Carvacrol/clay hybrids loaded into in situ gelling films.

The aim of the present work was the development of polymer films loaded with a carvacrol (CVR)/clay hybrid (HYBD) for the delivery of CRV in infected skin ulcer treatment. Different clays were considered: montmorrilonite, halloysite and palygorskite (PHC). CRV incorporation in PHC reduced its volatility. HYBD showed 20% w/w CRV loading capacity and was able to preserve CRV antioxidant properties. HYBD was characterized by improved antimicrobial properties against S. aureus and E. coli and cytocompatibility towards human fibroblasts with respect to pure CRV. Films were prepared by casting an aqueous dispersion containing poly(vinylalcohol) (PVA), poly(vinylpyrrolidone) (PVP), chitosan glutamate (CS), sericin and HYBD. Optimization of film composition was supported by a Design of Experiments (DoE) approach. In a screening phase, a full factorial design (FFD) was used and the following factors were investigated at two levels: PVA (12-14%w/w), PVP (2-4%w/w) and CS (0.134-0.5%w/w) concentrations. For the optimization phase, FFD was expanded to a "central composite design". The response variables considered were: elongation, tensile strength and buffer absorption of films, durability of the gels formed after film hydration. Upon hydration, the optimized film formed a viscoelastic gel able to protect the lesion area and to modulate CRV release.

"Sponge-like" dressings based on biopolymers for the delivery of platelet lysate to skin chronic wounds.

The aim of the present work was the development of sponge-like dressings, obtained by freeze-drying, based on chitosan glutamate and sodium hyaluronate for platelet lysate (PL) delivery to chronic skin wounds. A first phase of the research focused on the choice of the best dressing composition to obtain formulations endowed with the desired mechanical and hydration properties. In particular glycine amount (cryoprotectant agent), and water content were considered as formulation variables. The addition of glycerophosphate, used to solubilize chitosan at pH close to neutrality, was also investigated. In the second phase of the research, dressings were loaded with different amounts of PL. The influence of freeze-drying process and of excipients on the biological activity of platelet growth factors was investigated by means of a cell proliferation test using human fibroblasts. PDGF AB (platelet derived growth factor) content was assayed by means of ELISA test. Depending on composition, dressings showed different mechanical and hydration properties that make them suitable to wounds with different exudate amounts. Both freeze-drying process and excipients employed did not disturb the activity of platelet growth factors. The dressings loaded with platelet lysate were characterized by % proliferation values on fibroblast cell comparable to those observed for the fresh hemoderivate. The PDGF AB assay confirmed the results obtained from cell proliferation test.