Síntese e caracterização de Géis O-Carboximetil Quitosana/PVA/Nanoparticulas de Prata (AgNPS) para tratamento de queimaduras.

Abstract

Burns, a term defined as tissue damage caused by heat, is a big public health challenge in Brazil and worldwide. A burn causes besides tissue loss, the possibility of infection generated by lesion and microorganisms, which can aggravate the patient's clinical condition if not properly treated. Therefore, several studies have been conducted in search of the development of products based on polymers that help in the moisture and microbiological activity control of the lesion, as well as to promote the cicatrization, reepithelization and infection prevention in patients. Among these products are gels made of synthetic and/or natural polymers. In this work, we

made use of two biodegradable polymers, a natural (O-carboxymethylchitosan – O- CMQ) and synthetic (polyvinyl alcohol - PVA), associated with silver nanoparticles.

Thus, silver nanoparticles were synthesized by the chemical reduction method of silver ions with sodium borohydride (NaBH4), in the presence of hydrogen peroxide (H2O2), polyvinylpyrrolidone (PVP) and sodium citrate (SCT). With regard to the gels, we obtained and studied O-CMQ/PVA/AgNPs gels by using PVA/AgNPs solutions in different proportions. Silver nanoparticles (AgNPs) were characterized by UV-Vis Spectroscopy, Dynamic Light Scattering (DLS), Zeta Potential, Atomic Force Microscopy (AFM), Field Emission Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD. Thermal, chemical and rheological properties of O-CMQ/PVA gels were studied by gravimetry mass loss assays, UV-Vis Spectroscopy degradation kinetics, thermogravimetric analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR) and rheological analysis, respectively. The antimicrobial and cytotoxicological

properties (Agar Diffusion Method and MTT) of AgNPs, O-CMQ/PVA and O- CMQ/PVA/AgNPs gels were evaluated. As results, stable and monodisperse

triangular AgNPs-PVP with an average size of 38,17 ± 1,37 nm (unchanged over 1 month) were obtained, showing no toxicity against L929 cells or antimicrobial activity against S. strains. aureus (ATCC 25923) and E. coli (ATCC 25922). O-CMQ/PVA gels showed low moisture loss, degradation time of 1 day, behaving like Newtonian fluid. The O-CMQ/PVA/AgNPs extracts and gels showed no toxicity in any of their compositions, however, was not observed microbiological activity against S. aureus and E. coli strains. Thus, we obtained non-toxic O-CMQ/PVA/AgNPs gels with promising rheological, physical and chemical properties for use in the treatment of burns and injuries in general. However, microbiological studies involving the required AgNPs concentration for this gel should continue with the aim of providing microbiological control during its application.