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Free films were obtained by the solvent casting method from retrograded starch-pectin dispersions at different polymer proportions and concentrations with and without plasticizer. Film forming dispersions were characterized according to their hardness, birefringence and rheological properties. The polymer dispersions showed a predominantly viscous behavior (G″>G') and the absence of plasticizers lead to building of stronger structures, while the occurrence of Maltese crosses in the retrograded dispersions indicates the occurrence of a crystalline organization. Analyses of the films included mechanical properties, thickness, superficial and cross sectional morphology, water vapor permeability, liquid uptake ability, X-ray diffractometry, in vitro dissolution and enzymatic digestion. The high resistant starch content (65.8-96.8%) assured the resistance of materials against enzymatic digestion by pancreatin. Changes in the X-ray diffraction patterns indicated a more organized and crystalline structure of free films in relation to isolated polymers. Increasing of pectin proportion and pH values favored the dissolution and liquid uptake of films. Films prepared with lower polymer concentration presented better barrier function (WVP and mechanical properties).

A B S T R A C TKomagataeibacter rhaeticus, a bacterium isolated from Kombucha tea, was used to produce bacterial cellulose (BC) through its cultivation in a static sugarcane molasses (SCM) supplemented-culture medium (totally or partially), as an alternative carbon source. BC membranes were characterized by different physicochemical analysis using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission gunscanning electron microscopy (FEG-SEM), thermogravimetry analysis (TGA) and PeakForce quantitative nanomechanics atomic force microscopy (PeakForce (QNM-AFM)). FTIR, XRD and TGA results suggest great similarity among all membranes produced by distinct culture media. Although the glucose (F1) and SCM (F6) media presented the lowest BC yield, all SCM-supplemented culture media (from F2 to F5) showed BC yield values similar to the HS culture medium (F0). FEG-SEM analysis showed that as higher SCM concentrations on culture media higher dense nanofibers network could be prepared. Quantitative nanomechanical results obtained by AFM technique corroborate FEG-SEM analysis besides show smoother and more flexible BC membranes as a function of the increasing of the SCM concentrations. The modification of the carbon source of the culture medium with an important by-product of Brazilian agroindustry appears as a viable alternative to reduce cost of BC production (of up to 20.06%) besides increase the possibilities of industrial scale BC preparation.

Bacterial cellulose (BC) has been extensively exploited for applications in materials science, biomedical and technological fields. The BC production demands culture media rich in carbon sources. Agro-forestry residues constitute an interesting source of nutrients for microorganism, but they are frequently wasted. For cashew crop, exudate is periodically extracted from the tree trunks to increase the production of cashew nut, the most valuable product from cashew trees that produces about 700 g of exudate/year, which remains wasted. Here, we associated the nutritional properties of residues from cashew tree with the need of carbon sources for BC, in attempt to valorize the residue and to decrease the costs of BC production. The carbon source from Hestrin Schramm culture medium was totally or partially replaced by cashew tree residues and the BC production was evaluated. The produced BC membrane in static medium was characterized by FTIR, SEM and TGA and the kinetics of production was determined, suggesting the cashew tree residues as a potential carbon source for BC production.

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Although resistant starch/pectin (RS/P) films have previously displayed suitable properties for colon-specific drug delivery, nanocomposite films were developed aiming to enhance physicochemical, thermal, mechanical and barrier properties, as well as the low oral bioavailability of methotrexate (MTX). FEG-SEM micrographs of nanocomposite films showed different interaction patterns occurring among nanocellulose and RS/P. The nanofiller addition led to an increase in the thermal stability, probably due to its interaction with RS crystalline double helices. Results also displayed an improvement of the puncture strength, while barrier properties revealed a low water vapor permeability. Ex vivo bioadhesion test displayed the nanocomposites films to interact strongly with porcine gastrointestinal mucosa. In vitro drug release studies showed that the films developed enhanced the drug dissolution rates with approximately 80% of MTX release in 150min, suggesting the potential of these materials as a poor solubility drugs carrier, which constitutes an important tool for enhancing oral bioavailability.

Bacterial cellulose/carboxymethylcelullose (BC/CMC) biocomposites with different DS-CMC (DS from 0.7 to 1.2) were developed in order to evaluate their impact as a drug delivery system. Biocomposites were loaded with methotrexate (MTX) as an alternative for the topical treatment of psoriasis. Scanning electron microscopy and atomic force microscopy showed that the CMC coated the cellulose nanofibers, leading to the decrease of the elastic modulus as the DS of CMC increased. BC/CMC0.9 exhibited the lower liquid uptake (up to 11 times lower), suggesting that the more linear structure of the intermediate substitute CMC grade (0.9) was able to interact more strongly with BC, resulting in a denser structure. All samples showed a typical burst release effect in the first 15min of test, however the BC/CMC0.9 biocomposite promoted a slight lowering of MTX release rates, suggesting that the DS of CMC can be considered the key factor to modulate the BC properties.

Cellulose derivatives have been widely used as adsorbents for the removal of micropollutants such as drugs, dyes, and metals, due to their abundance, low cost and non-contaminating nature. In this context, several studies have been performed searching for new adsorbents (cellulose derivatives) efficient at contaminant removal from aqueous solutions. Thus, a new adsorbent was synthesized by chemical modification of cellulose with ethylenediamine in the absence of solvent and applied to the adsorption of amitriptyline (AMI) in aqueous solution. The modification reaction was confirmed by X-ray Diffraction (XRD), elemental analysis, Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetry/Differential Scanning Calorimeter (TG/DSC), solid state Nuclear Magnetic Resonance of 1H and 13C (1H-NMR and 13C-NMR). Moreover, the effectiveness of reaction was confirmed by computational calculations using Density Functional Theory (DFT) at level B3LYP/6-31G(d). This adsorption process was influenced by pH, time, concentration, temperature and did not show significant changes due to the ionic strength variation. Through these experiments, it was observed that the maximum adsorption capacity of AMI by CN polymer at 298 K, 300 min, and pH 7 was 87.66 ± 0.60 mg·g−1.