3T3 Swiss mouse fibroblast (cells responsible for wound healing) cells to the wound area treated with the silk patch. The wound was completely covered in 24 h.
Cytotoxicity studies also showed that the silk patch was not harmful to the cell lines.
Cells treated with silver alone and silk alone did not show such good wound-healing properties. “We will test the synergistic wound-healing and antibacterial activities of this silk patch on animal models and then this can be commercialised for clinical use” says Prof. Mukesh Doble, Professor at the Department of Biotechnology, IIT Madras and corresponding author of the paper.
