Wound-healing hydrogels synthetized by photopolymerization to improve skin tissue repair and disinfection

CAGNETTA GONZALO; GALLASTEGUI, ANTONELA; JOSEFA MARTUCCI; LUIS IBARRA; SOL MARTINEZ; RODRIGO PALACIOS; CARLOS CHESTA; MARÍA LORENA GÓMEZ

San Sebatian

Simposio; XVII Simposio Latinoamericano de Polímeros (SLAP 2022); 2022

IntroductionAn ideal dressing to treat wound-healing should present some general properties such as: protectthe wound from the environment, possess appropriate hydrophilicity [1,2], biocompatibility, antimicrobial activity, proper adhesion and flexibility allowing mobility. One of the mostversatile materials to this end is the use of dressings based on hydrogels. [3,4] We report here on the synthesis of hydrogels by photopolymerization, with improved properties toaid wound healing and disinfection processes. These hydrogels have excellent swelling capacity,good mechanical stability, ductility, adhesiveness and temperature response properties. In biological tests, these new materials showed high biocompatibility and antibacterial activity.ExperimentalWe synthetized three formulations of hydrogels containing METAC/NIPAM named as: F1 (25 % NIPAM, 75% METAC), F2 (50% NIPAM, 50% METAC) and F3 (75% METAC, 25% NIPAM). A silsesquioxano (SSO-1) was employed as a crosslinking agent and nanoparticles of poly(9,9- dioctylfluorene-alt-benzothiadiazole) as macro - photoinitiator [5]. Hydrogels were characterized by swelling capacity, DSC, FTIR, TGA, stress-strainand adhesiveness assays, etc. Biologicalproperties were carried-out in vitro thoughhemolysis, cellular viability and antibacterialactivity experiments.Results and DiscussionSwelling measurements were carried out in PBS (pH 7,4) at 25°C. Results are shown in Figure 1. Figure 1: Swelling degree from three formulations of hydrogels in PBS 7.4 at 25°C. In all cases a high degree of swelling is observed, being higher for hydrogels with major content of METAC (ionic monomer). We carried out tensile test with the objective of study the mechanical properties of the new materials. The formulations with higher content of NIPAM monomer have Young’s modulus (E)comparable with those reported in bibliography [6,7]; E decreased with increasing ionic monomercomposition [8-10]. These results are particularly important since suggest that hydrogels should maintain their mechanical properties during the time of healing.Biological studies were carried out to test the biocompatibility and inherent antimicrobial activityof the synthesized materials. To this end, MTT experiments were performed on eukaryotic cells toevaluate the biocompatibility of the new materials. These experiments were accomplished with theuse of human keratinocyte cultures (HaCaT) in the presence of hydrogels and with the use of silicone discs of similar dimensions to those of the polymers experiments as controls wells. Figure 2: Percentage of cell viability measured by MTT assay from cell line HaCaT after 24 h of exposure with hydrogels. As shown in Figure 2 there is only a minor decrease in the cellular activity compared to control experiments, which allows to affirm that hydrogels are biocompatible.Finally, to study the antibacterial activity we compared the kinetics of S. aureus bacterial growth in presence and absence of hydrogels in culture medium. Results are shown in Figure 3.As shown below, F1 and F2 hydrogels cause a clear reduction in bacterial activity, so they can beclassified as bactericides, while the F3 formulation revealed a bacteriostatic effect. Figure 3: Bacterial inhibition (S. aureus) kinetics for the three formulations of hydrogels with its corresponding controls in black squares.These experiments suggest that our hydrogels could aid in the healing process of wounds bykeeping the damaged area free of infection. In summary, the observed properties of the synthesized hydrogels suggest that they could be employed in the fabrication of biocompatible materials with applications in biomedicine, mainly in wound-healing and disinfection.References1 Sweeney, I. R. Miraftab, M. Collyer. G. (2012) Int Wound J, 9:601.2 Yari, A. Yeganeh, H. Bakhshi, H. (2012) J Mater Sci Mater Med, 23:2187.3 Boateng, S. (2008) J. Pharm Sci, 97:2892.4 Caló, E. Khutorynaskiy, V. (2015) Eor Polym J, 65: 252.5 Gallastegui, A. (2020) Macromol. Rapid Commun. 19006016 Omidian, H.P., (2010) Introduction to Hydrogels, Biomedical Applications of Hydrogels Handbook, R.M. Ottenbrite, Editor. SpringerScience+Business Media: New York, USA.7 Gatta, L. (2009). Journal of Biomedical Materials Research Part A, 90A(1):292.8 Takigawa, T. (1997). Polym. Gels Networks 5 (6):585.9 Haq, M.A. (2017) Materials Science and Engineering C 70 842. 10 Muniz, E. C. Geuskens, G. (2001) Macromolecules 34:4480.