Bacterial Cellulose Films Research Articles

Preparation and characterization of bacterial cellulose-beeswax films

Bacterial cellulose (BC) based polymer films containing carboxymethyl cellulose (CMC) and beeswax as additives were produced. Control film was prepared by mixing of BC slurry and CMC, while treated films were produced by the addition of beeswax/Tween 80 solution in various concentrations. The objective of this work was to study the effect of beeswax content on properties of BC films. The films were prepared by solution casting technique and dried in convection oven at 40 °C overnight. Addition of beeswax dissolved in Tween 80 affected mechanical properties, significantly reducing the tensile strength but increasing elongation of the control film by 22 and 43%, respectively. Beeswax+Tween80 addition also improved water solubility by doubled from 36 to 73-78%. However, there was no significant difference of WVTR and hydrophobic properties among those films with the addition of beeswax in Tween 80 into the mixtures of BC slurry+CMC.

Nanofibrillated bacterial cellulose and pectin edible films added with fruit purees

Bacterial cellulose (BC) is a water resistant and strong material for edible films. Previous studies have been conducted on edible films containing fruit purees, but not using BC. In this study, films with or without fruit (mango or guava) purees were prepared using different ratios of nanofibrillated BC (NFBC) to pectin. The addition of fruit purees increased water vapor permeability (in about 13–18 times), reduced tensile strength (in more than 90%) and modulus (in about 99%), and increased elongation (in about 13 times), due to plasticizing effects of fruit sugars and matrix dilution by the purees. The partial or total replacement of pectin with NFBC resulted in improved physical properties, making the films stronger, stiffer, more resistant to water, and with enhanced barrier to water vapor. Fruit containing films based on pectin are suggested for sachets, whereas applications for food wrapping or coating may benefit from the use of NFBC.

The Effect of the Drying Process on the Properties of Bacterial Cellulose Films from Gluconacetobacter hansenii

Bacterial cellulose (BC) is a polymeric material that presents unique structural and mechanical properties, high crystallinity, biocompatibility, and biodegradability. All these excellent properties make BC attractive for various biotechnological applications, ranging from biomedical to electronic devices. However, the cultivation conditions to produce BC as well as the downstream processing steps can affect the properties of BC films by modifying the microstructure of the material. This paper reports on the effect of drying method on BC films produced by Gluconacetobacter hansenii using two different procedures (oven drying at 50°C and freeze- drying). Structural changes in the BC films were evaluated using scanning electron microscopy (SEM), thermogravimetric analyses (TGA), X-ray diffraction (XRD), and Fourier-Transform Infrared (FT-IR). The two samples were visually different, as the oven dried BC was transparent while the freeze-dried BC was whitish. SEM micrographs showed that the samples had similar interweaving, but the freeze-dried material presented a higher porosity while oven dried presented collapsed fibers, leading to a volume reduction of the film. The analysis of the thermal stability showed that the films have a similar degradation profile, starting the process of degradation at 319 °C for the oven and at 325 °C for the freeze-dried samples. The BC films showed also similar crystallinities (85%), although their diffratograms exhibit different peaks suggesting that the drying process changed the percentage of Ia/Is polymorphs of the films, which was corroborated by the FT-IR results. These differences in the BC films characteristics submitted to different drying procedures can have an impact on their mechanical properties and water absorption capability, thus potentially influencing the type of possible applications.

Bacterial Cellulose/Alginate Nanocomposite for Antimicrobial Wound Dressing

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New insights into bacterial cellulose materials: production and modification strategies

Komagataeibacter xylinus cultures produced high amount of bacterial cellulose (BC), which has a structure of nanoporous network of interlaced fibers. When the culture is performed under static experimental conditions, a membrane with characteristics of highly hydrated hydrogel and good mechanical properties is obtained with promissory applications in the biomedical field. Bacterial cellulose films can be used from dermal dressing and even as a controlled drug release system. Besides, stirred cultures of K. xylinus produced amorphous cellulose structures dispersed in the medium with physical and mechanical characteristics different from the membrane. In addition, new properties of BC can be obtained or added if the hydrogel is mixed with other compounds or modified post-purification using both organic and inorganic compounds.

Bio-hybridization of nanobactericides with cellulose films for effective treatment against members of ESKAPE multi-drug-resistant pathogens

The rapid expansion of drug-resistant pathogens has created huge global impact and development of novel antimicrobial leads is one of the top priority studies in the current scenario. The present study aims to develop bio-hybridized nanocellulose films which comprise of phytogenic silver nanobactericides. The nanobactericides were synthesized by treating 1 mM silver nitrate with aqueous extract of Chamerion angustifolium which reduced the metal salt to produce polydispersed nanobactericides which were tested against the members of ESKAPE drug-resistant communities. The synthesized silver nanobactericides were subjected to characterization with UV–visible spectra which displayed maximum absorbance at 408 nm. The bio-molecular interaction of phyto-constituents to mediate synthesis and stabilization of nanobactericides was studied with Fourier-transform infrared spectroscopy (FTIR) which depicted functional groups associated with nanobactericides. The crystalline nature was studied with X-ray diffraction (XRD) which showed Bragg’s intensities at 2θ angle which denoted (111), (200), (220), and (311) planes. The morphological characteristics of silver nanobactericides were defined with transmission electron Microscopy (TEM) image which displayed polydispersity of silver nanobactericides with size ranging from 2 to 40 nm. The synthesized nanobactericides showed a significant activity against MRSA strain with 21 mm zone of inhibition. The minimal inhibitory concentration of silver nanobactericides to inhibit the growth of test pathogens was also determined which ranged between 0.625 and 1.25 μg/ml. The silver nanobactericides were bio-hybridized onto nanocellulose films produced by Komagataeibacter xylinus B-12068 culture strain. The films were dried to determine the mechanical properties which showed increased in Young’s modulus and tensile strength in comparison with control bacterial cellulose films. Overall, the results obtained in the present investigation are promising enough to report bactericidal activity of bio-hybridized nanobactericidal films against ESKAPE. These communities are reported to cause severe threats to all forms of lives irrespective to their habitats which can lead to huge economical crisis.

Bacterial cellulose-based hydrogel for wound healing: characterization and in vitro evaluation

Bacterial cellulose (BC) has been considered a promising biopolymer with applications in several areas of knowledge, including medicine, mainly due to its ability to assist in the treatment of dermal lesions. Many groups and companies have been making efforts to develop new BC-based materials in order to add new characteristics and therapeutic possibilities. Recently, Seven Indústria de Produtos Biotecnológicos Ltda company developed a BC-based hydrogel aiming to verify the interaction among the formulation components, its potential for wound healing and biocompatibility studies. BC-based hydrogel was characterized and compared with pristine BC film. Physicochemical characterization includes rheological measurements, thermal analyses, field emission gun - scanning electron microscopy (FE-SEM) and in vitro cell migration. BC-based hydrogel showed adequate interaction among the components of the formulation, which may positively influence its stability. In addition, the BC-based hydrogel accelerated the healing processes demonstrating its potential in dermal lesion treatment.

Transparent, Anisotropic Biofilm with Aligned Bacterial Cellulose Nanofibers

AbstractCellulose nanofibrils are attractive as building blocks for advanced photonic, optoelectronic, microfluidic, and bio‐based devices ranging from transistors and solar cells to fluidic and biocompatible injectable devices. For the first time, an ultrastrong and ultratough cellulose film, which is composed of densely packed bacterial cellulose (BC) nanofibrils with hierarchical fibril alignments, is successfully demonstrated. The molecular level alignment stems from the intrinsic parallel orientation of crystalline cellulose molecules produced by Acetobacter xylinum. These aligned long‐chain cellulose molecules form subfibrils with a diameter of 2–4 nm, which are further aligned to form nanofibril bundles. The BC film yields a record‐high tensile strength (≈1.0 GPa) and toughness (≈25 MJ m−3). Being ultrastrong and ultratough, yet the BC film is also highly flexible and can be folded into desirable shapes. The BC film exhibits a controllable manner of alignment and is highly transparent with modulated optical properties, paving the way to enabling new functionalities in mechanical, electrical, fluidic, photonics, and biocompatible applications.

Design of an optical sensor for ethylene based on nanofiber bacterial cellulose film and its application for determination of banana storage time

In this work, new ethylene gas sensor was developed on the basis of portable bacterial cellulose (BC) nanofiber film doped with KMnO4 (K‐BC). The relationship between the concentration of KMnO4 (8 × 10−3, 8 × 10−4, and 8 × 10−5 mol L−1) and the optical and morphological properties of ethylene sensor was investigated. The Fourier‐transform infrared results showed that some new interactions have occurred between BC membrane and KMnO4. The significant reduction in the relative intensity of the characteristic X‐ray diffraction peak of BC in the doped films clearly indicates that the crystalline fraction decreases as a result of KMnO4 addition. The fabricated K‐BC was used for determination of ethylene concentration. The color, clarity, and absorbance of film at different concentrations of ethylene (10‐2000 μg mL−1) were determined by spectrophotometer. Moisture absorption and water vapor permeability of BC were increased by the addition of KMnO4. Finally, the ethylene optical sensor was used for detection and determination of ethylene concentration in the bunch banana packages.

Effect of peroxide treatment on the structure and transparency of bacterial cellulose film

The cellulose extracts from plants are need of energy and have potential in damaging the environment so that an alternative cellulose source with more efficient results is by using bacteria to produce the cellulose fibers. This study aims to determine the effect of hydrogen peroxide (H2O2) treatment on the structure and transparency of biopolymer bacterial cellulose film (BCF). The method used is the making of BCF by utilizing pineapple peel extract and then cooking at 80°C for 120 min. with H2O2 concentration of 0%, 2.5%, 5%, and 7,5%. Drying is done in the electric oven and then observed the structure and morphology using X-ray diffraction and transparency test, respectively. The result of structure observation shows that the intensity of the highest diffraction peak lies at a diffraction angle of 22° achieved at 5% peroxide treatment with crystallinity and crystal index of 85.1% and 82.4%, respectively. Transparency testing shows that the higher the concentration of peroxide used, the better the transparency.

Структурные и механические свойства бактериальной целлюлозы, полученной при культивировании продуцента на средах с производственными отходами

Bacterial cellulose (BC) is a promising biopolymer with unique properties that make it possible towidely use it in biomedicine, tissue engineering, electrical engineering, food and textile industries. Theaim of a work was to determine the productivity of bacterial cellulose biosynthesis by propagation ofa producer strain on media on the basis of agricultural and food wastes. In present work, the effect of various culture media on strain productivity and structural properties of BC was studied. Three types offermentation media on the basis of agro- and food-processing wastes were used. The productivity of thestrain was evaluated according to biomass yield and BC weight by gravimetric method. The morphologyof BC films was studied by SEM method, and mechanical characteristics – by «Instron» tensile machine.The maximum yield of BC – 8.21+0.02 g/l was achieved by cultivating of a producer on medium containing wastes of sugar production – molasses. The resulting materials formed on classical HS mediumand industrial waste media had an interconnected porous matrix structure with a large surface area.Micro- (15-35 nm) and macrofibrils (50-150 nm) in BC films formed on a medium with molasses joinedinto ribbon-like fibers, providing high mechanical strength (tensile strength: 37.12+0.2, elongation :3.28+0.2%).Key words: bacterial cellulose, fermentation medium, Gluconacetobacter xylinus, industrial wastes

Elaboration of a bacterial cellulose matrix for the immobilisation of Escherichia coli cells

This paper is concerned with the studies of a natural nanomaterial which is bacterial cellulose synthesised by Gluconacetobacter hansenii producer strain. It covers different fields of bacterial cellulose use, including medicine. The research has proved that bacterial cellulose matrices with immobilised cells have high potential as immobilisers of cells, including making probiotics of prolonged action. The matrices consisted of bacterial cellulose films were prepared by static cultivation of G. hansenii GH-1/2008 strain in the liquid medium. We have developed methods of washing out end toxins and producer cells of the films in the solutions of sodium bicarbonate, sodium dodecyl sulphate, and sodium hydroxide. The LAL-test has revealed that washing the films with sodium dodecyl sulphate is more efficient. By means of electron scanning and atomic force microscopy (AFM), we have determined that bacterial cellulose matrices have a layered structure, smooth surface, and adhesion of E. coli test strain cells. The adhesive capacity, the energy of adhesion and contact angle is higher for 50 um thick films than for 20 um thick ones. The bacterial cellulose matrices obtained by the biosynthesis of G. hansenii strain can be recommended for the immobilisation of different producer cells.

Preliminary study on biosynthesis and characterization of bacteria cellulose films from coconut water

Bacterial cellulose produced by Acetobacter xylinum is a unique type of bacterial cellulose. It contains more than 90% of water. A preliminary study had shown that bacterial cellulose films has remarkable mechanical properties. The aim of this study was to investigate the optimum condition such as percentage of carbon source, time of cultivation, and pH to produce bacterial cellulose films from local coconut water, and its characterization on morphology, swelling ability and tensile strength of dried bacterial cellulose. A. xylinum was grown on coconut water culture medium with addition of 3%, 5%, and 7% of sugar, while the cultivation time was vary from 3 days, 5 days and 7 days. pH condition was conducted in pH 3, pH 5 and pH 7. Bacterial cellulose samples were dried using oven with temperature of 100°C until the moisture content reached 4-5%. This study showed that several parameters for optimum condition to produce bacterial cellulose films from local waste of coconut water had been obtained (5% of carbon source; pH 5; and 7 day of incubation period). The electron microscopy also showed that dried bacterial cellulose films had pores covered by fibrils on the surface. Therefore, the present work proposes the optimum formula and condition that can be used based on properties of end product needed.

Thin Layer Drying Model of Bacterial Cellulose Film

The bacterial cellulose film produced by Acetobacter xylinum using coconut water as a carbon source was dried at a temperature of 60 to 100 C. The drying process of bacterial cellulose film occur at falling rate drying period. Increasing drying temperature will shorten the drying time. The drying data fitted with thin layer drying models that widely used, Newton, Page and Henderson and Pabis models. All thin layer drying models describe the experimental data well, but Page model is better than the other models on all various temperature with coefficients of determination (R2) range from 0.9908 to 0.9979, chi square range from 0.000212 to 0.000851 and RMSE range from 0.014307 to 0.0289458.

Antibacterial properties of films of cellulose composites with silver nanoparticles and antibiotics

The present study describes production of bacterial cellulose composites with silver nanoparticles and antibiotics and compares their properties. Bacterial cellulose (BC) composites synthesized in the culture of the strain of acetic acid bacterium Komagataeibacter xylinus VKPM B-12068 with silver nanoparticles, BC/AgNps, were produced hydrothermally, under different AgNO3 concentrations (0.0001, 0.001, and 0.01 M) in the reaction medium. The presence of silver in the BC/AgNp composites was confirmed by elemental analysis conducted using scanning electron microscopy with a system of X-ray spectral analysis. Analysis showed that the average atomic number of silver particles in composite samples depended on the concentration of AgNO3: as AgNO3 concentration in the reaction solution was increased, silver content in the composites increased from 0.044 to 0.37 mg/cm2. BC composites with amikacin and ceftriaxone were prepared by immersing dry BC films in solutions containing different concentrations of the antibiotics. The surface structure and properties and physicochemical and mechanical characteristics of composites were investigated using SEM, DSC, X-ray analysis, the system for measuring water contact angles, and electromechanical tensile testing machine. The disk-diffusion method and the shake-flask culture method used in this study showed that all experimental composites had pronounced antibacterial activity against E. coli, Ps. eruginosa, K. pneumoniae, and St. aureus, and the BC/antibiotic composites were more active than BC/AgNp ones; S. aureus was the most susceptible to the effect of BC composites. No potential cytotoxicity was detected in any of the BC/AgNp composites in the NIH 3T3 mouse fibroblast cell culture, in contrast to the BC/antibiotic composites. These results suggest that BC composites constructed in the present study hold promise as dressings for managing wounds, including contaminated ones.

Production of Bacterial Cellulose by Gluconacetobacter hansenii Using Corn Steep Liquor As Nutrient Sources.

Cellulose is mainly produced by plants, although many bacteria, especially those belonging to the genus Gluconacetobacter, produce a very peculiar form of cellulose with mechanical and structural properties that can be exploited in numerous applications. However, the production cost of bacterial cellulose (BC) is very high to the use of expensive culture media, poor yields, downstream processing, and operating costs. Thus, the purpose of this work was to evaluate the use of industrial residues as nutrients for the production of BC by Gluconacetobacter hansenii UCP1619. BC pellicles were synthesized using the Hestrin–Schramm (HS) medium and alternative media formulated with different carbon (sugarcane molasses and acetylated glucose) and nitrogen sources [yeast extract, peptone, and corn steep liquor (CSL)]. A jeans laundry was also tested. None of the tested sources (beside CSL) worked as carbon and nutrient substitute. The alternative medium formulated with 1.5% glucose and 2.5% CSL led to the highest yield in terms of dry and hydrated mass. The BC mass produced in the alternative culture medium corresponded to 73% of that achieved with the HS culture medium. The BC pellicles demonstrated a high concentration of microfibrils and nanofibrils forming a homogenous, compact, and three-dimensional structure. The biopolymer produced in the alternative medium had greater thermal stability, as degradation began at 240°C, while degradation of the biopolymer produced in the HS medium began at 195°C. Both biopolymers exhibited high crystallinity. The mechanical tensile test revealed the maximum breaking strength and the elongation of the break of hydrated and dry pellicles. The dry BC film supported up to 48 MPa of the breaking strength and exhibited greater than 96.98% stiffness in comparison with the hydrated film. The dry film supported up to 48 MPa of the breaking strength and exhibited greater than 96.98% stiffness in comparison with the hydrated film. The values obtained for the Young’s modulus in the mechanical tests in the hydrated samples indicated low values for the variable rigidity. The presence of water in the interior and between the nanofibers of the hydrated BC only favored the results for the elasticity, which was 56.37% higher when compared to the dry biomaterial.

A bilayered PLGA/multiwall carbon nanotubes/bacterial cellulose composite membrane for tissue regeneration of maxillary canine periodontal bone defects

A bilayered polylactic-co-glycolic acid (PLGA)/multiwall carbon nanotubes (MWNTs)/bacterial cellulose (BC) composite membrane was prepared by vacuum freeze-drying and electrospinning for use as a guided tissue regeneration (GTR) membrane to repair maxillary canine periodontal defects in beagle dogs. Morphological and histological observations and analyses were performed to characterize the membrane. The bilayered membrane comprised a lower fibrous BC film layer and an upper electrospun PLGA/MWNTs film layer with a three-dimensional network structure. The histological results showed that the bilayered membrane promoted periodontal tissue regeneration. The BC/PLGA/MWNTs membrane may be an ideal GTR membrane candidate and thus has potential therapeutic applications in periodontal disease.

Drug release and antioxidant/antibacterial activities of silymarin-zein nanoparticle/bacterial cellulose nanofiber composite films

Bacterial cellulose (BC) is a biopolymer composed of nanofibers which has excellent film-forming ability. However, BC do not have antibacterial or antioxidant activity, thus limiting the applicability of BC for food and biomedical applications. In this study, flavonoid silymarin (SMN) and zein were assembled into spherical SMN-Zein nanoparticles that could be effectively adsorbed onto BC nanofibers. SMN-Zein nanoparticles greatly changed the wettability and swelling property of BC films due to the formation of nanoparticles/nanofibers nanocomposites. SMN-Zein nanoparticles enhanced the release of sparingly soluble silymarin from the nanocomposite films. The active films showed more effective antioxidant and antibacterial activities as compared with pure BC films and thus were able to protect salmon muscle from deterioration and lipid oxidation. These findings suggest that the nanoparticle/nanofiber composites may offer a suitable platform for modification of BC films with improved drug release properties and biological activities.

Light-emitting flexible transparent paper based on bacterial cellulose modified with semiconducting polymer MEH:PPV

We demonstrated flexible light-emitting transparent bacterial cellulose (BC) paper modified with semiconducting polymer operated by pulse voltage. We prepared thin (∼ 35 μm) transparent BC films modified with luminescent conjugated polymer MEH:PPV with Ag electrodes. It was shown that the photoluminescence (PL) spectrum of BC/MEH:PPV films contains emission contributions from both BC and MEH:PPV components and that the PL intensity of BC and MEH:PPV maxima versus excitation power is sublinear. This indicates that exciton–exciton annihilation occurs in the light-emitting polymer at high excitation power. We found that the dependences of the spike-like electroluminescence (EL) intensity of BC/MEH:PPV films excited by the pulse voltage at different frequencies versus applied pulse bias and pulse frequency are superlinear. We assume that the turn-on and turn-off spikes originate from the recombination of charges accumulated in the bulk of the semiconducting polymer (bulk de-trapping) during the voltage pulse. The results demonstrate that such composites are prospective for application as flexible, transparent and environmentally friendly light-emitting cellulose-based papers for displays and lighting as well as biosensors.

Preparation of bacterial cellulose films with regenerative effect

The filter medium plays an important role in modulating the performance of biological aerated filters (BAFs). In this study, a zeolite composite filter (ZCF) was fabricated using a mixture of natural zeolite powder as the main material, cement as the binder, and waste paper pulp as the pore-forming agent (slow-release carbon source). Scanning electron microscopy and porosimetry were then conducted to evaluate the properties of the ZCF. Results showed that the uniform and interconnected pores of the ZCF are suitable for microbial growth. ZCF and commercially available ceramsite (CAC) used in an upflow laboratory-scale BAF were investigated to determine their suitability for advanced wastewater treatment. The results indicated that the ZCF–BAF is superior to the CAC–BAF in terms of total organic carbon, total nitrogen, ammonia nitrogen, and phosphorus removal. The carbon source from the waste paper pulp was released slowly, which decisively influenced simultaneous nitrification and denitrification. Therefore, ZCF is suitable for use as a novel filter medium for the simultaneous removal of nitrogen and phosphorus in BAFs for advanced wastewater treatment.