Produção de fios contínuos a partir de nanofibras de policaprolactona/seda contendo pontos quânticos de carbono para aplicação em biotêxtil

Abstract

Biotextiles are an emergent field within biomaterials. Due to inherent properties such as lightweight, resistance, and tunability, this kind of structure can resemble biological tissues and be used to treat damaged body parts. In addition to that, textiles are flexible and able to adapt to complex anatomy. Biotextiles are primarily built from fibers, which can be natural, metallic, and synthetic, and combined into it randomly structures (nonwoven) or assembling it into oriented structures, such as yarns. In biomaterials, fiber orientation can act as a topographic clue that can contribute to cell adhesion. In this context, the present project proposed the development of continuous electrospun nanofiber yarns (NF-Ys), based on Polycaprolactone/silk/Carbon Quantum Dots (CDs) to be used in biotextiles. PCL/S micro/nanofibers can provide an interesting combination of mechanical properties and bioactivity. The present work was divided into three stages. Firstly, it investigated the effect of compositional and processing parameters, such as silk content (0-70%), flow rate, and rotatory collector speed on nanofibers morphology, tensile properties, and processability. Among the PCL/S formulations tested, PCL/S 50:50 demonstrated the most adequated balance between processability (continuity of electrospinning without breakage), tensile properties, and morphology. In the second phase, CDs were synthesized by microwave pyrolysis using silk protein as a precursor. CDs were investigated by TEM, FTIR, RMN, UV-Vis, and fluorescence assay. Highly fluorescent CDs were obtained with a mean diameter of 9,4 nm and having amide, amine, and carboxyl groups on the surface. The CDs were incorporated (0-3% w/w) to PCL/silk solution and electrospun into NF-Ys, and the resultant materials evaluated by SEM, mechanical tests, FTIR, Fluorescence and, biological assay (MTT). The addition of CDs to PCL/S NF-Ys resulted in highly fluorescent structures, contributed to increasing strength (1-2% CDs), and reduction of nanofiber diameter. NF-Y PCL/S 1% CDs had the best results considering fluorescence emission, and mechanical properties. In addition to that, PCL/S/CDs NF-Ys demonstrated low cytotoxicity, with cell viability results above 80%. In the last stage of this work, a biotextile prototype was knitted using an i-cord domestic device and PCL/S 1% CD. Such yarns show the potential to be assembled into larger structures such as biotextiles, with possible multi functionalities such as antimicrobial, and biosensing. By using a biomacromolecule that possesses outstanding mechanical properties, combined to a ductile polymer and highly fluorescent nanoparticles, it was proposed the production of fluorescent, resistant, biodegradable and biocompatible nanofiber yarns.