Synthesis-property-performance relationships of multifunctional bacterial cellulose composites fermented in situ alkali lignin medium

Balancing mechanical property and swelling behavior of bacterial cellulose film by in-situ adding chitosan oligosaccharide and covalent crosslinking with γ-PGA

Bacterial cellulose (BC) is an ideal candidate material for drug delivery, but the disbalance between the swelling behavior and mechanical properties limits its application. In this work, covalent crosslinking of γ-polyglutamic acid (γ-PGA) with the chitosan oligosaccharide (COS) embedded in BC was designed to remove the limitation. As a result, the dosage, time, and batch of COS addition significantly affected the mechanical properties and the yield of bacterial cellulose complex film (BCCF). The addition of 2.25 % COS at the incubation time of 0.5, 1.5, and 2 d increased the Young's modulus and the yield by 5.65 and 1.42 times, respectively, but decreased the swelling behavior to 1774 %, 46 % of that of native BC. Covalent γ-PGA transformed the dendritic structure of BCCF into a spider network, decreasing the porosity and increasing the swelling behavior by 3.46 times. The strategy balanced the swelling behavior and mechanical properties through tunning hydrogen bond, electrostatic interaction, and amido bond. The modified BCCF exhibited a desired behavior of benzalkonium chlorides transport, competent for drug delivery. Thereby, the strategy will be a competent candidate to modify BC for such potential applications as wound dressing, artificial skin, scar-inhibiting patch, and so on.

Enhanced mechanical properties and biocompatibility of bacterial cellulose composite films with inclusion of 2D MoS2 and helical carbon nanotubes for use as antimicrobial drug carriers

Bacterial cellulose (BC) is a biomaterial being investigated for a range of applications. Herein, BC films derived from nata de coco pieces are reinforced by two-dimensional molybdenum disulfide (MoS2) and helical carbon nanotubes (HCNTs) to enhance their tensile mechanical properties, and the biocompatibility of the BC composite films is demonstrated. A simple preparation is presented using a kitchen blender to disperse and blend the BC fibers and additives in a common fabrication medium, followed by vacuum filtration. The mechanical properties of the BC/MoS2/HCNTs composite films are enhanced due to the synergistic effect of MoS2 and HCNTs embedded in the BC films. The MoS2/HCNTs binary additive (1 phr) is capable of increasing the strength and Young's modulus by 148 % and 333 %, respectively, relative to the BC films. The cell cytotoxicity of the BC/MoS2/HCNTs films was assessed using an MTT assay. The composite films are biocompatible with a cell viability of L929 fibroblast cells >70 %, coupled with observations of direct cell attachment on the films. The composite films also exhibited good performance in absorbing and releasing gentamicin antibiotics to inhibit the growth of Escherichia coli and Staphylococcus aureus. The BC/MoS2/HCNTs films are thus potential BC-based candidates as biocompatible robust antibiotic carriers.

Production of Bacterial Exopolysaccharides: Xanthan and Bacterial Cellulose

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.

Biomedical engineering aspects of nanocellulose: a review

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.