Highly Stretchable, Adhesive, Biocompatible, and Antibacterial Hydrogel Dressings for Wound Healing.

CHAPTER 1 - Bacterial cellulose nanofibers for separation, drug delivery, wound dressing, and tissue engineering applications

Ecofriendly green biosynthesis and characterization of novel bacteriocin-loaded bacterial cellulose nanofiber from Gluconobacter cerinus HDX-1

Wound dressings play an essential role in wound care and healing, but the price is expensive for patients who have to treat for a long time such as patients from burns, scalds, etc. The objective of the research is to develop a wound dressing made with bacterial cellulose and local herb that has antibacterial properties, is cheap, and can be created by yourself. The bacterial cellulose (BC) produced from Acetobactor xylinum using coconut water waste to reduce costs. Its structure was changed to bacterial cellulose nanocrystals (BCNC) by acid hydrolysis, dried in 2 methods: Oven dried at 50 °C (dy) or freeze dried (fd). Then, herbal dressings were produced as a composite BC with herbs in 2 forms: A solution, i.e. C. Odorata leaf extract solution and a colloid, i.e. C. hystrix essential oil nanocapsule. The results for the production of a wound dressing showed that fd-BCNC had good quality, good fiber dispersion, high porosity and no antibacterial activity. It is suitable as a primary or secondary wound dressing, that does not help in wound healing. When fd-BCNC was loaded with herbs in 2 forms, it was found to be stable at room temperature, water adsorption, water vapor permeability and inhibit Staphylococcus aureus and Escherichia coli. Especially fd-BCNC of nanocapsule of C. hystrix peel essential oil has the best antibacterial effect. Therefore, you can apply this developed wound dressing to herbs used specifically for healing wounds. Moreover, we believe that this research will be a database that can be expanded to commercial production. HIGHLIGHTS Bacterial cellulose is produced using coconut water waste as culture medium Freeze-dried Bacterial cellulose nanocrystals is a promising for non antibacterial wound dressing Freeze-dried Bacterial cellulose nanocrystals composite with herbs are a promising for anti-bacterial wound dressing GRAPHICAL ABSTRACT

Bioactive bacterial cellulose wound dressings for burns with collagen in-situ and chitosan ex-situ impregnation

This paper presents a novel nanorod metal-organic framework made of silver nods configured within nicotinic acid (vitamin-B3) linkers (AgNA) aimed at wound healing applications. X-ray diffraction analysis indicated that the synthesized AgNA MOFs comprised of zigzag chains of silver (I) nicotinate with orthorhombic crystal structure. Electron microscopy showed nanorod structures for the MOFs with uniform dimensions and element distribution. By seeding the AgNA MOFs into the bacterial cellulose (BC) nanofibers, an innovative BC-xAgNA nanocomposite was fabricated for wound dressing applications. MTT assay demonstrated improved biocompatibility for the BC-AgNA nanocomposites up to more than 116% cell viability. The Acridine Orange staining showed more than 87% of live/dead cells ratio for the prepared wound dressings. The fibroblast cells attached on the BC-AgNA nanocomposite exhibited expanded morphologies with long filopodia. The in vitro cellular scratch analysis demonstrated excellent wound healing by more than of 96% wound closure rate of the wound cured with the BC-AgNA nanocomposite. Evaluating the BC-xAgNA nanocomposites revealed their appropriate antibacterial activities against different bacterial strains. Synergistic wound healing effects corresponding to vitamin-B3, Ag, and BC nanofibers were observed. The results confirmed that the designed BC-AgNA nanocomposite can potentially be considered for wound healing and damaged tissue regeneration.

ABSTRACTNanocomposite films for food packaging applications were developed using bacterial cellulose (BC) nanofibers in different amount in a poly(vinyl alcohol)/starch (PVA/St) matrix. In search of a better method to reduce the harmful ingredients in food packaging, the cellulose nanofibers were obtained by the mechanical defibrillation of BC pellicles thus avoiding the addition of chemicals in the final packaging material. Improved mechanical performances were obtained starting from just 1% BC nanofibers in PVA/St. Atomic force microscopy images showed a uniform dispersion of BC nanofibers on the surface of nanocomposites. A twofold increase of both tensile strength and modulus was obtained for 2 wt % BC in the composite. BC nanofibers have greatly improved the barrier properties of PVA/St matrix, a twofold increase of water vapor permeability being obtained for only 2 wt % BC nanofibers in the composite film. PVA/St/2BC was proposed as a high potential material for food packaging applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45800.

Multiwalled carbon nanotubes (MWCNTs) were embedded in electrospun bacterial cellulose (BC) nanofibers, which were prepared using an electrospinning method. In this study, Gluconacetobacter xylinum BRC5 was employed to produce a hydrogel-like bacterial cellulose (BC) sheet. BC was difficult to process in the solution stat because of the large concentration of intra- or inter-molecular hydrogen bonds. In this study, an ionic liquid, 1-allyl-3-methyl-imidazolium chloride, was used to dissolve BC. To form BC nanofibers, 5 wt% BC solutions both with and without MWCNTs were electrospun. Scanning electron microscopy and transmission electron microscopy showed that the MWCNTs were embedded and well aligned along the fiber axis. The crystalline polymorph transformed from cellulose I (pristine BC) to cellulose II (electrospun regenerated BC fibers). Moreover, the tensile strength and modulus of the MWCNT-embedded electrospun BC nanofibers increased by approximately 290% and 280%, respectively. Additionally, the thermal stability and electrical conductivity of the MWCNT-embedded electrospun BC nanofibers also increased compared to pristine BC.

The hybrid nanocomposite material of bacterial cellulose (BC) nanofibers and titaniumdioxide (TiO2) nanoparticles with improved visible light sensitivity was developed by doping nitrogen (N) and fluorine (F) on TiO2 nanoparticles embedded on BC nanofibers. To synthesize TiO2 nanoparticles on BC produced by Acetobacter xylinum (TISTR 975), titanium tetraisopropoxide (TTIP) was used as a titanium source and was directly hydrolyzed on BC nanofibers. After providing heat via the reflux technique to BC/TiO2 pellicle, the crystalline structure of TiO2 was changed to an anatase form on a three dimensional network structure of BC confirmed by XRD. Nitrogen (N) and fluorine (F) were successfully doped into TiO2 nanoparticles by using NH4F as the source of N and F (BC/N–F-co-doped TiO2). The TEM results showed that the average particle size of BC/N–F-co-doped TiO2 was smaller than the BC matrix containing none of the co-doped TiO2 (BC/TiO2) and N-doped TiO2 (BC/N–TiO2). In addition, BC/N–F-co-doped TiO2 demonstrated the high efficiency of photocatalytic disinfection activity against both gram-negative and gram-positive bacteria under fluorescence light. Nevertheless, the photocatalytic antibacterial activity of N–F-co-doped TiO2 also depended on the type of bacteria, and degree of N–F-co-doped TiO2.

The paper shows tensile properties of bacterial cellulose (BC) nanofibers and polyester (PO) matrix composites. Tensile properties including tensile strength (TS), modulus elasticity (ME), and elongation (EL) were observed respectively. BC nanofibers exist in the form of a sheet that was then varied in matrix PO. The BC sheet was mounted by one, three, five and seven pieces respectively in the matrix PO. The tensile strength of the composites was conducted by using the tensile equipment. The results showed that the tensile strength of the composite with a single sheet of BC was lower than that of pure PO. The ST value achieved maximum level in the number of layers of BC three pieces, but then it decreased for the composites reinforced five and seven pieces of BC nanofiber, respectively. Scanning Electron Microscope (SEM) observation exhibits bad interface bonding between BC nanofibers and PO matrix.

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

Bioactive wound dressing using bacterial cellulose loaded with papain composite: Morphology, loading/release and antibacterial properties

Surface oxidation of bacterial cellulose (BC) was done with the TEMPO-mediated oxidation mechanism system. After that, TEMPO-oxidized bacterial cellulose (TOBC) was impregnated with silver sulfadiazine (AgSD) to prepare nanocomposite membranes. Fourier transform infrared spectroscopy (FTIR) was carried out to determine the existence of aldehyde groups on BC nanofibers and X-ray diffraction (XRD) demonstrated the degree of crystallinity. FESEM analysis revealed the impregnation of AgSD nanoparticles at TOBC nanocomposites with the average diameter size ranging from 11 nm to 17.5 nm. The sample OBCS3 showed higher antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli by the disc diffusion method. The results showed AgSD content, dependent antibacterial activity against all tested bacteria, and degree of crystallinity increases with TOBC and AgSD. The main advantage of the applications of TEMPO-mediated oxidation to BC nanofibers is that the crystallinity of BC nanofibers is unchanged and increased after the oxidation. Also enhanced the reactivity of BC as it is one of the most promising method for cellulose fabrication and functionalization. We believe that the novel composite membrane could be a potential candidate for biomedical applications like wound dressing, BC scaffold, and tissue engineering.

Tunicate cellulose nanocrystal reinforced multifunctional hydrogel with super flexible, fatigue resistant, antifouling and self-adhesive capability for effective wound healing

SummaryAlthough several therapeutic approaches are available for wound and burn treatment and much progress has been made in this area, room for improvement still exists, driven by the urgent need of better strategies to accelerate wound healing and recovery, mostly for cases of severe burned patients. Bacterial cellulose (BC) is a biopolymer produced by bacteria with several advantages over vegetal cellulose, such as purity, high porosity, permeability to liquid and gases, elevated water uptake capacity and mechanical robustness. Besides its biocompatibility, BC can be modified in order to acquire antibacterial response and possible local drug delivery features. Due to its intrinsic versatility, BC is the perfect example of a biotechnological response to a clinical problem. In this review, we assess the BC main features and emphasis is given to a specific biomedical application: wound dressings. The production process and the physical–chemical properties that entitle this material to be used as wound dressing namely for burn healing are highlighted. An overview of the most common BC composites and their enhanced properties, in particular physical and biological, is provided, including the different production processes. A particular focus is given to the biochemistry and genetic manipulation of BC. A summary of the current marketed BC‐based wound dressing products is presented, and finally, future perspectives for the usage of BC as wound dressing are foreseen.

Characterization of TEMPO-oxidized bacterial cellulose scaffolds for tissue engineering applications