Bacterial cellulose: a versatile biopolymer for wound dressing applications

Bacterial cellulose: A versatile biomaterial for biomedical application

Bacterial cellulose, a unique biomaterial produced by several bacteria, has garnered biomedical interest to its versatility. This could be used in healthcare packaging, and textiles. Bacterial cellulose extraction is effective and affordable since it lacks lignin and hemicellulose. In wound healing, tissue engineering, drug delivery, and regenerative medicine, this material's unique properties have drawn interest. Bacterial cellulose has been studies as a skin substitute for severe burns and non-woven bandages for persistent wounds. In addition, bacterial cellulose has been used to make artificial skin, blood arteries, and wound dressings. Bacterial cellulose is ideal for biopolymer production due to its clean chemical composition, nano-fibrillar structure, and crystalline characteristics. This review explores the processing, content, characteristics, and applications of bacterial cellulose, revealing its function in tissue regeneration and disease resistance. Through careful inquiry and analysis, this work seeks to comprehend bacterial cellulose and its impact on biomedical research and technology.

Controlled release of antimicrobial peptides from nanocellulose wound dressings for treatment of wound infections

Wounds are highly prone to infection, which can delay healing and lead to severe complications such as gangrene and sepsis. Non-healing wounds significantly impact patients' physical and mental well-being and place a substantial financial burden on healthcare systems. Timely and effective treatment of wound infections is critical, but the rise of antibiotic-resistant pathogens complicates this process. In this study, we investigate a potent protease resistant antimicrobial peptide (AMP), PLNC8 αβ, for the treatment of wound infections and present a strategy for localized AMP delivery using functionalized advanced nanocellulose (NC) wound dressings. Two types of NC dressings were explored: bacterial cellulose (BC) and TEMPO-oxidized nanocellulose derived from wood powder (TC). In a porcine wound infection model, PLNC8 αβ exhibited high antimicrobial activity, successfully eradicating the infection while promoting wound re-epithelialization. To achieve controlled release of PLNC8 αβ from the NC dressings, the peptides were either physisorbed directly onto the nanofibrils or encapsulated within mesoporous silica nanoparticles (MSNs) that were incorporated into the dressings. The PLNC8 αβ functionalized dressings demonstrated low cytotoxicity toward human primary fibroblasts and keratinocytes. Both BC and TC dressings showed efficient contact inhibition of bacteria but were less effective in inhibiting bacteria in suspension. In contrast, MSN-functionalized dressings, displayed significantly enhanced peptide-loading and sustained release capacities, resulting in improved antimicrobial efficacy. These findings highlight the potential of PLNC8 αβ and PLNC8 αβ-functionalized nanocellulose wound dressings for the treatment of infected wounds, offering an effective alternative to conventional antibiotic therapies.

Unlocking the potential of bacterial cellulose: synthesis, functionalization, and industrial impact

In recent years, bacterial cellulose (BC), a crystalline and nanoscale fibrillar polymer, has garnered significant interest due to its superior physical, chemical, and mechanical properties compared to plant cellulose. Inherent features of BC, which include high biodegradability, mechanical strength, and biocompatibility, make it a suitable material for use in a wide variety of applications, particularly in the domains of biomedicine and environmental science. However, realizing its full potential requires targeted chemical or physical modifications. Recent developments have focused on in-situ and ex-situ BC modification for various applications. Incorporating functional compounds into cellulose during BC synthesis enhances its strength and functional properties. Additionally, the material properties of BC, such as water content, thermal stability, and antibacterial capabilities, can be enhanced through post-synthesis modifications, including chemical acetylation, phosphorylation, and integration with other biopolymers. Currently, the applicability of BC is being improved using new modification techniques, which involve genetically engineered strains to enhance polymer characteristics and market potential. The review highlights recent advancements in BC research and novel modification strategies that enhance its applications in advanced biomedical engineering and sustainable packaging.

Preparation and performance of regenerated cellulose/polylactic acid non-leaching antibacterial composite membrane

Composite membranes with excellent antibacterial properties, hydrophilic/hydrophobic differentiation, and selective permeability are preferred materials for wound dressings. In this work, antibacterial bromoacetyl and quaternary ammonium groups were chemically introduced into a regenerated cellulose nanofiber membrane. This hydrophilic membrane was then compounded with a polylactic acid (PLA) liquid film through a non-solvent-induced phase separation process to prepare a composite membrane. FTIR, XPS, and EDS results confirmed the successful chemical modification and presence of antibacterial groups. SEM analysis revealed a stable composite with an asymmetric structure. Modification time, particularly the bromoacetylation duration, had a certain impact on the structure and properties of the composite membrane. The optimized composite membrane exhibited excellent gas permeability (air and water vapor) and differentiated hydrophilic/hydrophobic properties. Membrane modified via bromoacetylation for over 3 h demonstrated >95 % antibacterial efficiency against Escherichia coli and Staphylococcus aureus, indicating broad-spectrum efficacy. The biomass-derived polymer matrix, scalable production process, and multifunctionality highlight its potential for healthcare applications, particularly in wound dressings.

Physicochemical properties of bacterial cellulose/phototherapeutic polypyrrole/antibacterial chitosan composite membranes and their evaluation as chronic wound dressings

Bacterial cellulose (BC) is a natural fiber membrane and has been applied in many biomedical applications. Herein, it was used as the main scaffold to prepare wound dressings for treating diabetic skin wounds. Polypyrrole (PPy) was first synthesized by in situ oxidative polymerization within BC membrane and applied as a photothermal agent, followed by coating with chitosan (CS) to improve the biocompatibility and antibacterial properties. SEM pictures revealed sub-micron PPy particles ranging from 100 to 200 nm were formed and attached to the BC fibrils, whereas CS formed a thin, porous layer on the surface. FTIR analysis showed that there was hydrogen bonding between BC, PPy and CS components. The crystalline structure of BC was maintained yet with decreased crystallinity by addition of PPy and CS. The water absorption capability and water vapor transmission rate decreased by PPy incorporation owing to its hydrophobic nature, but they were regained by addition of hydrophilic CS. The prepared BC/PPy/CS membrane was biocompatible toward L929 cells and maintained hemocompatibility. Additionally, both PPy and CS contributed to the antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, while they demonstrated a potential for synergistic antibacterial effects when combined. Finally, the near-infrared (NIR)-driven photothermal-hyperthermic effects by PPy on lesions upregulated heat-shock protein (HSP) expression and anti-inflammatory properties by CS boosted restoration of diabetic wounds in vivo without the addition of any antibiotics or anti-inflammatory drugs. The results thus support using the BC/PPy/CS membrane for diabetic wound regeneration.

Green synthesis of silver-modified bacterial cellulose with enhanced antimicrobial activity for advanced biomedical application

In this study, pure BC was biosynthesized and modified with silver (Ag) impregnation under an eco-friendly photocatalytic reduction reaction. For BC production, Acetobacter sp. was isolated from raw mango vinegar produced by the fermentation process under optimized conditions. The Ag-doped BC (BCAg) was characterized and confirmed using XRD, STA, FTIR, SEM, and EDS. The SEM and EDS data showed the aggregation of silver ions on the surface of a web-like cellulose fiber network and silver deposition is proportional to the increasing dose of AgNO3 treatment. The functionalized BCAg showed high hemocompatibility and tremendous activity against pathogenic bacteria and fungi. A clear zone of inhibition was observed against Listeria monocytogenes, Staphylococcus aureus, Salmonella abony, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans under the lowest BCAg concentration (0.0001 M treated). Whereas, in the long-term inhibition assay all concentrations of BCAg exhibited complete growth inhibition of the pathogens for 20 h and BCAg 0.01 M inhibited the growth of L. monocytogenes, S. abony, and C. albicans for over 100 h within the moist condition. Therefore, considering the extensive, long-term, and persistent bacteriostatic activity of synthesized silver doped-BC, it has a notable future in wound healing or other biomedical applications.

Highly Compatible Nanocomposite-Based Bacterial Cellulose Doped With Dopamine and Titanium Dioxide Nanoparticles: Study the Effect of Mode of Addition, Characterization, Antibacterial, and Wound Healing Efficiencies

Microbial resistance is an expenditure for a country's economy as a whole as well as its health systems. Metal oxide nanoparticles play a role in overcoming microbial resistance to antibiotics. Bacterial cellulose (BC) is a biopolymer that is friendly to the environment and has a wide range of economic uses, particularly in biomedicine. This work deals with the formulation of BC-doped titanium dioxide nanoparticles (TiO2NPs) and polydopamine (DOP), which are presented with antimicrobial activity. Additionally, the mode of addition of the doped materials was studied using physicochemical analysis, including Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD). Moreover, the topographical study used scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX). The antimicrobial activity was studied and showed the efficiency of the BC/DOP/TiO2NP composite against Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa, Escherichia coli) strains. Additionally, the wound healing was examined on rats that had been purposely wounded. The results observed that the mode of addition contributed to the molecular structure of the formulated BC-doped samples according to the physicochemical and topographical analysis. Moreover, the BC/DOP/TiO2NP composite enhanced wound healing for about 95% closure by Day 14 compared to 50% in the control group. Based on the results, we can suggest BC/DOP/TiO2NP as an excellent candidate for wound dressings.

Advances in biomedical applications of bacterial cellulose: from synthesis mechanisms to commercial innovations

Bacterial cellulose (BC) has various unique properties, such as sustainability and biocompatibility, which make it a "rising star" in biomedical applications. This comprehensive review delves into the intricacies of BC production and elucidates the pivotal role of rosette terminal complexes in the synthesis of BC. Moreover, it explores the diverse range of in-situ and ex-situ modifications, such as coating, genetic modification, and esterification, that can enhance its performance in biomedical applications, notably in tissue engineering, drug delivery and wound healing applications Beginning with an in-depth examination of BC synthesis mechanisms, this review sheds light on the fundamental processes underlying its unique structure and properties and subsequently delves into the vast landscape of modification strategies, encompassing techniques such as chemical functionalization, surface patterning, and composite formation. Of particular significance are the insights provided into commercial products derived from BC, which offers a comprehensive overview of their features and applications, followed by several recent case studies. By consolidating knowledge from the basic principles of BC synthesis to cutting-edge advancements in the field, this review illuminates the transformative impact of BC on the landscape of health and medical breakthroughs, paving the way for future advancements in biomedicine.

Decayed fruit waste juice as a sustainable medium for high-yield microbial cellulose production: optimization, characterization and bioactivity studies

In the present study, microbial cellulose (MC) was produced from decayed fruit waste juice as a fermentation medium using a consortium of microbes grown on vegetable and fruit waste as the inoculum. To optimize the MC yield, the central composite design (CCD) of response surface methodology (RSM) was applied. Four factors at five different levels were chosen in the design with a total of 26 experimental runs obtained from the CCD design. The optimal conditions were fruit waste extract (60% v/v), glucose concentration (0.75% w/v), inoculum size (5% v/v), and fermentation time (5 d) which displayed a 2.1-fold increase in MC yield of 21.719 g/L. The MC was characterized using Fourier Transform Infrared Spectroscopy, X-ray Diffraction, Scanning Electron Microscopy, and Thermogravimetric; and compared its properties to cellulose produced through other techniques. The produced MC was examined for its antioxidant properties using cyclic voltammetry (CV) displaying an anodic peak at 1.15 V. Lastly, the antimicrobial activity was tested against four different microbial strains. Among them, MC exhibited a clear zone of 7.661 ± 0.256 cm2 against E. coli. The results of this study concluded that decayed fruit waste juice is a sustainable and economical fermentation medium.

Novel Approaches in Production and Application of Bacterial Cellulose in Food Industries

Bacterial cellulose (BC) is a polymer produced by specific species of bacteria, most often by the species Komagataeibacter xylinus and Gluconacetobacter xylinus. BC may be distinguished from other types of cellulose by its origin. It is a kind of cellulose that is highly pure and robust, which is made up of long chains of glucose units that create a 3D network. The production of BC takes place via fermentation. During this process, the bacteria utilize sugar and produce cellulose as a byproduct. BC has been extensively researched for its potential use in the medical industry, food industry, and many other fields. Application includes development of an artificial skin for wound dressing because of its remarkable inter- and intramolecular hydrogen bonding and thermal and mechanical strength. BC has a large potential to be used in the food industry, where it can be combined with other polysaccharides to be used in food products as additives, edible film/coating, or active food packaging material to prolong the shelf life of the product and reduce the rate of chemical reactions and microbial growth in food products.

Synthesis of chitosan and carboxymethyl cellulose connect flavonoid (CH-Fla-CMC) composite and their investigation of antioxidant, cytotoxicity activities

This study successfully synthesised and characterised composites combining chitosan (CH), carboxymethyl cellulose (CMC), and various flavonoids (Fla). This innovative approach demonstrates the potential for developing functional materials with antioxidant and food preservation properties. The composites CH-Fla-CMC (1-5) was characterised using advanced techniques such as FT-IR, UV-Vis, XRD, SEM, TEM, and TGA, providing robust data on their structural, morphological, and thermal properties. CH-connected CMC has been used to prevent many diseases, based on the findings of this study. Therefore, dietary flavonoids (Fla = 1. 3-Hydroxyflavone; 2. rhamnetin; 3. natsudaidain; 4. isorhamnetin; 5. myricetin) was used to prepare the composites in this study. Dietary flavonoids play an important role in the prevention of degenerative diseases. In addition, oxygen permeability (OP), water solubility (WS), and moisture content (MS) were analysed. The synthesised composites were screened for antioxidant and cytotoxic activities. Multiple antioxidant assays (DPPH, H₂O₂, NO, ABTS•+, and AAPH) were conducted, confirming the superior radical scavenging activity of CH-Fla-CMC-5 compared to standards such as BHT and Trolox. The synthesised composite CH-Fla-CMC 5 was more active than the standard butylated hydroxytoluene (BHT) against 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydrogen peroxide (H2O2), and nitric oxide (NO) radical scavenging activity (DPPH: 10.30 vs. 33.88 μg/ml; H2O2: 13.26 vs. 27.16 μg/ml, and NO: 13.56 vs. 31.73 μg/ml), whereas 2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid radical cation (ABTS•+) decolourisation assay and lipid peroxidation method (AAPH) CH-Fla-CMC 5 was more active than the standard Trolox (ABTS: 91.26 ± 0.59 % vs. 85.28 ± 0.97 %; AAPH: 91.02 ± 0.01 % vs. 62.39 ± 0.35 %). The synthesis and characterisation methods are laboratory-based. This study primarily focused on in vitro antioxidant and cytotoxicity assays. The performance of these composites in living organisms and real-life food packaging scenarios remains untested. Cytotoxicity against only check these cell lines such as MCF-7, HeLa, HepG2, and normal Vero cancer cell lines was assessed. Only five flavonoids were tested, potentially limiting the generalisability of the findings to other dietary flavonoids. In the future, we plan to compare more cell lines with flavonoids. These laboratory-based methods have been converted into industrial production. The CH-Fla-CMC-5 composite performed better than the other compounds in all tests. Based on our findings, the synthesised CH-Fla-CMC-5 composite could be used to pack dishes that are watery, acidic, or alcoholic, as well as to coat freshly cut fruits.

Current Directions of Selected Plant-Origin Wastes' Valorization in Biotechnology of Food Additives and Other Important Chemicals

Environmental pollution and the accumulation of industrial waste are increasingly serious issues that impose financial burdens on businesses and pose threats to ecosystems. As industrial production continues to grow, the volume of waste generated by humanity is rising, leading to a heightened need to search for effective waste management and recycling methods. One promising approach is the concept of a circular economy, where industrial waste, including agricultural and food processing waste, is transformed into new products. The goal is to maximize the utilization of natural resources, particularly in food production. This article presents various concepts for utilizing specific types of plant-based waste, particularly lignocellulosic, pectin, and starch wastes, in biotechnological processes aimed at producing value-added food ingredients with a technological function. The literature clearly shows that this waste can be effectively used in the cultivation of different microorganisms to produce enzymes, polyols, oligosaccharides, carboxylic acids, and biopolymers, among other products. However, further research is needed to explore more efficient and environmentally friendly methods, especially in the utilization of lignocellulose in biotechnology. This research shows knowledge gaps in existing discussed solutions.

Development and Characterization of Antimicrobial Chitosan/Polyethylene Oxide/Bacterial Cellulose Nanofibers

This study introduces novel chitosan (CS) and polyethylene oxide (PEO) copolymers reinforced with bacterial cellulose (BC) to fabricate nanofibers using the electrospinning method. SEM analysis confirmed uniform nanofiber formation, with CS/PEO/BC nanofibers (~240 nm) exhibiting a larger diameter than CS/PEO ones (~190 nm). FTIR spectroscopy confirmed BC integration, while Differential scanning calorimetry analysis indicated minimal impact on glass transition temperature. Notably, as compared to CS/PEO nanofibers, the CS/PEO/BC ones demonstrated superior swelling capacity, accelerated biodegradation, and enhanced mechanical (i.e., tensile) properties, with maximum stress and strain values of ~3.41 MPa and ~0.01% vs. ~2.14 MPa and ~0.01%. Antimicrobial assays confirmed activity against bacterial strains, and biocompatibility tests showed high cell viability at day seven (99.26% for CS/PEO/BC nanofibers). These findings highlight the potential of CS/PEO/BC nanofibers as promising candidates for tissue engineering, offering improved strength, biodegradability, and antimicrobial properties.

Bifunctional modified bacterial cellulose-based hydrogel through sequence-dependent crosslinking towards enhanced antibacterial and cutaneous wound healing

Chronic wounds caused by microbial infection have emerged as a major challenge on patients and medical health system. Bacterial cellulose (BC) characterized by its excellent biocompatibility and porous network, holds promise for addressing complex wound issues. However, lack of inherent antibacterial activity and cross-linking sites in the molecular network of BC have constrained its efficacy in hydrogel design and treatment of bacterial-infected wounds. Additionally, few studies have explored the effects of precursor crosslinking sequences on hydrogel processing. Herein, a quaternary ammonium and aldehyde-biofunctionalized bacterial cellulose (OQBC) was synthesized and utilized for the development of double network (DN) hydrogels, incorporating the crosslinking sequences of thiol-alginate (SASH) and carboxymethyl chitosan (CMCS). Firstly, OQBC was characterized with bifunctional groups, which endows its inherent antibacterial activity and gel-forming property. Subsequently, DN hydrogels formed through thiol-aldehyde addition and amino-aldehyde reactions showed favorable injectability and self-healing ability. The sequential crosslinking via Schiff-base and thiohemiacetal bonds endowed the hydrogels with distinct features, including degradation behavior, pH-responsive swelling, water retention, surface roughness, and cell behavior. With the increasing OQBC content into hydrogels, bacteriostatic rate exceeded 90 % without obvious cytotoxicity. Hydrogels also exhibited antioxidant and sustained drug release properties. Moreover, in infected skin thickness defect rats, the selected hydrogel enhanced wound repair and regeneration by inhibiting inflammation and promoting collagen deposition and angiogenesis. This design of sequence-dependent crosslinked antibacterial DN hydrogel offers a promising tool for the development of advanced materials to treat infected wounds.

Self-pigmenting textiles grown from cellulose-producing bacteria with engineered tyrosinase expression

Environmental concerns are driving interest in postpetroleum synthetic textiles produced from microbial and fungal sources. Bacterial cellulose (BC) is a promising sustainable leather alternative, on account of its material properties, low infrastructure needs and biodegradability. However, for alternative textiles like BC to be fully sustainable, alternative ways to dye textiles need to be developed alongside alternative production methods. To address this, we genetically engineer Komagataeibacter rhaeticus to create a bacterial strain that grows self-pigmenting BC. Melanin biosynthesis in the bacteria from recombinant tyrosinase expression achieves dark black coloration robust to material use. Melanated BC production can be scaled up for the construction of prototype fashion products, and we illustrate the potential of combining engineered self-pigmentation with tools from synthetic biology, through the optogenetic patterning of gene expression in cellulose-producing bacteria. With this study, we demonstrate that combining genetic engineering with current and future methods of textile biofabrication has the potential to create a new class of textiles.

Characterization and antibacterial activity of cellulose extracted from Washingtonia robusta and Phoenix dactylifera L. impregnated with eugenol: Promising wound dressing

This paper aimed to valorize two varieties of date palm mesh, Washingtonia robusta (S1) and Phoenix Dactylifera L. (S2) by extracting their fibrous cellulose structures for potential application in wound dressings. The extracted fibrous dressings were analyzed by using Fourier Transforms Infrareded (FTIR), X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM). Additionally, mechanical properties, water absorption, and antimicrobial activity were analyzed. The results showed that S2 contained significantly higher fiber content (37.21 %) compared to S1 (12.63 %). FTIR analysis confirmed successful cellulose extraction from both palm varieties. SEM images showed that S1 fibers had a smooth-surface with smaller pores, contributing to a higher absorption capacity of 1289 ± 93 %. Therefore, S2 exhibited rougher-surfaced fibers, which enhanced its mechanical properties, as demonstrated by stress-strain tensile tests, and Young's modulus. Notably, S2 revealed superior mechanical strength compared to S1 fiber dressings. Water absorption for S2 was calculated at 509 ± 93 %. Both S1 and S2 exhibited high crystalline index (61.17 % and 62.88 %), with crystalline size of 3.54 nm for S1 and 10.03 nm for S2. Finally, Eugenol-enriched fibers showed significant activity against E. coli (3.8 mm and 2.3 mm), S. aureus (4.00 mm and 2.05 mm), and S. epidermidis (2.7 mm and 1.6 mm) for S1 and S2, respectively, suggesting their potential as effective new wound dressing materials.

Enzymatic functionalization of bacterial nanocellulose: current approaches and future prospects

Faced with the challenges of modern industry and medicine associated with the dynamic development of civilization, there is a constantly growing demand for the production of novel functional materials that are clearly oriented towards fulfilling specific applications. Herein, we provide an overview of the current status and recent findings related to the enzymatic functionalization of bacterial nanocellulose. Commonly, biocellulose modification involves the utilization of simple and cost-effective chemical and/or physical approaches. However, these methods may have an adverse effect on both the biological properties of the biomaterial and the natural environment. An alternative to these procedures is the highly specific enzymatic modification of bacterial nanocellulose, which perfectly fits into the assumptions of green technologies, making the process eco-friendly and not limiting any outlooks for further usage of the obtained biocomposites. The employment of enzymes for the targeted alteration of this material's properties is based on either a direct method, such as controlled hydrolysis and nanofication [i.e., synthesis of different morphological forms of bacterial cellulose (e.g., rod-shaped nanocrystals)] using cellulases, and/or attachment of reactive functional groups into the polymer structure via oxidation (e.g., utilizing a laccase/TEMPO catalytic system or lytic polysaccharide monooxygenases) and esterification catalyzed by lipases; or an indirect procedure involving the application of bacterial nanocellulose as a matrix for enzyme immobilization (e.g., laccase, glucose oxidase, horseradish peroxidase, lysozyme, bromelain, lipase, papain), thus creating a specific catalytic system. Overall, enzymatic functionalization of bacterial nanocellulose is a sustainable and promising strategy to create biocomposites with tailored properties for a wide range of industrial and medical applications.

Evaluation of Bacterial Cellulose/Alginate-Based Hydrogel and Frog Skin Dressings in Equine Skin Wound Healing

This study evaluates the wound-healing process in horses following the application of two treatment modalities: bacterial cellulose hydrogel with alginate (BCAW) and frog skin (FSW) dressings on experimentally induced skin wounds. Throughout the experiment, no clinical abnormalities were noted in the horses, although initial wound assessments indicated edema and sensitivity. Local hemorrhage was observed in some cases on Day 0, with granulation tissue formation evident by Day 14. Epithelialization began around Day 14 but did not reach complete healing in any group by Day 28. The analysis showed no significant differences in skin wound area or wound contraction rates among the treatment groups compared to control wounds (CWs) over the evaluation periods. Histopathological evaluations also indicated no significant differences in inflammatory responses or healing markers, such as fibroblast proliferation and neovascularization in skin wounds across groups. Despite expectations based on prior research in other species, the treatments with BCAW and FSW did not demonstrate substantial pro-healing effects in horses with induced skin wounds. These findings underscore the complexity of equine wound healing and suggest further investigation is needed to optimize treatment strategies in this species and enhance the translational potential for human clinical applications.

Polysaccharides and Peptides With Wound Healing Activity From Bacteria and Fungi

Bacteria and fungi are natural sources of metabolites exhibiting diverse bioactive properties such as wound healing, antioxidative, antibacterial, antifungal, anti-inflammatory, antidiabetic, and anticancer activities. Two important groups of bacteria or fungi-derived metabolites with wound-healing potential are polysaccharides and peptides. In addition to bacteria-derived cellulose and hyaluronic acid and fungi-derived chitin and chitosan, these organisms also produce different polysaccharides (e.g., exopolysaccharides) with wound-healing potential. The most commonly used bacterial peptides in wound healing studies are bacteriocins and lipopeptides. Bacteria or fungi-derived polysaccharides and peptides exhibit both the in vitro and the in vivo wound healing potency. In the in vivo models, including animals and humans, these metabolites positively affect wound healing by inhibiting pathogens, exhibiting antioxidant activity, modulating inflammatory response, moisturizing the wound environment, promoting the proliferation and migration of fibroblasts and keratinocytes, increasing collagen synthesis, re-epithelialization, and angiogenesis. Therefore, peptides and polysaccharides derived from bacteria and fungi have medicinal importance. This study aims to overview current literature knowledge (especially within the past 5 years) on the in vitro and in vivo wound repair potentials of polysaccharides and peptides obtained from bacteria (Actinobacteria, Bacteroidetes, Cyanobacteria, Firmicutes, and Proteobacteria) and fungi (yeasts, filamentous microfungi, and mushrooms).

Development of a cationic bacterial cellulose film loaded with anionic liposomes for prolonged release of oxacillin in wound dressing applications

Dressings should protect wounds, promote healing, absorb fluids, and maintain moisture. Bacterial cellulose is a biopolymer that stands out in biomaterials due to its high biocompatibility in several applications. In the area of dressings, it is already marketed as an alternative to traditional dressings. However, it lacks any intrinsic activity; among these, the need for antimicrobial activity in infected wounds stands out. We developed a cationic cellulose film by modifying cellulose with 1-(5-carboxypentyl)pyridin-1-ium bromide, enhancing its wettability (contact angle: 26.6°) and water retention capacity (2714.37 %). This modified film effectively retained oxacillin compared to the unmodified control. Liposomal encapsulation further prolonged oxacillin release up to 11 days. Both oxacillin-loaded films and liposomal formulations demonstrated antimicrobial activity against Staphylococcus aureus. Our findings demonstrate the potential of chemically modified cellulose as a platform for controlled anionic antibiotics and/or their formulations delivery in wound care.

Applications and interventions of polymers and nanomaterials in alveolar bone regeneration and tooth dentistry

Inflammatory diseases exert a significant influence on the periodontium, serving as a primary contributor to the development of periodontitis. The advancement of periodontitis, characterized by manifestations, such as gingival recession, increased periodontal pocket depth and resorption across the alveolar bone, cementum and periodontal ligaments, poses a significant risk of dental detachment. Untreated or delayed treatment further worsens these deleterious outcomes. This emphasizes the critical importance of timely and effective interventions in reducing the consequences associated with periodontitis. Addressing these challenges requires to focus on the fabrication of bioactive materials, particularly scaffolds, as pivotal elements in tissue engineering processes aimed at alveolar bone regeneration. The incorporation of natural polymers, particularly their amalgamation with clays and clay minerals, such as montmorillonite and LAPONITE®, has been identified as a prospective pathway for advancing biomaterials in the realm of dentistry. This amalgamation holds significant potential for the production of biomaterials with enhanced properties, underscoring its relevance and applicability in dental research. This review paper explores the current advancements in natural polymer-based biomaterials employed in various dental applications, including oral caries, regenerative medicine and alveolar bone regeneration. The principal aim of this investigation is to briefly compile and present the existing knowledge while updating information on the utilization of natural polymers in the formulation of biomaterials. Additionally, the paper aims to elucidate their applications within contemporary research trends and developments in the field of odontology. This article extensively delves into pertinent research to assess the progress of nanotechnology in the context of tissue regeneration and the treatment of oral diseases.

A review: Current trends and future perspectives of bacterial nanocellulose-based wound dressings

Bacterial cellulose (BC) has gained significant attention as a base material for wound dressings due to its superior physical properties, biocompatibility, and non-toxicity. However, to produce wound dressings that actively facilitate wound healing, BC modification is essential. To provide a comprehensive analysis of the potential research developments and the trends in bacterial cellulose-based wound dressings (BCWD), this review focuses on the BCWD research conducted in the last decade. The review highlights the optimization of BC usage as a base material for active wound dressing, including the incorporation of miscellaneous materials and the enhancement of BC properties such as ultra-transparency, anti-leakage, stretchability/flexibility, adhesiveness, conductivity, injectability, pattern, and pH-sensor ability.

Aerogels based on Bacterial Nanocellulose and their Applications

Microbial cellulose stands out for its exceptional characteristics in the form of biofilms formed by highly interlocked fibrils, namely, bacterial nanocellulose (BNC). Concurrently, bio-based aerogels are finding uses in innovative materials owing to their lightweight, high surface area, physical, mechanical, and thermal properties. In particular, bio-based aerogels based on BNC offer significant opportunities as alternatives to synthetic or mineral counterparts. BNC aerogels are proposed for diverse applications, ranging from sensors to medical devices, as well as thermal and electroactive systems. Due to the fibrous nanostructure of BNC and the micro-porosity of BNC aerogels, these materials enable the creation of tailored and specialized designs. Herein, a comprehensive review of BNC-based aerogels, their attributes, hierarchical, and multiscale features are provided. Their potential across various disciplines is highlighted, emphasizing their biocompatibility and suitability for physical and chemical modification. BNC aerogels are shown as feasible options to advance material science and foster sustainable solutions through biotechnology.

Three-dimensional printed polyelectrolyte construct containing mupirocin-loaded quaternized chitosan nanoparticles for skin repair

Despite substantial advancements in wound dressing development, effective skin repair remains a significant challenge, largely due to the persistent issue of recurrent infections. Three-dimensional printed constructs that integrate bioactive and antibacterial agents hold significant potential to address this challenge. In this study, a 3D-printed hydrogel scaffold composed of polyallylamine hydrochloride (PAH) and pectin (Pc), incorporated with mupirocin (Mp)-loaded quaternized chitosan nanoparticles (QC NPs) was fabricated. The primary objective of this study was to facilitate a controlled and sustained release of Mp via the QC NPs. The average size of QC-Mp nanoparticles was measured to be 66.05 nm and the average strand diameter and pore size of the 3D-printed construct were measured as 147.22 ± 5.83 and 388.44 ± 14.50 μm, respectively. The hemolysis rate of all scaffolds was below 2 %, indicating that they can be classified as non-hemolytic materials with sufficient blood compatibility. The PAH-Pc/QC-Mp scaffold exhibited significant antibacterial activity, enhanced cell viability in HaCat cells, sustained Mp release until day 7 (⁓60 %), and in-vivo wound healing promotion by stimulation of human keratinocytes. In conclusion, the proposed biocompatible construct demonstrates significant potential for the treatment of chronic and infected wounds by preventing infection and promoting accelerated wound healing.

Characterization and Performance Evaluation of Magnesium Chloride-Enriched Polyurethane Nanofiber Patches for Wound Dressings

Purpose

Wound patches are essential for wound healing, yet developing patches with enhanced mechanical and biological properties remains challenging. This study aimed to enhance the mechanical and biological properties of polyurethane (PU) by incorporating magnesium chloride (MgCl2) into the patch.

Methodology

The composite patch was fabricated using the electrospinning technique, producing nanofibers from a mixture of PU and MgCl2 solutions. The electrospun PU/MgCl2 was then evaluated for various physico-chemical characteristics and biological properties to determine its suitability for wound healing applications.

Results

Tensile strength testing showed that the mechanical properties of the composite patch (10.98 ± 0.18) were significantly improved compared to pristine PU (6.66 ± 0.44). Field scanning electron microscopy (FESEM) revealed that the electrospun nanofiber patch had a smooth, randomly oriented non-woven structure (PU - 830 ± 145 nm and PU/MgCl2 - 508 ± 151 nm). Fourier infrared spectroscopy (FTIR) confirmed magnesium chloride's presence in the polyurethane matrix via strong hydrogen bond formation. Blood compatibility studies using coagulation assays, including activated partial thromboplastin time (APTT), prothrombin time (PT), and hemolysis assays, demonstrated improved blood compatibility of the composite patch (APTT - 174 ± 0.5 s, PT - 91 ± 0.8s, and Hemolytic percentage - 1.78%) compared to pristine PU (APTT - 152 ± 1.2s, PT - 73 ± 1.7s, and Hemolytic percentage - 2.55%). Antimicrobial testing showed an enhanced zone of inhibition (Staphylococcus aureus - 21.5 ± 0.5 mm and Escherichia coli - 27.5 ± 2.5 mm) compared to the control, while cell viability assays confirmed the non-cytotoxic nature of the developed patches on fibroblast cells.

Conclusion

The study concludes that adding MgCl2 to PU significantly improves the mechanical, biological, and biocompatibility properties of the patch. This composite patch shows potential for future wound healing applications, with further studies needed to validate its efficacy in-vivo.

'Click' hydrogels from renewable polysaccharide resources: Bioorthogonal chemistry for the preparation of alginate, cellulose and other plant-based networks with biomedical applications

Click chemistry refers to a class of highly selective reactions that occur in one pot, are not disturbed by water or oxygen, proceed quickly to high yield and generate only inoffensive byproducts. Since its first definition by Barry Sharpless in 2001, click chemistry has increasingly been used for the preparation of hydrogels, which are water-swollen polymer networks with numerous biomedical applications. Polysaccharides, which can be obtained from renewable resources including plants, have drawn growing attention for use in hydrogels due to the recent focus on the development of a sustainable society and the reduction of the environmental impact of the chemical industry. Importantly, plant-based polysaccharides are often bioresorbable and exhibit excellent biocompatibility and biomimicry. This comprehensive review describes the synthesis, characterization and biomedical applications of hydrogels which combine the renewable and biocompatible aspects of polysaccharides with the chemically and biomedically favorable characteristics of click crosslinking. The manuscript focuses on click hydrogels prepared from alginate and cellulose, the most widely used polysaccharides for this type of hydrogel, but also click hydrogels based on other plant-derived polymers (e.g. pectin) are discussed. In addition, the challenges are described that should be overcome to facilitate translation from academia to the clinic.

Swelling Kinetics of Hydrogel Beads in Aqueous Glycerin Solutions

This study examines the swelling kinetics of polyacrylamide hydrogel beads in aqueous glycerin solutions of different concentrations. The total absorbed mass of the hydrogel beads remains nearly constant, independent of glycerin concentration, but the swelling process is markedly slower with increasing glycerin concentration in the aqueous solutions. Absorption capacity curves exhibit universal kinetics when time is rescaled using a characteristic time proportional to the viscosity of the solutions. Additionally, a novel visualization technique is employed to observe the core-shell structure of the hydrogel beads at early times in the swelling process. The evolution of the core-shell structure indicates a constant front velocity, which also reveals universal behavior with the same nondimensional time, suggesting a viscous dominated transport of the solution penetrating the beads.

Upcycling of tea processing waste into kombucha-derived bioactive cellulosic composite for prospective wound dressing action

The aim of the study was to utilize kombucha-derived bacterial cellulosic sheet [KBC], formed as a by-product of fermented, sugared black tea (in the presence of a symbiotic culture of bacteria and yeast), for potential wound dressing applications. KBC was functionalized using aqueous and ethanolic extracts of different phytochemical agents using two ex-situ methods- casting and impregnation. It was observed that casted KBC functionalized with ethanolic extract of Turmeric (1.2% w/w) yielded a maximum zone of inhibition (24.37 ± 0.42 mm) against Pseudomonas aeruginosa. The hemocompatibility test confirmed the composite's biocompatible nature as the percentage hemocompatibility was found to be less than 5%. The MTT assay established its viability and anti-cancerous properties with Turmeric extract loaded KBC showing higher efficiency compared to Tulsi extract. FTIR analysis and SEM imaging confirmed the functionalization of cellulose sheets and the change in morphology. The contact angle analysis showed improved hydrophilic properties of the sheets for absorbing wound exudates, and the water absorption study revealed maximum absorptivity of up to 321.20 ± 6.23%. Thus, it can be concluded from the study that tea processing waste can be reused to produce a value-added product that can act as an efficient, cost-effective biomaterial for wound dressing applications.

Enhancing cellulose-stabilized multiphase/Pickering emulsions systems: A molecular dynamics perspective

Cellulose stabilized multiphase systems (CSMS) have garnered significant attention due to their ultra-stabilization mechanism and vast potential across different fields. CSMS have found valuable applications in scientific disciplines, including Food Science, Pharmaceutical Science, Material Science, and related fields, owing to their beneficial attributes such as sustainability, safety, renewability, and non-toxicity. Furthermore, MPS exhibit novel characteristics that enable multiple mechanisms to produce HIPEs, aerogels, and oleogels revealing undiscovered information. Therefore, to explore the undiscovered phenomena of MPS, molecular level insights using advanced simulation/computational approaches are essential. The molecular dynamics simulation (MDS), play a valuable role in analyzing the interactions of ternary interphase. The MDS have successfully quantified the interactions of MPS by generating, visualizing, and analyzing trajectories. Through MDS, researchers have explored CSMS at the molecular level and advanced their applications in 3D printing, packaging, preparation, drug delivery, encapsulation, biosensors, electronic devices, biomaterials, and energy conservation. This review highlights the remarkable advancements in CSMS over the past five years, along with contributions of MDS in evaluating the relationships that dictate the functionality and properties of CSMS. By integrating experimental and computational methods, we underscore the potential to innovate and optimize these multiphase systems for groundbreaking applications.

Protein Immobilization on Bacterial Cellulose for Biomedical Application

New carriers for protein immobilization are objects of interest in various fields of biomedicine. Immobilization is a technique used to stabilize and provide physical support for biological micro- and macromolecules and whole cells. Special efforts have been made to develop new materials for protein immobilization that are non-toxic to both the body and the environment, inexpensive, readily available, and easy to modify. Currently, biodegradable and non-toxic polymers, including cellulose, are widely used for protein immobilization. Bacterial cellulose (BC) is a natural polymer with excellent biocompatibility, purity, high porosity, high water uptake capacity, non-immunogenicity, and ease of production and modification. BC is composed of glucose units and does not contain lignin or hemicellulose, which is an advantage allowing the avoidance of the chemical purification step before use. Recently, BC-protein composites have been developed as wound dressings, tissue engineering scaffolds, three-dimensional (3D) cell culture systems, drug delivery systems, and enzyme immobilization matrices. Proteins or peptides are often added to polymeric scaffolds to improve their biocompatibility and biological, physical-chemical, and mechanical properties. To broaden BC applications, various ex situ and in situ modifications of native BC are used to improve its properties for a specific application. In vivo studies showed that several BC-protein composites exhibited excellent biocompatibility, demonstrated prolonged treatment time, and increased the survival of animals. Today, there are several patents and commercial BC-based composites for wounds and vascular grafts. Therefore, further research on BC-protein composites has great prospects. This review focuses on the major advances in protein immobilization on BC for biomedical applications.

An Overview of Wound Dressing Materials

Wounds are an increasing global concern, mainly due to a sedentary lifestyle, frequently associated with the occidental way of life. The current prevalence of obesity in Western societies, leading to an increase in type II diabetes, and an elderly population, is also a key factor associated with the problem of wound healing. Therefore, it stands essential to find wound dressing systems that allow for reestablishing the skin integrity in the shortest possible time and with the lowest cost, avoiding further damage and promoting patients' well-being. Wounds can be classified into acute or chronic, depending essentially on the duration of the healing process, which is associated withextent and depth of the wound, localization, the level of infection, and the patient's health status. For each kind of wound and respective healing stage, there is a more suitable dressing. The aim of this review was to focus on the possible wound dressing management, aiming for a more adequate healing approach for each kind of wound.

Oxidized Bacterial Cellulose Membranes Immobilized with Papain for Dressing Applications: Physicochemical and In Vitro Biological Properties

This research consolidates our group's advances in developing a therapeutic dressing with innovative enzymatic debridement, focusing on the physicochemical and in vitro biological properties of papain immobilized in wet oxidized bacterial cellulose (OxBC-Papain) dressing. OxBC membranes were produced with Komagataeibacter hansenii oxidized with NaIO4, and papain was immobilized on them. They were characterized in terms of enzyme stability (over 100 days), absorption capacity, water vapor transmission (WVT), hemocompatibility, cytotoxicity, and cell adhesion. The OxBC-Papain membrane showed 68.5% proteolytic activity after 100 days, demonstrating the benefit of using the OxBC wet membrane for papain stability. It had a WVT rate of 678 g/m2·24 h and cell viability of 99% and 86% for L929 and HaCat cells, respectively. The membranes exhibited non-hemolytic behavior and maintained 26% clotting capacity after 1 h. The wet OxBC-Papain membrane shows significant potential as a natural biomolecule-based therapeutic dressing for wound care, offering efficient debridement, moisture maintenance, exudate absorption, gas exchange, and hemostasis without cytotoxic effects or cell adhesion to the dressing. Further research, especially using in vivo models, is needed to assess its efficacy in inducing epithelialization. This study advances stomatherapy knowledge, providing a cost-effective solution for enzymatic debridement in healthcare.

Preparation of composite calcium phosphate cement scaffold loaded with Hedysarum polysaccharides and its efficacy in repairing bone defects

It's imperative to create a more ideal biological scaffold for bone defect repair. Calcium phosphate bone cements (CPC) could be used as a scaffold. Some ingredients and osteogenic factors could be added to improve its poor mechanical properties and biological activity. As a macromolecule extracted from traditional Chinese medicine, Hedysarum polysaccharides (HPS) would significantly promote the osteogenic activity of bone biomaterials. Zirconium oxide and starch were added to the solid phase and citric acid was added to the liquid phase to optimize CPC. HPS was loaded onto the scaffold as an osteogenic factor, and the prepared CPS + HPS was characterized. Further, the cytocompatibility of CPS + HPS was assessed according to activity, differentiation, and calcification in neonatal rat calvarial osteoblasts, and the biosafety of CPS + HPS was evaluated according to acute toxicity, pyrogen, sensitization, and hemolysis. The success of CPS + HPS in repairing bone defects was evaluated by using a rabbit femur implantation experiment. After optimization, CPS-20-CA-5 containing 10% starch and 5% citric acid displayed the highest mechanical strength of 28.96 ± 0.03 MPa. HPS-50 was demonstrated to exert the best osteogenic effect. The combination of CPS + HPS achieved HPS-loaded CPC. Material characterization, cytocompatibility, biosafety, and femoral implantation experiments indicated that CPS + HPS possessed better pressure resistance and improved osteogenic ability in bone defect repair.CPS + HPS demonstrated effective pressure resistance and superior osteogenic ability, which may be of great significance for bone defects and bone tissue engineering to promote bone regeneration and repair.

Nanocomposite Based on Bacterial Cellulose and Silver Nanoparticles Improve Wound Healing Without Exhibiting Toxic Effect

Wound healing is an important and complex process, containing a multifaceted process governed by sequential yet overlapping phases. Certain treatments can optimize local physiological conditions and improve wound healing. Silver nanoparticles (AgNP) are widely known for their antimicrobial activity. On the other hand, bacterial cellulose (BC) films have been used as a dressing that temporarily substitutes the skin, offering many advantages in optimizing wound healing, in addition to being highly biocompatible. Considering the promising activities of AgNP and BC films, the present study aimed to evaluate the wound healing activity in Wistar Hannover rats using a nanocomposite based on bacterial cellulose containing AgNP (AgBC). In a period of 21 days, its influence on the wound area, microbial growth, histopathological parameters, and collagen content were analyzed. In addition, toxicity indicators were assessed, such as weight gain, water consumption, and creatinine and alanine transaminase levels. After 14 days of injury, the animals treated with AgBC showed a significant increase in wound contraction. The treatment with AgBC significantly reduced the number of microbial colonies compared to other treatments in the first 48 h after the injury. At the end of the 21 experimental days, an average wound contraction rate greater than 97 % in relation to the initial area was observed, in addition to a significant increase in the amount of collagen fibers at the edge of the wounds, lower scores of necrosis, angiogenesis and inflammation, associated with no systemic toxicity. Therefore, it is concluded that the combination of preexisting products to form a new nanocomposite based on BC and AgNP amplified the biological activity of these products, increasing the effectiveness of wound healing and minimizing possible toxic effects of silver.

Bacterial nanocellulose/calcium alginate hydrogel for the treatment of burns

PURPOSE

Bacterial cellulose (BC) has shown high capacity for the treatment of wounds and burns, providing a moisty environment. Calcium alginate can be associated with BC to create gels that aid in wound debridement and contribute to appropriate wound healing. This study is aimed at characterizing and evaluating the use of bacterial cellulose/alginate gel in skin burns in rats.

METHODS

Cellulose and cellulose/alginate gels were compared regarding the capacity of liquid absorption, moisture, viscosity, and potential cytotoxicity. The 2nd degree burns were produced using an aluminum metal plate (2.0cm) at 120ºC for 20s on the back of rats. The animals were divided into non-treated, CMC(Carboxymethylcellulose), Cellulose(CMC with bacterial cellulose), and Cellulose/alginate(CMC with bacterial cellulose and alginate). The animals received topical treatment 3 times/week. Biochemical (MPO, NAG and oxidative stress), histomorphometry and immunohistochemical assays (IL-1β IL-10 and VEGF) were conducted on the 14th, 21st, 28th, and 35th days.

RESULTS

Cellulose/Alginate gel showed higher absorption capacity and viscosity compared to Cellulose gel, with no cytotoxic effects. Cellulose/alginate presented lower MPO values, a higher percentage of IL-10, with greater and balanced oxidative stress profile.

CONCLUSIONS

The use of cellulose/alginate gel reduced neutrophils and macrophage activation and showed greater anti-inflammatory response, which can contribute to healing chronic wounds and burns.

Advancements in Aerogel Technology for Antimicrobial Therapy: A Review

This paper explores the latest advancements in aerogel technology for antimicrobial therapy, revealing their interesting capacity that could improve the current medical approaches for antimicrobial treatments. Aerogels are attractive matrices because they can have an antimicrobial effect on their own, but they can also provide efficient delivery of antimicrobial compounds. Their interesting properties, such as high porosity, ultra-lightweight, and large surface area, make them suitable for such applications. The fundamentals of aerogels and mechanisms of action are discussed. The paper also highlights aerogels' importance in addressing current pressing challenges related to infection management, like the limited drug delivery alternatives and growing resistance to antimicrobial agents. It also covers the potential applications of aerogels in antimicrobial therapy and their possible limitations.

Recent advancements in development and application of microbial cellulose in food and non-food systems

Microbial cellulose is a fermented form of very pure cellulose with a fibrous structure. The media rich in glucose or other carbon sources are fermented by bacteria to produce microbial cellulose. The bacteria use the carbon to produce cellulose, which grows as a dense, gel-like mat on the surface of the medium. The product was then collected, cleaned, and reused in various ways. The properties of microbial cellulose, such as water holding capacity, gas permeability, and ability to form a flexible, transparent film make it intriguing for food applications. Non-digestible microbial cellulose has been shown to improve digestive health and may have further advantages. It is also very absorbent, making it a great option for use in wound dressings. The review discusses the generation of microbial cellulose and several potential applications of microbial cellulose in fields including pharmacy, biology, materials research, and the food industry.

Development of nanocellulose hydrogels for application in the food and biomedical industries: A review

As the most abundant and renewable natural resource, cellulose has attracted significant attention and research interest for the production of hydrogels (HGs). To address environmental issues and emerging demands, the benefits of naturally produced HGs include excellent mechanical properties and superior biocompatibility. HGs are three-dimensional networks created by chemical or physical cross-linking of linear or branched hydrophilic polymers and have high capacity for absorption of water and biological fluids. Although widely used in the food and biomedical fields, most HGs are not biodegradable. Nanocellulose hydrogels (NC-HGs) have been extensively applied in the food industry for detection of freshness, chemical additives, and substitutes, as well as the biomedical field for use as bioengineering scaffolds and drug delivery systems owing to structural interchangeability and stimuli-responsive properties. In this review article, the sources, structures, and preparation methods of NC-HGs are described, applications in the food and biomedical industries are summarized, and current limitations and future trends are discussed.

A bacterial cellulose/polyvinyl alcohol/nitro graphene oxide double layer network hydrogel efficiency antibacterial and promotes wound healing

In this study, graphene oxide (GO) was chemically modified utilizing concentrated nitric acid to produce a nitrated graphene oxide derivative (NGO) with enhanced oxidation level, improved dispersibility, and increased antibacterial activity. A double-layer composite hydrogel material (BC/PVA/NGO) with a core-shell structure was fabricated by utilizing bacterial cellulose (BC) and polyvinyl alcohol (PVA) binary composite hydrogel scaffold as the inner network template, and hydrophilic polymer (PVA) loaded with antibacterial material (NGO) as the outer network. The fabrication process involved physical crosslinking based on repeated freezing and thawing. The resulting BC/PVA/NGO hydrogel exhibited a porous structure, favorable mechanical properties, antibacterial efficacy, and biocompatibility. Subsequently, the performance of BC/PVA/NGO hydrogel in promoting wound healing was evaluated using a mouse skin injury model. The findings demonstrated that the BC/PVA/NGO hydrogel treatment group facilitated improved wound healing in the mouse skin injury model compared to the control group and the BC/PVA group. This enhanced wound healing capability was attributed primarily to the excellent antibacterial and tissue repair properties of the BC/PVA/NGO hydrogel.

Development of silanized bacterial cellulose aerogels for the incorporation of natural oils with healing properties: Copaiba (Copaifera officinalis), bourbon geranium (Pelargonium X ssp.) essential oils and buriti (Mauritia flexuosa) vegetable oil

Bacterial cellulose (BC) represents a promising biomaterial, due to its unique and versatile properties. We report, herein, on purposely-designed structural modifications of BC that enhance its application as a wound dressing material. Chemical modification of the functional groups of BC was performed initially to introduce a hydrophobic/oleophilic character to its surface. Specifically, silanization was carried out in an aqueous medium using methyltrimethoxisilane (MTMS) as the silanizing agent, and aerogels were subsequently prepared by freeze-drying. The BC-MTMS aerogel obtained displayed a highly porous (99 %) and lightweight structure with an oil absorption capacity of up to 52 times its dry weight. The XRD pattern indicated that the characteristic crystallographic planes of the native BC were maintained after the silanization process. Thermal analysis showed that the thermal stability of the BC-MTMS aerogel increased, as compared to the pure BC aerogel (pBC). Moreover, the BC-MTMS aerogel was not cytotoxic to fibroblasts and keratinocytes. In the second step of the study, the incorporation of natural oils into the aerogel's matrix was found to endow antimicrobial and/or healing properties to BC-MTMS. Bourbon geranium (Pelargonium X ssp.) essential oil (GEO) was the only oil that exhibited antimicrobial activity against the tested microorganisms, whereas buriti (Mauritia flexuosa) vegetable oil (BVO) was non-cytotoxic to the cells. This study demonstrates that the characteristics of the BC structure can be modified, while preserving its intrinsic features, offering new possibilities for the development of BC-derived materials for specific applications in the biomedical field.

Exploring the evolution of bacterial cellulose precursors and their potential use as cellulose-based building blocks

Natural polymers have found increased use in a wider range of applications due to their less harmful effects. Notably, bacterial cellulose has gained significant consideration due to its exceptional physical and chemical properties and its substantial biocompatibility, which makes it an attractive candidate for several biomedical applications. This study attempts to thoroughly unravel the microstructure of bacterial cellulose precursors, known as bioflocculants, which to date have been poorly characterised, by employing both electron and optical microscopy techniques. Here, starting from bioflocculants from Symbiotic Culture of Bacteria and Yeast (SCOBY), we proved that their microstructural features, such as porosity percentage, cellulose assembly degree, fibres' density and fraction, change in a spatio-temporal manner during their rising toward the liquid-air interface. Furthermore, our research identified a correlation between electron and optical microscopy parameters, enabling the assessment of bioflocculants' microstructure without necessitating offline sample preparation procedures. The ultimate goal was to determine their potential suitability as a novel cellulose-based building block material with tuneable structural properties. Our investigations substantiate the capability of SCOBY bioflocculants, characterized by distinct microstructures, to successfully assemble within a microfluidic device, thereby generating a cellulose sheet endowed with specific and purposefully designed structural features.

Improved Treatment Outcome Following the Use of a Wound Dressings in Cutaneous Leishmaniasis Lesions

Leishmaniasis, caused by Leishmania parasites, is a neglected tropical disease and Cutaneous Leishmaniasis (CL) is the most common form. Despite the associated toxicity and adverse effects, Meglumine antimoniate (MA) remains the first-choice treatment for CL in Brazil, pressing the need for the development of better alternatives. Bacterial NanoCellulose (BNC), a biocompatible nanomaterial, has unique properties regarding wound healing. In a previous study, we showed that use of topical BNC + systemic MA significantly increased the cure rate of CL patients, compared to treatment with MA alone. Herein, we performed a study comparing the combination of a wound dressing (BNC or placebo) plus systemic MA versus systemic MA alone, in CL caused by Leishmania braziliensis. We show that patients treated with the combination treatment (BNC or placebo) + MA showed improved cure rates and decreased need for rescue treatment, although differences compared to controls (systemic MA alone) were not significant. However, the overall time-to-cure was significantly lower in groups treated with the combination treatment (BNC+ systemic MA or placebo + systemic MA) in comparison to controls (MA alone), indicating that the use of a wound dressing improves CL treatment outcome. Assessment of the immune response in peripheral blood showed an overall downmodulation in the inflammatory landscape and a significant decrease in the production of IL-1a (p < 0.05) in patients treated with topical BNC + systemic MA. Our results show that the application of wound dressings to CL lesions can improve chemotherapy outcome in CL caused by L. braziliensis.

An antibacterial membrane based on Janus bacterial cellulose with nano-sized copper oxide through polydopamine conjugation for infectious wound healing

Bacterial cellulose (BC) produced by Acetobacter xylinum has great advantages in wound dressing. However, the structural limitation under static culture, and lack of antibacterial properties restrict its application, especially for infectious wound healing. The present study reported an original wound dressing, which was composed of a Janus BC membrane with antibacterial nano-sized copper oxide (CuO) through polydopamine (PDA) conjugation to promote wound healing under infectious condition. The finished product (CuO/PDA/BC membrane) exhibited favorable air permeability, high hydrophilicity and good mechanical properties, as well as strong antibacterial effects by the sustained release of CuO and photothermal effect of CuO/PDA. Furthermore, CuO/PDA/BC membrane inhibited inflammatory response and promoted wound healing in an infectious wound model in vivo. These results suggested that our CuO/PDA/BC membrane had great potential as wound dressing for infectious wound healing.

Citrate-buffered Yamanaka medium allows to produce high-yield bacterial nanocellulose in static culture using Komagataeibacter strains isolated from apple cider vinegar

Bacterial nanocellulose (BNC) is a sustainable, renewable, and eco-friendly nanomaterial, which has gained great attentions in both academic and industrial fields. Two bacterial nanocellulose-producing strains (CVV and CVN) were isolated from apple vinegar sources, presenting high 16S rRNA gene sequence similarities (96%-98%) with Komagataeibacter species. The biofilm was characterized by scanning electron microscopy (SEM), revealing the presence of rod-shaped bacteria intricately embedded in the polymeric matrix composed of nanofibers of bacterial nanocellulose. FTIR spectrum and XRD pattern additionally confirmed the characteristic chemical structure associated with this material. The yields and productivities achieved during 10 days of fermentation were compared with Komagataeibacter xylinus ATCC 53524, resulting in low levels of BNC production. However, a remarkable increase in the BNC yield was achieved for CVV (690% increase) and CVN (750% increase) strains at day 6 of the fermentation upon adding 22 mM citrate buffer into the medium. This effect is mainly attributed to the buffering capacity of the modified Yakamana medium, which allowed to maintain pH close to 4.0 until day 6, though in combination with additional factors including stimulation of the gluconeogenesis pathway and citrate assimilation as a carbon source. In addition, the productivities determined for both isolated strains (0.850 and 0.917 g L-1 d-1) compare favorably to previous works, supporting current efforts to improve fermentation performance in static cultures and the feasibility of scaling-up BNC production in these systems.

Bacterial nanocellulose loaded with bromelain and nisin as a promising bioactive material for wound debridement

The bacterial nanocellulose (BnC) membranes were produced extracellularly by a novel aerobic acetic acid bacterium Komagataeibacter melomenusus. The BnC was modified in situ by adding carboxymethyl cellulose (CMC) into the culture media, obtaining a BnC-CMC product with denser fibril arrangement, improved rehydration ratio and elasticity in comparison to BnC. The proteolytic enzyme bromelain (Br) and antimicrobial peptide nisin (N) were immobilized to BnC matrix by ex situ covalent binding and/or adsorption. The optimal Br immobilization conditions towards the maximized specific proteolytic activity were investigated by response surface methodology as factor variables. At optimal conditions, i.e., 8.8 mg/mL CMC and 10 mg/mL Br, hyperactivation of the enzyme was achieved, leading to the specific proteolytic activity of 2.3 U/mg and immobilization efficiency of 39.1 %. The antimicrobial activity was observed against Gram-positive bacteria (S. epidermidis, S. aureus and E. faecalis) for membranes with immobilized N and was superior when in situ modified BnC membranes were used. N immobilized on the BnC or BnC-CMC membranes was cytocompatible and did not cause changes in normal human dermal fibroblast cell morphology. BnC membranes perform as an efficient carrier for Br or N immobilization, holding promise in wound debridement and providing antimicrobial action against Gram-positive bacteria, respectively.

Multihydrogen Bond Modulated Polyzwitterionic Removable Adhesive Hydrogel with Antibacterial and Hemostatic Function for Wound Healing

Wound management is a major challenge worldwide, placing a huge financial burden on the government of every nation. Wound dressings that can protect wounds, accelerate healing, prevent infection, and avoid secondary damage continue to be a major focus of research in the health care and clinical communities. Herein, a novel zwitterionic polymer (LST) hydrogel incorporated with [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (SBMA), mussel-inspired N-[tris(hydroxymethyl)methyl] acrylamide (THMA), and lithium magnesium salt was prepared for functional wound dressings. The incorporation of the THMA monomer containing three hydroxyl groups gives the hydrogel suitable adhesion properties (∼6.0 KPa). This allows the LST zwitterionic hydrogels to bind well to the skin, which not only protects the wound and ensures its therapeutic efficacy but also allows for painless removal and reduced patient pain. Zwitterionic sulfobetaine units of SBMA provide antimicrobial and mechanical properties. The chemical structure and microscopic morphology of LST zwitterionic hydrogels were systematically studied, along with their swelling ratio, adhesion, and mechanical properties. The results showed that the LST zwitterionic hydrogels had a uniform and compact porous structure with the highest swelling and mechanical strain of 1607% and 1068.74%, respectively. The antibacterial rate of LST zwitterionic hydrogels was as high as 99.49%, and the hemostatic effect was about 1.5 times that of the commercial gelatin hemostatic sponges group. In further studies, a full-thickness mouse skin model was selected to evaluate the wound healing performance. Wounds covered by LST zwitterionic hydrogels had a complete epithelial reformation and new connective tissue, and its vascular regenerative capacity was increased to about 2.4 times that of the commercial group, and the wound could completely heal within 12-13 days. This study provides significant advances in the design and construction of multifunctional zwitterionic hydrogel adhesives and wound dressings.

Investigation of anti-adherence and antimicrobial properties of prodigiosin-functionalized bacterial cellulose membrane for biomedical applications

In this study, novel biomaterial that consisted entirely of bacterial products was developed with the approach of designing cost effective material for biomedical applications. With this aim, bacterial cellulose membranes (BCMs) which synthesized by Komagataeibacter intermedius were produced. Moreover, to impart antimicrobial properties to enhance the capacity of BCMs for biomedical usage, prodigiosin (PG) pigment of Serratia marcescens which presents wide range of antimicrobial activities was loaded to BCMs. Firstly, high yield of PG production was achieved, and then crude pigment was purified with silica gel column. The purified PG was characterized with thin layer chromatography and UV-visible spectrometry. The antimicrobial effect of the produced pigment on Gram-positive and negative bacteria and a yeast was investigated. The success of modification in PG-modified BCMs has been demonstrated by FTIR and SEM. Moreover, antimicrobial and antiadhesive ability of novel PG-BCMs were examined with disc diffusion and plate counting methods. As a result, it was established that PG-BCMs were able to inhibit the growth of all tested microorganisms. Furthermore, excellent antiadhesive effect was observed for the tested microorganisms with the inhibition rates of 82.05-96.25 %. Finally, cytotoxicity test with L929 cell line demonstrated that PG-BCM is biocompatible at a level that can be applied in in vivo studies.

Antimicrobial polyacrylic acid/tannic acid hydrogel wound dressing facilitating full-thickness skin healing

Polyphenolic compound-modified hydrogel wound dressings with excellent wet tissue adhesion, antimicrobial properties, stretchability, and full-thickness skin healing properties are still extremely rare so far. Polyphenolic compounds such as tannic acid or dopamine can improve the antibacterial and bioadhesive properties of hydrogels, and are also polymerization inhibitors for free radical polymerization. In this study, polyacrylic acid (PAA) aqueous solution was first synthesized, and then antibacterial PAA-TA hydrogel was prepared by mixing it with tannic acid (TA) and the crosslinker 1,6-hexanediol bis(2-methyl-1-propionic acid azide) (HBMAP). This method avoids the hindrance of the phenolic hydroxyl groups in TA on acrylic acid polymerization, and we were able to obtain a series of TA hydrogels (in the range of 0-15 wt.%. We applied these PAA-TA hydrogels to wound dressings and found that they had excellent adhesion to biological tissues, and the tensile strength and elongation at break of PAA-TA hydrogels with 15 wt.%TA content were as high as 1.72 MPa and 1446.3% in tensile strength evaluation. In addition, microbiological analysis showed that wound dressings had significant antimicrobial activity against Staphylococcus aureus and Escherichia coli. In vitro wound healing experiments confirmed that the wound dressing was biocompatible and could significantly promote the healing of full-thickness skin defects in the guinea pig model. Our work describes an injectable, self-healing, antimicrobial hydrogel that may have promising clinical applications as a wound dressing material.

Cubosome-carrying bacterial cellulose membrane as a versatile drug delivery platform

Using advanced nanotechnology membranes has opened up new possibilities in the field of biomedicine, particularly for controlled drug delivery and especially for topical use. Bacterial cellulose membranes (BCM), particularly, have gained prominence owing to their distinctive attributes, including remarkable water retention, safety, biodegradability, and tunable gas exchange. However, they are aqueous matrices and, for this reason, of limited capacity for incorporation of apolar compounds. Cubosomes are lipid nanoparticles composed of a surfactant bicontinuous reverse cubic phase, which, owing to their bicontinuous structure, can incorporate both polar and apolar compounds. Therefore, these particles present a promising avenue for encapsulating and releasing drugs and biomolecules due to their superior entrapment efficiency. In this study, we aim to extend earlier investigations using polymeric hydrogels for cubosome immobilization, now using BCMs, a more resilient biocompatible matrix. Phytantriol cubosome-loaded BCMs were prepared by three distinct protocols: ex situ incorporation into wet BCMs, ex situ incorporation by swelling of dry BCMs, and an in situ process with the growth of BCMs in a sterile medium already containing cubosomes. Our investigation revealed that these methodologies ensured that cubosomes remained integral, uniformly distributed, and thoroughly dispersed within the membrane, as confirmed using Small-Angle X-ray Scattering (SAXS) and high-resolution confocal microscopy. The effective incorporation and sustained release of diclofenac were validated across the different BCMs and compared with hyaluronic acid (HA) hydrogel in our previous studies. Furthermore, the resistance against cubosome leaching from the three BCM and HA hydrogel samples was quantitatively evaluated and contrasted. We hope that the outcomes from this research will pave the way for innovative use of this platform in the incorporation and controlled release of varied active agents, amplifying the already multifaceted applicability of BCMs.

Hydrogels in Cutaneous Wound Healing: Insights into Characterization, Properties, Formulation and Therapeutic Potential

Hydrogels are polymeric materials that possess a set of characteristics meeting various requirements of an ideal wound dressing, making them promising for wound care. These features include, among others, the ability to absorb and retain large amounts of water and the capacity to closely mimic native structures, such as the extracellular matrix, facilitating various cellular processes like proliferation and differentiation. The polymers used in hydrogel formulations exhibit a broad spectrum of properties, allowing them to be classified into two main categories: natural polymers like collagen and chitosan, and synthetic polymers such as polyurethane and polyethylene glycol. This review offers a comprehensive overview and critical analysis of the key polymers that can constitute hydrogels, beginning with a brief contextualization of the polymers. It delves into their function, origin, and chemical structure, highlighting key sources of extraction and obtaining. Additionally, this review encompasses the main intrinsic properties of these polymers and their roles in the wound healing process, accompanied, whenever available, by explanations of the underlying mechanisms of action. It also addresses limitations and describes some studies on the effectiveness of isolated polymers in promoting skin regeneration and wound healing. Subsequently, we briefly discuss some application strategies of hydrogels derived from their intrinsic potential to promote the wound healing process. This can be achieved due to their role in the stimulation of angiogenesis, for example, or through the incorporation of substances like growth factors or drugs, such as antimicrobials, imparting new properties to the hydrogels. In addition to substance incorporation, the potential of hydrogels is also related to their ability to serve as a three-dimensional matrix for cell culture, whether it involves loading cells into the hydrogel or recruiting cells to the wound site, where they proliferate on the scaffold to form new tissue. The latter strategy presupposes the incorporation of biosensors into the hydrogel for real-time monitoring of wound conditions, such as temperature and pH. Future prospects are then ultimately addressed. As far as we are aware, this manuscript represents the first comprehensive approach that brings together and critically analyzes fundamental aspects of both natural and synthetic polymers constituting hydrogels in the context of cutaneous wound healing. It will serve as a foundational point for future studies, aiming to contribute to the development of an effective and environmentally friendly dressing for wounds.