Palladium-bacterial cellulose membranes for fuel cells

Metal-based nanoparticle in cancer treatment: lessons learned and challenges

Cancer, being one of the deadliest diseases, poses significant challenges despite the existence of traditional treatment approaches. This has led to a growing demand for innovative pharmaceutical agents that specifically target cancer cells for effective treatment. In recent years, the use of metal nanoparticles (NPs) as a promising alternative to conventional therapies has gained prominence in cancer research. Metal NPs exhibit unique properties that hold tremendous potential for various applications in cancer treatment. Studies have demonstrated that certain metals possess inherent or acquired anticancer capabilities through their surfaces. These properties make metal NPs an attractive focus for therapeutic development. In this review, we will investigate the applicability of several distinct classes of metal NPs for tumor targeting in cancer treatment. These classes may include gold, silver, iron oxide, and other metals with unique properties that can be exploited for therapeutic purposes. Additionally, we will provide a comprehensive summary of the risk factors associated with the therapeutic application of metal NPs. Understanding and addressing these factors will be crucial for successful clinical translation and to mitigate any potential challenges or failures in the translation of metal NP-based therapies. By exploring the therapeutic potential of metal NPs and identifying the associated risk factors, this review aims to contribute to the advancement of cancer treatment strategies. The anticipated outcome of this review is to provide valuable insights and pave the way for the advancement of effective and targeted therapies utilizing metal NPs specifically for cancer patients.

Effect of Reduction Methods on the Properties of Composite Films of Bacterial Cellulose-Silver Nanoparticles

Composite films of bacterial cellulose-silver nanoparticles (BC-Ag) were prepared by different methods of in situ reduction of silver ions, using sodium hydroxide, ascorbic acid, chitosan, and UV irradiation. The effects of the reduction methods on their properties were investigated. The chitosan-reduced composite exhibited dispersed silver nanoparticles (AgNPs) within the nanocellulose matrix with the smallest size, while the ascorbic-reduced composite displayed the largest size. The incorporation of AgNPs tended to reduce the crystallinity of the composites, except for the ascorbic-reduced composite, which exhibited an increase in crystallinity. Mechanical testing revealed that the ascorbic-reduced composite had the highest Young's modulus of 8960 MPa, whereas the UV-reduced composite had the highest tensile strength and elongation at break. Thermal analysis of BC-Ag composites indicated similar glass transition temperature and decomposition profiles to BC, with additional weight-loss steps at high temperatures. The sodium hydroxide-reduced composite demonstrated the highest electrical conductivity of 1.1 × 10^-7 S/cm. Water absorption capacity was reduced by the incorporation of AgNPs, except for the chitosan-reduced composite, which showed an enhanced water absorption capacity of 344%. All BC-Ag composites displayed very strong antibacterial activities against Staphylococcus aureus and Escherichia coli. These results also highlight the potential uses of BC-Ag composites for various applications.

Production efficiency and properties of bacterial cellulose membranes in a novel grape pomace hydrolysate by Komagataeibacter melomenusus AV436T and Komagataeibacter xylinus LMG 1518

The microbial production of cellulose using different bacterial species has been extensively examined for various industrial applications. However, the cost-effectiveness of all these biotechnological processes is strongly related to the culture medium for bacterial cellulose (BC) production. Herein, we examined a simple and modified procedure for preparing grape pomace (GP) hydrolysate, without enzymatic treatment, as a sole growth medium for BC production by acetic acid bacteria (AAB). The central composite design (CCD) was used to optimise the GP hydrolysate preparation toward the highest reducing sugar contents (10.4 g/L) and minimal phenolic contents (4.8 g/L). The experimental screening of 4 differently prepared hydrolysates and 20 AAB strains identified the recently described species Komagataeibacter melomenusus AV436^T as the most efficient BC producer (up to 1.24 g/L dry BC membrane), followed by Komagataeibacter xylinus LMG 1518 (up to 0.98 g/L dry BC membrane). The membranes were synthesized in only 4 days of bacteria culturing, 1 st day with shaking, followed by 3 days of static incubation. The produced BC membranes in GP-hydrolysates showed, in comparison to the membranes made in a complex RAE medium 34 % reduction of crystallinity index with the presence of diverse cellulose allomorphs, presence of GP-related components within the BC network responsible for the increase of hydrophobicity, the reduction of thermal stability and 48.75 %, 13.6 % and 43 % lower tensile strength, tensile modulus, and elongation, respectively. Here presented study is the first report on utilising a GP-hydrolysate without enzymatic treatment as a sole culture medium for efficient BC production by AAB, with recently described species Komagataeibacter melomenusus AV436^T as the most efficient producer in this type of food-waste material. The scale-up protocol of the scheme presented here will be needed for the cost-optimisation of BC production at the industrial levels.

Low-Voltage Driven Ionic Polymer-Metal Composite Actuators: Structures, Materials, and Applications

With the characteristics of low driving voltage, light weight, and flexibility, ionic polymer-metal composites (IPMCs) have attracted much attention as excellent candidates for artificial muscle materials in the fields of biomedical devices, flexible robots, and microelectromechanical systems. Under small voltage excitation, ions inside the IPMC proton exchange membrane migrate directionally, leading to differences in the expansion rate of the cathode and the anode, which in turn deform. This behavior is caused by the synergistic action of a three-layer structure consisting of an external electrode layer and an internal proton exchange membrane, but the electrode layer is more dominant in this process due to the migration and storage of ions. The exploration of modifications and alternatives for proton exchange membranes and recent advances in the fabrication and characterization of conductive materials, especially carbon-based materials and conductive polymers, have contributed significantly to the development of IPMCs. This paper reviews the progress in the application of proton exchange membranes and electrode materials for IPMCs, discusses various processes currently applied to IPMCs preparation, and introduces various promising applications of cutting-edge IPMCs with high performance to provide new ideas and approaches for the research of  new generation of low-voltage ionic soft actuators.

Non-Solvent- and Temperature-Induced Phase Separations of Polylaurolactam Solutions in Benzyl Alcohol as Methods for Producing Microfiltration Membranes

The possibility of obtaining porous films through solutions of polylaurolactam (PA12) in benzyl alcohol (BA) was considered. The theoretical calculation of the phase diagram showed the presence of the upper critical solution temperature (UCST) for the PA12/BA system at 157 °C. The PA12 completely dissolved in BA at higher temperatures, but the resulting solutions underwent phase separation upon cooling down to 120–140 °C because of the PA12’s crystallization. The viscosity of the 10–40% PA12 solutions increased according to a power law but remained low and did not exceed 5 Pa·s at 160 °C. Regardless of the concentration, PA12 formed a dispersed phase when its solutions were cooled, which did not allow for the obtention of strong films. On the contrary, the phase separation of the 20–30% PA12 solutions under the action of a non-solvent (isopropanol) leads to the formation of flexible microporous films. The measurement of the porosity, wettability, strength, permeability, and rejection of submicron particles showed the best results for a porous film produced from a 30% solution by non-solvent-induced phase separation. This process makes it possible to obtain a membrane material with a 240 nm particle rejection of 99.6% and a permeate flow of 1.5 kg/m2hbar for contaminated water and 69.9 kg/m2hbar for pure water.

Bacterial Cellulose-Based Polymer Nanocomposites: A Review

Bacterial cellulose (BC) is currently one of the most popular environmentally friendly materials with unique structural and physicochemical properties for obtaining various functional materials for a wide range of applications. In this regard, the literature reporting on bacterial nanocellulose has increased exponentially in the past decade. Currently, extensive investigations aim at promoting the manufacturing of BC-based nanocomposites with other components such as nanoparticles, polymers, and biomolecules, and that will enable to develop of a wide range of materials with advanced and novel functionalities. However, the commercial production of such materials is limited by the high cost and low yield of BC, and the lack of highly efficient industrial production technologies as well. Therefore, the present review aimed at studying the current literature data in the field of highly efficient BC production for the purpose of its further usage to obtain polymer nanocomposites. The review highlights the progress in synthesizing BC-based nanocomposites and their applications in biomedical fields, such as wound healing, drug delivery, tissue engineering. Bacterial nanocellulose-based biosensors and adsorbents were introduced herein.

Bacterial Cellulose and Its Applications

The sharp increase in the use of cellulose seems to be in increasing demand in wood; much more research related to sustainable or alternative materials is necessary as a lot of the arable land and natural resources use is unsustainable. In accordance, attention has focused on bacterial cellulose as a new functional material. It possesses a three-dimensional, gelatinous structure consisting of cellulose with mechanical and thermal properties. Moreover, while a plant-originated cellulose is composed of cellulose, hemi-cellulose, and lignin, bacterial cellulose attributable to the composition of a pure cellulose nanofiber mesh spun is not necessary in the elimination of other components. Moreover, due to its hydrophilic nature caused by binding water, consequently being a hydrogel as well as biocompatibility, it has only not only used in medical fields including artificial skin, cartilage, vessel, and wound dressing, but also in delivery; some products have even been commercialized. In addition, it is widely used in various technologies including food, paper, textile, electronic and electrical applications, and is being considered as a highly versatile green material with tremendous potential. However, many efforts have been conducted for the evolution of novel and sophisticated materials with environmental affinity, which accompany the empowerment and enhancement of specific properties. In this review article, we summarized only industry and research status regarding BC and contemplated its potential in the use of BC.

Nanocomposite and bio-nanocomposite polymeric materials/membranes development in energy and medical sector: A review

Nanocomposite and bio-nanocomposite polymer materials/membranes have fascinated prominent attention in the energy as well as the medical sector. Their composites make them appropriate choices for various applications in the medical, energy and industrial sectors. Composite materials are subject of interest in the polymer industry. Different kinds of fillers, such as cellulose-based fillers, carbon black, clay nanomaterials, glass fibers, ceramic nanomaterial, carbon quantum dots, talc and many others have been incorporated into polymers to improve the quality of the final product. These results are dependent on a variety of factors; however, nanoparticle dispersion and distribution are major obstacles to fully using nanocomposites/bio-nanocomposites materials/membranes in various applications. This review examines the various nanocomposite and bio-nanocomposite materials applications in the energy and medical sector. The review also covers the variety of ways for increasing nanocomposite and bio-nanocomposite materials features, each with its own set of applications. Recent researches on composite materials have shown that polymeric nanocomposites and bio-nanocomposites are promising materials that have been intensively explored for many applications that include electronics, environmental remediation, energy, sensing (biosensor) and energy storage devices among other applications. In this review, we studied various nanocomposite and bio-nanocomposite materials, their controlling parameters to develop the product and examine their features and applications in the fields of energy and the medical sector.

Bacterial cellulose in food industry: Current research and future prospects

Bacterial cellulose, a pure exocellular polysaccharide produced by microorganisms, has many excellent properties as compared with plant-derived cellulose, including high water holding capability, high surface area, rheological properties, biocompatibility. Due to its suspending, thickening, water holding, stabilizing, bulking and fluid properties, BC has been demonstrated as a promising low calorie bulking ingredient for the development of novel rich functional foods of different forms such as powder gelatinous or shred foams, which facilitate its application in food industry. In this review, the recent reports on the biosynthesis, structure and general application of bacterial cellulose in food industry have been summarized and discussed. The main application of bacterial cellulose in current food industry includes raw food materials, additive ingredients, packing materials, delivery system, enzyme and cell immobilizers. In addition, we also propose the potential challenges and explore the solution of expanding the application of BC in various fields.

Development of an antimicrobial bioactive paper made from bacterial cellulose

Bacterial cellulose (BC) has emerged as an attractive adsorptive material for antimicrobial agents due to its fine network structure, its large surface area, and its high porosity. In the present study, BC paper was first produced and then lysozyme was immobilized onto it by physical adsorption, obtaining a composite of lysozyme-BC paper. The morphology and the crystalline structure of the composite were similar to that of BC paper as examined by scanning electron microscopy and X-ray diffraction, respectively. Regarding operational properties, specific activities of immobilized and free lysozyme were similar. Moreover, immobilized enzyme showed a broader working temperature and higher thermal stability. The composites maintained its activity for at least 80 days without any special storage. Lysozyme-BC paper displayed antimicrobial activity against Gram-positive and Gram-negative bacteria, inhibiting their growth by 82% and 68%, respectively. Additionally, the presence of lysozyme increased the antioxidant activity of BC paper by 30%. The results indicated that BC is a suitable material to produce bioactive paper as it provides a biocompatible environment without compromising the activity of the immobilized protein. BC paper with antimicrobial and antioxidant properties may have application in the field of active packaging.

Fabrication of noble metal nanoparticles decorated on one dimensional hierarchical polypyrrole@MoS2 microtubes

Herein, we present a facile strategy to fabricate noble metal (Ag, Au, Pd) decorated on PPy@MoS₂ microtubes. As a proof of application, the ternary PPy@MoS₂@Au hybrids reveal excellent enzyme-like catalytic performance.

Statistical optimization and characterization of a biocellulose produced by local Egyptian isolate Komagataeibacter hansenii AS.5

Optimization of the culture parameters used for biocellulose (BC) production by a previously isolated bacterial strain (Komagataeibacter hansenii AS.5) was carried out. The effect of nine culture parameters on BC production was evaluated by implementing the Plackett-Burman design, and the results revealed that, the most significant variables affecting BC production were MgSO₄, ethanol, pH and yeast extract. A three-level and four-factor Box-Behnken design was applied to determine the optimum level of each significant variable. According to the results of the Plackett-Burman (PBD) and Box-Behnken designs (BBD), the following medium composition and parameters were calculated to be optimum (g/l): glucose 25, yeast extract 13, MgSO₄ 0.15, KH₂PO₄ 2, ethanol 7.18 ml/l, pH 5.5, inoclume size 7%, cultivation temperature 20 °C and incubation time 9 days. Characterization of purified BC was performed to determine the network morphology by scanning electron microscopy, crystallinity by X-ray diffraction, chemical structure and functional groups by Fourier-transform infrared spectroscopy, thermal stability by thermogravimetric analysis and mechanical properties such as Young's modulus, tensile strength and elongation at beak % of BC.

Engineering of keratin functionality for the realization of bendable all-biopolymeric micro-electrode array as humidity sensor

The technological quest for flexible devices to be interfaced with the biological world has driven the recent reinvention of bioderived polymers as multifunctional active and passive constituent elements for electronic and photonic devices to use in the biomedical field. Keratin is one of the most important structural proteins in nature to be used as biomaterial platform in view of the recently reported advances in the extraction and processing from hair and wool fibers. In this article we report for the first time the simultaneous use of naturally extracted keratin as both active ionic electrolyte for water ions sensing and as bendable and insoluble substrate into the same multielectrode array-based device. We implemented the multifunctional system exclusively made by keratin as a bendable sensor for monitoring the humidity flow. The enhancement of the functional and structural properties of keratin such as bendability and insolubility were obtained by unprecedented selective chemical doping. The mechanisms at the basis of the sensing of humidity in the device were investigated by cyclic voltammetry and rationalized by reversible binding and extraction of water ions from the volume of the keratin active layer, while the figures of merit of the biopolymer such as the ionic conductivity and relaxation time were determined by means of electrical impedance and dielectric relaxation spectroscopy. A reliable linear correlation between the controlled-humidity level and the amperometric output signal together with the assessment on measure variance are demonstrated. Collectively, the fine-tuned ionic-electrical characterization and the validation in controlled conditions of the free-standing insoluble all-keratin made microelectrode array ionic sensor pave the way for the effective use of keratin biopolymer in wearable or edible electronics where conformability, reliability and biocompatibility are key-enabling features.

Multifunctional nanocellulose/metal and metal oxide nanoparticle hybrid nanomaterials

Nanocellulose materials are derived from cellulose, the most abundant biopolymer on the earth. Nanocellulose have been extensively used in the field of food packaging materials, wastewater treatment, drug delivery, tissue engineering, hydrogels, aerogels, sensors, pharmaceuticals, and electronic sectors due to their unique chemical structure and excellent mechanical properties. On the other hand, metal and metal oxide nanoparticles (NP) such as Ag NP, ZnO NP, CuO NP, and Fe₃O₄ NP have a variety of functional properties such as UV-barrier, antimicrobial, and magnetic properties. Recently, nanocelluloses materials have been used as a green template for producing metal or metal oxide nanoparticles. As a result, multifunctional nanocellulose/metal or metal oxide hybrid nanomaterials with high antibacterial properties, ultraviolet barrier properties, and mechanical properties were prepared. This review emphasized recent information on the synthesis, properties, and potential applications of multifunctional nanocellulose-based hybrid nanomaterials with metal or metal oxides such as Ag NP, ZnO NP, CuO NP, and Fe₃O₄ NP. The nanocellulose-based hybrid nanomaterials have huge potential applications in the area of food packaging, biopharmaceuticals, biomedical, and cosmetics.

Production of bacterial nanocellulose (BNC) and its application as a solid support in transition metal catalysed cross-coupling reactions

Bacterial nanocellulose (BNC) emerged as an attractive advanced biomaterial that provides desirable properties such as high strength, lightweight, tailorable surface chemistry, hydrophilicity, and biodegradability. BNC was successfully obtained from a wide range of carbon sources including sugars derived from grass biomass using Komagataeibacter medellinensis ID13488 strain with yields up to 6 g L^-1 in static fermentation. Produced BNC was utilized in straightforward catalyst preparation as a solid support for two different transition metals, palladium and copper with metal loading of 20 and 3 wt%, respectively. Sustainable catalysts were applied in the synthesis of valuable fine chemicals, such as biphenyl-4-amine and 4'-fluorobiphenyl-4-amine, used in drug discovery, perfumes and dye industries with excellent product yields of up to 99%. Pd/BNC catalyst was reused 4 times and applied in two consecutive reactions, Suzuki-Miyaura cross-coupling reaction followed by hydrogenation of nitro to amino group while Cu/BNC catalyst was examined in Chan-Lam coupling reaction. Overall, the environmentally benign process of obtaining nanocellulose from biomass, followed by its utilisation as a solid support in metal-catalysed reactions and its recovery has been described. These findings reveal that BNC is a good support material, and it can be used as a support for different catalytic systems.

Liquid Cell Transmission Electron Microscopy Sheds Light on The Mechanism of Palladium Electrodeposition

Electrodeposition is widely used to fabricate tunable nanostructured materials in applications ranging from biosensing to energy conversion. A model based on 3D island growth is widely accepted in the explanation of the initial stages of nucleation and growth in electrodeposition. However, there are regions in the electrodeposition parameter space where this model becomes inapplicable. We use liquid cell transmission electron microscopy along with post situ scanning electron microscopy to investigate electrodeposition in this parameter space, focusing on the effect of the supporting electrolyte, and to shed light on the nucleation and growth of palladium. Using a collection of electron microscopy images and current time transients recorded during electrodeposition, we discover that electrochemical aggregative growth, rather than 3D island growth, best describes the electrodeposition process. We then use this model to explain the change in the morphology of palladium electrodeposits from spherical to open clusters with nonspherical morphology when HCl is added to the electrolyte solution. The enhanced understanding of the early stages of palladium nucleation and growth and the role of electrolyte in this process provides a systematic route toward the electrochemical fabrication of nanostructured materials.

Poly(bis[2-(methacryloyloxy)ethyl] phosphate)/Bacterial Cellulose Nanocomposites: Preparation, Characterization and Application as Polymer Electrolyte Membranes

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.

Hierarchically Porous Zirconia Monolith Fabricated from Bacterial Cellulose and Preceramic Polymer

A hierarchically porous zirconia (ZrO₂) monolith was successfully fabricated by using bacterial cellulose (BC) as a biotemplate and preceramic polymer as a zirconium resource, via freeze-drying and two-step calcination process. Images of scanning electron microscopy showed that the ZrO₂ monolith well-replicated a three-dimensional reticulated structure of pristine BC and possessed good morphology stability till 1100 °C in air. Results of N₂ adsorption/desorption and mercury porosimetry analysis revealed the hierarchically porous structure and large specific area (9.7 m²·g^-1) of the ZrO₂ monolith, respectively. Patterns of X-ray powder diffraction indicated that the monoclinic phase and tetragonal phase coexisted in the ZrO₂ monolith with the former as the main phase. In addition, the ZrO₂ monolith possessed low bulk density (0.13 g·cm^-3) and good mechanical strength. These properties suggest that the as-prepared ZrO₂ monolith has a great potential to serve as an ideal catalyst or catalyst support.

Synthetic polymeric biomaterials for wound healing: a review

Wounds are of a variety of types and each category has its own distinctive healing requirements. This realization has spurred the development of a myriad of wound dressings, each with specific characteristics. It is unrealistic to expect a singular dressing to embrace all characteristics that would fulfill generic needs for wound healing. However, each dressing may approach the ideal requirements by deviating from the 'one size fits all approach', if it conforms strictly to the specifications of the wound and the patient. Indeed, a functional wound dressing should achieve healing of the wound with minimal time and cost expenditures. This article offers an insight into several different types of polymeric materials clinically used in wound dressings and the events taking place at cellular level, which aid the process of healing, while the biomaterial dressing interacts with the body tissue. Hence, the significance of using synthetic polymer films, foam dressings, hydrocolloids, alginate dressings, and hydrogels has been reviewed, and the properties of these materials that conform to wound-healing requirements have been explored. A special section on bioactive dressings and bioengineered skin substitutes that play an active part in healing process has been re-examined in this work.

Functionalization of bacterial cellulose wound dressings with the antimicrobial peptide ε-poly-L-Lysine

Wound dressings based on bacterial cellulose (BC) can form a soft and conformable protective layer that can stimulate wound healing while preventing bacteria from entering the wound. Bacteria already present in the wound can, however, thrive in the moist environment created by the BC dressing which can aggravate the healing process. Possibilities to render the BC antimicrobial without affecting the beneficial structural and mechanical properties of the material would hence be highly attractive. Here we present methods for functionalization of BC with ε-poly-L-Lysine (ε-PLL), a non-toxic biopolymer with broad-spectrum antimicrobial activity. Low molecular weight ε-PLL was cross-linked in pristine BC membranes and to carboxymethyl cellulose functionalized BC using carbodiimide chemistry. The functionalization of BC with ε-PLL inhibited growth of S. epidermidis on the membranes but did not affect the cytocompatibility to cultured human fibroblasts as compared to native BC. The functionalization had no significant effects on the nanofibrous structure and mechanical properties of the BC. The possibility to functionalize BC with ε-PLL is a promising, green and versatile approach to improve the performance of BC in wound care and other biomedical applications.

Enhanced bacterial cellulose production by Gluconacetobacter xylinus via expression of Vitreoscilla hemoglobin and oxygen tension regulation

Oxygen plays a key role during bacterial cellulose (BC) biosynthesis by Gluconacetobacter xylinus. In this study, the Vitreoscilla hemoglobin (VHb)-encoding gene vgb, which has been widely applied to improve cell survival during hypoxia, was heterologously expressed in G. xylinus via the pBla-VHb-122 plasmid. G. xylinus and G. xylinus-vgb ⁺ were statically cultured under hypoxic (10 and 15% oxygen tension in the gaseous phase), atmospheric (21%), and oxygen-enriched conditions (40 and 80%) to investigate the effect of oxygen on cell growth and BC production. Irrespective of vgb expression, we found that cell density increased with oxygen tension (10-80%) during the exponential growth phase but plateaued to the same value in the stationary phase. In contrast, BC production was found to significantly increase at lower oxygen tensions. In addition, we found that BC production at oxygen tensions of 10 and 15% was 26.5 and 58.6% higher, respectively, in G. xylinus-vgb ⁺ than that in G. xylinus. The maximum BC yield and glucose conversion rate, of 4.3 g/L and 184.7 mg/g, respectively, were observed in G. xylinus-vgb ⁺ at an oxygen tension of 15%. Finally, BC characterization suggested that hypoxic conditions enhance BC's mass density, Young's modulus, and thermostability, with G. xylinus-vgb ⁺ synthesizing softer BC than G. xylinus under hypoxia as a result of a decreased Young's modulus. These results will facilitate the use of static culture for the production of BC.

Production and Status of Bacterial Cellulose in Biomedical Engineering

Bacterial cellulose (BC) is a highly pure and crystalline material generated by aerobic bacteria, which has received significant interest due to its unique physiochemical characteristics in comparison with plant cellulose. BC, alone or in combination with different components (e.g., biopolymers and nanoparticles), can be used for a wide range of applications, such as medical products, electrical instruments, and food ingredients. In recent years, biomedical devices have gained important attention due to the increase in medical engineering products for wound care, regeneration of organs, diagnosis of diseases, and drug transportation. Bacterial cellulose has potential applications across several medical sectors and permits the development of innovative materials. This paper reviews the progress of related research, including overall information about bacterial cellulose, production by microorganisms, mechanisms as well as BC cultivation and its nanocomposites. The latest use of BC in the biomedical field is thoroughly discussed with its applications in both a pure and composite form. This paper concludes the further investigations of BC in the future that are required to make it marketable in vital biomaterials.

Cellulose-gold nanoparticle hybrid materials

Cellulose and gold nanoparticles have exciting characteristics and new combinations of both materials may lead to promising functional nanocomposites with unique properties. We have reviewed current research on cellulose-gold nanoparticle composite materials, and we present an overview of the preparation methods of cellulose-gold composite materials and discuss their applications. We start with the nanocomposite fabrication methods, covering in situ gold reduction, blending, and dip-coating methods to prepare gold-cellulose nanocomposite hybrids. We then move on to a discussion of the ensuing properties where the combination of gold nanoparticles with cellulose results in functional materials with specific catalytic, antimicrobial, sensing, antioxidant and Surface Enhanced Raman Scattering (SERS) performance. Studies have also been carried out on orientationally ordered composite materials and on the chiral nematic phase behaviour of these nanocomposites. To exert even more control over the structure formation and the resultant properties of these functional materials, fundamental studies on the physico-chemical interactions of cellulose and gold are necessary to understand better the driving forces and limitations towards structuring of gold-cellulose hybrid materials.

Correlation between type of alkali rinsing, cytotoxicity of bio-nanocellulose and presence of metabolites within cellulose membranes

The study aimed at evaluation of various types of alkali rinsing with regard to their efficacy in terms of removal, not only of bacteria but also bacterial metabolites, from cellulose matrices formed by three Komagataeibacter xylinus strains. Moreover, we tested the type of alkali rinsing on membrane cytotoxicity in vitro in fibroblast and osteoblast cells and we compared matrices' ability to induce oxidative stress in macrophages. We identified 11 metabolites of bacterial origin that remained in cellulose after rinsing. Moreover, our results indicated that the type of alkali rinsing should be adjusted to specific K. xylinus strains that are used as cellulose producers to obtain safe biomaterials in the context of low cytotoxicity and macrophage induction. The findings have translational importance and may be of direct significance to cellulose dressing manufacturers.

In Situ Development of Nanosilver-Impregnated Bacterial Cellulose for Sustainable Released Antimicrobial Wound Dressing

Purpose

Bacterial cellulose (BC) is an interesting biomaterial found application in various fields due to its novel characteristics like purity, water holding capacity, degree of polymerization and mechanical strength. BC as wound dressing material has limitation because it has no antimicrobial activity. To circumvent this problem, the present study was carried out by impregnation of silver on bacterial cellulose surface.

Methods

Bacterial cellulose was produced by Gluconoacetobacter hansenii (strain NCIM 2529) by shaking culture method. The sodium borohydride and classical Tollens reaction was used for silver nanoparticle synthesis.

Results

The effectiveness of sodium borohydride method compared with Tollens reaction was evaluated on the basis of silver nanoparticle formation and its impregnation on BC as evidenced by UV-Vis spectrum analysis, FE-SEM-EDS analysis and FT-IR spectrum. The potential of nano silver impregnated BC was determined for sustained release antimicrobial wound dressing material by swelling ratio, mechanical properties and antimicrobial activity against Staphylococcus aureus.

Conclusions

Thus the nanosilver impregnated bacterial cellulose as promising antimicrobial wound dressing material was evidenced.

Recyclable glucose-derived palladium(0) nanoparticles as in situ-formed catalysts for cross-coupling reactions in aqueous media

Renewable sugar-derived palladium(0) nanoparticles (PdNPs) are effective as in situ formed catalysts for cross-coupling reactions in aqueous solutions.

Production of bacterial cellulose with controlled deuterium-hydrogen substitution for neutron scattering studies

Isotopic enrichment of biomacromolecules is a widely used technique that enables the investigation of the structural and dynamic properties to provide information not accessible with natural abundance isotopic composition. This study reports an approach for deuterium incorporation into bacterial cellulose. A media formulation for growth of Acetobacter xylinus subsp. sucrofermentans and Gluconacetobacter hansenii was formulated that supports cellulose production in deuterium (D) oxide. The level of D incorporation can be varied by altering the ratio of deuterated and protiated glycerol used during cell growth in the D2O-based growth medium. Spectroscopic analysis and mass spectrometry show that the level of deuterium incorporation is high (>90%) for the perdeuterated form of bacterial cellulose. The small-angle neutron scattering profiles of the cellulose with different amounts of D incorporation are all similar indicating that there are no structural changes in the cellulose due to substitution of deuterium for hydrogen. In addition, by varying the amount of deuterated glycerol in the media it was possible to vary the scattering length density of the deuterated cellulose. The ability to control deuterium content of cellulose extends the range of experiments using techniques such as neutron scattering to reveal information about the structure and dynamics of cellulose, and its interactions with other biomacromolecules as well as synthetic polymers used for development of composite materials.