Bacterial Nanocellulose Membranes Research Articles

Optimization of bacterial nanocellulose fermentation using recycled paper sludge and development of novel composites.

In this work, recycled paper sludge (RPS), composed of non-recyclable fibres, was used as a carbon source for bacterial nanocellulose (BNC) production. The biomass was enzymatically hydrolysed with Cellic CTec 2 to produce a sugar syrup with 45.40g/L glucose, 1.69g/L cellobiose and 2.89g/L xylose. This hydrolysate was used for the optimization of BNC fermentation by static culture, using Komagataeibacter xylinus ATCC 700178, through response surface methodology (RSM). After analysis and validation of the model, a maximum BNC yield (5.69g/L, dry basis) was obtained using 1.50% m/v RPS hydrolysate, 1.0% v/v ethanol and 1.45% m/v yeast extract/peptone (YE/P). Further, the BNC obtained was used to produce composites. A mixture of an amino-PolyDiMethylSiloxane-based softener, polyethyleneglycol (PEG) 400 and acrylated epoxidized soybean oil (AESO), was incorporated into the BNC membranes through an exhaustion process. The results show that BNC composites with distinct performances can be easily designed by simply varying the polymers percentage contents. This strategy represents a simple approach towards the production of BNC and BNC-based composites.

Enhancing Specific Capacitance and Cyclic Stability through Incorporation of MnO2 into Bacterial Nanocellulose/PPy·CuCl2 Flexible Electrodes

This study reports the polymerization of polypyrrole (PPy) in bacterial nanocellulose (BNC) membranes impregnated with manganese oxide (MnO2). Prior to polymerization, nanosized MnO2 is synthesized in situ using H2SO4 and KMnO4. PPy is then polymerized in situ in the MnO2 impregnated BNC membranes via chemical oxidation using copper chloride dihydrate (CuCl2·2H2O) as the oxidizing agent using two different concentrations of pyrrole (Py): 0.04 and 0.08 mol L−1 with a 1:4 molar ratio of Py/CuCl2·2H2O. Assembled symmetric supercapacitor devices exhibit specific capacitances as high as 1073 mF cm−2 (259 F cm−3) and a capacitance retention of 99.5% after 1000 cycles, which show that the combination of BNC membranes with a conductive polymer and a metallic oxide can be promising as an electrode for energy storage devices.

Structural changes of bacterial nanocellulose pellicles induced by genetic modification of Komagataeibacter hansenii ATCC 23769

Bacterial nanocellulose (BNC) synthesized by Komagataeibacter hansenii is a polymer that recently gained an attention of tissue engineers, since its features make it a suitable material for scaffolds production. Nevertheless, it is still necessary to modify BNC to improve its properties in order to make it more suitable for biomedical use. One approach to address this issue is to genetically engineer K. hansenii cells towards synthesis of BNC with modified features. One of possible ways to achieve that is to influence the bacterial movement or cell morphology. In this paper, we described for the first time, K. hansenii ATCC 23769 motA+ and motB+ overexpression mutants, which displayed elongated cell phenotype, increased motility, and productivity. Moreover, the mutant cells produced thicker ribbons of cellulose arranged in looser network when compared to the wild-type strain. In this paper, we present a novel development in obtaining BNC membranes with improved properties using genetic engineering tools.

Scaffolds for Chondrogenic Cells Cultivation Prepared from Bacterial Cellulose with Relaxed Fibers Structure Induced Genetically.

Development of three-dimensional scaffolds mimicking in vivo cells’ environment is an ongoing challenge for tissue engineering. Bacterial nano-cellulose (BNC) is a well-known biocompatible material with enormous water-holding capacity. However, a tight spatial organization of cellulose fibers limits cell ingrowth and restricts practical use of BNC-based scaffolds. The aim of this study was to address this issue avoiding any chemical treatment of natural nanomaterial. Genetic modifications of Komagataeibacter hansenii ATCC 23769 strain along with structural and mechanical properties characterization of obtained BNC membranes were conducted. Furthermore, the membranes were evaluated as scaffolds in in vitro assays to verify cells viability and glycosaminoglycan synthesis by chondrogenic ATDC5 cells line as well as RBL-2H3 mast cells degranulation. K. hansenii mutants with increased cell lengths and motility were shown to produce BNC membranes with increased pore sizes. Novel, BNC membranes with relaxed fiber structure revealed superior properties as scaffolds when compared to membranes produced by a wild-type strain. Obtained results confirm that a genetic modification of productive bacterial strain is a plausible way of adjustment of bacterial cellulose properties for tissue engineering applications without the employment of any chemical modifications.

Nanocellulose biosynthesis by Komagataeibacter hansenii in a defined minimal culture medium

This study evaluates the capability of Komagataeibacter hansenii ATCC 23769 to synthesize bacterial nanocellulose (BNC) under strict limitation of nutrients with different carbon and nitrogen sources in a defined minimal culture medium in static culture. Five carbon sources were prepared based on the C-molar basis concentration: glycerol, glucose, fructose, mannitol and saccharose, combined with three different nitrogen sources: NH4Cl, NH4NO3 and (NH4)2SO4. BNC production yields were determined based on the dry weight of the produced BNC-Minimal membranes and the carbon consumption for each condition. The combination of 25 mM of glucose and 10 mM of NH4Cl showed the best concentration of C and N sources regarding BNC yield and membrane stability. This is a new proposal of defined minimal culture medium that supports growth of BNC membranes production, without the addition of complex elements such as yeast extract and peptone. BNC membranes produced under these conditions exhibited great optical transparency compared to the membranes produced in complex media (Mannitol and Hestrin–Schramm), therefore increasing a wide range of technological applications.

Flexible TiO2-coated nanocellulose membranes incorporated with CdTe as electrodes in photoelectrochemical cells

Incorporation of quantum dots (QDs) into porous matrices has triggered the development of novel optical devices. In this work, TiO2 sensitized by CdTe incorporated into bacterial nanocellulose (BNC) membranes were tested as photoelectrodes in a photoelectrochemical cell directed to the water splitting for hydrogen generation. The flexible membranes were produced by immersing BNC membranes in an aqueous solution of CdTe capped with glutathione (CdTe–GSH) and further deposited over a thin layer of TiO2. Incorporation of CdTe–GSH into BNC membranes was confirmed by infrared spectroscopy. Fluorescence spectroscopy revealed that the luminescence intensity increased with the immersion time in the CdTe–GSH solution. Field-emission gun scanning electron microscopy (FEG-SEM) images revealed that the CdTe/QDs (5 nm) were homogeneously dispersed on the cellulose nanofibers. BNC/CdTe–GSH membranes was tested as photoelectrodes. Photoelectrochemical cells exhibited a significant photocurrent in wavelengths ranging from 400 to 800 nm, which indicates their potential for applications as flexible electrodes, sensors and photovoltaic systems.

Anti-inflammatory and antioxidant nanostructured cellulose membranes loaded with phenolic-based ionic liquids for cutaneous application

The utilization of natural compounds, such as phenolic acids and biopolymers, in the healthcare domain is gaining increasing attention. In this study, bacterial nanocellulose (BC) membranes were loaded with ionic liquids (ILs) based on phenolic acids. These ionic compounds, with improved solubility and bioavailability, were prepared by combining the cholinium cation with anions derived from caffeic, ellagic and gallic acids. The obtained BC-ILs membranes were homogeneous, conformable and their swelling ability agreed with the solubility of each IL. These membranes revealed a controlled ILs dissolution rate in the wet state and high antioxidant activity. In vitro assays performed with Raw 264.7 macrophages and HaCaT keratinocytes revealed that these novel BC-ILs membranes are non-cytotoxic and present relevant anti-inflammatory properties. Diffusion studies with Hanson vertical diffusion cells showed a prolonged release profile of the ILs from the BC membranes. Thus, this work, successfully demonstrates the potential of BC-ILs membranes for skin treatment.

Bacterial nanocellulose membranes combined with nisin: a strategy to prevent microbial growth

Consumer concerns about synthetic additives is increasing and it can be interesting to apply natural antioxidants with antimicrobial properties. Developing a packing material composed by a natural polymer, such as bacterial nanocellulose membrane (BNCm) loaded with nisin may be applied as a method to keep food quality and to inhibit growth of microbial contaminants. For this reason, the aim of this study was to evaluate antimicrobial activity of BNCm loaded with nisin. Antimicrobial activity of nisin, utilizing or not EDTA solution,was assessed by minimal inhibitory concentration and agar diffusion assay, utilizing Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Antioxidant activity and physico-chemical properties were also evaluated. For the MIC evaluation, the combination of nisin solution with EDTA showed a synergistic effect. Concerning E. coli nisin with EDTA 20–40 mM, MIC was 31.25 μg/mL. Concerning P. aeruginosa nisin with EDTA 10–20 mM, MIC was 125 μg/mL. Concerning S. aureus nisin with EDTA 10 mM, MIC was 15.63 μg/mL, two times lower than without EDTA. The BNCm antimicrobial activity for E. coli, by agar diffusion assay, was observed when nisin was loaded at 250 or 500 μg/mL with EDTA 10 or 20 mM. However, for S. aureus, the antimicrobial activity was observed for BNCm loaded with nisin 15 μg/mL with 10 mM EDTA. For P. aeruginosa, antimicrobial activity was not observed. Nisin exhibited significant antimicrobial and antioxidant activity. The results provide evidence that BNCm loaded with nisin is a promising control strategy to prevent microorganism contamination.

Flexible PEDOT-nanocellulose composites produced by in situ oxidative polymerization for passive components in frequency filters

Conducting undoped poly(3,4- ethylenedioxythiophene) (PEDOT)-coated bacterial nanocellulose membranes were prepared through in situ oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) on the surface of the nanocellulose fibers using Iron (III) p-toluenesulfonate as an oxidant agent. The effect of polymerization conditions (i.e. reaction time and EDOT:oxidant molar ratio) on electrical conductivity, morphology, thermal stability and mechanical properties of the nanocomposites was investigated. High-quality and flexible PEDOT-nanocellulose membranes with an electrical conductivity as high as 1.5 S cm−1 were obtained. The electrical conductivity of nanocomposite membranes increased with increasing the monomer concentration and reaction time due to the formation of a continuous PEDOT layer that completely coated the surface of the nanofibers. The elongation at break of the membranes increased significantly from 3 to 5 days of reaction. The flexible membranes were applied as passive elements in frequency filters. The results revealed a potential use of such class of composites for flexible organic electronics.