Preparation and Evaluation of Nanocomposite Films Containing Silver and Calcium Phosphate Nanoparticles for Burn Wound Healing

Globally, burns are considered to be a serious public health problem. Following a burn, due to disruption of the protective barrier function of the skin, topical dressings with high concentrations of antimicrobial agents are needed to protect the body against environmental flora. Metallic silver in the form of nanoparticles has made a remarkable return as a potent antimicrobial agent since the pathogenic bacteria have developed resistance against several antibiotics. Calcium has an established role in the normal homeostasis of mammalian skin and serves as a modulator in keratinocyte proliferation and differentiation. The present work therefore introduces a novel dressing for burn wounds, containing both silver and calcium phosphate nanoparticles incorporated into polymeric nanocomposite films. Initially, both silver and calcium phosphate nanosuspensions were separately prepared in aqueous media using bottom up methods. Silver nanoparticles were generated by reduction of a solution of silver nitrate by trisodium citrate. Calcium phosphate nanoparticles were synthesized via a reaction between calcium chloride and sodium phosphate in presence of trisodium citrate as stabilizer. Both types of nanoparticles were characterized for size prior to incorporation into films. Hydroxy propyl methyl cellulose as film forming polymer with glycerin as plasticizer were dissolved in a mixture of the silver and calcium phosphate nanosuspensions. The composition was prepared into films using the laboratory friendly solvent casting method followed by drying in a hot air oven. The prepared films were cut into 1 x 1 cm square size and evaluated for physical parameters such as weight, thickness and folding endurance and for content of silver and calcium by atomic emissionspectroscopy. The films were pasted onto a bigger sized adhesive surgical tape to enable application. The efficiency of the nanocomposite films in burn wound healing was evaluated in swiss albino mice induced with burn wounds, through wound measurements and histopathological examination. Both silver and calcium phosphate nanoparticles were prepared with average size less than 100nm. The nanocomposite films incorporating these particles were elegant, uniform in thickness and weight and had suitable content of the minerals. From the wound healing studies in swiss albino mice, the difference in wound measurements for the different groups, including the untreated control group, when compared statistically using ANOVA proved to be significant (p<0.05). The results suggested that the nanocomposite films developed herein, similar films, but containing only silver nanoparticles and marketed silver-based cream, all produced comparable healing in terms of reduction in the size of the wound. However, histopathological studies revealed that re-epithelialization occurred to the highest extent in case of the mice treated with the nanocomposite film containing both silver and calcium. The presence of calcium phosphate nanoparticles was thus found to aid in the wound healing process. The present studies have therefore resulted in a simple, but superior dressing for topical treatment of burn wounds.