Dr. M. Carmen Morán Badenas, Associate professor, Department of Biochemistry and Physiology-Section of Physiology- Faculty of Pharmacy and Food Science, University of Barcelona,Spain

Title: Stimulus Triggered Delivery Systems for Chronic Wound Healing

Abstract: In recent years, there has been increasing effort in the development of stimuli-responsive nanomaterials with the hope that they will be developed into effective drug delivery or diagnostic vehicles. These synthetic systems utilize an assortment of endogenous or exogenous stimuli to induce a variety of responses that can facilitate targeted drug delivery. These stimuli include local environmental factors, such as pH, temperature, or redox state.

Wound healing is a complex regeneration process, which is characterised by intercalating degradation and re-assembly of connective tissue and epidermal layer. The pH value within the wound-milieu influences indirectly and directly all biochemical reactions taking place in this process of healing. Both acute and chronic wounds with an elevated alkaline pH have demonstrated lower rates of healing.

Recent studies in our lab have demonstrated that the gelification properties of gelatin as well as the strong dependence of gelatin ionization with pH makes this compound an interesting candidate to be used to the effective delivery of active biomacromolecules. Differences of isoelectric point between gelatin type B (between pH 4.8 and 5.2) and gelatin type (ranged between 7 and 9 linked to the Bloom value) might be used to form nanoparticles (NPs) at pH of the skin (pK 5.5) by interaction with oppositely charged compounds. Among the therapeutical molecules to be incorporated, ascorbic acid could stabilizes free radicals and is essential for normal collagen formation.

In the present work, the preparation and physicochemical characterization of gelatin-based NPs for the sustainable delivery of ascorbic acid has been described. The response of the NPs co-incubated in buffers at defined pHs that mimic chronic wound environments have been also determined. In vitro experiments have been performed in order to determine the cytotoxicity, wound healing assay and migration of selected skin cell lines incubated in the presence of these NPs.

Keywords: pH, nanoparticles, chronic wounds, release, entrapment efficiency, in vitro wound healing assay