Preparation and characterization of bacterial cellulose/heparin hybrid nanofiber for potential vascular tissue engineering scaffolds

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

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

Fabrication strategies and biomedical applications of three-dimensional bacterial cellulose-based scaffolds: A review

Bacterial cellulose (BC), an extracellular polysaccharide, is a versatile biopolymer due to its intrinsic physicochemical properties, broad-spectrum applications, and remarkable achievements in different fields, especially in the biomedical field. Presently, the focus of BC-related research is on the development of scaffolds containing other materials for in-vitro and in-vivo biomedical applications. To this end, prime research objectives concern the biocompatibility of BC and the development of three-dimensional (3D) BC-based scaffolds. This review summarizes the techniques used to develop 3D BC scaffolds and discusses their potential merits and limitations. In addition, we discuss the various biomedical applications of BC-based scaffolds for which the 3D BC matrix confers desired structural and conformational features. Overall, this review provides comprehensive coverage of the idea, requirements, synthetic strategies, and current and prospective applications of 3D BC scaffolds, and thus, should be useful for researchers working with polysaccharides, biopolymers, or composite materials.

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.

Bacterial cellulose-based biomaterials: From fabrication to application

Driven by its excellent physical and chemical properties, BC (bacterial cellulose) has achieved significant progress in the last decade, rendering with many novel applications. Due to its resemblance to the structure of extracellular matrix, BC-based biomaterials have been widely explored for biomedical applications such as tissue engineering and drug delivery. The recent advances in nanotechnology endow further modifications on BC and generate BC-based composites for different applications. This article presents a review on the research advancement on BC-based biomaterials from fabrication methods to biomedical applications, including wound dressing, artificial skin, vascular tissue engineering, bone tissue regeneration, drug delivery, and other applications. The preparation of these materials and their potential applications are reviewed and summarized. Important factors for the applications of BC in biomedical applications including degradation and pore structure characteristic are discussed in detail. Finally, the challenges in future development and potential advances of these materials are also discussed.

Bacterial Cellulose-A Remarkable Polymer as a Source for Biomaterials Tailoring

Nowadays, the development of new eco-friendly and biocompatible materials using ‘green’ technologies represents a significant challenge for the biomedical and pharmaceutical fields to reduce the destructive actions of scientific research on the human body and the environment. Thus, bacterial cellulose (BC) has a central place among these novel tailored biomaterials. BC is a non-pathogenic bacteria-produced polysaccharide with a 3D nanofibrous structure, chemically identical to plant cellulose, but exhibiting greater purity and crystallinity. Bacterial cellulose possesses excellent physicochemical and mechanical properties, adequate capacity to absorb a large quantity of water, non-toxicity, chemical inertness, biocompatibility, biodegradability, proper capacity to form films and to stabilize emulsions, high porosity, and a large surface area. Due to its suitable characteristics, this ecological material can combine with multiple polymers and diverse bioactive agents to develop new materials and composites. Bacterial cellulose alone, and with its mixtures, exhibits numerous applications, including in the food and electronic industries and in the biotechnological and biomedical areas (such as in wound dressing, tissue engineering, dental implants, drug delivery systems, and cell culture). This review presents an overview of the main properties and uses of bacterial cellulose and the latest promising future applications, such as in biological diagnosis, biosensors, personalized regenerative medicine, and nerve and ocular tissue engineering.

Bacterial Cellulose (BC) and BC Composites: Production and Properties

The synthesis of bacterial cellulose (BC) by Komagataeibacter xylinus strain B-12068 was investigated on various C-substrates, under submerged conditions with stirring and in static surface cultures. We implemented the synthesis of BC on glycerol, glucose, beet molasses, sprat oil, and a mixture of glucose with sunflower oil. The most productive process was obtained during the production of inoculum in submerged culture and subsequent growth of large BC films (up to 0.2 m2 and more) in a static surface culture. The highest productivity of the BC synthesis process was obtained with the growth of bacteria on molasses and glycerol, 1.20 and 1.45 g/L per day, respectively. We obtained BC composites with silver nanoparticles (BC/AgNPs) and antibacterial drugs (chlorhexidine, baneocin, cefotaxime, and doripenem), and investigated the structure, physicochemical, and mechanical properties of composites. The disc-diffusion method showed pronounced antibacterial activity of BC composites against E. coli ATCC 25922 and S. aureus ATCC 25923.

Applications of Bacterial Cellulose as a Natural Polymer in Tissue Engineering

Choosing the material with the best regeneration potential and properties closest to that of the extracellular matrix is one of the main challenges in tissue engineering and regenerative medicine. Natural polymers, such as collagen, elastin, and cellulose, are widely used for this purpose in tissue engineering. Cellulose derived from bacteria has excellent mechanical properties, high hydrophilicity, crystallinity, and a high degree of polymerization and, therefore, can be used as scaffold/membrane for tissue engineering. In the current study, we reviewed the latest trends in the application of bacterial cellulose (BC) polymers as a scaffold in different types of tissue, including bone, vascular, skin, and cartilage. Also, we mentioned the biological and mechanical advantages and disadvantages of BC polymers. Given the data presented in this study, BC polymer could be suggested as a favorable natural polymer in the design of tissue scaffolds. Implementing novel composites that combine this polymer with other materials through modern or rapid prototyping methods can open up a great prospect in the future of tissue engineering and regenerative medicine.

Controllable synthesis of biomimetic nano/submicro-fibrous tubes for potential small-diameter vascular grafts

Mimicking the morphological structure of native blood vessels is critical for the development of vascular grafts. Herein, small-diameter composite vascular grafts that integrate the nanofibrous bacterial cellulose (BC) and submicrofibrous cellulose acetate (CA) were fabricated via a combined electrospinning and step-by-step in situ biosynthesis. Scanning electron microscopy (SEM) observation shows the nano/submicro-fibrous morphology and well-interconnected porous structure of the BC/CA grafts. It is found that the BC/CA graft with a suitable BC content demonstrates lower potential of thrombus formation and enhanced endothelialization as compared to the BC and CA counterparts. Western blotting and RT-qPCR results suggest that the BC/CA-2 graft promotes endothelialization by improving expressions of genes vWF-1 and CD31 and protein CD31. The in vivo tests demonstrate much lower inflammatory response to the BC/CA graft. These results suggest that the BC/CA graft shows a great potential as an artificial graft for rapid formation of an endothelial cell monolayer.

Heparin-Eluting Tissue-Engineered Bioabsorbable Vascular Grafts

The creation of small-diameter tissue-engineered vascular grafts using biodegradable materials has the potential to change the quality of cardiovascular surgery in the future. The implantation of these tissue-engineered arterial grafts has yet to reach clinical application. One of the reasons for this is thrombus occlusion of the graft in the acute phase. In this paper, we first describe the causes of accelerated thrombus formation and discuss the drugs that are thought to inhibit thrombus formation. We then review the latest research on methods to locally bind the anticoagulant heparin to biodegradable materials and methods to extend the duration of sustained heparin release. We also discuss the results of studies using large animal models and the challenges that need to be overcome for future clinical applications.

PVA based nanofiber containing CQDs modified with silica NPs and silk fibroin accelerates wound healing in a rat model

In recent years, applying various wound dressings with antibacterial activities to expedite tissue repair stages has gained remarkable attention. The intertwined three-dimensional structure of nanofibers provides unique spaces for carrying drugs and repair agents during the wound healing process. In this research, a carbon quantum dot (CQD)/silica nanoparticle (Si NP)/silk fibroin (SF) nanocomposite was synthesized, and two novel wound dressings, a BC-CQD/Si NP/SF nanocomposite and a PVA-CQD/Si NP/SF nanofiber, were prepared by Spray Printing and Electrospinning methods and successfully characterized. The water-uptake capacity of the BC-CQD/Si NP/SF nanocomposite has been optimized to evaluate its swelling behavior. To determine the antibacterial effects of the synthesized materials both MIC and Optical Density (OD) methods were performed, and the results imply that materials have high antibacterial activity and could successfully inhibit the growth of both S. aureus and E. coli bacteria. Cell toxicity, viability, and proliferation on NIH 3T3 fibroblast cells with the MTT assay have proved that the CQD/Si NP/SF nanocomposite not only has no toxicity but also can accelerate cell viability and proliferation. To assess the effect of the CQD/Si NP/SF nanocomposite on cell migration and in vitro wound healing scratch, a wound assay was performed, and the nanocomposite exhibits the ability to promote wound healing. The PVA-CQD/Si NP/SF nanofiber was used to investigate wound healing in an animal model. The results show that the PVA-CQD/Si NP/SF nanofiber effectively accelerates the skin and hair follicle regeneration. Therefore, the PVA-CQD/Si NP/SF nanofiber is a promising wound dressing for inhibiting bacterial growth and promoting skin wound repair and hair regeneration.

Production of bacterial cellulose from whey-current state and prospects

Bacterial cellulose (BC) is a biopolymer with a wide range of potential applications starting from the food industry and biomedicine to electronics and cosmetics. Despite that, BC industrial production to date still is associated with certain difficulties. One of them is the high cost of growth media, which can reach up to 30% of production costs. To decrease production costs, use of industrial and agricultural by-products, including whey, as alternative growth media has been reported. Whey, as the main high-volume by-product of dairy industry, which is known for its low valorisation opportunities and negative environmental impact, can nevertheless be considered as an alternative growth medium for BC production. To date, several studies aimed at evaluating BC production on whey and lactose substrates have been reported, but they are still insufficient. Reviews of them showed that, in general, BC production on untreated whey- and lactose-containing media was lower than that on the standard medium. However, some wild and recombinant strains have been reported to produce BC on whey as good as the standard medium. Enzymatic and acidic pre-treatment of whey significantly enhanced BC yield. Changes in the microstructure of BC obtained from whey were also recognised, which should be considered regarding the impact on physical properties of the desired BC product. This mini-review indicates that currently whey can be recognised as quite a problematic alternative growth substrate for industrial BC production; however, further extensive studies may improve the prospects in both the search for a cheap alternative growth substrate for industrial BC production and valorisation of whey. KEY POINTS: • Whey is a by-product in which valorisation is still challenging. • Whey can be used for bacterial cellulose (BC) production. • BC yield and properties vary upon cultivation conditions and producer strains.

Bacterial Cellulose: Production, Modification and Perspectives in Biomedical Applications

Bacterial cellulose (BC) is ultrafine, nanofibrillar material with an exclusive combination of properties such as high crystallinity (84%-89%) and polymerization degree, high surface area (high aspect ratio of fibers with diameter 20-100 nm), high flexibility and tensile strength (Young modulus of 15-18 GPa), high water-holding capacity (over 100 times of its own weight), etc. Due to high purity, i.e., absence of lignin and hemicellulose, BC is considered as a non-cytotoxic, non-genotoxic and highly biocompatible material, attracting interest in diverse areas with hallmarks in medicine. The presented review summarizes the microbial aspects of BC production (bacterial strains, carbon sources and media) and versatile in situ and ex situ methods applied in BC modification, especially towards bionic design for applications in regenerative medicine, from wound healing and artificial skin, blood vessels, coverings in nerve surgery, dura mater prosthesis, arterial stent coating, cartilage and bone repair implants, etc. The paper concludes with challenges and perspectives in light of further translation in highly valuable medical products.

Nanocellulose-based polymer hybrids and their emerging applications in biomedical engineering and water purification

Nanocellulose, derived from cellulose hydrolysis, has unique optical and mechanical properties, high surface area, and good biocompatibility. It is frequently used as a reinforcing agent to improve the native properties of materials. The presence of functional groups in its surface enables the alteration of its behavior and its use under different conditions. Nanocellulose is typically used in the form of cellulose nanocrystals (CNCs), cellulose nanofibers (CNFs), or bacterial nanocellulose (BNC). CNCs and CNFs have a high aspect ratio with typical lengths of ∼100-250 nm and 0.1-2 μm, respectively; BNC is nanostructured cellulose produced by bacteria. Nanohybrid materials are a combination of organic or inorganic nanomaterials with macromolecules forming a single composite and typically exhibit superior optical, thermal, and mechanical properties to those of native polymers, owing to the greater interactions between the macromolecule matrix and the nanomaterials. Excellent biocompatibility and biodegradability make nanocellulose an ideal material for applications in biomedicine. Unlike native polymers, nanocellulose-based nanohybrids exhibit a sustained drug release ability, which can be further optimized by changing the content or chemical environment of the nanocellulose, as well as the external stimuli, such as the pH and electric fields. In this review, we describe the process of extraction of nanocellulose from different natural sources; its effects on the structural, morphological, and mechanical properties of polymers; and its various applications.

Biological Engineered Living Materials: Growing Functional Materials with Genetically Programmable Properties

Natural biological materials exhibit remarkable properties: self-assembly from simple raw materials, precise control of morphology, diverse physical and chemical properties, self-repair, and the ability to sense-and-respond to environmental stimuli. Despite having found numerous uses in human industry and society, the utility of natural biological materials is limited. But, could it be possible to genetically program microbes to create entirely new and useful biological materials? At the intersection between microbiology, material science, and synthetic biology, the emerging field of biological engineered living materials (ELMs) aims to answer this question. Here we review recent efforts to program cells to produce living materials with novel functional properties, focusing on microbial systems that can be engineered to grow materials and on new genetic circuits for pattern formation that could be used to produce the more complex systems of the future.

Novel Bionanocellulose/κ-Carrageenan Composites for Tissue Engineering

In this work, novel bacterial cellulose/κ-carrageenan (BNC/κ-Car) composites, being potential scaffolds for tissue engineering (TE), and outperforming the two polymers when used as scaffolds separately, were for the first time obtained using an in situ method, based on the stationary culture of bacteria Komagateibacter xylinus E25. The composites were compared with native BNC in terms of the morphology of fibers, chemical composition, crystallinity, tensile and compression strength, water holding capacity, water retention ratio and swelling properties. Murine chondrogenic ATDC5 cells were applied to assess the utility of the BNC/κ-Car composites as potential scaffolds. The impact of the composites on the cells viability, chondrogenic differentiation, and expression patterns of Col1α1, Col2α1, Runx2, and Sox9, which are indicative of ATDC5 chondrogenic differentiation, was determined. None of the composites obtained in this study caused the chondrocyte hypertrophy. All of them supported the differentiation of ATDC5 cells to more chondrogenic phenotype.

Preparation and Characterization of Resorbable Bacterial Cellulose Membranes Treated by Electron Beam Irradiation for Guided Bone Regeneration

Bacterial cellulose (BC) is an excellent biomaterial with many medical applications. In this study, resorbable BC membranes were prepared for guided bone regeneration (GBR) using an irradiation technique for applications in the dental field. Electron beam irradiation (EI) increases biodegradation by severing the glucose bonds of BC. BC membranes irradiated at 100 kGy or 300 kGy were used to determine optimal electron beam doses. Electron beam irradiated BC membranes (EI-BCMs) were evaluated by scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, thermal gravimetric analysis (TGA), and using wet tensile strength measurements. In addition, in vitro cell studies were conducted in order to confirm the cytocompatibility of EI-BCMs. Cell viabilities of NIH3T3 cells on 100k and 300k EI-BCMs (100 kGy and 300 kGy irradiated BC membranes) were significantly greater than on NI-BCMs after 3 and 7 days (p < 0.05). Bone regeneration by EI-BCMs and their biodegradabilities were also evaluated using in vivo rat calvarial defect models for 4 and 8 weeks. Histometric results showed 100k EI-BCMs exhibited significantly larger new bone area (NBA; %) than 300k EI-BCMs at 8 weeks after implantation (p < 0.05). Mechanical, chemical, and biological analyses showed EI-BCMs effectively interacted with cells and promoted bone regeneration.

In situ and ex situ modifications of bacterial cellulose for applications in tissue engineering

Bacterial cellulose (BC) is secreted by a few strains of bacteria and consists of a cellulose nanofiber network with unique characteristics. Because of its excellent mechanical properties, outstanding biocompatibilities, and abilities to form porous structures, BC has been studied for a variety of applications in different fields, including the use as a biomaterial for scaffolds in tissue engineering. To extend its applications in tissue engineering, native BC is normally modified to enhance its properties. Generally, BC modifications can be made by either in situ modification during cell culture or ex situ modification of existing BC microfibers. In this review we will first provide a brief introduction of BC and its attributes; this will set the stage for in-depth and up-to-date discussions on modified BC. Finally, the review will focus on in situ and ex situ modifications of BC and its applications in tissue engineering, particularly in bone regeneration and wound dressing.

Advances in biomedical and pharmaceutical applications of functional bacterial cellulose-based nanocomposites

Bacterial cellulose (BC) synthesized by certain species of bacteria, is a fascinating biopolymer with unique physical and mechanical properties. BC's applications range from traditional dessert, gelling, stabilizing and thickening agent in the food industry to advanced high-tech applications, such as immobilization of enzymes, bacteria and fungi, tissue engineering, heart valve prosthesis, artificial blood vessels, bone, cartilage, cornea and skin, and dental root treatment. Various BC-composites have been designed and investigated in order to enhance its biological applicability. This review focuses on the application of BC-based composites for microbial control, wound dressing, cardiovascular, ophthalmic, skeletal, and endodontics systems. Moreover, applications in controlled drug delivery, biosensors/bioanalysis, immobilization of enzymes and cells, stem cell therapy and skin tissue repair are also highlighted. This review will provide new insights for academia and industry to further assess the BC-based composites in terms of practical applications and future commercialization for biomedical and pharmaceutical purposes.

A multipurpose natural and renewable polymer in medical applications: Bacterial cellulose

Bacterial cellulose (BC) produced by some bacteria, among them Gluconacetobacter xylinum, which secrets an abundant 3D networks fibrils, represents an interesting emerging biocompatible nanomaterial. Since its discovery BC has shown tremendous potential in a wide range of biomedical applications, such as artificial skin, artificial blood vessels and microvessels, wound dressing, among others. BC can be easily manipulated to improve its properties and/or functionalities resulting in several BC based nanocomposites. As example BC/collagen, BC/gelatin, BC/Fibroin, BC/Chitosan, etc. Thus, the aim of this review is to discuss about the applicability in biomedicine by demonstrating a variety of forms of this biopolymer highlighting in detail some qualities of bacterial cellulose. Therefore, various biomedical applications ranging from implants and scaffolds, carriers for drug delivery, wound-dressing materials, etc. that were reported until date will be presented.

The effect of bacterial cellulose membrane compared with collagen membrane on guided bone regeneration

PURPOSE

This study was to evaluate the effects of bacterial cellulose (BC) membranes as a barrier membrane on guided bone regeneration (GBR) in comparison with those of the resorbable collagen membranes.

MATERIALS AND METHODS

BC membranes were fabricated using biomimetic technology. Surface properties were analyzed, Mechanical properties were measured, in vitro cell proliferation test were performed with NIH3T3 cells and in vivo study were performed with rat calvarial defect and histomorphometric analysis was done. The Mann-Whitney U test and the Wilcoxon signed rank test was used (α<.05).

RESULTS

BC membrane showed significantly higher mechanical properties such as wet tensile strength than collagen membrane and represented a three-dimensional multilayered structure cross-linked by nano-fibers with 60 % porosity. In vitro study, cell adhesion and proliferation were observed on BC membrane. However, morphology of the cells was found to be less differentiated, and the cell proliferation rate was lower than those of the cells on collagen membrane. In vivo study, the grafted BC membrane did not induce inflammatory response, and maintained adequate space for bone regeneration. An amount of new bone formation in defect region loaded with BC membrane was significantly similar to that of collagen membrane application.

CONCLUSION

BC membrane has potential to be used as a barrier membrane, and efficacy of the membrane on GBR is comparable to that of collagen membrane.

Do bacterial cellulose membranes have potential in drug-delivery systems?

INTRODUCTION

Bacterial cellulose (BC) is an extremely pure form of cellulose, which, due to its unique properties, such as high purity, water-holding capacity, three-dimensional nanofibrilar network, mechanical strength, biodegradability and biocompatibility, shows a high potential as nanomaterial in a wide range of high-tech domains including biomedical applications, and most notably in controlled drug-delivery systems.

AREAS COVERED

This appraisal is intended to cover the major characteristics of BC, followed by the key aspects of BC production both in static and agitated conditions, and a glance of the major applications of BC, giving some emphasis to biomedical applications. Finally, a detailed discussion of the different applications of BC in controlled drug-delivery systems will be put forward, with focus on topical and oral drug-delivery systems, using either native BC or composite materials thereof.

EXPERT OPINION

The limited number of studies carried out so far demonstrated that BC, or materials prepared from it, are interesting materials for drug-delivery systems. There is, however, a large field of systematic research ahead to develop new and more selectively responsive materials and eventually to conjugate them with other biomedical applications of BC under development.

Evolution of morphology of bacterial cellulose scaffolds during early culture

Morphological characteristics of a fibrous tissue engineering (TE) scaffold are key parameters affecting cell behavior. However, no study regarding the evolution of morphology of bacterial cellulose (BC) scaffolds during the culture process has been reported to date. In this work, BC scaffolds cultured for different times starting from 0.5h were characterized. The results demonstrated that the formation of an integrated scaffold and its 3D network structure, porosity, fiber diameter, light transmittance, and the morphology of hydroxyapatite (HAp)-deposited BC scaffolds changed with culture time. However, the surface and crystal structure of BC fibers did not change with culture time and no difference was found in the crystal structure of HAp deposited on BC templates regardless of BC culture time. The findings presented herein suggest that proper selection of culture time can potentially enhance the biological function of BC TE scaffold by optimizing its morphological characteristics.