Bacterial Nanocellulose Hydrogels Research Articles

Edge-functionalized coal-derived graphene oxide in bacterial nanocellulose hydrogel for active wound healing

This work presents a comparison of physicochemical and in vitro active wound healing properties of two distinct graphene oxides (GOs) from graphene and coal. These GOs are incorporated in Bacterial nanocellulose (BNC) to form hydrogels. The performance and limitations of the loading fraction of both GOs in BNC are controlled by the processing technology and the source materials from which GOs are derived. Edge functionalization with C-GO offers an advantage of facilitating edge-to-face assembly in the hydrogel leading to better dispersion compared to the face-to-face assembly of basal functionalized G-GO. The latter leads to more aggregation of G-GO, resulting in a lower optimal loading fraction. Our investigation into the antibacterial properties of the BNC and BNC/GO hydrogels against gram-negative E. coli revealed inhibitory effects of the BNC/GO hydrogels that intensified with an increase in the concentration of GO. Furthermore, an in vitro wound scratch assay demonstrated that BNC/C-GO hydrogels promote better cell migration, confirming their superior biocompatibility and suitability as active wound dressings, albeit limited by loading fraction due to agglomeration. These findings shed light on the performance and limitations of GOs for diverse applications, emphasizing the significance of exploring the influence of different methods and source materials of GOs.

Bacterial Nanocellulose Hydrogel for the Green Cleaning of Copper Stains from Marble.

Cultural heritage stone materials frequently experience significant discoloration induced by copper corrosion products, especially calcareous stones associated with bronze or copper statues and architectural elements. This alteration originates from the corrosion of unprotected copper, resulting in the formation of various Cu minerals and the migration of soluble ions to adjacent stone materials. Traditional cleaning methods involve mechanical, chemical, and laser techniques, which are generally time-consuming, costly, not ecological, or can possibly damage original materials. The loading of highly effective chelating agents, such as ethylenediaminetetraacetic acid (EDTA), into hydrogels has recently been exploited. However, the preference for synthetic hydrogels has been prominent until now, although they lack renewability and biodegradability and require high costs. This study explores for the first time the potential to clean copper corrosion with bacterial nanocellulose (BC) loaded with EDTA as a biologically based, sustainable, and biodegradable hydrogel. The BC hydrogel was characterised by field emission-scanning electron microscopy (FE-SEM), X-ray diffraction analysis (XRD), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), simultaneous thermal analysis (TG-DSC), and tensile testing. It revealed a nano-fibrous structure with high crystallinity and purity and mechanical properties suitable for cultural heritage applications. The EDTA-loaded hydrogel effectively removed copper stains from marble after 120 min of application. Micro-Raman and colorimetric analyses assessed the cleaning efficacy. The study introduces bacterial nanocellulose as a green and effective alternative for heritage conservation, aligning with sustainable methodologies in stone conservation.

Bacterial Nanocellulose Hydrogel: A Promising Alternative Material for the Fabrication of Engineered Vascular Grafts.

Blood vessels are crucial in the human body, providing essential nutrients to all tissues while facilitating waste removal. As the incidence of cardiovascular disease rises, the demand for efficient treatments increases concurrently. Currently, the predominant interventions for cardiovascular disease are autografts and allografts. Although effective, they present limitations including high costs and inconsistent success rates. Recently, synthetic vascular grafts, made from artificial materials, have emerged as promising alternatives to traditional methods. Among these materials, bacterial cellulose hydrogel exhibits significant potential for tissue engineering applications, particularly in developing nanoscale platforms that regulate cell behavior and promote tissue regeneration, attributed to its notable physicochemical and biocompatible properties. This study reviews recent progress in fabricating engineered vascular grafts using bacterial nanocellulose, demonstrating the efficacy of bacterial cellulose hydrogel as a biomaterial for synthetic vascular grafts, specifically for stimulating angiogenesis and neovascularization.

Porous biomorphic silicon carbide nanofibers from bacterial nanocellulose

This paper reports the synthesis of biomorphic SiC from bacterial nanocellulose (BNC) aerogel templates through silicon vapor infiltration-reaction. The as-received bacterial nanocellulose hydrogels were submitted to CO2 supercritical drying to form BNC aerogels that were pyrolyzed at 800 °C. The carbon aerogels were placed on top of a silicon powder bed and heated to 1300 °C for Si-vapor infiltration-reaction. XRD phase analysis confirmed that biomorphic β-SiC nanofibers resulted from Si reaction with carbon. Morphological characterization by scanning electron microscopy revealed that the formed SiC maintained the original nanofibrous structure of BNC. Residual carbon was observed in the thermogravimetric analysis. The specific surface area decreased after vapor infiltration, although the porosity remained above 90%. The resulting electrical resistivity of 3.7 Ω cm for highly porous β-SiC is above other studies on SiC with similar structure.

Antimicrobial Formulation of a Bacterial Nanocellulose/Propolis-Containing Photosensitizer for Biomedical Applications

With the aim of contributing to the development of more efficient materials for wound care, new topical formulations based on bacterial nanocellulose (BNC) hydrogels containing propolis were produced. Characterizations confirmed the incorporation of propolis into the BNC matrix, maintaining its structure and properties. Rheological analysis confirmed that the hydrogels showed thixotropic behavior appropriate for topical application. Chromatographic profiles showed sustained release of propolis biomarkers for at least 20 h. The formulations did not present mutagenicity. For application in photodynamic inactivation (PDI), BNC/propolis hydrogels were prepared with the photosensitizers methylene blue (MB). Spectroscopy and confocal fluorescence microscopy confirmed the interaction of MB and propolis in BNC hydrogels, as well as the formation of a new composite material. In the antibacterial assays, formulations containing MB and propolis significantly reduced Staphylococcus aureus growth. In the presence of light, BNC/MB hydrogels completely inhibited the microorganism. Therefore, the results suggest potential materials for the prevention or treatment of Staphylococcus aureus infections in wounds.

One-step biosynthesis of a bilayered graphene oxide embedded bacterial nanocellulose hydrogel for versatile photothermal membrane applications

We illustrate the facile one-step biosynthesis of a bilayer structured hydrogel composite of reduced-graphene oxide (rGO) and bacterial nanocellulose (BNC) for multiple filtration and photothermal water treatment applications.

Influence of Drying Method and Argon Plasma Modification of Bacterial Nanocellulose on Keratinocyte Adhesion and Growth.

Due to its nanostructure, bacterial nanocellulose (BC) has several advantages over plant cellulose, but it exhibits weak cell adhesion. To overcome this drawback, we studied the drying method of BC and subsequent argon plasma modification (PM). BC hydrogels were prepared using the Komagataeibacter sucrofermentans (ATCC 700178) bacteria strain. The hydrogels were transformed into solid samples via air-drying (BC-AD) or lyophilization (BC-L). The sample surfaces were then modified by argon plasma. SEM revealed that compared to BC-AD, the BC-L samples maintained their nanostructure and had higher porosity. After PM, the contact angle decreased while the porosity increased. XPS showed that the O/C ratio was higher after PM. The cell culture experiments revealed that the initial adhesion of human keratinocytes (HaCaT) was supported better on BC-L, while the subsequent growth of these cells and final cell population density were higher on BC-AD. The PM improved the final colonization of both BC-L and BC-AD with HaCaT, leading to formation of continuous cell layers. Our work indicates that the surface modification of BC renders this material highly promising for skin tissue engineering and wound healing.

Nanocellulose-Reinforced Hydroxyapatite Nanobelt Membrane as a Stem Cell Multi-Lineage Differentiation Platform for Biomimetic Construction of Bioactive 3D Osteoid Tissue In Vitro.

Severe bone defects, especially accompanied by vascular and peripheral nerve injuries, remain a massive challenge. Most studies related to bone tissue engineering have focused on osteogenic differentiation of mesenchymal stem cells (MSCs), and ignored the formation of blood vessels and nerves in the newly generated bone owing to the lack of proper materials and methodology for tuning stem cells differentiated into osteogenic, neuronal, and endothelial cells (ECs) in the same scaffold system. Herein, a nanocellulose-reinforced hybrid membrane with good mechanical properties and control over biodegradation by assembling ultralong hydroxyapatite nanobelts in a bacterial nanocellulose hydrogel is designed and synthesized. Osteogenic, neuronal cells are successfully differentiated on this hybrid membrane. Based on the multi-lineage differentiation property of the membrane, a bioactive 3D osteoid tissue (osteogenic, neural, and ECs) is mimetically constructed in vitro using layer-by-layer culture and integration. The bone regeneration ability of the as-prepared bioactive osteoid tissue is assessed in vivo via heterotopic osteogenesis experiments for eight weeks. The rapid new bone growth and formation of blood capillaries and nerve fibers prove that the hybrid membrane can be universally applied as a stem cell multi-lineage differentiation platform, which has significant applications in bone tissue engineering.

Multifunctional cellulosic nanofiber film with enhanced antimicrobial and anticancer properties by incorporation of ethanolic extract of Garcinia mangostana peel

Natural polymeric nanofibers-based materials for medical application is an intensive research area due to the unique features of natural polymeric nanofibers. Bacterial nanocellulose (BC) films containing various concentrations of mangosteen (Garcinia mangostana) peel extract were prepared and evaluated as a multifunctional nanofiber film. The extract was absorbed into BC hydrogel and air dried to entrap the extract into nanofiber network. The resulting films contained about 3, 35, and 294 mg of total phenolic compounds and 2, 24, and 250 mg of α-mangostin per cm3 of the dried films. The film containing the highest phenolic compounds and α-mangostin performed the inhibitory effect to Staphylococcus epidermidis, Propionibacterium acnes, and Staphylococcus aureus. High anticancer activity against B16F10 melanoma and MCF-7 breast cancer cells having viabilities of 10 and 5%, respectively after 48 h were detected after the treatments with the film. However, the film had a low toxicity against normal fibroblast and keratinocyte cells with 41 and 99% viability, respectively. The research suggested that the prepared films were a multifunctional nanofiber films with antimicrobial and anticancer properties.

Effects of Bacterial Nanocellulose Loaded with Curcumin and Its Degradation Products on Human Dermal Fibroblasts.

Bacterial nanocellulose has found applications in tissue engineering, in skin tissue repair, and in wound healing. Its large surface area enables the adsorption of various substances. Bacterial nanocellulose with adsorbed substances can serve as a substrate for drug-delivery of specific bioactive healing agents into wounds. In this study, we loaded a bacterial nanocellulose hydrogel with curcumin, i.e., an important anti-bacterial and healing agent, and its degradation products. These products were prepared by thermal decomposition of curcumin (DC) at a temperature of 180 °C (DC 180) or of 300 °C (DC 300). The main thermal decomposition products were tumerone, vanillin, and feruloylmethane. Curcumin and its degradation products were loaded into the bacterial nanocellulose by an autoclaving process. The increased temperature during autoclaving enhanced the solubility and the penetration of the agents into the nanocellulose. The aim of this study was to investigate the cytotoxicity and the antimicrobial activity of pure curcumin, its degradation products, and finally of bacterial nanocellulose loaded with these agents. In vitro tests performed on human dermal fibroblasts revealed that the degradation products of curcumin, i.e., DC 180 and DC 300, were more cytotoxic than pure curcumin. However, if DC 300 was loaded into nanocellulose, the cytotoxic effect was not as strong as in the case of DC 300 powder added into the culture medium. DC 300 was found to be the least soluble product in water, which probably resulted in the poor loading of this agent into the nanocellulose. Nanocellulose loaded with pure curcumin or DC 180 exhibited more antibacterial activity than pristine nanocellulose.

Manufacture of a novel anisotropic bacterial nanocellulose hydrogel membrane by using a rotary drum bioreactor

Since anisotropic hydrogel membranes have great potential in tissue engineering and bioseparation, the aim of this study was to produce an anisotropic BNC hydrogel membrane for the first time with enhanced BNC productivity by using a newly designed 30-L horizontal rotary drum bioreactor. As compared with the traditional tray static cultivation, the BNC hydrogel from the rotary drum bioreactor showed anisotropic morphology, sparser network, lower dry matter content of 0.16 w/w%, thicker fiber diameter, and lower degree of polymerization that was still 1.8 times higher than cotton, and featured with much higher ultraviolet-visible light transmittance, as well as demonstrated anisotropic tensile properties, lower Young’s modulus of 0.23 MPa and compressive modulus of 0.99 kPa. The productivity of dry and wet BNC was enhanced by 1.65 times and 3.73 times, respectively. The proposed technology may not only obtain anisotropic BNC hydrogel membranes with high transparency, but also promote the BNC productivity.

Immobilization of Heparin on Bacterial Nanocellulose Hydrogels Induces Tubulogenesis of Human Endothelial Cells

Models that mimic the angiogenesis initial processes, as adhesion, migration, proliferation and tubulogenesis, are extremely valuable for investigating the action of new anti-cancer drugs. There still is a need for an angiogenesis model that reflects in vivo environment. To address this challenge, we developed a 3D matrix well-defined based on covalently immobilization of heparin (HEP) on bacterial nanocellulose (BNC) hydrogels. Successful immobilization was confirmed by qualitative and quantification analysis. Human umbilical vein endothelial cells (HUVECs) were seeded on bottom and top surfaces of BNC and BNC-HEP hydrogels and cells behavior were analyzed. The bottom surfaces of BNC-HEP hydrogels were able to support cell adhesion and promote proliferation and tubulogenesis formation. Results here presented indicate that the tubulogenesis process could be controlled by physico-chemical properties of the developed hydrogel. The interaction between the bioactive molecule, heparin, and the particular microstructure of BNC induced tubulogenenic behavior of HUVECs in vitro.

Evaluation of nanocellulose carriers produced by four different bacterial strains for laccase immobilization

Properties of bacterial nanocellulose (BNC) produced by four different strains were studied and compared for laccase immobilization. Scanning electron microscope inspection indicated the four types of BNC had obvious differences in fiber density, diameter and distribution. BNC hydrogel demonstrated the highest fracture stress of 2.44 Mpa and the highest Young's modulus of 12.76 Mpa. Brunauer-Emmett-Teller analysis suggested the four BNC had significant difference in specific surface area, total pore volume and average pore size. Laccase was immobilized on BNC carriers via adsorption. Kinetic studies showed that the four types of BNC-immobilized laccase had different affinity with substrate, and all types of immobilized laccase showed high operational stability after ten consecutive biocatalytic cycles of reaction. The results suggest that the structure diversity of BNC from various strains may directly result in different efficiency in laccase immobilization, and a looser fiber network in BNC with larger porosity is helpful for enzyme immobilization.

Nanocellulose as a natural source for groundbreaking applications in materials science: Today’s state

Cellulose is one of the most important natural polymers on earth and its various nanoscale forms provide new opportunities for groundbreaking discoveries in materials science. The current state of nanocellulose research and development, in terms of production and processing (including international market launch), structural details, properties, and innovative applications in life sciences and engineering technology is featured. Nanocelluloses are natural materials with at least one dimension in the nano-scale. They combine important cellulose properties with the features of nanomaterials and open new horizons for materials science and its applications. The field of nanocellulose materials is subdivided into three domains: biotechnologically produced bacterial nanocellulose hydrogels, mechanically delaminated cellulose nanofibers, and hydrolytically extracted cellulose nanocrystals. This review article describes today’s state regarding the production, structural details, physicochemical properties, and innovative applications of these nanocelluloses. Promising technical applications including gels/foams, thickeners/stabilizers as well as reinforcing agents have been proposed and research from last five years indicates new potential for groundbreaking innovations in the areas of cosmetic products, wound dressings, drug carriers, medical implants, tissue engineering, food and composites. The current state of worldwide commercialization and the challenge of reducing nanocellulose production costs are also discussed.

Bacterial nanocellulose-IKVAV hydrogel matrix modulates melanoma tumor cell adhesion and proliferation and induces vasculogenic mimicry in vitro.

Vasculogenic mimicry process has generated great interest over the past decade. So far, however, there have been only a few matrices available that allow us to study that process in vitro. Here, we have developed an innovative hydrogel platform with defined composition that mimics the structural architecture and biological functions of the extracellular matrix for vasculogenic mimicry of human melanoma cells (SK-MEL-28). We chemically immobilized IKVAV peptide on bacterial nanocellulose (BNC) fibers. BNC-IKVAV hydrogel was found to improve the adhesion and proliferation of SK-MEL-28 cells on the top and bottom surfaces. Particularly, the bottom surface of BNC-IKVAV induced SK-MEL-28 cells to organize themselves as well-established networks related to the vasculogenic mimicry process. Finally, our results showed that not only BNC-IKVAV but also BNC hydrogels can potentially be used as a three-dimensional platform that allows the screening of antitumor drugs. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2741-2749, 2018.

Using in situ nanocellulose-coating technology based on dynamic bacterial cultures for upgrading conventional biomedical materials and reinforcing nanocellulose hydrogels.

Bacterial nanocellulose (BNC) is a microbial nanofibrillar hydrogel with many potential applications. Its use is largely restricted by insufficient strength when in a highly swollen state and by inefficient production using static cultivation. In this study, an in situ nanocellulose-coating technology created a fabric-frame reinforced nanocomposite of BNC hydrogel with superior strength but retained BNC native attributes. By using the proposed technology, production time could be reduced from 10 to 3 days to obtain a desirable hydrogel sheet with approximately the same thickness. This novel technology is easier to scale up and is more suitable for industrial-scale manufacture. The mechanical properties (tensile strength, suture retention strength) and gel characteristics (water holding, absorption and wicking ability) of the fabric-reinforced BNC hydrogel were investigated and compared with those of ordinary BNC hydrogel sheets. The results reveal that the fabric-reinforced BNC hydrogel was equivalent with regard to gel characteristics, and exhibited a qualitative improvement with regard to its mechanical properties. For more advanced applications, coating technology via dynamic bacterial cultures could be used to upgrade conventional biomedical fabrics, i.e. medical cotton gauze or other mesh materials, with nanocellulose. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1077-1084, 2016.

Using In situ Dynamic Cultures to Rapidly Biofabricate Fabric-Reinforced Composites of Chitosan/Bacterial Nanocellulose for Antibacterial Wound Dressings.

Bacterial nano-cellulose (BNC) is considered to possess incredible potential in biomedical applications due to its innate unrivaled nano-fibrillar structure and versatile properties. However, its use is largely restricted by inefficient production and by insufficient strength when it is in a highly swollen state. In this study, a fabric skeleton reinforced chitosan (CS)/BNC hydrogel with high mechanical reliability and antibacterial activity was fabricated by using an efficient dynamic culture that could reserve the nano-fibrillar structure. By adding CS in culture media to 0.25–0.75% (w/v) during bacterial cultivation, the CS/BNC composite hydrogel was biosynthesized in situ on a rotating drum composed of fabrics. With the proposed method, BNC biosynthesis became less sensitive to the adverse antibacterial effects of CS and the production time of the composite hydrogel with desirable thickness could be halved from 10 to 5 days as compared to the conventional static cultures. Although, its concentration was low in the medium, CS accounted for more than 38% of the CS/BNC dry weight. FE-SEM observation confirmed conservation of the nano-fibrillar networks and covering of CS on BNC. ATR-FTIR showed a decrease in the degree of intra-molecular hydrogen bonding and water absorption capacity was improved after compositing with CS. The fabric-reinforced CS/BNC composite exhibited bacteriostatic properties against Escherichia coli and Staphylococcus aureus and significantly improved mechanical properties as compared to the BNC sheets from static culture. In summary, the fabric-reinforced CS/BNC composite constitutes a desired candidate for advanced wound dressings. From another perspective, coating of BNC or CS/BNC could upgrade the conventional wound dressings made of cotton gauze to reduce pain during wound healing, especially for burn patients.

Micromechanical model of biphasic biomaterials with internal adhesion: Application to nanocellulose hydrogel composites

The mechanical properties of hydrated biomaterials are non-recoverable upon unconfined compression if adhesion occurs between the structural components in the material upon fluid loss and apparent plastic behaviour. We explore these micromechanical phenomena by introducing an aggregation force and a critical yield pressure into the constitutive biphasic formulation for transversely isotropic tissues. The underlying hypothesis is that continual fluid pressure build-up during compression temporarily supresses aggregation. Once compression stops and the pressure falls below some critical value, internal aggregation occurs over a time scale comparable to the poroelastic time. We demonstrate this model by predicting the mechanical response of bacterial nanocellulose hydrogel composites, which are promising biomaterials and a structural mimetic for the plant cell wall. Cross-linking of cellulose by xyloglucan creates an extensional resistance and substantially increases the compressive modulus under large compression and densification. In comparison, incorporating non-crosslinking arabinoxylan into the hydrogel has little effect on its mechanics at the strain rates investigated. These results assist in elucidating the mechanical role of these polysaccharides in the complex plant cell wall structure. They also suggest xyloglucan is a suitable candidate to tailor the stiffness of nanocellulose hydrogels in biomaterial design, which includes modulating cell-adhesion in tissue engineering applications. The model and overall approach may be utilised to characterise and design a myriad of biomaterials and mammalian tissues, particularly those with a fibrillar structure. Statement of SignificanceThe mechanical properties of hydrated biomaterials can be non-recoverable upon compression due to increased adhesion occurring between the structural components in the material. Cellulose–hemicellulose composite hydrogels constitute a classical example of this phenomenon, since fibres can freely re-orient and adhere upon fluid loss to produce significant variations in the mechanical response to compression. Here, we model their micromechanics by introducing an aggregation force and a critical yield pressure into the constitutive formulation for transversely isotropic biphasic materials. The resulting model is easy to implement for routine characterization of this type of hydrated biomaterials through unconfined compression testing and produces physically meaningful and reproducible mechanical parameters.

Potential of PVA-doped bacterial nano-cellulose tubular composites for artificial blood vessels.

Bacterial nano-cellulose (BNC) hydrogel has been suggested as a promising biomaterial for artificial blood vessels. However, some properties of BNC do not achieve all of the requirements of a native blood vessel - compliance, for instance. In order to improve the properties of BNC tubes, poly(vinyl alcohol) (PVA) was introduced in the BNC tubes to make composites. Two types of pristine BNC tubes with different inner structures were produced in two bioreactors. A PVA tube and PVA-BNC tubular composites were made for comparison by using a thermally-induced phase separation method. The morphology, water permeability, cytotoxicity, and mechanical properties, including the axial stretch strength, suture retention, burst pressure, and compliance of all the tubes, were evaluated and compared. The results indicated that PVA impregnated into BNC tubes and then significantly improved the properties of BNC, especially the mechanical properties and water permeability. The BNC tube itself played a great role in the performances of the composites as the skeleton base material. The PVA-BNC composite tubes could constitute new biomaterial candidates for vascular grafts.

Biocompatibility evaluation of densified bacterial nanocellulose hydrogel as an implant material for auricular cartilage regeneration.

Bacterial nanocellulose (BNC), synthesized by the bacterium Gluconacetobacter xylinus, is composed of highly hydrated fibrils (99 % water) with high mechanical strength. These exceptional material properties make BNC a novel biomaterial for many potential medical and tissue engineering applications. Recently, BNC with cellulose content of 15 % has been proposed as an implant material for auricular cartilage replacement, since it matches the mechanical requirements of human auricular cartilage. This study investigates the biocompatibility of BNC with increased cellulose content (17 %) to evaluate its response in vitro and in vivo. Cylindrical BNC structures (Ø48 × 20 mm) were produced, purified in a built-in house perfusion system, and compressed to increase the cellulose content in BNC hydrogels. The reduction of endotoxicity of the material was quantified by bacterial endotoxin analysis throughout the purification process. Afterward, the biocompatibility of the purified BNC hydrogels with cellulose content of 17 % was assessed in vitro and in vivo, according to standards set forth in ISO 10993. The endotoxin content in non-purified BNC (2,390 endotoxin units (EU)/ml) was reduced to 0.10 EU/ml after the purification process, level well below the endotoxin threshold set for medical devices. Furthermore, the biocompatibility tests demonstrated that densified BNC hydrogels are non-cytotoxic and cause a minimal foreign body response. In support with our previous findings, this study concludes that BNC with increased cellulose content of 17 % is a promising non-resorbable biomaterial for auricular cartilage tissue engineering, due to its similarity with auricular cartilage in terms of mechanical strength and host tissue response.