Unmodified Bacterial Cellulose Research Articles

Crosslinked bacterial cellulose hydrogels for biomedical applications

Recently, increasing attention has been given to bacterial cellulose-based membranes to be applied as dressings for healing purposes. Bacterial cellulose (BC) is an attractive biomaterial due to its unique structural characteristics such as high porosity, high water retention capacity, high mechanical strength, low density, and biodegradability. One drawback of bacterial cellulose hydrogels is that, after the first dehydration, the water retention capacity is hindered. In this work we produced, modified, and characterized hydrated and de-hydrated BC membranes for biomedical applications. Two crosslinking methods were adopted (using citric acid and epichlorohydrin as crosslinking agents), and the results obtained from the characterization, such as water retention capacity, mechanical properties or contact angle, were compared to those of unmodified bacterial cellulose. We demonstrate that the cross-linked bacterial cellulose membranes present physical properties suitable to be used as wound dressings when hydrated, or as exuding wound dressings, when dehydrated.

The Antimicrobial Effects of Bacterial Cellulose Produced by Komagataeibacter intermedius in Promoting Wound Healing in Diabetic Mice.

As a conventional medical dressing, medical gauze does not adequately protect complex and hard-to-heal diabetic wounds and is likely to permit bacterial entry and infections. Therefore, it is necessary to develop novel dressings to promote wound healing in diabetic patients. Komagataeibacter intermedius was used to produce unmodified bacterial cellulose, which is rarely applied directly to diabetic wounds. The produced cellulose was evaluated for wound recovery rate, level of inflammation, epidermal histopathology, and antimicrobial activities in treated wounds. Diabetic mices’ wounds treated with bacterial cellulose healed 1.63 times faster than those treated with gauze; the values for the skin indicators in bacterial cellulose treated wounds were more significant than those treated with gauze. Bacterial cellulose was more effective than gauze in promoting tissue proliferation with more complete epidermal layers and the formation of compact collagen in the histological examination. Moreover, wounds treated with bacterial cellulose alone had less water and glucose content than those treated with gauze; this led to an increase of 6.82 times in antimicrobial protection, lower levels of TNF-α and IL-6 (39.6% and 83.2%), and higher levels of IL-10 (2.07 times) than in mice wounds treated with gauze. The results show that bacterial cellulose produced using K. intermedius beneficially affects diabetic wound healing and creates a hygienic microenvironment by preventing inflammation. We suggest that bacterial cellulose can replace medical gauze as a wound dressing for diabetic patients.

Modulation of morphology, water uptake/retention, and rheological properties by in-situ modification of bacterial cellulose with the addition of biopolymers

In situ modification of bacterial cellulose (BC) allows structural and morphological tuning which determines the crucial properties such as water absorption/retention and rheological behaviour. This work reports the effect of in situ modification carried out by adding two biopolymers Agar and Chitosan to the standard culture media for bacterial cellulose synthesis. The agar modified BC (Agar-BC) form a BC network with reduced pore volume, and a much denser network, leading to lesser water absorption and further lower retention time than BC. Agar-BC also demonstrates a higher storage modulus, while the yield point is observed at a lower shear strain. This indicates a behaviour similar to that of a crosslinked polymer with a low strain onset of plasticity. On the other hand, chitosan-modified BC (Chitosan-BC) also exhibits a lower pore volume with a lower densely packed structure and with lower swellability and water retention reduced to 1 h (7 h for BC). Chitosan-BC presents a lower modulus with a yield strain similar to that of unmodified BC. The water absorption-retention behaviour is discussed in detail considering the relative pore shape-size distribution, fibre dimension and surface area. The mechanism of viscoelastic deformation for each of the cases is explained.

Chemical Functionalization of Bacterial Cellulose Film for Enhancing Output Performance of Bio-Triboelectric Nanogenerator

Triboelectric nanogenerator (TENG) is a promising technology for converting mechanical energy into electrical energy. In the present research, a bio-TENG based on bacterial cellulose (BC) was fabricated, and the performance was improved by surface modification. The BC films were chemically functionalized by phosphorylation and sulfonation processes. The FTIR technique confirmed the functional groups on the phosphorylated and sulfonated BCs. The hydrophobic/hydrophilic properties were studied and found that the unmodified BC, as well as the functionalized BC, were both hydrophilic. The structure and morphology of the BC nanofibers were investigated by SEM imaging. It was shown that after phosphorylation and sulfonation, the BC nanofiber surface became rougher, and the fibers were densely packed. The pores between the nanofibers almost disappeared. These have resulted from the coating of the phosphate and sulfonic functional groups on the BC nanofibers. For TENG measurement, the BC film was paired with PTFE under a single-electrode measuring mode. The functionalized BC showed improved output performance compared to the unmodified BC, possibly due to the rougher and denser BC surface and the change in the BC triboelectric potential. This research demonstrated a novel but straightforward way to enhance the output performance of the bio-TENG.

Superabsorbent crosslinked bacterial cellulose biomaterials for chronic wound dressings

In this work, we present a novel ex situ modification of bacterial cellulose (BC) polymer, that significantly improves its ability to absorb water after drying. The method involves a single inexpensive and easy-to-perform process of BC crosslinking, using citric acid along with catalysts, such as disodium phosphate, sodium bicarbonate, ammonium bicarbonate or their mixtures. In particular, the mixture of disodium phosphate and sodium bicarbonate was the most promising, yielding significantly greater water capacity (over 5 times higher as compared to the unmodified BC) and slower water release (over 6 times as compared to the unmodified BC). Further, our optimized crosslinked BC had over 1.5x higher water capacity than modern commercial dressings dedicated to highly exuding wounds, while exhibiting no cytotoxic effects against fibroblast cell line L929 in vitro. Therefore, our novel BC biomaterial may find application in super-absorbent dressings, designed for chronic wounds with imbalanced moisture level.

Bacterial cellulose sponges obtained with green cross-linkers for tissue engineering.

Three-dimensional (3D) porous structures with controlled pore size and interconnected pores, good mechanical properties and biocompatibility are of great interest for tissue engineering. In this work we propose a new strategy to obtain highly porous 3D structures with improved properties using bacterial cellulose (BC) and eco-friendly additives and processes. Glucose, vanillin and citric acid were used as non-toxic and cheap cross-linkers and γ-aminopropyltriethoxysilane was used to partially replace the surface OH groups of cellulose with amino groups. The efficiency of grafting and cross-linking reactions was confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The morphological investigation of BC sponges revealed a multi-hierarchical organization after functionalization and cross-linking. Micro-computed tomography analysis showed 80-90% open porosity in modified BC sponges. The thermal and mechanical properties of the sponges were influenced by the cross-linker type and concentration. The strength-to-weight ratio of BC sponges cross-linked with glucose and citric acid was 150% and 120% higher compared to that of unmodified BC sponge. In vitro assays revealed that the modified BC sponges are non-cytotoxic and do not trigger an inflammatory response in macrophages. This study provides a simple and green method to obtain highly porous cellulose sponges with hierarchical design, biocompatibility and good mechanical properties.

Succinylated Bacterial Cellulose Induce Carbonated Hydroxyapatite Deposition in a Solution Mimicking Body Fluid

Incorporation of bone-like hydroxyapatite into bacterial cellulose (BC) is an attractive approach for the fabrication of a bioactive three-dimensional (3D) scaffold for bone tissue regeneration. This study investigates the influence of the succinylation of BC on its ability to incorporate bone-like hydroxyapatite. A biomimetic process using a 1.5 × Simulated Body Fluid (SBF) was used to deposit the hydroxyapatite into the succinylated-BC. After soaking the succinylated-BC in the 1.5 × SBF for six days, Scanning Electron Microscope (SEM) images were taken and the composition of the succinylated-BC was analyzed by energy dispersive X-ray spectrometry. The biocompatibility of the scaffolds was tested in vitro using rat Bone Marrow Stromal Cells (rBMSCs). The SEM images and Fourier Transform Infrared Spectroscopy (FTIR) spectra showed that carbonated hydroxyapatite was deposited on the succinylated-BC. In contrast, only a small amount of carbonated hydroxyapatite deposition was observed on unmodified BC, indicating that the succinyl group in the BC is effective for inducing hydroxyapatite deposition. In vitro studies using rBMSCs revealed the biocompatibility of the scaffold. Combining with the ability of the cells to differentiate into bone cells, the succinylated-BC scaffold is a promising 3D scaffold for bone tissue regeneration.

An efficient method of Yarrowia lipolytica immobilization using oil- and emulsion-modified bacterial cellulose carriers

Abstract Background Yarrowia lipolytica is a nonconventional, dimorphic yeast with multiple biotechnological applications. Considering the size of Y. lipolytica cells and a plethora of its morphological forms (spherical cells or hyphae and pseudohyphae), it is highly difficult to select a suitable carrier for this useful microorganism. Bacterial cellulose (BC) is currently considered one of the most promising immobilization carriers. In the current study, the usefulness of oil- and emulsion-modified BCs as a carrier for Y. lipolytica immobilization was investigated. Static and agitated cultures were conducted in media supplemented with oil or emulsion to improve carrier porosity. Results It was found that the application of oil- and emulsion-modified BCs correlated with significantly higher efficiency of Y. lipolytica immobilization and hence higher yield than the yield achieved with an unmodified carrier. Increased efficiency of immobilization correlated with BC porosity-related parameters, which, in turn, depended on the size of oil droplets introduced into the culture medium. Moreover, changes in porosity-related parameters caused by the addition of oil or emulsion to the medium were observed when the cultures were conducted only under static conditions and not under agitated conditions. Conclusion The application of oil- and emulsion-modified BCs as carriers significantly increased the efficiency of Y. lipolytica immobilization as compared to unmodified BC. The addition of oil or emulsion to the culture medium can be a simple but effective method to modify the porosity of BC-based carriers. How to cite: Żywicka A, Wenelska K, Junka A, et al. An efficient method of Yarrowia lipolytica immobilization using oil- and emulsion-modified bacterial cellulose carrier. Electron J Biotechnol 2019;41. https://doi.org/10.1016/j.ejbt.2019.06.004 .

Nanocomposites Based on Poly(lactic acid) and Bacterial Cellulose Acetylated by an α-Hydroxyacid Catalyzed Route

Poly(lactic acid) (PLA) nanocomposite films reinforced with acetylated bacterial cellulose nanoribbons were prepared by solvent casting. Acetylation of bacterial cellulose (BC) was performed by an innovative and sustainable direct solvent-free route catalyzed by citric acid. The effect of derivatization and its extent on the morphological, optical, thermal and mechanical properties of the nanocomposites was analyzed. Data collected from the above studies showed that acetylation of BC nanoribbons clearly improved the nanofibers dispersion in the PLA matrix with respect to unmodified BC, which in turn resulted in increased transparency and mechanical properties of the nanocomposites produced.

Patterned bacterial cellulose wound dressing for hypertrophic scar inhibition behavior

Hypertrophic scar (HS) is a kind of fibroproliferative disorder with gross and inordinate fiber bundles twisted in the deep scar and it often occurs after deep dermal injury. In this paper, bacterial cellulose (BC), a good candidate for wound dressing, was modified with a stripe pattern by a simple static culture method using patterned PDMS templates in order to investigate the inhibition of cicatricial contractions. The obtained patterned bacterial celluloses (pBC) with different sizes were characterized by optical microscopy and field emission scanning electron microscopy. Different nanofiber structures were observed in bulges and depressions, indicating different cell behaviors on the pBC. In vitro experiments demonstrated that L929 cells showed a clear stripe distribution. Moreover, pBC had an obvious inhibitory effect on L929 cells proliferation, especially pBC with 10 μm stripes which was close to the size of the cells. Furthermore, in vivo experiments of injury model demonstrated that pBC effectively inhibited inflammatory response, reduced accumulation of fibroblasts, and significantly decreased the scar contraction compared to the control and standard groups, indicating its good HS inhibition effect. Compared with that for unmodified BC, the scar thickness for the pBC wound dressing significantly decreased from 428.7 ± 61.9 to 261.5 ± 89.6 µm, which was at least two times less than that of the standard and blank control groups. Excitingly, it was found that if the width of the stripes matched the size of the cell, the pBC had better anti-scar effect, which can also be extended to other dressings.

Polyethyleneimine-bacterial cellulose bioadsorbent for effective removal of copper and lead ions from aqueous solution

Bacterial cellulose (BC) is a green biopolymer suitable for heavy metal ion removal from aqueous solution due to its nano-porous microstructure. Polyethyleneimine-bacterial cellulose (PEI-BC) was prepared by reductive amination of dialdehyde BC with polyethyleneimine. The capacity of PEI-BC in Cu(II) and Pb(II) adsorption from aqueous solution was investigated. The adsorption kinetics could be well expressed by pseudo-second-order model and the adsorption isotherm data were well fitted with Freundlich model. Adsorption processes of Cu(II) and Pb(II) by PEI-BC reached equilibrium very rapid in 30 and 60min, respectively. The maximum adsorption capacity of PEI-BC on Cu(II) and Pb(II) was found to be 148 and 141mg/g, respectively, which was higher than that of unmodified BC and other modified BC reported. PEI-BC also showed good reusability in the adsorption of Cu(II) and Pb(II). This study demonstrates that polyethyleneimine modification makes BC a potential bioadsorbent for heavy metal ion removal in waste water.

Nanocelluloses obtained by ammonium persulfate (APS) oxidation of bleached kraft pulp (BKP) and bacterial cellulose (BC) and their application in biocomposite films together with chitosan

Abstract Bleached birch kraft pulp (BKP, Södra Cell AB, Sweden) and unmodified bacterial cellulose (BC) pellicles, biosynthesized by the bacterium Komagataeibacter rhaeticus, were converted to cellulose nanofibers via ammonium persulfate (APS) oxidation. Fiber dimensions were investigated in an atomic force microscope, and the crystallite size was calculated by Rietveld analysis. Saos-2 osteosarcoma cell line served to assess the in vitro cytocompatibility of the biocomposite films. Results showed that individual cellulose nanofibers with an average width of 80±15 nm and a length between 600 and 1200 nm are formed by APS oxidation. The obtained BC nanofibers can be promising constituents in nanocellulose films and in chitosan-matrix films with improved physical-mechanical and biological properties. Good cellular biocompatibility was found for chitosan/oxidized cellulose films; the viability of Saos-2 osteosarcoma cells was higher on chitosan/oxidized BC films compared to chitosan/oxidized BKP films.

Application of Wet Nanostructured Bacterial Cellulose as a Novel Hydrogel Bioanode for Microbial Fuel Cells

AbstractIn this study, wet bacterial cellulose (BC) with a water content of more than 98% was utilized as a novel scaffold to design bioanodes for microbial fuel cells (MFCs). At first, unmodified wet BC was used a bioanode. Then a simple in situ synthesis of polypyrrole (PPYR) at various pyrrole concentrations was subsequently performed on the BC‘s fibers to generate the novel bioanodes. Characterization of the BC‐PPYR nanobiocomposites was conducted by using ATR‐FTIR, XRD, and FESEM. The performance of the nanobiocomposites was studied in a MFC system by using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and polarization curves. A power density of 136 mW/m2 and a current density of 662 mA/m2 were found for BC‐PPYR, which are superior to those of graphite (1 mW/m2 and 9 mA/m2, respectively). The results were attributed to a good adhesion of bacterial cells to the fibrous surface of BC, permanent capillary transfer of nutrients, the conductive content of hydrogel BC, and good conductivity and catalytic activity of PPYR in the nanocomposite.

Bio-based nanomaterials–versatile materials for industrial and biomedical applications

In this work, unmodified bacterial cellulose pellicles, biosynthesized by the bacterium Komagataeibacter rhaeticus, bleached birch Kraft pulp (Södra Cell AB, Sweden) and birch bark supplied by the plywood industry (JSC Latvijas Finieris, Latvia), were used to obtain the nanoparticles. The results showed that cellulose nanoparticles fabricated by the ammonium persulfate oxidation method, an alternative method developed at the Latvian State Institute of Wood Chemistry, are promising constituents for producing nanopaper. Cellulose and birch bark nanofillers show the potential to improve the physical-mechanical and biological properties of chitosan-matrix films.

Microwave-Assisted Synthesis of Esterified Bacterial Celluloses to Effectively Remove Pb(Ⅱ)

Two modified bacterial celluloses, xanthate-modified bacterial cellulose (XMBC) and sulfate-modified bacterial cellulose (SMBC), were prepared from bacterial cellulose (BC) esterified with xanthate and sulfate, respectively, using microwave irradiation. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS), Fourier transform infrared (FT-IR) spectroscopy, and Brunauer-Emmett-Teller (BET) surface analysis. Batch experiments were carried out to determine the ability of XMBC and SMBC to remove Pb(II) from solution. The effects of pH, contact time, temperature, initial adsorption concentration, and ionic strength on Pb(II) removal were investigated along with regeneration performance. Both the specific surface area and total pore volume of the modified biosorbents were higher than those of unmodified bacterial cellulose. The adsorption of Pb(II) decreased with increasing temperature and ionic strength, and the optimal pH was 5.0. The introduction of thiol groups on bacterial cellulose increased its adsorption capacity for Pb(II); the modified biosorbents exhibited adsorption capacities of 144.93 mg∙g-1 for XMBC and 126.58 mg∙g-1 for SMBC. The adsorption rate closely followed a pseudo-second order model and the adsorption isotherm data were consistent with the Langmuir model. The adsorption of Pb(II) was 753 Acta Phys. -Chim. Sin. 2016 Vol.32

Immobilization of gelatin onto acrylic acid grafted bacterial cellulose for regulating cell behaviors using gamma-irradiation

Event Abstract Back to Event Immobilization of gelatin onto acrylic acid grafted bacterial cellulose for regulating cell behaviors using gamma-irradiation Youn-Mook Lim1, Jin-Oh Jeong1*, Sung-Jun Ahn1*, Sung In Jeong1*, Hui-Jeong Gwon1, Jong-Seok Park1 and Jae Young Lee2 1 Korea Atomic Energy Research Institute, Research Division for Industry & Environment, Korea 2 Gwangju Institute of Science and Technology, School of Materials Science & Engineering, Korea Bacterial cellulose(BC) scaffolds are generated from gluconacetobacter hansenii TL-2C. BC has been shown to have a high-burst pressure and ultrafine highly nanofibrous structure similar with that in a natural extracellular matrix (ECM) for tissue engineering. In this study, acrylic acid(AAc) was grafted onto BC surface using gamma-irradiation and then gelatin immobilized it using EDC/NHS reaction. The characterization of the scaffolds was performed by scanning electron microscopy, ATR-FTIR spectroscopy, a toluidine blue O assay, and 2,4,6,-trinitro-benzensulfonic acid assay. The surface morphology of scaffolds was confirmed BC membranes by SEM for gelatin and AAc grafted it, so that it did not change surface morphology. The adhesion and spreading of human mesenchymal stem cells was improved on the gelatin-AAc-BC nanofiber compared to unmodified BC and AAc-BC nanofiber. Therefore, gelatin and AAc grafted BC scaffolds have been possible to tissue scaffold that accelerate the cell behavior for biomedical applications. Keywords: Tissue Engineering, biomaterial, Biocompatibility, 3D scaffold Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: Poster Topic: Biomimetic materials Citation: Lim Y, Jeong J, Ahn S, Jeong S, Gwon H, Park J and Lee J (2016). Immobilization of gelatin onto acrylic acid grafted bacterial cellulose for regulating cell behaviors using gamma-irradiation. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.01743 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. * Correspondence: Dr. Jin-Oh Jeong, Korea Atomic Energy Research Institute, Research Division for Industry & Environment, Jeongeup-si, Jeollabuk-do, Korea, nanjinoh@gmail.com Dr. Sung-Jun Ahn, Korea Atomic Energy Research Institute, Research Division for Industry & Environment, Jeongeup-si, Jeollabuk-do, Korea, Email1 Dr. Sung In Jeong, Korea Atomic Energy Research Institute, Research Division for Industry & Environment, Jeongeup-si, Jeollabuk-do, Korea, Email2 Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Youn-Mook Lim Jin-Oh Jeong Sung-Jun Ahn Sung In Jeong Hui-Jeong Gwon Jong-Seok Park Jae Young Lee Google Youn-Mook Lim Jin-Oh Jeong Sung-Jun Ahn Sung In Jeong Hui-Jeong Gwon Jong-Seok Park Jae Young Lee Google Scholar Youn-Mook Lim Jin-Oh Jeong Sung-Jun Ahn Sung In Jeong Hui-Jeong Gwon Jong-Seok Park Jae Young Lee PubMed Youn-Mook Lim Jin-Oh Jeong Sung-Jun Ahn Sung In Jeong Hui-Jeong Gwon Jong-Seok Park Jae Young Lee Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Bacterial Cellulose-Based Biomimetic Nanofibrous Scaffold with Muscle Cells for Hollow Organ Tissue Engineering.

In this study, we built a bilayer nanofibrous material by utilizing the gelatinization properties of potato starch (PS) to interrupt bacterial cellulose (BC) assembly during static culture to create more free spaces within the fibrous network. Then, muscle cells were cultured on the loose surface of the BC/PS scaffolds to build biomaterials for hollow organ reconstruction. Our results showed that the BC/PS scaffolds exhibited similar mechanical characters to those in the traditional BC scaffolds. And the pore sizes and porosities of BC/PS scaffolds could be controlled by adjusting the starch content. The average nanofiber diameters of unmodified BC and BC/PS composites is approximately to that of the urethral acellular matrix. Those scaffolds permit the muscle cells infiltration into the loose layer and the BC/PS membranes with muscle cells could enhance wound healing in vivo and vitro. Our study suggested that the use of bilayer BC/PS nanofibrous scaffolds may lead to improved vessel formation. BC/PS nanofibrous scaffolds with muscle cells enhanced the repair in dog urethral defect models, resulting in patent urethra. Improved organized muscle bundles and epithelial layer were observed in animals treated with BC/PS scaffold seeded by muscle cells compared with those treated with pure BC/PS scaffold. This study suggests that this biomaterial could be suitable for tissue engineered urinary tract reconstruction and this type of composite scaffold could be used for numerous other types of hollow organ tissue engineering grafts, including vascular, bladder, ureter, esophagus, and intestine.

Physicochemical characterization of gelatin-immobilized, acrylic acid-bacterial cellulose nanofibers as cell scaffolds using gamma-irradiation

Bacterial cellulose (BC) has been shown to have a high-burst pressure, high-water contact, and ultrafine highly nanofibrous structure similar with that in a natural extracellular matrix (ECM). In the present study, we developed a BC-based functional scaffold for tissue engineering using radiation technology. BC was generated by Gluconacetobacter hansenii TL-2C. Acrylic acid (AAc) was grafted onto BC surfaces under aqueous conditions using gamma-ray irradiation. The characterization of the scaffold was performed by scanning electron microscopy, ATR-FTIR spectroscopy, a toluidine blue O assay, and 2,4,6,-trinitro-benzensulfonic acid assay. AAc was grafted on the BC under gamma-ray irradiation. Gelatin was chemically conjugated on the AAc-BC scaffolds through EDC chemistry. The morphology of the modified BC nanofibers did not change, while representative features of AAc and gelatin were maintained. The adhesion and spreading of human mesenchymal stem cells was improved on the gelatin-AAc-BC nanofibers compared to unmodified BC and AAc-BC nanofibers. Our results suggest that gelatin-immobilized BC nanofiber scaffolds can be a promising way to fabricate three-dimentional, nanofibrous scaffolds that accelerate cell behavior for biomedical applications.

Decolorization of Bemacid azo-dyes by Aspergillus niger

Recently, increasing attention has been given to bacterial cellulose-based membranes to be applied as dressings for healing purposes. Bacterial cellulose (BC) is an attractive biomaterial due to its unique structural characteristics such as high porosity, high water retention capacity, high mechanical strength, low density, and biodegradability. One drawback of bacterial cellulose hydrogels is that, after the first dehydration, the water retention capacity is hindered. In this work we produced, modified, and characterized hydrated and de-hydrated BC membranes for biomedical applications. Two crosslinking methods were adopted (using citric acid and epichlorohydrin as crosslinking agents), and the results obtained from the characterization, such as water retention capacity, mechanical properties or contact angle, were compared to those of unmodified bacterial cellulose. We demonstrate that the cross-linked bacterial cellulose membranes present physical properties suitable to be used as wound dressings when hydrated, or as exuding wound dressings, when dehydrated.

Agarose particle-templated porous bacterial cellulose and its application in cartilage growth in vitro

Bacterial cellulose (BC) is a biocompatible hydrogel with a three-dimensional (3-D) structure formed by a dense network of cellulose nanofibers. A limitation of using BC for applications in tissue engineering is that the pore size of the material (∼0.02–10μm) is smaller than the dimensions of mammalian cells and prevents cells from penetrating into the material and growing into 3-D structures that mimic tissues. This paper describes a new route to porous bacterial cellulose (pBC) scaffolds by cultivating Acetobacter xylinum in the presence of agarose microparticles deposited on the surface of a growing BC pellicle. Monodisperse agarose microparticles with a diameter of 300–500μm were created using a microfluidic technique, layered on growing BC pellicles and incorporated into the polymer as A. xylinum cells moved upward through the growing pellicle. Removing the agarose microparticles by autoclaving produced BC gels containing a continuous, interconnected network of pores with diameters ranging from 300 to 500μm. Human P1 chondrocytes seeded on the scaffolds, replicated, invaded the 3-D porous network and distributed evenly throughout the substrate. Chondrocytes grown on pBC substrates displayed a higher viability compared to growth on the surface of unmodified BC substrates. The approach described in this paper introduces a new method for creating pBC substrates with user-defined control over the physical dimensions of the pore network, and demonstrates the application of these materials for tissue engineering.