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An environmentally feasible approach was adopted for the green synthesis of silver nanoparticles (AgNPs) in the BC membrane using Komagataeibacter intermedius (MBS-88) strain. BC production was optimized, resulting in 14.72 g/L of BC when crude glycerol was utilized as a carbon source. The produced BC has a tensile strength of 387 N/m2, an elongation at break % of 2.04, and a Young's modulus of 304 MPa. The bacterial cellulose/AgNP composites have been successfully synthesized using BC as a template via the hydrothermal synthesis in which bacterial cellulose itself acts as a reducing and stabilizing agent. The characterization of the synthesized AgNPs was carried out using electron microscopy (SEM and TEM), Fourier transform infrared microscopy (FT-IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Adherence of AgNPs to the surface of the BC matrix was observed under SEM. Particle size distribution shows nanoparticles are in the range of 5–45 nm. XRD shows AgNPs peaks at 38.2° (111), 46.3° (200), and 64.5° (220). Peaks of Ag 3d at 367.58 eV and 373.55 eV, along with C 1 s at 284.26 eV and O 1 s at 532.16 eV, were observed in XPS spectra. BC/Ag nanocomposite disk showed better antibacterial activities against Staphylococcus epidermidis ATCC 2228 (6.5 ± 0.1 mm), Staphylococcus aureus 29,213 (6 ± 0.2 mm), and Pseudomonas aeruginosa (5.1 ± 0.2 mm). Thus, the synthesized BC–AgNPs could be used in controlling wound infections as an alternative to chemical synthesis that might have deleterious effects on the ecosystem. [ABSTRACT FROM AUTHOR]

Preliminary studies are presented showing to what extent nutrients available in the growth environment of Kombucha microorganisms affect the physical and mechanical properties of synthesized cellulose. With an increase in the amount of sucrose in the growth medium and with the presence of additional nutrients, peptone and tea extract, the thickness and strength of the biopolymer increased, while elongation was reduced. The best physical and mechanical parameters were obtained for bacterial cellulose from cultures with the addition of 10% sucrose and 0.25% peptone content. The increase in elongation correlated with the decrease in the degree of polymerization, which means that in media rich in nutrients, the number of molecules building the polymer decreases. The presented data is important in order to select ingredients that will help synthesize bacterial cellulose with the desired physio-mechanical properties. [ABSTRACT FROM AUTHOR]

In this study, bacterial cellulose was produced through the fermentation of a mixture of black tea, ginger, and sugar, and used to create bio-textile films on sugarcane-based media. Characterization included ribosomal RNA gene sequencing, FTIR spectroscopy, XRD, and SEM was used to examine surface morphology. The bio-textile films showed increasing UV resistance beyond 10 days of cultivation (T.UVA%; 0.13 ± 0.02, T.UVB%; 0.22 ± 0.01, UPF; 629 ± 2.12) and antimicrobial resistance was assessed by quantifying Colony-Forming Units (CFU), resulting in a 100% reduction in growth for both Escherichia coli and Staphylococcus aureus. Subsequently, after 15 days of cultivation, antimicrobial activity was evaluated using the disc agar diffusion method, yielding noteworthy outcomes. E. coli displayed a 25 mm zone of inhibition, S. aureus exhibited a 31 mm zone of inhibition, Candida albicans showed a 35 mm zone of inhibition, and Aspergillus niger presented a 22 mm zone of inhibition. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) is a pure exocellular polysaccharide produced by micro-organisms. It has several properties in comparison with plant-derived cellulose that make it perfectly suitable for many applications, ranging from the food industry to the biomedical area. Different production methods and modification or functionalization procedures have been investigated in response to the many possible attractive applications of BC. This review overviews the different fermentation techniques and functionalization methods together with the main possible biotechnological applications of BC for food industry and biomedical purposes. [ABSTRACT FROM AUTHOR]

This study aimed to determine the effect of the structural properties of acetylated bacterial cellulose (ABC) on its in vitro biological performance. Acetylation resulted in several improvements to the ABC, including relaxed fiber arrangement, increased optical transparency (95.5%), and enhanced hydrophobicity, mechanical strength, and thermal stability. The ABC also demonstrated increased fiber diameter (0.122 ± 0.034 µm), pore diameter (333 Å), pore volume (0.533 cc/g), and surface area (195 m2/g) as compared to the pristine BC. Phase-contrast and electron microscopy showed that NIH 3T3 cells adhered to and spread on ABC scaffolds in a 3D growth pattern with extended filopodia. WST-1 assay showed improved cell proliferation on ABC scaffolds and led to the downregulation of Notch receptors in NIH 3T3 cells. Confocal microscopy showed infiltration of cells up to 650 µm into the ABC scaffolds after 14 days. The whole blood clotting assay, plasma recalcification profile, half-maximum absorbance EC50 time (14.55 ± 1.21 min), and Factor XII activation demonstrated that acetylation reduced the thrombogenicity of the ABC scaffolds. Hemolysis rates were within the permissible level (< 5%), and the scaffolds were able to adsorb platelet-poor plasma and plasma proteins (human serum albumin, γ-globulin, human fibrinogen). The improved cell adhesion and proliferation, 3D cell growth pattern, hemocompatibility, and protein adsorption indicate a positive impact of acetylation on the biological properties of ABC scaffolds, suggesting their potential use in tissue engineering and regenerative medicines. [ABSTRACT FROM AUTHOR]

Recently, degradable biopolymers have become increasingly important as potential environmentally friendly biomaterials, providing a wide range of applications in various fields. Bacterial exopolysaccharides (EPSs) are biomacromolecules, which due to their unique properties have found applications in biomedicine, foodstuff, textiles, cosmetics, petroleum, pharmaceuticals, nanoelectronics, and environmental remediation. One of the important commercial polysaccharides produced on an industrial scale is xanthan. In recent years, the range of its application has expanded significantly. Bacterial cellulose (BC) is another unique EPS with a rapidly increasing range of applications. Due to the great prospects for their practical application, the development of their highly efficient production remains an important task. The present review summarizes the strategies for the cost-effective production of such important biomacromolecules as xanthan and BC and demonstrates for the first time common approaches to their efficient production and to obtaining new functional materials for a wide range of applications, including wound healing, drug delivery, tissue engineering, environmental remediation, nanoelectronics, and 3D bioprinting. In the end, we discuss present limitations of xanthan and BC production and the line of future research. [ABSTRACT FROM AUTHOR]

Bacteria are considered mini chemical factories that help us in providing a wide range of products for various purposes. These days, bacterial cellulose (BC) is getting attention by researchers due to its quality, eco‐friendly nature, and excellent physical‐mechanical qualities. It is being used in the fabrication of nanocomposites. Its nanocomposites can be used in various industries, including medicine, food, leather, textiles, environment, electronics, and cosmetics. This area of research is emerging and still in its infancy stage, as new applications are still coming up. Most of the work on BC has been done during the last two decades and serious inputs are required in this direction in order to make the production process commercially viable and ultimately the application part. Biowastes, such as fruits and vegetables wastes, can be used as a cost‐effective medium to minimize the cost for large‐scale production of BC‐based nanocomposites thus will valorize the biowaste material into a valuable product. Using biowaste as media will also aid in better waste management along with reduction in detrimental environmental effects. This review will help the readers to understand the potential applications of BC and its nanocomposites as well as their vital role in our daily lives. [ABSTRACT FROM AUTHOR]

Here we propose a macromolecular approach for developing a composite using collagen and functionalized bacterial cellulose (f-BC) for tissue engineering with improved cell adhesion and an acceptable degradation profile. In this study, the pure bacterial cellulose (BC) synthesized from Acetobacter xylinus using a standard Hestrin–Schramm medium has been functionalized through four different chemical routes. The successful functionalization of BC was primarily evaluated using conductometric titration, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy, X-ray diffraction, and zeta potential measurements. The nano fibrous surface morphologies of the scaffolds were confirmed using field emission scanning electron microscopy. The porosity and surface area analysis of the scaffolds were carried out using N2 adsorption–desorption using standard BET and BJH methods. Hydrophilicity, comprehensive degradation profile, and buffer uptake ability of the scaffolds were found to be satisfactory for tissue engineering applications. After a series of in vitro characterizations, f-BC treated with amine (positively charged) and f-BC treated with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (negatively charged) were further selected for composite preparation with collagen and genipin as crosslinker for potential skin and bone tissue engineering. The functionalization process was carried out merely not only to enhance the biological functions of pure BC yet also to introduce sites for grafting other biomolecules to fabricate stable composites. The enhanced cell viability efficacy and non-toxicity were further observed for the proposed f-BC/collagen composite. [ABSTRACT FROM AUTHOR]

Bacterial cellulose-based functional nanocomposite membranes were fabricated using an efficient and scalable papermaking process (filtration and hot pressing), with bacterial cellulose (BC), chitin nanofibrils (CH), and zein nanoparticles (ZN) as nanosized building blocks. The effects of the mass ratio of BC to CH and the content of ZN on the structure and properties of the composite membranes were studied. The effect of incorporating thymol (TH) on the thermal stability and antibacterial properties of the membranes were further investigated. The results showed that the tensile strength (from 183.45 MPa to 171.38 MPa) and elongation at break (from 2.58% to 2.11%) of the composite film did not significantly change when the mass ratio of BC to CH was decreased from 10:0 to 5:5, respectively. Scanning electron microscopy, thickness evaluation, Fourier transform infrared spectroscopy, and elemental analysis confirmed that ZN could be effectively incorporated into the BC-CH membranes. Further, the contact angle data (from 49.15° to 77.28°) indicated that the surface hydrophobicity of the composites was improved in the presence of ZN. The thermal stability of the composite membranes was not affected by the addition of thymol, but their antibacterial effect was improved. Thus, the surface hydrophobicity of BC can be improved by compositing with CH, ZN, and TH to prepare new BC-based functional membrane materials. These results can provide guidance for the development of BC composite membrane with additional functional properties. [ABSTRACT FROM AUTHOR]

Human-friendly electronic devices including medical active devices, soft haptic devices, artificial muscle, and wearable electronics, will require the use of high-performance soft actuators with bio-friendly property, large bending deformation, and low actuation voltage. Herein, we report a novel ionic electroactive actuator based on carboxylated bacterial cellulose (CBC), ionic liquid (IL), multi-walled carbon nanotubes (MWCNT), and PEDOT: PSS electrodes. The designed actuator displayed superior electro-chemo-mechanical properties due to its ionic crosslinking structure formed by the strong ionic interactions among CBC, MWCNT, and IL. Specifically, the actuator demonstrated large bending strain (8.2 mm under 1.0 V sinusoidal input voltage at 0.1 Hz), low actuation voltage (< 2 V), excellent actuation durability (95% retention in 2 h), high Young's modulus (349.1 MPa), and specific capacitance (76.97 mF cm–2). More importantly, the artificial soft robotic fingers using the CBC-IL-MWCNT actuators were successfully realized. Therefore, the designed actuator will promote the advancement of artificial muscles, soft haptic devices, biomimetic robots, soft robots, wearable devices, and tactile devices. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) is a natural biodegradable, eco-friendly fiber, lying within the nanoscale range. It is reputable for its various physical and chemical qualities, like high hydrophilicity, immense crystallinity, ease of sterility, being toxin-free, and extremely pure. Adding to its wide applicability in different fields, this study evaluated the applicability of a developed gelling substitute for plant tissue culture media. The BC matrix was characterized under the acronym PLATIBACGEL (PLAnt TIssue Culture BActerial Cellulose GEL), formed by Komagataeibacter hansenii AS.5, preisolated from rotten apple waste. Scanning electron microscope, Fourier-transform infrared, X-ray diffractometer, and tensile strength analyses confirmed the formation of purified, porous, and heterogeneous densely packed multiple network polymers possessing cellulose properties. The water holding capacity (WHC) values of wet and dried BC membranes were 9179% and 226.9%, respectively, and the water absorption rate (WAR) of dry BC membranes was higher than that of wet membranes. Using BC as a tissue culture gelling agent, six genotypes from tomato and wheat seeds were cultured in vitro, for guaranteeing explant genetic diversity, over seven treatments. Treatment 5, included PLATIBACGEL as the main constituent, improved and sustained all in vitro seed germination, root penetration, and plant support. Likewise, repeated tomato micropropagation subcultures were successful. Results demonstrated applying PLATIBACGEL as a promising, reusable, cheap, and reliable alternative plant micropropagation media gelling agent. Wherefore, plant cellular developers and tissue-culturists can utilize bio-polymers like BC for better understanding plant cell response to different in vitro culturing conditions, with expected beneficial returns on gelling agents industry and markets as well. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC), a promising polysaccharide of microbial origin, is usually produced through synthetic (chemically defined) or natural media comprising of various environmental wastes (with exact composition unknown), through low-cost and readily available means. Various agricultural, industrial, and food processing wastes have been explored for sustainable BC production. Both conventional (using one variable at a time) and statistical approaches have been used for BC optimization, either during the static fermentation to obtain BC membranes (pellicle) or agitated fermentation that yields suspended fibers (pellets). Multiple studies have addressed BC production, however, the strategies applied in utilizing various wastes for BC production have not been fully covered. The present study reviews the nutritional requirements for maximal BC production including different optimization strategies for the cultivation conditions. Furthermore, commonly-used applications of BC, in various fields, including recent developments, and our current understanding have also been summarized. [ABSTRACT FROM AUTHOR]

Cellulose is one of the most abundant renewable biopolymer in nature and is present as major constituent in both plant cell walls as well as synthesized by some microorganisms as extracellular products. In both the systems, cellulose self-assembles into a hierarchical ordered architecture to form micro to nano-fibrillated structures, on basis of which it is classified into various forms. Nanocellulose (NCs) exist as rod-shaped highly crystalline cellulose nanocrystals to high aspect ratio cellulose nanofibers, micro-fibrillated cellulose and bacterial cellulose (BC), depending upon the origin, structural and morphological properties. Moreover, NCs have been processed into diversified products ranging from composite films, coatings, hydrogels, aerogels, xerogels, organogels, rheological modifiers, optically active birefringent colored films using traditional-to-advanced manufacturing techniques. With such versatility in structure-property, NCs have profound application in areas of healthcare, packaging, cosmetics, energy, food, electronics, bioremediation, and biomedicine with promising commercial potential. Herein this review, we highlight the recent advancements in synthesis, fabrication, processing of NCs, with strategic chemical modification routes to tailor its properties for targeted biomedical applications. We also study the basic mechanism and models for biosynthesis of cellulose in both plant and microbial systems and understand the structural insights of NC polymorphism. The kinetics study for both enzymatic/chemical modifications of NCs and microbial growth behavior of BC under various reactor configurations are studied. The challenges associated with the commercial aspects as well as industrial scale production of pristine and functionalized NCs to meet the growing demands of market are discussed and prospective strategies to mitigate them are described. Finally, post chemical modification evaluation of biological and inherent properties of NC are important to determine their efficacy for development of various products and technologies directed for biomedical applications. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) has found applications in various fields ranging from healthcare to electronics. Functionalization of cellulose to impart conductive properties has been met with challenges due to superficial coating rather than uniform interactions with the conducting polymers. In this work, mechanical disruption is shown to be a facile strategy to develop BC-PEDOT:PSS conductive foams without the use of any harsh chemical treatments to functionalize cellulose. The strategy allows for uniform polymer intercalation with the cellulose nanofibers imparting superior conductive properties to the functional material. The conductive foams with low PEDOT:PSS ratio exhibit conductivity of 0.7 S/cm and are cytocompatible with human dermal fibroblasts (HDFa) cells. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) exhibits a unique combination of porosity, tensile strength, reticulated crystal structure and biocompatibility useful for many applications in the food, biomedical and other industries. Polysaccharide addition has been shown to improve the production and the mechanical properties of BC nanocomposites. This study examined the effect of pullulan on BC fermentation as well as the co-culturing of the BC producer with Aureobasidium pullulans, a fungal strain that produces pullulan as an exopolysaccharide. Results showed that a 1% pullulan addition improved Young's modulus of BC pellicles for sixfold. Addition of pullulan at 1.5% and 2% levels could increase the BC production from 0.447 to 0.814 and 1.997 g/L, respectively. The co-culture fermentation demonstrated a mixed effect on the aggregation and bundling of BC while resulting in a significant improvement in mechanical properties. The study provided a polysaccharide additive and a novel fermentation method to produce BC with improved properties. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) can be produced by an agitated or static fermentation process in presence of suitable media. Groups of microorganisms such as fungi, bacteria, and algae are responsible for the synthesis of BC. Under agitated cultivation, BC yield is enhanced as compared to static cultivation. BC is pure cellulose, so it can easily interact with hydrophilic or hydrophobic biopolymers. In this review paper, we have discussed the preparation and characterization of BC reinforced biopolymer (polylactic acid, cellulosic fibers, agar, and Mater-Bi) based biocomposites and biopolymer (natural rubber, chitosan, polycaprolactone, hydroxyapatite) reinforced BC-based biocomposites related research carried out in last 2 decades. The high moisture content of BC results in reduced compatibility to most hydrophobic biopolymers as compared to hydrophilic biopolymers. Mechanical properties of BC before and after reinforcement were compared as it is important parameters in the production of green composites with targeted application in tissue engineering, wound dressing, dental implants, artificial blood vessels, surgical mesh, bone fillings, heart valve, and artificial cartilage. This review paper will help in exploring various applications of BC-based biocomposites in addition to several parameters that affect the production of BC. [ABSTRACT FROM AUTHOR]

Currently, the production and application of non-biodegradable petroleum-based synthetic polymer (commonly known as plastic) are highly prevalent. As synthetic polymers as mostly non-biodegradable, they adversely affect the environment and result in the generation of excessive solid waste. The increasing awareness about the ill-effects of synthetic polymers among consumers has resulted in a demand for natural, disposable, biodegradable, reusable, or recyclable food packaging materials. Bio-based polymers and biopolymers have been one of the most favorable alternatives to be exploited and developed into eco-friendly food packaging materials. Certain microorganisms, such as Gluconoacetobacter xylinus, produce cellulose by a fully green procedure which is called bacterial cellulose. Bacterial cellulose demonstrates exceptional properties such as being a chemically pure material, highly flexible, high water absorbency, great tensile strength, highly crystalline nature, highly moldable, non-toxic nature, and biocompatible. However, there are some limitations such as lack of antibacterial properties, optical transparency, and stress-bearing capability which can be overcome by developing bacterial cellulose composites using hydrocolloids like proteins, starches, pectins, etc. The bacterial cellulose composites are employed to develop packaging films with properties such as high mechanical strength; antimicrobial, transparent, biodegradable, with air, water, and oil resistance properties, thus, making it an appropriate material for packaging. [ABSTRACT FROM AUTHOR]

A series of morphology-controlled BiOBr nano/macrostructures was successfully synthesized via a novel biomass-route derived from bacterial cellulose (BC). In the BiOBr/BC system compared with pure BiOBr, the three-dimensional BC scaffolds not only effectively prevented the aggregation of BiOBr units by pore confinement, but also strengthened the controllability of BiOBr size with the help of abundant anchoring sites provided by cross-linked BC fibers. By associating the results of characterizations and the photodegradation of RhB dye, the relationship between morphology and photocatalytic activity of BiOBr/BC was investigated. In addition, a possible mechanism for the enhanced photocatalytic activity of the optimized BiOBr/BC has been discussed. This biomass-derived route provides a platform for further design of bismuth-based composite photocatalysts with potential advantages of being anti-aggregation, highly-dispersed, easily recovered and having enhanced catalytic performance. [ABSTRACT FROM AUTHOR]

This review covers the use of nanocelluloses in water treatment applications with particular focus on membranes and filters made either entirely from (nano)cellulose or in composite approaches. Nanocelluloses are among the emerging materials of this century, having found an abundance of potential applications in the fields of composites, medicine, functional additives or water treatment. Water treatment applications in particular have received significant academic and commercial attention, with a large variety of approaches developed in order to address arguably one of the largest problems that humanity is confronted with in the 21st century: clean water. In this regard, treatment of both potable water and wastewater is of high importance. The reason for the viability of nanocelluloses as base material relies upon their high specific surface area and abundance of OH groups that already exhibit certain attraction toward pollutants carrying ionic structures or dyes and also can be easily modified to significantly increase the affinity of nanocelluloses toward these pollutants. Nanocelluloses in their various forms (cellulose nanocrystals, cellulose nanofibrils, bacterial cellulose) have been applied in water treatment, with membranes and filters (size exclusion, e.g. for nanoparticle filtration, or affinity membranes) as well as adsorbents (e.g. heavy metal ions, dyes, nitrates) being the most studied. © 2020 The Author. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) has known as a cellulose material produced by bacteria, which is characterized by its purity, high porosity and randomly cellulose fibrils network arrangement. Static magnetic field (SMF) is a promising method, which can be used to modify the structure of BC. The aim of this study was to investigate the influence of an SMF on the morphology and the physical and chemical properties of BC by varying the intensity of the SMF (45 mT, 110 mT and 140 mT) through the culture medium. The results showed that the SMF did not disturb the cellulose production yield of the BC. Changes between SMF-modified and conventional BC were shown on the side-section perpendicular and parallel to SMF. The porous structure of SMF-modified BC recorded under Scanning Electron Microscopy was more aligned. The changes of cellulose fibrils arrangement and porous structure resulted in the increase of mechanical property of the SMF modified BC. Feature characteristic of high porosity and crystallinity of BC maintained under an SMF. This study suggested a novel method to modify BC by the use of an SMF. [ABSTRACT FROM AUTHOR]

In this work, a large size of macroporous phenolic resin (PR)/bacterial cellulose (BC) composite with double-network structure was fabricated simply by soaking, heating, solvent exchange, and ambient pressure drying. The mechanism and influence factors for the fabrication of this macroporous composite were systematically elaborated. One network of macroporous composite was composed of PR beads, and the other derived from original BC nanofibers. They supported and reinforced each other, avoiding the collapse of interconnected porous structure and achieving low density (0.29 g/cm3), high porosity (77.7%), low thermal conductivity (0.10 W/m K), and excellent compressive strength (7.97 ± 2.24 MPa). Through further carbonization, carbon counterpart that maintained fine structure and good performance can also be obtained. The surface of macroporous composite was extremely hydrophilic. On the contrary, its carbon counterpart possessed a highly hydrophobic surface (contact angle = 118.2°). These properties suggest that the macroporous composite and carbon counterpart may have potential applications for filtration, separation, and thermal insulation materials. Moreover, this work will provide a novel perspective for the fabrication of porous composites with BC as the template and 3D nanofiber reinforcement simultaneously. [ABSTRACT FROM AUTHOR]

Raman and Fourier Transform Infrared (FT-IR) spectroscopy was used for investigation of structural differences of bacterial celluloses (BC), obtained by cultivation native and immobilized cells of Gluconacetobacter sucrofermentans during static and dynamic regimes of cultivation on a molasses media. It was found that the Raman and FT-IR spectra could characterized the groups of the cellulose molecules. The culturing bacterial cellulose in the presence of results in an increase of crystalline and it increased during cultivated on a molasses media with the addition of 1.5% ethanol—75.62%. The degree of BC crystallinity increased during dynamic regime of cultivation is higher than under static regime one. The maximal BC content was observed when 0.5% ascorbic acid was added to the cultivation medium with molasses and native cells. It was found, the degree of BC crystallinity during static regime cultivation on a molasses medium with ethanol, increased significantly to 73.5%, and during dynamic regime—75.6%. So, in this study, the changes of the bacterial cellulose conformation of were revealed during bacterial cultivation in a medium containing molasses in various cultivation modes. [ABSTRACT FROM AUTHOR]

Cellulose is the main structural component of plant cell walls. Cellulose is a fibrous, water-insoluble substance and is considered to be the most abundant bio-derived polymer on earth. From an industrial perspective, plant cellulose has been the mainstay of the wood industries for the past 100 years. The hierarchical organization and semicrystalline nature of cellulose found in plant fibers allows the extraction of nanofibers and nanocrystals using mechanical and chemical top-down de-structuring strategies. Bacterial cellulose has also been increasingly investigated. Bacterial cellulose is composed of cellulose nanofibers secreted extracellularly by some bacteria; bacterial cellulose is therefore obtained using bottom-up synthesis. The unique nanofibrillar structure of bacterial cellulose confers excellent physical and mechanical properties such as high porosity, high elastic modulus and high crystallinity. Research on nanocellulose is accelerating due actual fossil fuel issues such as CO2 emissions, plastic pollution and lack of renewable energy. Nanocellulose materials are non-toxic, biodegradable and recyclable, with no adverse effects on health and the environment. Here, we review cellulose production methods, properties and applications, focusing on the food industry, biomedical materials and electronic devices. We compare vegetal nanocellulose and bacterial cellulose. The increase in the number of publications on nanocellulose is also discussed. [ABSTRACT FROM AUTHOR]

Featured Application: (1) Composite membrane with both filtration and antibacterial function. (2) PVA mechanical performance is stronger by adding BC. (3) Reuse of resources by using waste corn stover as biochar material. (4) C-Ag structure is more stable, Ag+ release ability is stronger. Pathogenic bacteria and microorganisms in drinking water can cause various diseases, and new types of antibacterial material for water treatment and filtration are urgently needed. In this work, polyvinyl alcohol/bacterial cellulose/biochar–nanosilver (PVA/BC/C-Ag) antibacterial composite membrane materials were prepared by uniformly dispersing C-Ag particles in a PVA/BC mixed gel. Fourier-transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), scanning electron microscopy (SEM), and thermogravimetric differential scanning calorimetry (TG-DSC) were used to characterize the composite membranes. Results indicated that the BC was uniformly mixed into the PVA gel and that the C-Ag particles were uniformly immobilized in the PVA/BC hybrid membrane. The PVA/BC/C-Ag composite membranes exhibited excellent antibacterial activity against Escherichia coli when assayed using a plate-counting technique. When used to treat actual contaminated water, the composite membranes demonstrated sustained antibacterial activity and good reusability. PVA/BC/C-Ag composite membranes have great potential for the development of drinking water treatment applications. [ABSTRACT FROM AUTHOR]

The present study aimed to improve the properties of bacterial cellulose nonwoven fabrics by physical entrapment of lauryl gallate oligomers. The lauryl gallate oligomerization process was conducted by laccase-mediated oligomerization. Lauryl gallate was chemically confirmed by matrix-assisted laser desorption/ionization with time-of-flight analyses. The oligomerization conditions were controlled considering the surface properties (water contact angle, surface energy, and water absorption time) of bacterial cellulose nonwoven fabrics. The controlled oligomerization conditions were 160 U/mL of laccase and 20 mM lauryl gallate. After bacterial cellulose was treated by the physical entrapment of lauryl gallate oligomers, X-ray photoelectron spectroscopy analysis showed that the N1 atomic composition (%) of bacterial cellulose increased from 0.78% to 4.32%. This indicates that the lauryl gallate oligomer molecules were introduced into the bacterial cellulose nanofiber structure. In addition, the water contact angle was measured after washing the bacterial cellulose nonwoven fabric treated by the physical entrapment of lauryl gallate oligomers for 180 minutes, and it was found to maintain a water contact angle of 88°. The durability of bacterial cellulose nonwoven fabric treated by the physical entrapment of lauryl gallate oligomers was confirmed by measuring the tensile strength after wetting and dimensional stability. As a result, the tensile strength after wetting was about five times higher and the dimensional stability was three times higher than that of untreated bacterial cellulose nonwoven fabric. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) is an extracellular natural polymer produced by many microorganisms and its properties could be tailored via specific fabrication methods and culture conditions. There is a growing interest in BC derived materials due to the main features of BC such as porous fibrous structure, high crystallinity, impressive physico-mechanical properties, and high water content. However, pristine BC lacks some features, limiting its practical use in varied applications. Thus, fabrication of BC composites has been attempted to overcome these constraints. This review article overviews most recent advance in the development of BC composites and their potential in biomedicine including wound dressing, tissue engineering scaffolds, and drug delivery. Special emphasis is placed on the fabrication and applications of BC-containing nanofibrous composites for biomedical usage. It summarizes electrospinning of BC-based nanofibers and their surface modification with an outline on challenges and future perspective. [ABSTRACT FROM AUTHOR]

Poly(lactic acid)/bacterial cellulose nanocomposites were prepared by solvent casting. Aiming to reduce the incompatibility between polar bacterial cellulose (BC) and the nonpolar poly(lactic acid) (PLA) matrix which induces filler aggregation and poor reinforcement dispersion, BC was acetylated by the use of a non-conventional route catalyzed by citric acid. The derivatized BC (AcBC) was incorporated into de PLA matrix at varying filler loadings, and optical, morphological, structural, thermal, tensile and barrier (water vapor) properties of PLA/AcBC in comparison with PLA/BC were evaluated. Noticeable changes in the nanocomposite properties were ascribed to the success of the route proposed to surface hydrophobize BC, which significantly improved its dispersibility within the PLA matrix and the matrix-filler interaction. By the way, the variation of filler loading allowed attaining remarkable increases in the nanocomposite films stiffness without significant reductions in tensile strength and water vapor permeability. [ABSTRACT FROM AUTHOR]

The present study describes the impregnation of coffee extract (CE) into bacterial cellulose synthesized from kombucha tea fungus (KBC) of different cellulose content, incubated for different incubation periods (2, 4, and 10 days), to prepare biocomposites having the potential for wound healing applications. Total polyphenols in hydroalcoholic extracts from ground roasted coffee and its release from the prepared biocomposites were determined as gallic acid equivalent. The polyphenols content was found to be 13.66 mg/g and the minimum inhibitory concentration (MIC) of the CE was determined using colony-forming unit (CFU) method against Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus where the growth inhibition was 86 and 97% respectively. Biocomposites (KBC/CE) with the lowest cellulose and CE content showed the highest wet tensile stress (3.35 MPa), absorption of pseudo extracellular fluid (154.32% ± 4.84), and water vapor transmission rate (3184.94 ± 198.07 g/m2/day), whereas it showed the lowest polyphenols' release (51.85% ± 2.94)when immersed in PBS buffer of pH 7.4. The impregnation of CE into KBC provided biocomposites that can enlarge the range of BC in the biomedical application. [ABSTRACT FROM AUTHOR]

In recent years, the accumulation of synthetic plastics has led to the development of a serious environmental problem. Nowadays, biodegradable films and coatings have been identified as a new approach to solve this problem by preparing renewable, abundant, low-cost materials. Gums are considered a large group of polysaccharides and polysaccharide derivatives that can easily form viscous solutions at low concentrations. Gums are mainly soluble in water and are composed of sugars like glucose, fructose, and mannose. These compounds are categorized into three groups: plant-origin gums, seaweed-based gums, and microbial gums. Microbial gums are listed as generally recognized as safe (GRAS) by the Food and Drug Administration and have a broad range of physicochemical properties suitable for various pharmacy, medicine, and food applications. In the food industry, they can be used as gelling, viscous, stabilizing, and thickening agents. Among the various materials that can potentially improve the properties of biodegradable packaging films, microbial gums such as gellan, xanthan, pullulan, bacterial cellulose, and curdlan have been the subject of numerous studies. These gums can be extruded into films and coatings with considerable barrier properties against the transport of moisture and oxygen. Microbial gums, due to their microbiological stability, adhesion, cohesion, wettability, solubility, transparency, and mechanical properties, can be used as edible films or coatings. Also, these gums can be applied in combination with bioactive compounds that induce the shelf-life extension of highly perishable products. This review focuses on the properties of films and coatings consisting of xanthan, curdlan, pullulan, gellan, and bacterial cellulose. [ABSTRACT FROM AUTHOR]

Composite bacterial cellulose (BC) membranes containing collagen fibrils or collagen monomers (named BC/Col-fibre or BC/Col, respectively) were fabricated by immersing macroporous BC in a 3.0 mg/mL collagen solution for 50 h at 4 °C with or without collagen fibrillogenesis before lyophilization. The structure of the membranes was characterized by scanning electron microscope, nitrogen adsorption–desorption experiment, and X-ray diffraction. The structure became much more compact upon the introduction of collagen but the crystal structure of BC did not change. The thermal stability and the cytocompatibility of the membranes were evaluated by thermogravimetric analysis and a cell adhesion assay, respectively. The thermal stability of BC was enhanced by collagen incorporation and by fibrillogenesis. The adhesive ability and the proliferation of NIH/3 T3 fibroblast cells in BC/Col-fibre were better than that in BC/Col, which was still superior to that in BC. Bacterial cellulose/collagen composite membranes (BC/Col) with and without collagen fibrils were fabricated. The collagen amount was improved to 12% by immersing the macroporous BC in a 3.0 mg/mL collagen solution for 50 h at 4 °C. The collagen fibrils interpenetrated with the BC nanofiber networks to improve the thermostability and the cytocompatibility of BC/Col. [ABSTRACT FROM AUTHOR]

Abstract: Due to its dense nanofibril network and inadequate biocompatibility, virgin bacterial cellulose (BC) has limitations in fulfilling the complex biological requirements of cartilage tissue engineering. To address these limits, we herein demonstrate the synthetic protocol of a BC-based scaffold endowed with several added features. A combinatorial approach was adopted to sequentially conduct surface modification by lotus root starch (LRS), three-dimensional (3D) architecture construction by agarose porogen templating, and hydroxyapitate (HA) deposition on the same BC substrate. Scanning electron microscopy revealed that the target scaffold pBC/LRS-M/HA has a nanoporous hierarchical structure with a pore size of 300-500 μm. In vitro LIVE/DEAD assay further indicated that effective cell growth and successful chondrocytes distribution in 3D were achieved on such scaffold with significantly higher cell viability and total cell numbers after 14 days cultivation. Moreover, alkaline phosphatase (ALP) activity assay showed significantly higher ALP activity by approximately 50% and 100% increments, respectively, on pBC/LRS-M/HA than the two control scaffolds. These results comprehensively prove that the overall performance of the BC-based scaffold was enhanced in a synergistic manner. The devised protocol is facile, non-toxic and the pore-size is tunable.Graphical abstract: [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to obtain bacterial cellulose (BC) nanofibrils by using a high speed blender on BC previously oxidized with 2,2,6,6-tetramethyl-1-piperidinoxyl (TEMPO) radical. The resulting oxidized nanofibrillated bacterial cellulose (BCOXNF) was characterized chemically, thermally, and morphologically, presenting high crystallinity index (92%), great dispersion stability (zeta potential, − 52 mV) and appropriate morphology (40 nm in diameter). In addition, freeze dried nanofibrils were evaluated for their redispersibility in water, in order to check whether the process was effective in preventing hornification (nanofibril aggregation upon drying). In fact, the obtained material presented better redispersibility in water (zeta potential, − 63 mV) after freeze drying when compared to non-oxidized BC.Graphical abstract: [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Green and facile approaches aiming at the manufacture of biocompatible paper-based optical sensors reporting the presence of photoluminescence (PL) modulating compounds is an emerging field of research. This study investigates the preparation of bacterial cellulose nanopaper containing covalently immobilized carbon dots for potential biosensing applications. Preliminary work of this feasibility study included TEMPO-mediated ((2,2,6,6-tetramethylpiperidin-1-yl)oxyl-mediated) oxidation and nanofibrillation of bacterial cellulose (TOBC) on the one hand as well as synthesis and comparative analysis of different types of carbon dots (CDs) on the other hand. The two source materials of the targeted functional nanopaper were finally linked to each other by two different N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride/ N-hydroxysuccinimide (EDC/NHS) coupling approaches to clarify whether grafting of CDs prior to or after TOBC paper formation would be the method of choice. Synthesis of the carbon nanodots was accomplished by microwave-assisted co-hydrothermolysis of appropriate precursor compounds. After isolation and purification by dialysis particles in the single-digit nanometer-range were obtained and characterized with regard to their photoluminescence properties in terms of emission wavelength, pH stability, and quantum yield. All types of synthesized CDs reached their PL maxima (450–480 nm; light blue) in a narrow excitation wavelength range of 340–360 nm. Variation of molar (C/N) ratio of the CD precursors and substitution of the nitrogen donor EDEA by urea increased PL and quantum yield (QY), respectively. The highest relative QY of nearly 32% was obtained for CDs synthesized from citric acid and urea. PL of all CDs was virtually insensitive to pH changes in the range of 4–10. Tensile testing of hybrid nanopaper prepared after EDC/NHS-mediated grafting of GEA-type CDs onto TOBC (0.52 mmol·g−1 COOH) in dispersion state revealed that both stiffness and strength are not compromised by incorporation of carbon dots, while plastic deformation and elongation at break increased slightly compared to nanopaper formed prior to decoration with CDs. Water contact angle of the nanopaper is unaffected by introduction of carbon dots which is supposedly due to the presence of surface amino- and amide groups compensating for the loss of carboxyl groups by grafting. [ABSTRACT FROM AUTHOR]

Although a variety of nanoparticles with better-than-bulk material performances can be synthesized, it remains a challenge to scale the extraordinary properties of individual nanoscale units to the macroscopic level for bulk nanostructured materials. Here, we report a general and scalable biosynthesis strategy that involves simultaneous growth of cellulose nanofibrils through microbial fermentation and co-deposition of various kinds of nanoscale building blocks (NBBs) through aerosol feeding on solid culture substrates. We employ this biosynthesis strategy to assemble a wide range of NBBs into cellulose nanofibril-based bulk nanocomposites. In particular, the biosynthesized carbon nanotubes/bacterial cellulose nanocomposites that consist of integrated 3D cellulose nanofibril networks simultaneously achieve an extremely high mechanical strength and electrical conductivity, and thus exhibit outstanding performance as high-strength lightweight electromagnetic interference shielding materials. The biosynthesis approach represents a general and efficient strategy for large-scale production of functional bulk nanocomposites with enhanced performances for practical applications. Industrial-scale production of these bulk nanocomposite materials for practical applications can be expected in the near future. [ABSTRACT FROM AUTHOR]

Abstract: Monolithic titania (TiO2) aerogel was fabricated by using bacterial cellulose (BC) as the bio-template and preceramic polymer as titanium resource, via freeze-drying and two-step calcination process. As-prepared TiO2 aerogel BCTi-air-2 h possessed low bulk density (0.04 g/cm3) and moderate mechanical strength. SEM images showed that TiO2 aerogel was composed of 3D reticulate TiO2 nanofibers. The anatase crystalline structure of TiO2 with crystal size around several nanometers was revealed by XRD measurements. N2 adsorption/desorption analysis indicated that TiO2 aerogel possessed high specific area (115 m2/g) and macroporous structure, which contributed to the high photocatalytic activity. Most importantly, the monolithic state will ease the usage, recycling, and regeneration of TiO2 aerogel as photocatalyst.Graphical abstract: [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) nanofibers, with and without silane surface modification, were incorporated into self-reinforced poly(lactic acid) (SR-PLA) nanocomposites at 1 and 10 wt%. Disintegrated BC was combined with electrospun PLA fiber mats by film stacking and compression molding at 165 °C for 40 sec to obtain SR-PLA/BC hybrid films. The effect of nanocellulose addition and its surface modification on the structure, morphology, and properties of the resulting composites were investigated. It was found that BC was a highly effective reinforcement for SR-PLA nanocomposites, providing a noticeable increase in the film's strength and modulus. Moreover, surface modification of BC was shown to further enhance the film performances due to an improved PLA/BC interfacial interaction. At an optimum BC content, these hybrid films also exhibited outstanding ductility and toughness. Water vapor barrier properties were also enhanced, especially when modified BC was integrated in the SR-PLA films. [ABSTRACT FROM AUTHOR]

Recent studies have demonstrated the potential of bacterial cellulose (BC) as a substrate for the design of bio-based ion exchange membranes with an excellent combination of conductive and mechanical properties for application in devices entailing functional ion conducting elements. In this context, the present study aims at fabricating polyelectrolyte nanocomposite membranes based on poly(bis[2-(methacryloyloxy)ethyl] phosphate) [P(bisMEP)] and BC via the in-situ free radical polymerization of bis[2-(methacryloyloxy)ethyl] phosphate (bisMEP) inside the BC three-dimensional network under eco-friendly reaction conditions. The resulting polyelectrolyte nanocomposites exhibit thermal stability up to 200 °C, good mechanical performance (Young’s modulus > 2 GPa), water-uptake ability (79–155%) and ion exchange capacity ([H+] = 1.1–3.0 mmol g−1). Furthermore, a maximum protonic conductivity of ca. 0.03 S cm−1 was observed for the membrane with P(bisMEP)/BC of 1:1 in weight, at 80 °C and 98% relative humidity. The use of a bifunctional monomer that obviates the need of using a cross-linker to retain the polyelectrolyte inside the BC network is the main contribution of this study, thus opening alternative routes for the development of bio-based polyelectrolyte membranes for application in e.g., fuel cells and other devices based on proton separators. [ABSTRACT FROM AUTHOR]

Biobased aerogels were used as environmentally friendly replacement for synthetic polymers as electrolyte carrier membranes in quantum dot-sensitized solar cell (QDSC). Integration of polymeric components in solar cells has received increased attention for sustainable energy generation. In this context, biobased aerogels were fabricated to apply as freestanding, porous and eco-friendly electrolyte holding membranes in QDSC. Bacterial cellulose (BC), cellulose nanofibers (CNF), chitin nanofibers (ChNF) and TEMPO-oxidized CNF (TOCNF) were selected because of their fibrilar structures and water-holding capability to investigate their inherent differences in terms of surface groups and electrostatic charge on the electrolyte redox reaction and the photocell function. BC, CNF, ChNF and TOCNF were selected due to different surface functional groups (hydroxyl, N-acetylglucosamine and carboxyl units) and fibrilar structures that can form highly interconnected and robust network. These aerogels enabled easy handling, effective electrolyte filling and efficient redox reactions, while keeping the solar cell performance on par to that of traditional reference cells without membranes. The aerogel membranes maintained the photocell performance since they took only a very small space of the electrolyte volume, which allowed efficient charge transfer. The results indicated that aerogels did not interfere with the cell operation, as confirmed by quartz crystal microgravimetry with bio-interphases in contact with the polysulfide-based electrolyte. The electrochemical measurements also suggested that the respective functional groups (hydroxyl, N-acetylglucosamine and carboxyl units) did not interfere with the redox reaction of the polysulfide electrolyte. [ABSTRACT FROM AUTHOR]

We report a systematic computational investigation on the electronic and optical properties of the principal chromophores found in bacterial cellulose (BC). In particular, we focus on the three chromophoric leading structures that were isolated from aged BC (1) 2,5-dihydroxy-[1,4]benzoquinone (2) 5,8-dihydroxy-[1,4]naphthoquinone and (3) 2,5-dihydroxyacetophenone. For the isolated molecules we performed all-electrons density functional theory (DFT) and time dependent DFT calculations with a localized Gaussian basis set and the hybrid exchange correlation functional B3LYP. We quantified key molecular properties relevant as electron affinities, ionization energies, quasi-particle energy gaps, optical absorption spectra, and exciton binding energies. We address moreover the impact of the solvent on the optical properties of the above systems using starting configurations obtained after classical molecular dynamics simulations in water. Our results could be of importance to comprehend the mechanisms underlying the processes of degradation of BC, which are of fundamental relevance for cultural heritage applications. [ABSTRACT FROM AUTHOR]

Cellulose nanopapers have gained significant attention in recent years as large-scale reinforcement for high-loading cellulose nanocomposites, substrates for printed electronics and filter nanopapers for water treatment. The mechanical properties of nanopapers are of fundamental importance for all these applications. Cellulose nanopapers can simply be prepared by filtering a suspension of nanocellulose, followed by heat consolidation. It was already demonstrated that the mechanical properties of cellulose nanopapers can be tailored by the fineness of the fibrils used or by modifying nanocellulose fibrils for instance by polymer adsorption, but nanocellulose blends remain underexplored. In this work, we show that the mechanical and physical properties of cellulose nanopapers can be tuned by creating nanopapers from blends of various grades of nanocellulose, i.e. (mechanically refined) bacterial cellulose or cellulose nanofibrils extracted from never-dried bleached softwood pulp by chemical and mechanical pre-treatments. We found that nanopapers made from blends of two or three nanocellulose grades show synergistic effects resulting in improved stiffness, strength, ductility, toughness and physical properties. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) exhibits unique properties such as high purity compared to plant-based cellulose; however, commercial production of BC has remained a challenge, primarily due to the strain properties of cellulose-producing bacteria. Herein, we developed a functional and stable BC production system in genetically modified (GM) Escherichia coli by recombinant expression of both the BC synthase operon ( bcsABCD) and the upstream operon ( cmcax, ccp Ax). BC production was achieved in GM HMS174 (DE3) and in GM C41 (DE3) by optimization of the culture temperature (22 °C, 30 °C, and 37 °C) and IPTG concentration. BC biosynthesis was detected much earlier in GM C41 (DE3) cultures (3 h after IPTG induction) than those of Gluconacetobacter hansenii. GM HMS174 (DE3) produced dense fibres having a length of approximately 1000-3000 μm and a diameter of 10-20 μm, which were remarkably larger than the fibres of BC typically produced by G. hansenii. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC), which is a hemicellulose- and lignin-free type of cellulose with unique properties, was produced by Komagataeibacter medellinensis, a new acid-resistant bacterial strain, using not suitable human consumption and sub-valorized food supply chain waste (FSCW) and agricultural by-products, namely, rotten banana, rotten mango and cheese whey. The BC was analyzed using Fourier transform infrared (ATR-FTIR), tensile test, atomic absorption spectroscopy and thermogravimetric analysis. The properties of the BC obtained from each culture medium used were different, ranging from a material with high resistance and stiffness (280.6 MPa, 9.4 GPa) to a material with low resistance and less stiffness (17.7 MPa, 0.8 GPa). These properties provide considerable opportunities for obtaining different materials with multiple applications, such as composite reinforcements, wound dressings and edible films. The highest production of BC was achieved with rotten banana medium, and this BC also had the highest tensile properties. Meanwhile, the BC produced from cheese whey medium had the highest maximum rate of degradation temperature at 368 °C. This research demonstrated that FSCW and agrowaste by-products are advantageous alternative feedstocks in terms of economics and environmental concerns for producing BC with multiple properties and fields of application. [ABSTRACT FROM AUTHOR]

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 aundry 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 n 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. [ABSTRACT FROM AUTHOR]

Composite films comprised of bacterial cellulose (BC) and collagen (COL) were developed using BC hydrogel membranes as the base material and COL as the reinforcing material. Glutaraldehyde (GT) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC·HCl) were then used as cross-linking agents to prepare cross-linked BC/COL composite films by a wet chemical method. The effects of chemical cross-linking on the thermal and mechanical properties of composite films were investigated in detail. The COL molecules were adsorbed and deposited inside of 3D nanofiber networks of BC, coated on the surface of BC fibers. Chemical bonds formed between BC molecules, and between BC and COL molecules after cross-linking. Compared with BC, the obtained composite films showed 57.9 and 70.8% improvement in tensile strength after being cross-linked by GT and EDC·HCl, respectively. Cross-linking also enhanced the thermal stability of the specimens. [ABSTRACT FROM AUTHOR]

Patients with diabetes mellitus have an increased cardiovascular risk due to the abnormality of hemostatic system components. Therefore, hemostasis is an important concept when considering that diabetics are under risk due to potential bleeding complications during surgical operation. The aim of our study was to examine the efficiency of a fabricated nano/microbilayer hemostatic dressing for bleeding control in diabetic patients. For this purpose, we prepared a nano/microbilayer hemostatic dressing that has a porous sublayer, including chitosan (CTS), bacterial cellulose (BC) as basement and active agents in coagulation cascade, such as vitamin K (Vit K), protamine sulfate (PS), and kaolin (Kao) as a filler and an upper layer consisting of silk fibroin (SF) or SF/phosphatidylcholine (PC) blend to achieve complete hemostasis in diabetic rats. Coagulative performances of the prepared hemostatic dressings were examined by the determination of bleeding time, blood loss, and mortality rate through diabetic rat femoral artery injury model. The percent of diabetic rat blood absorption was found to be 247 ± 5% for gauze as opposed to 2214 ± 56% for SF-coated PS/BC/CTS. Vit K-reinforced within 138 s and SF-coated BC/CTS hemostatic dressings within 144 s showed a rapid coagulation time. In vivo coagulation studies demonstrated that hemostatic agent-reinforced BC/CTS hemostatic dressing, especially PS/BC/CTS showed a significant hemostatic plug formation. This study suggests that the high positive charge and porosity give to these hemostatic agents reinforced hemostatic dressings the ability to rapidly swell and to promote the accumulation of red blood cells and platelets through electrostatic interactions. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1573-1585, 2017. [ABSTRACT FROM AUTHOR]

Agarose is an abundant and biodegradable polymer with strength comparable or higher than other commonly used natural polymers. Agarose can be used for wound dressing and tissue engineering applications. Excessive water uptake and moderate strength limit its applicability for various applications. The objective of this study was to enhance its strength by reinforcing with bacterial cellulose. The addition of bacterial cellulose exhibited remarkable enhancement of 140% in the tensile strength of agarose bioplastic. The strength increased from 25.1 MPa for agarose bioplastic to a maximum of 60.2 MPa for 20% (w/w) of bacterial cellulose. There was a decrease in the amount of water absorption; at 37 °C, the composite films absorbed 450% of their own weight of water, as against 700% absorption by un-reinforced bioplastic films at the same temperature. Thermogravimetric analysis did not reveal any perceivable change in the thermal stability of the bioplastic. Biodegradability of composite films was also established. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) is a unique biomaterial with interesting physico-chemical properties and potential technological applications (i.e. removal of heavy metals from wastewater, manufacturing electrical and electronic devices, papermaking and biomedical technologies among others). In this work, we describe the growth of well formed micro-crystals of the one-dimensional spin crossover (SCO) compound {[Fe(Htrz)(trz)](BF)} in a matrix of BC. The thermal dependence of the magnetic, optical, calorimetric and vibrational properties associated with the SCO properties of the resulting composite material have been investigated and compare well with those of the bulk SCO. The SCO-BC composite films display reversible thermomagnetic (diamagnetic ↔ paramagnetic) and thermochromic bistability (purple ↔ pale-yellow) determined by a well-defined hysteresis in the temperature range ca. 345-380 K where these properties depend on the history of the sample (memory effect). [ABSTRACT FROM AUTHOR]