Nanopartículas poliméricas de azul de metileno associadas a filmes de carragenana para potencial tratamento de feridas crônicas empregando terapia fotodinâmica

Abstract

Skin lesions are a global health challenge, as they can result in physical, psychosocial, and financial harm to the community. The healing process, physiologically, is capable of promoting wound recovery, but in cases where the healing stages are interrupted, the risks to patients can be fatal. In this sense, the present work is based on the fact that carrageenan-based polymeric films containing polymeric nanoparticles with methylene blue, associated with photodynamic therapy, can overcome several limitations of conventional treatments, such as antimicrobial resistance, risk of infections, and secondary lesions. For this purpose, films based on carrageenan (2.5%) with glycerol (35% w/w in relation to carrageenan) and tween 20 (0.5% w/w in relation to carrageenan) were obtained. Then, polymeric nanoparticles with particle size of 164.7 nm, PDI of 0.153 and zeta potential of -9.83 mV and encapsulation efficiency (%EE) of 98.70% were incorporated. The films were characterized in terms of thickness, mechanical properties, water vapor permeability, wettability and optical properties. Regarding thickness, values of 0.024 ± 0.004 mm were observed, close to those described in the literature. Regarding mechanical properties, the film containing nanoparticles with methylene blue (FNPAM) presented stress at break and deformation values of 14.77 ± 3.71 MPa and 15.47%, respectively, similar to other studies, with a Young's modulus of 198.4 ± 102.03 MPa, demonstrating some rigidity of the material. The films presented acceptable values of water vapor transmission (WVTP) and water vapor permeability (WPV) at 96.12 ± 11.75 g/h.m² and 0.52093 ± 0.10 g.mm/kPa.h.m², respectively, demonstrating their possible ability to maintain moisture balance. With wettability around 45.66 ± 3.41°, the hydrophilic character of the films was confirmed. DSC, FTIR and SEM tests were also performed. FTIR, DSC and SEM confirmed the compatibility between the constituents of the formulation. Morphologically, the polymeric films did not present such a relevant difference after the inclusion of nanoparticles, suggesting a good accommodation of the nanocarriers in the polymeric matrix and efficient dispersion. Microbiological assays demonstrated the role of photodynamic therapy (PDT) associated with methylene blue nanoparticles incorporated into polymeric films as a differential in controlling the formation of Candida albicans (ATCC 928 and ATCC 14053) biofilms, based on the evaluation of biomass by crystal violet. Morphological evaluation by scanning electron microscopy (SEM) supported previous findings, in which treatments with formulation associated with PDT demonstrated a clear capacity to reduce the production of C. albicans biofilms, indicating antimicrobial efficacy, as expected. Therefore, it is possible to conclude that polymeric films, based on carrageenan, containing methylene blue nanoparticles were appropriately developed as promising delivery systems and potential wound dressings.