ANA PAULA HONORATO RIBEIRO
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Resumo IPEN-doc 29449 Solubility study of Kraft lignin for the development of electrospun nanofibers2022 - NOGUEIRA, K.M.; VARCA, J.O.; LIMA, C.S.; CRUZ, C.C. da; RIBEIRO, A.H.; FREITAS, L.F.; VARCA, G.H.; LUGAO, A.B.Lignin is a high-volume byproduct of paper manufacturing which has been explored in many research fields, especially for the development of fiber and nanofiber for biomedical applications [1,2]. This work presents a solubility study performed through gravimetry for kraft lignin considering its application for the development of electrospun nanofibers [3]. In practical terms, lignin was solubilized in alkaline aqueous solution, dimethylformamide and dimethylsulfoxide, at concentrations of 10, 15 and 20% (w/v) and varying temperatures of 25, 50 and 75 ºC, under constant stirring. After solubilizing, the solution was filtered, and the insoluble fraction was dried in the oven at 100 ºC. At 25 ºC lignin was insoluble in all solvents tested, as predicted using Hansen solubility parameters. Although the increase in temperature promoted lignin solubilization in all solvents tested, at the highest temperature assayed, the solubilization was facilitated, presenting the smallest levels of the insoluble fraction. Lignin was soluble in all solvents tested, and optimum solubility conditions were achieved using 10% lignin solutions (w/v), without significant insoluble fraction, and therefore ideal concentration for the development of lignin based fibers.Resumo IPEN-doc 27642 Development of Lignin/PEO nanofibers by electrospinning technique for tissue engineering application2020 - NOGUEIRA, K.M.; VARCA, J.O.; LIMA, C.S.; CRUZ, C.C. da; RIBEIRO, A.H.; FREITAS, L.F.; VARCA, G.H.; LUGAO, A.B.Lignin is a renewable carbon source and has been widely explored in different areas over the last years, especially in biomaterials such as dressings and other biomedical devices due its natural origin and low cost. Its chemical structure confers interesting properties such as antioxidant capacity, UV protection, bactericidal action and appropriate adsorption. Poly (ethylene oxide) (PEO) is used in electrospinning to facilitate the formation polymer fibers. The electrospinning technique has been largely explored in the bioengineering area towards designing nanomaterial with minimum defect and high surface area. The present work aimed the development of a lignin/PEO nanofiber by electrospinning technique. In practical terms, lignin/PEO solution was prepared following two different methods. In the first approach, polymer stock solutions were prepared in alkaline water by stirring at 70 °C. In the second, the polymer powders were mixed and dissolved together in dimethylformamide (DMF) under stirring at 80 °C. By both methods, PEO/lignin solutions were prepared at 10, 20 e 30% (w,v) solid content, at the ratios 99/1 and 95/5. For electrospinning parameters, the distance between ejector and plate collector was set to 15-20 cm, voltage to 20 kV and injection flow to 1 mL/h, chamber temperature to 40 °C and 30%. Nanofiber morphology was assessed by scanning electron microscopy and optical coherence tomography. Apparent porosity was measured by classical Archimedes method. Due to higher DMF dielectric constant compared to water, results showed that nanofibers made using DMF presented smaller beats formation and smaller fiber diameter. Nanofibers with higher solid content presented more uniform fibers with larger diameter. Nanofibers with higher lignin concentration presented larger number of beats and higher fiber diameter. However, lignin improved the system porosity in all cases. Further mechanical and biological experiments will be done, nevertheless, the nanofiber developed is a promising material to be applied in tissue engineering.Resumo IPEN-doc 27640 CMC and PVA hydrogel containing papain nanoparticles for drug delivery2020 - LIMA, C.S.; VARCA, G.H.; OLIVEIRA, J.R.; NOGUEIRA, K.M.; SANTOS, F.A.; RIBEIRO, A.H.; LUGAO, A.B.; FREITAS, L.F.; ROGERO, S.O.Four hydrogel formulations of Carboxymethylcellulose (CMC) and Poly (vinyl alcohol) (PVA) were prepared with native papain (AP and BP) and papain nanoparticles (AN and BN) for drug delivery. The formulations were evaluated for their preliminary stability, protein distribution in the matrix and cytotoxicity. Three methods for sterilization purposes were compared: irradiation by 60Co source, electron-beam and UV light. The preliminary stability test confirmed that the system was stable since there was no precipitation or alteration of the organoleptic properties of the samples in the evaluated period. The distribution of proteins in the hydrogel was very homogeneous in all the formulations. Quantification of the enzymatic activity of papain after contact with the gel showed that native papain maintained its activity high (86% and 93% for AP and BP gels, respectively), whereas there was a considerable drop in the activity of the papain nanoparticles to 60.54% and 69.44% for AP and BP gels, respectively. Such loss of activity is attributed to processing and/or process steps. The cell viability assay showed that the polymer matrix shows no cytotoxicity, corroborating with the literature, since the material is biocompatible. Thus, it is possible to affirm that the developed system presents potential for biomedical application, either as a vehicle of papain itself or for the transport of other drugs through complexation with papain nanoparticles. However, the need for further studies of stability, controlled release capacity and biocompatibility is required.