Desenvolvimento e caracterização de membranas co-eletrofiadas de poliácido lático/policaprolactona com incorporação de extrato de uxi-amarelo (Endopleura uchi) para aplicação biomédica

Abstract

There is a growing demand for more affordable and viable biomaterials. Co-electrospinning has emerged as a promising alternative technique. It enables the production of hybrid electrospun membranes composed simultaneously of two or more polymer types with tunable properties. However, the co-electrospun membrane alone lacks antifungal or antimicrobial properties. Consequently, incorporating extracts such as uxi amarelo, which possesses antimicrobial and antifungal properties presents a promising alternative. Therefore, this study aimed to develop and characterize electrospun and co-electrospun membranes made of polylactic acid (PLA) and polycaprolactone (PCL) for biomedical applications. Membranes of pure PLA and PCL were produced, as well as co-electrospun membranes in PCL:PLA (w/w) ratios of 1:2, 1:1, and 2:1. The samples were characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermal analysis (TG/DTG and DSC), tensile testing, scanning electron microscopy (SEM), and contact angle measurements. Finally, *uxi amarelo* bark extract was incorporated into the polymer matrix to evaluate antimicrobial and antifungal properties. FTIR results confirmed the preservation of the polymers' chemical structures following the electrospinning and co-electrospinning processes, evidenced by the presence of characteristic bands for ester, carbonyl (C=O), C–H, and C–O–C groups, with no formation of new chemical bonds. In the co-electrospun membranes, the coexistence of bands typical of both polymers was observed, with no appearance of new bands or significant spectral shifts, indicating that the interaction between PLA and PCL is predominantly physical. FTIR results confirmed the preservation of the polymers' chemical structures following the electrospinning and co-electrospinning processes, evidenced by the presence of characteristic bands for ester, carbonyl (C=O), C–H, and C–O–C groups, without the formation of new chemical bonds. X-ray diffraction (XRD) analyses demonstrated the coexistence of crystalline phases characteristic of PLA and PCL, indicating the formation of a physical blend between the polymers. A reduction in crystallinity was observed in the co-electrospun membranes compared to pure PCL, which exhibited a crystallinity of 50.14%, whereas the PCL/PLA 1:1, PCL/PLA 1:2, and PCL/PLA 2:1 membranes showed indices of 22.10%, 21.15%, and 28.66%, respectively. Thermal analyses revealed the membranes' thermal stability up to approximately 280–300 °C, as well as the preservation of the glass transition (Tg), crystallization (Tc), and melting (Tm) temperatures characteristic of the constituent polymers. Tensile mechanical tests showed that incorporating PCL into PLA increased the membranes' deformation capacity, imparting greater flexibility, while the presence of PLA contributed to higher mechanical strength. The PCL/PLA 1:1 composition exhibited the best balance between tensile strength (6.7 MPa), elastic modulus (32 MPa), and strain at break (290%). SEM morphological analyses revealed continuous, highly porous fibrous structures with randomly distributed fibers characteristics favorable for biomedical applications with diameters ranging from 0 to 7 µm. The membranes exhibited hydrophobic behavior, with contact angles exceeding 120°; higher values were observed for the 1:1 and 2:1 PCL/PLA co-electrospun membranes, attributed to increased surface roughness resulting in angles above 130°. Overall, the results demonstrated that the co-electrospinning of PLA and PCL is an efficient strategy for producing membranes with tunable structural, thermal, mechanical, and surface properties. Among the compositions evaluated, the 1:1 PCL/PLA membrane stood out for its balanced set of properties, highlighting its potential for biomedical applications; upon surface incorporation of uxi amarelo (yellow uxi) bark extract, the 1:1 PCL/PLA co-electrospun membrane demonstrated antimicrobial and antifungal activity against Staphylococcus aureus, Pseudomonas aeruginosa, Candida tropicalis, and Candida albicans.