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In this work, polyethylene glycol (PEG), of tree distinct molar masses (200, 300 and 400 g mol −1 ), was grafted onto mercerized bacterial nanocellulose (BNC m ) and applied to produce nanofilms (BNC m -PEG). The products BNC m -PEG were characterized by NMR and thermal analysis. Solid-state NMR and X-ray diffraction analyses exhibited no significant differences in index of BNC m -PEG derivatives compared to BNC m , indicating that grafting reaction did not modify the BNC m crystalline structure. The apparent contact angle of the films showed that BNC m -PEG films exhibited a pronounced increase in the polar components (BNC m : 8.1 mN m −1 vs BNC m -PEG400: 29.4 mN m −1 ), and a decrease in dispersive components (BNC m : 41.7 mN m −1 vs BNC m -PEG400: 35.2 mN m −1 ) of the surface free energy. The BNC m -PEG films were more hydrophilic than BNC m and retained the biocompatibility with L929 fibroblast cells culture. [ABSTRACT FROM AUTHOR]

Abstract: Copaifera langsdorfii (Desf.) Kuntze (copaiba) seeds are abundantly produced and have not yet been characterized. The seed oil presents a characteristic odor of coumarin (250.1±6.57mg/g determined through LC). The fatty acid composition of the oil was determined through CG/FID, being 45.3% linoleic acid, 32.3% monounsaturated, and 22.4% saturated fat. For the lipid-free seeds, the total carbohydrate, protein and moisture were 75.4%, 6.8% and 14.8%, respectively. The C. langsdorfii xyloglucan had an intrinsic viscosity of 804mL/g, and the average molar mass (M w) was 7.82×105 g/mol and R g of 65nm. The degree of polydispersion was 1.7, indicating the polydisperse family of polysaccharides. Its homogeneity, low degree of polymer contaminants and high intrinsic viscosity and molecular mass, represent good potential as a thickening agent. The presence of coumarin and xyloglucan as major components of C. langsdorfii seeds denotes its potential for use in the cosmetic or pharmaceutical industries. [Copyright &y& Elsevier]

Hydroxypropyl methylcellulose (HPMC) and xyloglucan (XG) crosslinked with citric acid over a range of HPMC/XG weight ratios formed sustainable blend films characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, tensile tests, circular dichroism and determination of inhibitory activity against Staphylococcus aureus and Escherichia coli . Both in solution and in the crosslinked films, HPMC chains lost the original ordered conformation upon interacting with XG, giving rise to an entropic gain. The highest values of tensile strength (25 MPa) and Young’s modulus (689 MPa) occurred for the 50:50 HPMC/XG blend films. In vitro loading of gentamicin sulfate (GS) in the films amounted to 0.18 ± 0.05 −0.37 ± 0.05 g of GS per g polymer. At pH 7.4 and 37 °C, the GS release kinetics from the films fitted with the Korsmeyer–Peppas model revealed a non-Fickian release mechanism with diffusional coefficient n ∼ 0.7. The cross-linked films of HPMC, XG and their blends loaded with GS showed outstanding antibacterial activity against Staphylococcus aureus and Escherichia coli , disclosing their potential for novel biomedical applications. [ABSTRACT FROM AUTHOR]

The structural changes resulting from the conversion of native cellulose I (Cel I) into allomorphs II (Cel II) and III I (Cel III I ) have usually been studied using powder samples from plant or algal cellulose. In this work, the conversion of Cel I into Cel II and Cel III I was performed on bacterial cellulose films without any mechanical disruption. The surface texture of the films was observed by atomic force microscopy (AFM) and the morphology of the constituting cellulose ribbons, by transmission electron microscopy (TEM). The structural changes were characterized using solid-state NMR spectroscopy as well as X-ray and electron diffraction. The allomorphic change into Cel II and Cel III I resulted in films with different crystallinity, roughness and hydrophobic/hydrophilicity surface and the films remained intact during all process of allomorphic conversion. [ABSTRACT FROM AUTHOR]

Abstract: Bacterial cellulose (BC), biosynthesized by Acetobacter xylinum, was produced in a medium consisting of rice bark pre-treated with an enzymatic pool. Rice bark was evaluated as a carbon source by complete enzymatic hydrolysis and monosaccharide composition (GC-MS of derived alditol acetates). It was treated enzymatically and then enriched with glucose up to 4% (w/v). The BC produced by static and aerated processes was purified by immersion in 0.1 M NaOH, was characterized by FT-IR, X-ray diffraction and the biosynthetic nanostructures were evaluated by Scanning Electronic (SEM), Transmission Electronic (TEM) and Atomic Force Microscopy (AFM). The BC films arising from static fermentation with rice bark/glucose and glucose are tightly intertwined, partially crystalline, being type II cellulose produced with rice bark/glucose, and type I to the produced in a glucose medium. The nanostructurated biopolymer obtained from the rice bark/glucose medium, produced in a reactor with air flux had micro- and nanospheres linked to nanofibers of cellulose. These results indicate that the bark components, namely lignins, hemicelluloses or mineral contents, interact with the cellulose forming micro- and nanostructures with potential use to incorporate drugs. [Copyright &y& Elsevier]

In this work, polyethylene glycol (PEG), of tree distinct molar masses (200, 300 and 400 g mol(-1)), was grafted onto mercerized bacterial nanocellulose (BNCm) and applied to produce nanofilms (BNCm-PEG). The products BNCm-PEG were characterized by NMR and thermal analysis. Solid-state NMR and X-ray diffraction analyses exhibited no significant differences in index of BNCm-PEG derivatives compared to BNCm, indicating that grafting reaction did not modify the BNCm crystalline structure. The apparent contact angle of the films showed that BNCm-PEG films exhibited a pronounced increase in the polar components (BNCm: 8.1 mN m(-1) vs BNCm-PEG400: 29.4 mN m(-1)), and a decrease in dispersive components (BNCm: 41.7 mN m(-1) vs BNCm-PEG400: 35.2 mN m(-1)) of the surface free energy. The BNCm-PEG films were more hydrophilic than BNCm and retained the biocompatibility with L929 fibroblast cells culture., (Copyright © 2016 Elsevier B.V. All rights reserved.)