Available on-demand - S.SM08.05.35
Chitosan-Lactic Acid Films as Low-Cost Bovine Milk Whey Protein Carriers for Enhanced Skin Wound Healing
Gerardo Cedillo-Servin1,Ma. Concepcion Peña-Juarez2,Ricardo Vera-Graziano1
Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico1,Facultad de Estudios Superiores Cuautitlan2
In chronic and burn wounds, novel low-cost therapeutic devices and agents are still sought after in order to actively stimulate skin regeneration at the structural, vascular, and immune levels. Recently, bovine milk extracts have been described to have regenerative capabilities comparable to phenytoin in skin-wound in vivo models , thus drawing interest in exploiting this potential. Chitosan films are useful in skin regeneration due to their highly adhesive and antimicrobial properties , though their use as protein delivery agents needs to be further explored. Additionally, when supplied cutaneously, lactic acid has been found to promote angiogenesis, collagen deposition, and growth factor production, resulting in accelerated skin regeneration for in vivo models . Here we report the isolation and loading of bovine milk whey proteins onto chitosan-lactic acid films, as well as the evaluation of their chemical, thermal, and mechanical properties and release profiles. The incorporation of chitosan (CS), lactic acid (LA), and milk whey proteins (MWP) is expected to yield low-cost, scalable cutaneous delivery biomaterials with antimicrobial, angiogenic, and immunomodulating capabilities as a result of their respective individual properties.
Milk whey was isolated from commercial pasteurized bovine milk by pH adjustments, centrifugation, and salting out. The protein precipitates were quantified with a Bradford colorimetric assay and analyzed via SDS-PAGE. This analysis revealed that the isolated proteins did not degrade as a result of the process, thus validating the whey isolation protocol as reliable. Gel permeation and cationic exchange chromatographies were performed to confirm the identities of the protein components in the isolated milk whey. The deacetylation degree of the chitosan samples was determined by nuclear magnetic resonance. Dialyzed, freeze-dried milk whey protein isolate was loaded onto chitosan films prepared from chitosan-lactic acid solutions. The resulting CS-LA-MWP films were analyzed using texturometry, FTIR, TGA, and DSC to evaluate film adhesion strength on human skin, elastic modulus, and elongation to break; the incorporation of all components; and the degradation and glass transition temperatures. Protein release kinetics were determined by UV-vis spectroscopy. Antibacterial activity in vitro and water vapor permeability were also determined for CS-LA-MWP films.
Overall, the protein isolation and film preparation processes reported in this work yielded CS-LA-MWP films that were found to be highly elastic and adhesive, while inhibiting bacterial proliferation and releasing their protein load with an appropriate release profile for skin delivery applications. The regenerative potential of these films will be evaluated shortly in murine skin-wound models.
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The authors wish to thank Victor Zaldivar-Machorro, Martin Vargas-Suarez, Gerardo Cedillo-Valverde, and Karla Reyes-Morales for technical support in characterization techniques. The authors also thank Maria Cristina Piña-Barba for access to centrifugation and freeze-drying equipment. G.C.S. acknowledges financial support from CONACyT through a graduate studies scholarship. R.V.G. acknowledges financial support awarded by PAPIIT-UNAM through grant IG100220.