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This work aimed to produce porous carboxymethylchitosan-based membranes to be used in the treatment of skin lesions. Thus, β-chitin extracted from squid pens was subjected to ultrasound assisted deacetylation (USAD process), resulting in USAD chitosan with acetylation degree (GGGG ) 63% and viscosity-average molecular weight (MMMM ) 10.3 ± 0.4 x 105 g mol-1. Carboxymethylchitosan (CMCh) was synthesized under heterogeneous condition from the reaction between USAD chitosan and monochloroacetic acid in alkaline medium for 4 hours at 30 °C, resulting in CMCh with average degrees of substitution and deacetylation (GGGG ) = 1,1 and GGGG  = 70 %, respectively. In the second step of the present study, porous membranes based on CMCh and polyvinyl alcohol (PVA) were produced by freeze-drying aqueous solutions of CMQ and PVA, or blends containing different weight ratios CMCh/PVA, namely 75/25, 50/50, 25/75. The membranes were characterized with respect to morphology, porosity, hydration capacity and mechanical and thermal properties (TG). Additionally, the effects of crosslinking with genipin on the physicochemical and mechanical properties of membranes were evaluated. The results of this step revealed that the materials presented porous surfaces and interconnected pores, exhibiting high porosity and swelling capacity. It was observed that the presence of PVA in the polymer blends employed to produce the CMCh/PVA membranes resulted in materials poorly soluble in aqueous medium and thermally more stable as compared to CMCh and PVA membranes. Thus, the membrane prepared from the blends with lower content of PVA showed higher thermal stability when compared to the CMCh membrane. The tensile tests showed that from PVA rich blends, the membranes were more resistant were produced, but less subject to elongation as compared to the CMCh membrane. In general, the crosslinking process allowed to obtain membranes stable in aqueous media, and also more porous and more resistant. However, the crosslinked membranes presented lower thermal stability, water absorption capacity and elongation. The results obtained in this stage of the study indicated that the membranes that presented the greatest potential for application as a curative for skin lesions were composed only of CMCh reticulated with genipine (R(CMCh)) and the non-reticulated CMCh/PVA mass ratio of 25/75 ((CMCh/PVA)25/75). In order to potentiate its use in the treatment of skin lesions and confer new properties on R(CMCh) and (CMCh/PVA)25/75 membranes, ZnO or TiO2 nanoparticles were added to these formulations in different proportions in relation to the total polymer mass, to know, 1%, 2.5% and 5%, totaling four new sets of samples. In addition to the physicochemical and mechanical characterization, the four new membrane sets were also submitted to in vitro enzymatic degradation and susceptibility tests with respect to the Balb / C 3T3 fibroblast cell line clone A 31. The results of this step revealed that the incorporation of nanoparticles resulted in membranes with more defined pores and with greater water absorption capacity. Regarding the thermal and mechanical properties, the assemblies behaved differently according to the nature and content of nanoparticles and as a function of the membrane composition. The presence of nanoparticles in the membranes did not affect the susceptibility to enzymatic degradation, being verified that only the composition of the polymer matrix influenced the stability of the membranes. Membranes composed only of CMCh crosslinked with genipine completely degraded after four days, whereas samples containing PVA, regardless of the presence of nanoparticles or crosslinking with genipine, were not susceptible to the action of the enzyme. Finally, all samples, except for sample R(CMCh)_5ZnO, were shown to be nontoxic in relation to Balb / C 3T3 fibroblasts clone A 31. In general, membranes consisting of CMCh/PVA containing ZnO nanoparticles or of TiO2 exhibited the most promising physical-chemical, mechanical and biological characteristics when considering the potential application of these materials as curatives for skin lesions.

Membranas porosas à base de carboximetilquitosana e poli (álcool vinílico) para o tratamento de lesões de pele