Flexible Amoxicillin-Grafted Bacterial Cellulose Sponges for Wound Dressing: In Vitro and in Vivo Evaluation

Bacterial cellulose: Is it really a promising biomedical material?

Bacterial cellulose (BC) is currently considered a promising biomaterial due to its specific structure and properties. However, despite extensive research, questions about its fundamental properties, especially biocompatibility, remain. Thus, the purpose of this review is to analyze the results of in vivo trials from different areas of biomedicine, including wound healing, tissue engineering, drug delivery, and biomedical implants. The primary question guiding our review was "Why is bacterial cellulose still not used in clinical practice?" Analysis of the literature has shown that the results of in vivo studies often contradict each other. For example, BC caused and did not cause an immune response in an equal number of reviewed articles. Its efficacy in pure form generally does not differ significantly from that of materials already on the market. Conversely, BC may prove to be a valuable material in the long term, not because of its efficacy, but rather because of its affordability and ease of use. Additionally, challenges associated with immune reactions, long-term biocompatibility, and the necessity for standardized experimental protocols must be addressed. We expect that this review will encourage a more thoughtful investigation of BC to bring it into practical medicine.

Bacterial cellulose-based flexible phase change gel for potential release-controllable wound dressings

Long-term protection of skin-defect wounds is challenging for the common wound dressings cotton gauze due to its weak skin adhesion, limited drug-loading capacity and frequent replacement. Hydrogels are considered as the promising wound dressings benefiting by their good mechanical compatibility and biocompatibility. Nevertheless, the hydrogels always suffer from the drawbacks of fast water evaporation, lack of antibacterial ability and uncontrollable drug release, which greatly shorten their long-term wound protection duration. Herein, a novel and multifunctional phase change gel (PCG) combining flexibility of hydrogel and release-controllable ability of phase change materials (PCMs) was fabricated through a facile solvent-exchange strategy. Specifically, the bacterial cellulose (BC)/polyethylene glycol based phase change gels (BC/PEG PCGs) were prepared by direct impregnation of BC hydrogel into massive PEG melts. The solvent-exchange mechanism between BC hydrogel and PCM melts was firstly studied based on the impregnation experiments of BC gels into various PCMs. The as-prepared BC/PEG PCGs were then characterized in terms of structure, mechanical, phase change and wound dressing properties, subsequently. This work provides a comprehensive understanding of the structure relationship on their excellent flexibility, good adhesive, skin-cooling, antibacterial and controllable drug-release functions of BC/PEG PCGs, extending their potential in the long-term protection of skin-defect wounds.

Carboxymethyl bacterial cellulose electrospun nanofibers loaded with zinc oxide nanoparticles and polyhexamethylene biguanide for wound healing promotion

This study explores the development of a novel wound dressing incorporating bacterial cellulose (BC) produced by Acetobacter xylinum, which was carboxymethylated to enhance its biomedical applicability. Zinc oxide nanoparticles (ZnONPs) were biosynthesized using a green method with Quercus infectoria gall extracts (QIG). The composite dressing, composed of BC and polyurethane (PU) nanofibers, was further functionalized with ZnONPs and polyhexamethylene biguanide (PHMB) to provide enhanced antibacterial and wound healing properties. The PU/BC/ZnONPs/PHMB nanofiber mat exhibited strong antibacterial activity against Methicillin-resistant Staphylococcus aureus (MRSA), with inhibition zones of 28 and 29 mm for PU/BC/ZnONPs and PU/BC/ZnONPs/PHMB, respectively, surpassing the 12 mm inhibition zone of the Cefoxitin control. The nanofibers had an optimal mean diameter of 71.12 nm, ensuring a high surface area for cell attachment. Mechanical tests confirmed excellent tensile strength and flexibility, while an optimized water vapor transmission rate (∼2000-3000 g/m2/day) facilitated a moist wound environment for enhanced healing. L929 fibroblast studies demonstrated high cell viability (∼95-98%) and enhanced migration, confirming the nanofiber mat's biocompatibility. In vivo wound healing tests showed that PU/BC/ZnONPs/PHMB significantly accelerated wound closure, achieving 90-100% healing by day 10, outperforming PU and PU/BC groups. Bacterial counts were significantly reduced, with complete bacterial inhibition observed by day 5. In conclusion, the PU/BC/ZnONPs/PHMB nanofiber dressing demonstrated superior antibacterial activity, mechanical strength, moisture regulation, and wound healing potential, making it a promising candidate for advanced clinical wound management.

A multifunctional bacterial cellulose-based dressing modified by quaternized chitosan and grafted protocatechuic acid for diabetic ulcer

Herein, we developed a multifunctional bacterial cellulose-based dressing (PHBC) modified by quaternized chitosan (HACC) along with protocatechuic acid (PA), through in situ biosynthesis combined with covalent immobilization. The obtained PHBC dressing maintained the excellent physicochemical characteristics of BC, such as high porosity (above 76 %); high water absorption ratio, >80 % of water absorption rate (approximately 30 g/g) has completed in half an hour; favorable hydrophilicity with contact angle of about 50° and excellent flexibility. The introduction of PA-grafted HACC endows exhibited outstanding antibacterial properties against, anti-inflammatory performance and antioxidant capacity. Furthermore, PHBC II, with the reaction solubility of PA was 3 mg/mL, could promote NIH3T3 and HUVECs proliferation and spread. In vivo experiments further verified that PHBC II can effectively promote new granulation tissue hyperplasia and collagen deposition and expression around diabetic ulcers, reduce the inflammatory phenomenon around the wound, and promote the internal capillaries of the wound. The repair and regeneration of the network can promote better and faster wound healing. These results illustrate that the PHBC functional dressing has an important reference value for the clinical treatment of diabetic ulcers.

In Situ Self-Assembled Naringin/ZIF-8 Nanoparticle-Embedded Bacterial Cellulose Sponges for Infected Diabetic Wound Healing

The treatment of diabetic foot ulcers (DFUs) represents a significant challenge due to the complexity of the wound microenvironment. Several factors, including infection, inflammation, and impaired angiogenesis, can complicate the healing process and reduce the effectiveness of current clinical treatments. To address these challenges, this work develops a multifunctional sponge containing a zeolitic imidazolate framework-8/bacterial cellulose (ZIF-8/BC) matrix loaded with the antioxidant naringin (Nar). This sponge is fabricated using a straightforward method that involves in situ synthesis followed by lyophilization. The as-prepared Nar/ZIF-8/BC sponge exhibits excellent mechanical properties (e.g., tensile strength reaching 2.28 MPa), high exudate management performance (water absorption approximately 70 times), and excellent antimicrobial activity (100%). Additionally, the pH-responsive properties of ZIF-8 enable the composite sponge to release naringin in response to the DFU microenvironment. The released drug promotes angiogenesis, resulting in antioxidant and anti-inflammatory effects, which further encourage the healing of infected wounds in diabetic rats. Overall, the Nar/ZIF-8/BC sponge is a promising multifunctional dressing for DFU healing, providing an efficient solution for intractable wounds by regulating the microenvironment, which meets complex clinical demands.

Copper doped carbon dots modified bacterial cellulose with enhanced antibacterial and immune regulatory functions for accelerating wound healing

The microenvironment of wound healing is susceptible to bacterial infection, chronic inflammation, oxidative stress, and inadequate angiogenesis, requiring the development of innovative wound dressings with antibacterial, anti-inflammatory, antioxidant, and angiogenic capabilities. This research crafted a new multifunctional bacterial cellulose composite membrane infused with copper-doped carbon dots (BC/Cu(II)-RCDs). Findings validated the successful loading of copper-doped carbon dots onto the BC membrane via hydrogen bonding interactions. Compared to the pure BC membrane, the BC/Cu(II)-RCDs composite membrane exhibited significantly enhanced hydrophilicity, tensile properties, and thermal stability. Diverse in vitro assays demonstrated excellent biocompatibility and antibacterial activity of BC/Cu(II)-RCDs composite membranes, alongside their ability to expedite the inflammatory phase and stimulate angiogenesis. In vivo trials corroborated the membrane's ability to foster epithelial regeneration, collagen deposition, and tissue regrowth in full-thickness skin wounds in rats while also curbing inflammation in infected full-thickness skin wounds. More importantly, the treatment of the BC/Cu(II)-RCDs composite membrane may result in the activation of VEGF and MAPK signaling proteins, which are key players in cell migration, angiogenesis, and skin tissue development. In essence, the developed BC/Cu(II)-RCDs composite membrane shows promise for treating infected wounds and serves as a viable alternative material for medicinal bandages.

An Asymmetric Bacterial Cellulose Membrane Incorporating CuPt Nanozymes and Curcumin for Accelerating Wound Healing

Damaged skin compromises its ability to effectively prevent the invasion of harmful bacteria into the tissue, leading to bacterial infection of the wound and hindering the healing process. To address this challenge, we have developed a multifunctional asymmetric wound dressing (CuPt-Cur-ABC) that effectively addresses the lack of bactericidal activity and the release of active ingredients in conventional bacterial cellulose (BC), which can be employed to create a barrier of defense between the wound and its surrounding environment. Compared with BC, asymmetric bacterial cellulose (ABC) used starch as a pore-causing agent, forming holes of different sizes at the top and bottom, which enhanced the ability of ABC to load and moderate-release drugs. First, as-synthesized CuPt nanozymes with an octopod nanoframe structure had multiple enzymatic activities including peroxidase-like, catalase-like, and glutathione peroxidase-like activities. Then, CuPt and curcumin (Cur) were loaded into ABC under ultrasound. Under 808 nm laser irradiation, the nanocomposites possessed good photothermal properties. So the photothermal therapy combined with chemodynamic therapy and inherent antibacterial performance of Cur achieved 99.3% and 99.6% in vitro bactericidal efficacy against Staphylococcus aureus and Escherichia coli, respectively. Moderate release of Cur can clear the excess reactive oxygen species and promote the polarization of macrophages toward the M2 type. In vivo experiments additionally confirmed that the constructed wound dressing achieved multiple functions, including effective antibacterial activity, reversing the inflammatory microenvironment, and promoting wound healing.

Degree of sulfation of freeze-dried calcium alginate sulfate scaffolds dramatically influence healing rate of full-thickness diabetic wounds

Diabetic foot ulcer (DFU) is a chronic and non-healing wound in all age categories with a high prevalence and mortality in the world. An ideal wound dressing for DFU should possess the ability of adsorbing high contents of exudate and actively promote wound healing. Here, we introduced the calcium alginate sulfate as a new biomaterial appropriate for use in wound dressing to promote the healing of full-thickness ulcers in a diabetic mouse model. In this regard, alginate sulfate (Alg-S) solutions with different degrees of substitution (DS) of 0.2, 0.5, and 0.9 were synthesized, freeze-dried, crosslinked by calcium cations, purified by washing and refreeze-dried. Primary analyses including swelling ratio, porosity content and mechanical properties revealed that all Alg-S scaffolds possess necessities for use as a wound dressing. After confirming the cytocompatibility of both alginate and alginate sulfate-based scaffolds by MTT assay, they were used as wound dressing for healing of full-thickness ulcers in diabetic mice. The results of wound healing process confirmed that calcium alginate sulfate scaffolds can heal the wounds faster than both alginate-treated and non-treated wounds. Furthermore, the histological analyses of healed tissues reveled normal regeneration of the skin tissue layers and collagen deposition similar to the healthy tissue.

Antibacterial and antioxidative hydrogel dressings based on tannic acid-gelatin/oxidized sodium alginate loaded with zinc oxide nanoparticles for promoting wound healing

Wound infection resulting in delayed wound healing and wound deterioration remains a clinical challenge. Recently, multifunctional hydrogel dressing was a promising strategy which has attracted wide attention in preventing wound infection and promoting wound healing. In this study, a hybrid hydrogel made of gelatin (GL), tannic acid (TA), oxidized sodium alginate (OSA), and zinc oxide nanoparticles (ZnO NPs) was prepared mainly by double network cross-linking approach, named tannic acid-gelatin/oxidized sodium alginate/zinc oxide (TA-GL/OSA/ZnO). The composite hydrogels exhibited improved mechanical properties, which provided by TA modified the structure of GL network, Schiff base reaction between GL and OSA, and the strengthening effect of ZnO NPs. Meanwhile, the composite hydrogel showed high antibacterial activity against Staphylococcus aureus (S. aureus) (97.8 % ± 0.9 %) and Escherichia coli (E. coli) (96.6 % ± 1.2 %), attributed to the synergistic effect of TA and ZnO NPs. Furthermore, benefiting from the good antioxidative properties of TA, the sustain-released Zn2+ with the good capability to kill bacteria, and promoting the regeneration of skin epithelial tissues in BALB/c mice constantly, the multifunctional hydrogel had a significant therapeutic effect on wound healing and broad application prospects.

Lysine-Mediated Yttrium Oxide Nanoparticle-Incorporated Nanofibrous Scaffolds with Tunable Cell Adhesion, Proliferation, and Antimicrobial Potency for In Vitro Wound-Healing Applications

The intricate healing mechanism of chronic wounds and their multitude of healing-related obstacles, such as infections, compromised cellular processes, and impediments to the healing process, pose a significant healthcare problem. Exploration of metal oxide nanoparticles, such as yttrium oxide (Y2O3) nanoparticles, can lead to innovative discoveries in the field of chronic wound healing by offering cues that promote cell proliferation in the scaffolds. To achieve this, Y2O3 nanoparticles were synthesized and incorporated within poly(vinyl alcohol) (PVA) nanofibrous scaffolds. Moreover, lysine was infused in the nanofibrous scaffolds to tune its cell adhesion and antimicrobial property. The structure and morphology of the synthesized nanofibers were confirmed through various physicochemical characterizations. Notably, all the fabricated scaffolds have remarkably tuned WVTR values within the range of 2000-2500 g/m2/day, favorable for removing the wound exudate, which facilitate the healing process. The scaffolds exhibited substantial antimicrobial property of approximately 68% and 72.2% against both E. coli and S. aureus at optimized Y2O3 loading. They further prevented the formation of biofilm by 68.6% for S. aureus and 51.2% for P. aeruginosa, suggesting the inhibition of recurrent wound infection. The scaffolds illustrated good blood biocompatibility, cytocompatibility, and cell adhesion capabilities. In vitro ROS inhibition study also corroborated the antioxidant property of the scaffold. Similarly, the wound scratching experiment showed high proliferative capability of a yttria-loaded PVA/lysine (S3) sample through the development of an extracellular matrix support. Molecular insight of wound healing was also validated through flow cytometry analysis and immunocytochemistry imaging studies. The findings revealed increased collagen I (Col-I) expression of approximately 19.48% in cultured fibrocytes. The findings are validated from immunocytochemistry imaging. In summary, the results furnish a captivating paradigm for the use of these scaffolds as a therapeutic biomaterial and to foster their potential efficacy toward wound care management.

Advances in the preparation and application of cellulose-based antimicrobial materials: A review

The rise of polymer materials in modern life has drawn attention to renewable, easily biodegradable, environmentally-friendly bio-based polymers. Notably, significant research has been dedicated to creating green antimicrobial functional materials for the biomedical field using natural polymer materials. Cellulose is a rich natural biomass organic polymer material. Given its favorable attributes like film-forming capability, biodegradability, and biocompatibility, it is extensively employed to tackle a wide range of challenges confronting humanity today. However, its inherent drawbacks, such as insolubility in water and most organic solvents, hygroscopic nature, difficulty in melting, and limited antimicrobial properties, continue to pose challenges for realizing the high-value applications of cellulose. Achieving multifunctionality and more efficient application of cellulose still poses major challenges. In this regard, the current development status of cellulose materials was reviewed, covering the classification, preparation methods, and application status of cellulose-based antimicrobial materials. The application value of cellulose-based antimicrobial materials in biomedicine, textiles, food packaging, cosmetics and wastewater treatment was summarised. Finally, insights were provided into the developing prospects of cellulose-based antimicrobial materials were provided.

Amoxicillin-laded sodium alginate/cellulose nanocrystals/polyvinyl alcohol composite nanonetwork sponges with enhanced wound healing and antibacterial performance

Wound healing is a complex process and reuires a long repair process. Poor healing effect is normally a challenge for wound healing. Designing sponge dressings with drug-assisted therapy, good breathability, and multiple functional structures effectively promotes wound healing. In this work, a flexible amoxicillin-laded (AMX) sodium alginate (SA)/cellulose nanocrystals (CNCS)/ polyvinyl alcoho (PVA) (SA/CNCS/PVA-AMX, SCP-AMX) wound dressing was designed and built with an excellent porous structure, suitable porosity, and anti-bacterial properties for promoting wound tissue reparation. The porous structure of the wound dressing was fabricated by freeze-thawing cyclic and freeze-dried molding process. This wound dressing exhibited a 3D porous structure for soft-tissue-engineering application, including high porosity (84.2 %), swelling ratio (1513 %), tensile strength (1.79 MPA), and flexibility. With the inhibition zones of Escherichia Coli (E. coli) and Staphylococcus Aureus (S, Aureus) being 1.96 and4.58 cm, respectively, this wound dressing demonstrated good antibacterial activity against E. coli and S. aureus. More importantly, wound healing Assay in vivo indicates that SCP-AMX could inhibit wound infection, promote collagen deposition, reduce inflammation, and accelerate granulation tissue and wound healing. Thus, the reported wounding dressings present excellent biocompatibility, high antibacterial activities, and excellent biosafety with great potential in wound healing applications.

A chitosan-based hydrogel loaded with fenofibrate for diabetic wound healing

Diabetic wounds represent a common chronic condition, posing significant challenges in the treatment process due to bacterial infections, increased generation of reactive oxygen species (ROS) and exacerbated inflammation. Fenofibrate (FEN) is a clinical medication used for lipid regulation. In this study, it was utilized for the first time as an effective component of wound dressings for treating diabetic ulcers, exploring its novel applications further. Therefore, we prepared a polyvinyl alcohol/chitosan/FEN (PCF) hydrogel using a freeze-thaw method and conducted physicochemical characterization of the PCF hydrogel to further elucidate its biological functions. In vitro studies demonstrated that the PCF hydrogel exhibits excellent biocompatibility along with significant antimicrobial, pro-angiogenic, ROS-scavenging, and anti-inflammatory properties. Subsequent animal experiments indicated that the PCF hydrogel has the ability to promote blood vessel formation and collagen deposition. Additionally, the PCF hydrogel showed a significant inhibitory effect on the inflammatory response, as evidenced by the reductions in the levels of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). These compelling findings accentuate the promising application of the PCF hydrogel in the treatment of diabetic wounds.

Electrospun polysuccinimide scaffolds containing different salts as potential wound dressing material

In this research, we applied electrospinning to create a two-component biodegradable polymeric scaffold containing polysuccinimide (PSI) and antibacterial salts. Antibacterial agents for therapeutical purposes mostly contain silver ions which are associated with high environmental impact and, in some cases, may cause undesired immune reactions. In our work, we prepared nanofibrous systems containing antibacterial and tissue-regenerating salts of zinc acetate or strontium nitrate in different concentrations, whose structures may be suitable for developing biomedical wound dressing systems in the future. Several experiments have been conducted to optimize the physicochemical, mechanical, and biological properties of the scaffolds developed for application as wound dressings. The scaffold systems obtained by PSI synthesis, salt addition, and fiber formation were first investigated by scanning electron microscopy. In almost all cases, different salts caused a decrease in the fiber diameter of PSI polymer-based systems (<500 nm). Fourier-transform infrared spectroscopy was applied to verify the presence of salts in the scaffolds and to determine the interaction between the salt and the polymer. Another analysis, energy-dispersive X-ray spectroscopy, was carried out to determine strontium and zinc atoms in the scaffolds. Our result showed that the salts influence the mechanical properties of the polymer scaffold, both in terms of specific load capacity and relative elongation values. According to the dissolution experiments, the whole amount of strontium nitrate was dissolved from the scaffold in 8 h; however, only 50% of the zinc acetate was dissolved. In addition, antibacterial activity tests were performed with four different bacterial strains relevant to skin surface injuries, leading to the appearance of inhibition zones around the scaffold discs in most cases. We also investigated the potential cytotoxicity of the scaffolds on human tumorous and healthy cells. Except for the ones containing zinc acetate salt, the scaffolds are not cytotoxic to either tumor or healthy cells.

Janus Flexible Device with Microcone Channels for Sampling and Analysis of Biological Microfluidics

Controlling the spontaneous directional transport of droplets plays an important role in the application of microchemical reactions and microdroplet detection. Although the relevant technologies have been widely studied, the existing spontaneous droplet transport strategies still face problems of complex structure, single function, and poor flexibility. Inspired by the spontaneous droplet transport strategy in nature, an asymmetric wettability surface with microcone channels (AWS-MC) is prepared on a flexible fabric by combining surface modification and femtosecond laser manufacturing technology. On this surface, the capillary force and Laplace pressure induced by the wettability gradient and the geometric structure gradient drive the droplet transport from the hydrophobic surface to the hydrophilic surface. Notably, droplets in adjacent hydrophilic regions do not exchange substances even if the gap in the hydrophilic region is only 1 mm, which provides an ideal platform for numerous detections by a single drop. The droplet transport strategy does not require external energy and can adapt to the manipulation of various droplet types. Application of this surface in the blood of organisms is demonstrated. This work provides an effective method for microdroplet-directed self-transport and microdroplet detection.

Fabrication of a modified bacterial cellulose with different alkyl chains and its prevention of abdominal adhesion

Abdominal hernia mesh is a common product which is used for prevention of abdominal adhesion and repairing abdominal wall defect. Currently, designing and preparing a novel bio-mesh material with prevention of adhesion, promoting repair and good biocompatibility simultaneously remain a great bottleneck. In this study, a novel siloxane-modified bacterial cellulose (BC) was designed and fabricated by chemical vapor deposition silylation, then the effects of different alkyl chains length of siloxane on surface properties and cell behaviors were explored. The effect of preventing of abdominal adhesion and repairing abdominal wall defect in rats with the siloxane-modified BC was evaluated. As the grafted alkyl chains become longer, the surface of the siloxane-modified BC can be transformed from super hydrophilic to hydrophobic. In vivo results showed that BC-C16 had good long-term anti-adhesion effect, good tissue adaptability and histocompatibility, which is expected to be used as a new anti-adhesion hernia repair material in clinic.

Covalently grafting polycation to bacterial cellulose for antibacterial and anti-cell adhesive wound dressings

Hydrogel-based wound dressings are becoming increasingly important for wound healing. Bacterial cellulose (BC) has been commonly used as wound dressings due to its good in vitro and in vivo biocompatibility. However, pure BC does not possess antibacterial properties. In this regard, polycation gel was grafted onto the BC using a surface-initiated activator regenerated by electron transfer atom transfer radical polymerization (SI-ARGET ATRP) with subsequent quaternization for antibacterial wound dressing. Dimethylethyl methacrylate (DMAEMA) was successfully polymerized on the BC surface which was confirmed by Fourier transform infrared spectroscopy and elemental analysis. The morphology structure, specific surface area, pore size, and mechanical properties were also characterized. The quaternized PDMAEMA grafted on the BC endowed it with excellent antibacterial activity against E. coli (Gram-negative) and S. aureus (Gram-positive) with a killing rate of 89.2 % and 93.4 %, respectively. The number of cells was significantly reduced on QPD/BC hydrogel, demonstrating its good anti-adhesion ability. In vitro cellular evaluation revealed that the antibacterial wound dressing exhibited good biocompatibility. Overall, this study provides a feasible method to develop antibacterial and anti-cell adhesive hydrogel, which has a promising potential for wound healing.

In situ densification and heparin immobilization of bacterial cellulose vascular patch for potential vascular applications

Nowadays, developing vascular grafts (e.g., vascular patches and tubular grafts) is challenging. Bacterial cellulose (BC) with 3D fibrous network has been widely investigated for vascular applications. In this work, different from BC vascular patch cultured with the routine culture medium, dopamine (DA)-containing culture medium is employed to in situ synthesize dense BC fibrous structure with significantly increased fiber diameter and density. Simultaneously, BC fibers are modified by DA during in situ synthesis process. Then DA on BC fibers can self-polymerize into polydopamine (PDA) accompanied with the removal of bacteria in NaOH solution, obtaining PDA-modified dense BC (PDBC) vascular patch. Heparin (Hep) is subsequently covalently immobilized on PDBC fibers to form Hep-immobilized PDBC (Hep@PDBC) vascular patch. The obtained results indicate that Hep@PDBC vascular patch exhibits remarkable tensile and burst strength due to its dense fibrous structure. More importantly, compared with BC and PDBC vascular patches, Hep@PDBC vascular patch not only displays reduced platelet adhesion and improved anticoagulation activity, but also promotes the proliferation, adhesion, spreading, and protein expression of human umbilical vein endothelial cells, contributing to the endothelialization process. The combined strategy of in situ densification and Hep immobilization provides a feasible guidance for the construction of BC-based vascular patches.

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.

Infection induced inflammation impairs wound healing through IL-1β signaling

Wound healing is impaired by infection; however, how microbe-induced inflammation modulates tissue repair remains unclear. We took advantage of the optical transparency of zebrafish and a genetically tractable microbe, Listeria monocytogenes, to probe the role of infection and inflammation in wound healing. Infection with bacteria engineered to activate the inflammasome, Lm-Pyro, induced persistent inflammation and impaired healing despite low bacterial burden. Inflammatory infections induced il1b expression and blocking IL-1R signaling partially rescued wound healing in the presence of persistent infection. We found a critical window of microbial clearance necessary to limit persistent inflammation and enable efficient wound repair. Taken together, our findings suggest that the dynamics of microbe-induced tissue inflammation impacts repair in complex tissue damage independent of bacterial load, with a critical early window for efficient tissue repair.

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.

Keratin-containing scaffolds for tissue engineering applications: a review

In tissue engineering and regenerative medicine applications, the utilization of bioactive materials has become a routine tool. The goal of tissue engineering is to create new organs and tissues by combining cell biology, materials science, reactor engineering, and clinical research. As part of the growth pattern for primary cells in an organ, backing material is frequently used as a supporting material. A porous three-dimensional (3D) scaffold can provide cells with optimal conditions for proliferating, migrating, differentiating, and functioning as a framework. Optimizing the scaffolds' structure and altering their surface may improve cell adhesion and proliferation. A keratin-based biomaterials platform has been developed as a result of discoveries made over the past century in the extraction, purification, and characterization of keratin proteins from hair and wool fibers. Biocompatibility, biodegradability, intrinsic biological activity, and cellular binding motifs make keratin an attractive biomaterial for tissue engineering scaffolds. Scaffolds for tissue engineering have been developed from extracted keratin proteins because of their capacity to self-assemble and polymerize into intricate 3D structures. In this review article, applications of keratin-based scaffolds in different tissues including bone, skin, nerve, and vascular are explained based on common methods of fabrication such as electrospinning, freeze-drying process, and sponge replication method.

Functionalization of bacterial cellulose: Exploring diverse applications and biomedical innovations: A review

The demand for the functionalization of additive materials based on bacterial cellulose (BC) is currently high due to their potential applications across various sectors. The preparation of BC-based additive materials typically involves two approaches: in situ and ex situ. In situ modifications entail the incorporation of additive materials, such as soluble and dispersed substances, which are non-toxic and not essential for bacterial cell growth during the production process. However, these materials can impact the yield and self-assembly of BC. In contrast, ex situ modification occurs subsequent to the formation of BC, where the additive materials are not only adsorbed on the surface but also impregnated into the BC pellicle, while the BC slurry was homogenized with other additive materials and gelling agents to create composite films using the casting method. This review will primarily focus on the in situ and ex situ functionalization of BC then sheds light on the pivotal role of functionalized BC in advancing biomedical technologies, wound healing, tissue engineering, drug delivery, bone regeneration, and biosensors.

A review of the current state of natural biomaterials in wound healing applications

Skin, the largest biological organ, consists of three main parts: the epidermis, dermis, and subcutaneous tissue. Wounds are abnormal wounds in various forms, such as lacerations, burns, chronic wounds, diabetic wounds, acute wounds, and fractures. The wound healing process is dynamic, complex, and lengthy in four stages involving cells, macrophages, and growth factors. Wound dressing refers to a substance that covers the surface of a wound to prevent infection and secondary damage. Biomaterials applied in wound management have advanced significantly. Natural biomaterials are increasingly used due to their advantages including biomimicry of ECM, convenient accessibility, and involvement in native wound healing. However, there are still limitations such as low mechanical properties and expensive extraction methods. Therefore, their combination with synthetic biomaterials and/or adding bioactive agents has become an option for researchers in this field. In the present study, the stages of natural wound healing and the effect of biomaterials on its direction, type, and level will be investigated. Then, different types of polysaccharides and proteins were selected as desirable natural biomaterials, polymers as synthetic biomaterials with variable and suitable properties, and bioactive agents as effective additives. In the following, the structure of selected biomaterials, their extraction and production methods, their participation in wound healing, and quality control techniques of biomaterials-based wound dressings will be discussed.

MXene-based polysaccharide aerogel with multifunctional enduring antimicrobial effects for infected wound healing

Wound infection is a predominant etiological factor contributing to delayed wound healing in open wounds. Hence, it holds paramount clinical significance to devise wound dressings endowed with superior antibacterial properties. In this study, a Schiff base-crosslinked aerogel comprising sodium alginate oxide (OSA), carboxymethyl chitosan (CMCS), and Nb2C@Ag/PDA (NAP) was developed. The resultant OSA/CMCS-Nb2C@Ag/PDA (OC/NAP) composite aerogel exhibited commendable attributes including exceptional swelling characteristics, porosity, biocompatibility, and sustained antimicrobial efficacy. In vitro antimicrobial assays unequivocally demonstrated that the OC/NAP composite aerogel maintained nearly 100 % inhibition of Staphylococcus aureus and Escherichia coli under an 808 nm laser even after 25 h. Crucially, the outcomes of in vivo infected wound healing experiments demonstrated that the wound healing rate of the OC/NAP composite aerogel group reached approximately 100 % within a span of 14 days, which was significantly greater than that of the blank control group. In vitro and in vivo hemostatic experiments also revealed that the composite aerogel had excellent hemostatic properties. The results of this study demonstrate the remarkable potential of OC/NAP aerogel as a multifunctional clinical wound dressing, especially for infected wounds.

Bacterial Cellulose Applied in Wound Dressing Materials: Production and Functional Modification - A Review

In recent years, the development of new type wound dressings has gradually attracted more attention. Bacterial cellulose (BC) is a natural polymer material with various unique properties, such as ultrafine 3D nanonetwork structure, high water retention capacity, and biocompatibility. These properties allow BC to be used independently or in combination with different components (such as biopolymers and nanoparticles) to achieve diverse effects. This means that BC has great potential as a wound dressing. However, systematic summaries for the production and commercial application of BC-based wound dressings are still lacking. Therefore, this review provides a detailed introduction to the production fermentation process of BC, including various production strains and their biosynthetic mechanisms. Subsequently, with regard to the functional deficiencies of bacterial cellulose as a wound dressing, recent research progress in this area is enumerated. Finally, prospects are discussed for the low-cost production and high-value-added product development of BC-based wound dressings.

An Erythrocyte-Templated Iron Single-Atom Nanozyme for Wound Healing

Iron single-atom nanozymes represent a promising artificial enzyme with superior activity owing to uniform active sites that can precisely mimic active center of nature enzymes. However, current synthetic strategies are hard to guarantee each active site at single-atom state. In this work, an erythrocyte-templated strategy by utilizing intrinsic hemin active center of hemoglobin as sing-atom source for nanozyme formation is developed. By combining cell fixation, porous salinization, and high-temperature carbonization, erythrocytes are successfully served as uniform templates to synthesize nanozymes with fully single-atom FeN4 active sites which derived from hemin of hemoglobin, resulting in an enhanced peroxidase (POD)-like activity. Interestingly, the catalytic activity of erythrocyte-templated nanozyme (ETN) shows dependence on animal species, among which murine ETN performed superior catalytic efficiency. In addition, the as-prepared ETNs display a honeycomb-like network structure, serving as a sponge to accelerate hemostasis based on the interactions with prothrombin and fibrinogen. These features enable ETN to effectively kill methicillin-resistant Staphylococcus aureus (MRSA) by combining POD-like catalysis with near-infrared (NIR) induced photothermal effect, and subsequently suitable to promote wound healing. This study provides a proof-of-concept for facile fabrication of multifunctional nanozymes with uniform single-atom active sites by utilizing intrinsic iron structure characteristics of biogenic source like erythrocytes.

Establishment of bone-targeted nano-platform and the study of its combination with 2-deoxy-d-glucose enhanced photodynamic therapy to inhibit bone metastasis

At present, simple anti-tumor drugs are ineffective at targeting bone tissue and are not purposed to treat patients with bone metastasis. In this study, zoledronic acid (ZOL) demonstrated excellent bone-targeting properties as a bone-targeting ligand. The metal-organic framework (MOF) known as ZIF-90 was modified with ZOL to construct a bone-targeting-based drug delivery system. Chlorin e6 (Ce6) was loaded in the bone-targeted drug delivery system and combined with 2-deoxy-D-glucose (2-DG), which successfully treated bone tumors when enhanced photodynamic therapy was applied. The Ce6@ZIF-PEG-ZOL (Ce6@ZPZ) nanoparticles were observed to have uniform morphology, a particle size of approximately 210 nm, and a potential of approximately -30.4 mV. The results of the bone-targeting experiments showed that Ce6@ZPZ exhibited a superior bone-targeted effect when compared to Ce6@ZIF-90-PEG. The Ce6@ZPZ solution was subjected to 660 nm irradiation and the resulting production of reactive oxygen species increased over time, which could be further increased when Ce6@ZPZ was used in combination with 2-DG. Their combination had a stronger inhibitory capacity against tumor cells than either 2-DG or Ce6@ZPZ alone, increasing the rate of tumor cell apoptosis. The apoptosis rate caused by HGC-27 was 61.56% when 2-DG was combined with Ce6@ZPZ. In vivo results also showed that Ce6@ZPZ combined with 2-DG maximally inhibited tumor growth and prolonged mice survival compared to the other experimental groups. Therefore, the combination of PDT and glycolytic inhibitors serves as a potential option for the treatment of cancer.

Fabrication and characterization of new levan@CBD biocomposite sponges as potential materials in natural, non-toxic wound dressing applications

Wound healing is a complex process; therefore, new dressings are frequently required to facilitate it. In this study, porous bacterial levan-based sponges containing cannabis oil (Lev@CBDs) were prepared and fully characterized. The sponges exhibited a suitable swelling ratio, proper water vapor transmission rate, sufficient thermal stability, desired mechanical properties, and good antioxidant and anti-inflammatory properties. The obtained Lev@CBD materials were evaluated in terms of their interaction with proteins, human serum albumin and fibrinogen, of which fibrinogen revealed the highest binding effect. Moreover, the obtained biomaterials exhibited antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, as well as being non-hemolytic material as indicated by hemolysis tests. Furthermore, the sponges were non-toxic and compatible with L929 mouse fibroblasts and HDF cells. Most significantly, the levan sponge with the highest content of cannabis oil, in comparison to others, retained its non-hemolytic, anti-inflammatory, and antimicrobial properties after prolonged storage in a climate chamber at a constant temperature and relative humidity. The designed sponges have conclusively proven their beneficial physicochemical properties and, at the preliminary stage, biocompatibility as well, and therefore can be considered a promising material for wound dressings in future in vivo applications.

Adhesive injectable cellulose-based hydrogels with rapid self-healing and sustained drug release capability for promoting wound healing

Injectable biocompatible hydrogels with multiple functions, including self-healing, adhesion, antibacterial activity, and suitable mechanical properties, are highly desirable for enhancing wound healing. In this study, a new class of multi-functional injectable self-healing cellulose-based hydrogels was synthesised using dynamic covalent acylhydrazone linkages for wound dressing. The carboxymethyl cellulose-graft-adipic dihydrazide (CMC-ADH)/4-Formylbenzoic acid-terminated poly(ethylene glycol) (PEG-FBA) (CMC-ADH/PEG-FBA) hydrogels have adjustable gelation time and excellent self-healing ability. In addition, drug release and in vitro antibacterial activities against Gram-positive and Gram-negative bacteria confirmed the sustained drug-release capacity of the hydrogels. Moreover, haemostasis and wound-healing effects were investigated using an in vivo haemorrhaging liver mouse model and a full-thickness skin defect model, and the results indicated that they not only promoted the wound-healing process but also presented excellent haemostatic effects. The CMC-ADH/PEG-FBA gels also exhibited good adhesion to irregular wounds and significantly enhanced angiogenic ability in vivo. This excellent wound-healing performance occurs because hydrogels can quickly stop bleeding, provide a moist and closed environment for the wound to prevent bacterial invasion, release ciprofloxacin (CIP), reduce inflammatory reactions, and promote wound tissue regeneration. In summary, the synthesised multi-functional gels are ideal candidates for treating haemorrhages and irregular wounds.

Multifunctional Asymmetric Bacterial Cellulose Membrane with Enhanced Anti-Bacterial and Anti-Inflammatory Activities for Promoting Infected Wound Healing

An asymmetric wound dressing acts as a skin-like structure serves as a protective barrier between a wound and its surroundings. It allows for the absorption of tissue fluids and the release of active substances at the wound site, thus speeding up the healing process. However, the production of such wound dressings requires the acquisition of specialized tools, expensive polymers, and solvents that contain harmful byproducts. In this study, an asymmetric bacterial cellulose (ABC) wound dressing using starch as a porogen has been developed. By incorporating silver-metal organic frameworks (Ag-MOF) and curcumin into the ABC membrane, the wound dressing gains antioxidant, reactive oxygen species (ROS) scavenging, and anti-bacterial activities. Compared to BC-based wound dressings, this dressing promotes efficient dissolution and controlled release of curcumin and silver ions. In a full-thickness skin defect model, wound dressing not only inhibits the growth of bacteria on infected wounds but also regulates the release of curcumin to reduce inflammation and promote the production of epithelium, blood vessels, and collagen. Consequently, this dressing provides superior wound treatment compared to BC-based dressing.

Tailored biomedical materials for wound healing

Wound healing is a long-term, multi-stage biological process that mainly includes haemostatic, inflammatory, proliferative and tissue remodelling phases. Controlling infection and inflammation and promoting tissue regeneration can contribute well to wound healing. Smart biomaterials offer significant advantages in wound healing because of their ability to control wound healing in time and space. Understanding how biomaterials are designed for different stages of wound healing will facilitate future personalized material tailoring for different wounds, making them beneficial for wound therapy. This review summarizes the design approaches of biomaterials in the field of anti-inflammatory, antimicrobial and tissue regeneration, highlights the advanced precise control achieved by biomaterials in different stages of wound healing and outlines the clinical and practical applications of biomaterials in wound healing.

Asymmetric fabrication and in vivo evaluation of the wound healing potency of electrospun biomimetic nanofibrous scaffolds based on collagen crosslinked modified-chitosan and graphene oxide quantum dot nanocomposites

Asymmetric scaffolds were developed through electrospinning by utilizing biocompatible materials for effective wound healing applications. First of all, the chitosan surface was modified with decanoyl chloride and crosslinked with collagen to synthesize collagen crosslinked modified-chitosan (CG-cross-CS-g-Dc). Then, the asymmetric scaffolds were fabricated through electrospinning, where the top layer was a monoaxial nanofiber of the PCL/graphene oxide quantum dot (GOQD) nanocomposite and the bottom layer was a coaxial nanofiber having PCL in the core and the CG-cross-CS-g-Dc/GOQD nanocomposite in the shell layer. The formation of monoaxial (∼130 ± 50 nm) and coaxial (∼320 ± 40 nm) nanofibers was confirmed by transmission electron microscopy (TEM). The presence of GOQDs contributed to antioxidant and antimicrobial efficacy. These scaffolds showed substantial antibacterial activity against the common wound pathogens Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The scaffolds exhibited excellent cytocompatibility (MTT assay) and anti-inflammatory behaviour as analysed via the cytokine assay and biochemical analysis. The in vivo wound healing potential of the nanofibrous scaffolds was assessed with full-thickness excisional wounds in a rat model. The scaffolds accelerated the re-epithelialization as well as the collagen deposition, thereby facilitating the wound healing process in a very short span of time (10 days). Both in vitro and in vivo analyses thus provide a compelling argument for the use of these scaffolds as therapeutic biomaterials and their suitability for application in rapid wound regeneration and repair.

Current advances of nanocellulose application in biomedical field

Nanocellulose (NC) is a natural fiber that can be extracted in fibrils or crystals form from different natural sources, including plants, bacteria, and algae. In recent years, nanocellulose has emerged as a sustainable biomaterial for various medicinal applications including drug delivery systems, wound healing, tissue engineering, and antimicrobial treatment due to its biocompatibility, low cytotoxicity, and exceptional water holding capacity for cell immobilization. Many antimicrobial products can be produced due to the chemical functionality of nanocellulose, such disposable antibacterial smart masks for healthcare use. This article discusses comprehensively three types of nanocellulose: cellulose nanocrystals (CNC), cellulose nanofibrils (CNF), and bacterial nanocellulose (BNC) in view of their structural and functional properties, extraction methods, and the distinctive biomedical applications based on the recently published work. On top of that, the biosafety profile and the future perspectives of nanocellulose-based biomaterials have been further discussed in this review.

Polysaccharide based transdermal patches for chronic wound healing: Recent advances and clinical perspective

Polysaccharides form a major class of natural polymers with diverse applications in biomedical science and tissue engineering. One of the key thrust areas for polysaccharide materials is skin tissue engineering and regeneration, whose market is estimated to reach around 31 billion USD globally by 2030, with a compounded annual growth rate of 10.46 %. Out of this, chronic wound healing and management is a major concern, especially for underdeveloped and developing nations, mainly due to poor access to medical interventions for such societies. Polysaccharide materials have shown promising results and clinical potential in recent decades with regard to chronic wound healing. Their low cost, ease of fabrication, biodegradability, and ability to form hydrogels make them ideal candidates for managing and healing such difficult-to-heal wounds. The present review presents a summary of the recently explored polysaccharide-based transdermal patches for managing and healing chronic wounds. Their efficacy and potency of healing both as active and passive wound dressings are evaluated in several in-vitro and in-vivo models. Finally, their clinical performances and future challenges are summarized to draw a road map towards their role in advanced wound care.

Bacterial-Nanocellulose-Based Biointerfaces and Biomimetic Constructs for Blood-Contacting Medical Applications

Understanding the interaction between biomaterials and blood is critical in the design of novel biomaterials for use in biomedical applications. Depending on the application, biomaterials can be designed to promote hemostasis, slow or stop bleeding in an internal or external wound, or prevent thrombosis for use in permanent or temporary medical implants. Bacterial nanocellulose (BNC) is a natural, biocompatible biopolymer that has recently gained interest for its potential use in blood-contacting biomedical applications (e.g., artificial vascular grafts), due to its high porosity, shapeability, and tissue-like properties. To promote hemostasis, BNC has been modified through oxidation or functionalization with various peptides, proteins, polysaccharides, and minerals that interact with the coagulation cascade. For use as an artificial vascular graft or to promote vascularization, BNC has been extensively researched, with studies investigating different modification techniques to enhance endothelialization such as functionalizing with adhesion peptides or extracellular matrix (ECM) proteins as well as tuning the structural properties of BNC such as surface roughness, pore size, and fiber size. While BNC inherently exhibits comparable mechanical characteristics to endogenous blood vessels, these mechanical properties can be enhanced through chemical functionalization or through altering the fabrication method. In this review, we provide a comprehensive overview of the various modification techniques that have been implemented to enhance the suitability of BNC for blood-contacting biomedical applications and different testing techniques that can be applied to evaluate their performance. Initially, we focused on the modification techniques that have been applied to BNC for hemostatic applications. Subsequently, we outline the different methods used for the production of BNC-based artificial vascular grafts and to generate vasculature in tissue engineered constructs. This sequential organization enables a clear and concise discussion of the various modifications of BNC for different blood-contacting biomedical applications and highlights the diverse and versatile nature of BNC as a natural biomaterial.

Progress of Hydrogel Dressings with Wound Monitoring and Treatment Functions

Hydrogels are widely used in wound dressings due to their moisturizing properties and biocompatibility. However, traditional hydrogel dressings cannot monitor wounds and provide accurate treatment. Recent advancements focus on hydrogel dressings with integrated monitoring and treatment functions, using sensors or intelligent materials to detect changes in the wound microenvironment. These dressings enable responsive treatment to promote wound healing. They can carry out responsive dynamic treatment in time to effectively promote wound healing. However, there is still a lack of comprehensive reviews of hydrogel wound dressings that incorporate both wound micro-environment monitoring and treatment functions. Therefore, this review categorizes hydrogel dressings according to wound types and examines their current status, progress, challenges, and future trends. It discusses various wound types, including infected wounds, burns, and diabetic and pressure ulcers, and explores the wound healing process. The review presents hydrogel dressings that monitor wound conditions and provide tailored treatment, such as pH-sensitive, temperature-sensitive, glucose-sensitive, pressure-sensitive, and nano-composite hydrogel dressings. Challenges include developing dressings that meet the standards of excellent biocompatibility, improving monitoring accuracy and sensitivity, and overcoming obstacles to production and commercialization. Furthermore, it provides the current status, progress, challenges, and future trends in this field, aiming to give a clear view of its past, present, and future.

The biosynthesis of amidated bacterial cellulose derivatives via in-situ strategy

Bacterial cellulose, as a kind of natural biopolymer produced by bacterial fermentation, has attracted wide attention owing its unique physical and chemical properties. Nevertheless, the single functional group on the surface of BC greatly hinders its wider application. The functionalization of BC is of great significance to broaden the application of BC. In this work, N-acetylated bacterial cellulose (ABC) was successfully prepared using K. nataicola RZS01-based direct synthetic method. FT-IR, NMR and XPS confirmed the in-situ modification of BC by acetylation. The SEM and XRD results demonstrated that ABC has a lower crystallinity and higher fiber width compare with pristine 88 BCE % cell viability on NIH-3 T3 cell and near zero hemolysis ratio indicate its good biocompatibility. In addition, the as-prepared acetyl amine modified BC was further treated by nitrifying bacteria to enrich its functionalized diversity. This study provides a mild in-situ pathway to construct BC derivatives in an environmentally friendly way during its metabolism.

Corn stalk modified chitin composite sponge for effective hemostasis and promoting wound healing

The hemorrhage in daily life was a great challenge for the life health. Before hospitalization and infection, stopping traumatic bleeding timely is an important measure to decrease the death threat. The high crystallinity and low porous structure of chitin (CH) make texture of sole CH sponge not soft enough, which limit its hemostatic properties. In this work, loose corn stalk (CS) was used to modify the structures and properties of sole CH sponge. The novel hemostatic composite sponge of CH/CS4 was prepared by cross-linking and freeze-drying process of chitin and corn stalk suspension. The composite sponge obtained best physical and hemostatic properties at the 1:1 volume ratio of chitin and corn stalk. Thanks to the porous structures, CH/CS4 possessed high water/blood absorption ability (34 ± 2 g/g and 32.7 ± 2 g/g), rapid hemostatic time (31 s) and low blood loss (0.31 g), allowing it to be delivered into the wound bleeding sites to reduce the wound bleeding by robust physical barrier and pressure effect. Furthermore, CH/CS4 displayed excellent hemostatic performance than sole CH and commercial polyvinyl fluoride sponge (PVF). Moreover, CH/CS4 displayed superior wound healing ability and cytocompatibility. Therefore, the CH/CS4 has high potential application in medical hemostatic field.

Biodegradable Polymers and Polymer Composites with Antibacterial Properties

Antibiotic resistance is one of the greatest threats to global health and food security today. It becomes increasingly difficult to treat infectious disorders because antibiotics, even the newest ones, are becoming less and less effective. One of the ways taken in the Global Plan of Action announced at the World Health Assembly in May 2015 is to ensure the prevention and treatment of infectious diseases. In order to do so, attempts are made to develop new antimicrobial therapeutics, including biomaterials with antibacterial activity, such as polycationic polymers, polypeptides, and polymeric systems, to provide non-antibiotic therapeutic agents, such as selected biologically active nanoparticles and chemical compounds. Another key issue is preventing food from contamination by developing antibacterial packaging materials, particularly based on degradable polymers and biocomposites. This review, in a cross-sectional way, describes the most significant research activities conducted in recent years in the field of the development of polymeric materials and polymer composites with antibacterial properties. We particularly focus on natural polymers, i.e., polysaccharides and polypeptides, which present a mechanism for combating many highly pathogenic microorganisms. We also attempt to use this knowledge to obtain synthetic polymers with similar antibacterial activity.

Multifunctional Bletilla striata polysaccharide/copper/peony leaf sponge for the full-stage wound healing

Conventional wound dressings fail to satisfy the requirements and needs of wounds in various stages. It is challenging to develop a multifunctional dressing that is hemostatic, antibacterial, anti-inflammatory, and promotes wound healing. Therefore, this study aimed to develop a multifunctional sponge dressing for the full-stage wound healing based on copper and two natural products, Bletilla striata polysaccharide (BSP) and peony leaf extract (PLE). The developed BSP-Cu-PLE sponges were characterized by SEM, XRD, FTIR, and XPS to assess micromorphology and elemental composition. Their properties and bioactivities were also verified by the further experiments, whereby the findings revealed that the BSP-Cu-PLE sponges had improved water absorption and porosity while exhibiting excellent antioxidative, biocompatible, and biodegradable properties. Moreover, the antibacterial test revealed that BSP-Cu-PLE sponges had superior antibacterial activity against S. aureus and E. coli. Furthermore, the hemostatic activity of BSP-Cu-PLE sponges was significantly enhanced in a rat liver trauma model. Most notably, further studies have demonstrated that the BSP-Cu-PLE sponges could significantly (p < 0.05) accelerate the healing process of skin wounds by stimulating collagen deposition, promoting angiogenesis, and decreasing inflammatory cells. In summary, the BSP-Cu-PLE sponges could provide a new strategy for application in clinical setting for full-stage wound healing.

Mussel-Inspired Multifunctional Hydrogels with Adhesive, Self-Healing, Antioxidative, and Antibacterial Activity for Wound Healing

Antibacterial hydrogel wound dressings with adhesive and antioxidant activity are desirable for treating skin injuries in clinical care. Hereby, a series of multifunctional hydrogel wound dressings with high adhesive, self-healing, antioxidant, and antibacterial activity were designed and fabricated using dopamine (DA) and quercetin (QT). The multifunctional hydrogels were constructed by the interpenetrated quaternized chitosan chain segments and polyacrylamide network. The catechol groups on DA, QT, and the quaternary ammonium groups in the hydrogel system endow hydrogels with high strength, excellent adhesion, and self-healing ability. The results confirmed the admirable hemocompatibility and remarkable antibacterial activity of the multifunction hydrogels against Staphylococcus aureus and Escherichia coli. Consequently, multifunction hydrogels with satisfactory adhesive and antibacterial activity are appropriate alternative materials in the fields of tissue adhesive and wound dressing applications.

Integrated photo-inspired antibacterial polyvinyl alcohol/carboxymethyl cellulose hydrogel dressings for pH real-time monitoring and accelerated wound healing

Recurrent infection of chronic wounds remains a major clinical challenge. Recently, the hydrogel antibacterial materials have attracted extensive attention for preventing infection in wound healing. In this study, a hybrid hydrogel made of polyvinyl alcohol - iodine (PAI), sodium carboxymethyl cellulose (CMC), and carbamino quantum dot (CQDs) was prepared by the cross-linking of hydrogen bonds, named as polyvinyl alcohol‑iodine/sodium carboxymethyl cellulose/carbon quantum dots (PAI/CMC/CQDs). The composite hydrogels exhibited the outstanding photothermal conversion efficiency with near infrared (NIR) light irradiation, and the high antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Meanwhile, the elevated temperature of the composite hydrogels up to ~45 °C was able to stimulate the migration of epidermal cell to accelerate skin repair. Given that PAI and CQDs could respond to different pH values (5-8), the real-time would pH information was provided by the visible light and fluorescent light dual monitoring system by naked eye. Moreover, the visible-fluorescent images could be collected and transformed into RGB signals to quantify the would pH levels, avoiding secondary injuries caused by frequent dressing changes. PAI/CMC/CQDs was demonstrated the significant therapeutic effect on chronic wounds by eliminating bacterial infections and promoting skin repair under the smart RGB monitoring system.

Highly hygroscopicity and antioxidant nanofibrous dressing base on alginate for accelerating wound healing

The removal of bacterium and free radicals is important for wound healing. Therefore, it is necessary to prepare biological dressings with antibacterial and antioxidant properties. In this study, high-performance calcium alginate/carbon polymer dots/forsythin composite nanofibrous membrane (CA/CPDs/FT) was explored under the influence of carbon polymer dots and forsythin. The addition of carbon polymer dots improved the nanofiber morphology and therefore enhanced the mechanical strength of the composite membrane. Moreover, CA/CPDs/FT membranes displayed satisfactory antibacterial and antioxidant properties because of the natural properties of forsythin. Meanwhile, outstanding hygroscopicity over 700% was also obtained for the composite membrane. In vitro and in vivo experiments showed that the CA/CPDs/FT nanofibrous membrane could prevent the invasion of bacteria, scavenge free radicals, and promote wound healing. Moreover, its good hygroscopicity and antioxidation characteristics were friendly for the clinical application of high-exudate wounds.

Application of TOPSIS algorithm in describing bacterial cellulose-based composite hydrogel performance in incorporating methylene blue as a model drug

A multi-component hydrogel was developed using bacterial cellulose, alginate, and gelatin with the aid of glycerol as trihydric alcohol which participates in re-distribution of hydrogen bonds in the test system. FTIR, XRD, SEM, and TGA as instrumental techniques were used to structurally characterize the physical/chemical properties of the formed composite hydrogel. By using an exponential equation, swelling behavior of the hydrogel was evaluated. By incorporating a model drug (methylene blue-MB) in the formed hydrogel, experiments were directed to study release characteristics of the MB where the medium solution for the release was prepared at four different pHs. The maximum cumulative drug release at pH 2.8, 6, 7.4, and 9 were 42.8, 63, 80, and 84.5%, respectively. Data fitting process was carried out using five kinetic models (Korsmeyer-Peppas, Higuchi, Hopfenberg, zero-order, and first-order equations) and the preferred kinetic model at each pH was estimated by applying TOPSIS algorithmic technique. The adsorption capacity of the hydrogel in relation to MB was determined while thermodynamic properties of this relationship were quantified ([Formula: see text] and [Formula: see text]). The results of the present study were in favor of the potential usage of the developed composite hydrogel in drug delivery systems.

Wound healing promotion by flaxseed extract-loaded polyvinyl alcohol/chitosan nanofibrous scaffolds

Impaired wound healing is a severe complication of sufferers, related to prolonged wound closure, a high infection rate, and eventually disabilities of organs. To aid resolve this issue, we developed the electrospun polyvinyl alcohol and chitosan (PVA/CS) nanofibrous scaffold-loaded flaxseed extract. The scaffold containing 10 wt% of the extract indicated a three-dimensional cross-network with a nano-scale diameter (257 ± 37 nm) and smooth surface. Also, the relevant analyses confirmed high water absorption, porosity, and wettability of the scaffold. Fourier-transform infrared (FTIR), degradation, and mechanical studies revealed the intact presence and loading of the extract into the scaffold, the complete degradation over 48 h, and a high tensile elastic modulus. Besides, the advanced scaffold displayed remarkable anti-oxidant and could inhibit the growth of both Gram-positive and negative bacteria compared to the free PVA/CS scaffold. Desired fibroblast viability and blood compatibility of flaxseed-loaded scaffold endorsed the biocompatibility for wound zones. The in vitro studies showed that the flaxseed-loaded scaffold resulted in an accelerated wound healing process and 100 % closure of the scratched area within 48 h. The results obtained reveal that the flaxseed-loaded PVA/CS electrospun scaffold could be effectively applied for wound healing promotion.

Hybrid gelatin-sulfated alginate scaffolds as dermal substitutes can dramatically accelerate healing of full-thickness diabetic wounds

Diabetic foot ulcers (DFUs) are defined as chronic and non-healing wounds that cause skin disorders. Here, we introduce a novel biodegradable gelatin/sulfated alginate hybrid scaffold as a dermal substitute to accelerate the healing of full-thickness diabetic ulcers in a diabetic mouse model. The hybrid scaffold possessing different weight ratios of sulfated alginate, from 10 % up to 50 %, were prepared through chemical crosslinking by carbodiimide chemistry and further freeze-drying. Based on the in vitro cytotoxicity experiments, the hybrid scaffolds not only showed no cytotoxicity, but the cell growth also dramatically increased by increasing the sulfated alginate content. Finally, the pathology of hybrid scaffolds as the dermal substitutes for healing of full-thickness diabetic wounds showed the more appropriate formation of epidermal layer, more homogeneous distribution of collagenous tissue and lower penetration of immune cells for the hybrid scaffolds-treated wounds.

Local Drug Delivery Strategies towards Wound Healing

A particular biological process known as wound healing is connected to the overall phenomena of growth and tissue regeneration. Several cellular and matrix elements work together to restore the integrity of injured tissue. The goal of the present review paper focused on the physiology of wound healing, medications used to treat wound healing, and local drug delivery systems for possible skin wound therapy. The capacity of the skin to heal a wound is the result of a highly intricate process that involves several different processes, such as vascular response, blood coagulation, fibrin network creation, re-epithelialisation, collagen maturation, and connective tissue remodelling. Wound healing may be controlled with topical antiseptics, topical antibiotics, herbal remedies, and cellular initiators. In order to effectively eradicate infections and shorten the healing process, contemporary antimicrobial treatments that include antibiotics or antiseptics must be investigated. A variety of delivery systems were described, including innovative delivery systems, hydrogels, microspheres, gold and silver nanoparticles, vesicles, emulsifying systems, nanofibres, artificial dressings, three-dimensional printed skin replacements, dendrimers and carbon nanotubes. It may be inferred that enhanced local delivery methods might be used to provide wound healing agents for faster healing of skin wounds.

Antibacterial Collagen-Based Nanocomposite Dressings for Promoting Infected Wound Healing

Pathogenic bacterial infection is the most frequent wound complication, which has become a major clinical and healthcare challenge in wound management worldwide, leading to impaired healing processes, the risk of amputation, and even death. Here, collagen-based nanocomposite dressings (APZC) with broad-spectrum antibacterial activity are developed to promote the infected full-thickness wound healing. Short rod-like shaped ZnO NPs are synthesized and then coated with polydopamine (PDA) to obtain PDA coated ZnO NPs (PDA@ZnO NPs). Afterward, PDA@ZnO NPs are conjugated on the backbone of a collagen chain, and the obtained collagen-PDA@ZnO NPs conjugate is crosslinked by dialdehyde sodium alginate to fabricate APZC dressings. PDA@ZnO NPs show well dispersibility and are uniformly incorporated into the collagen matrix. APZC dressings have interconnected microporous structure and great physicochemical properties, besides good blood coagulation performance and well cytocompatibility. APZC dressings demonstrate long-lasting and excellently broad-spectrum antimicrobial activity, which can relieve the inflammatory reaction by killing pathogenic bacteria and induce the generation of blood vessels and the orderly deposition of collagen in the wound site, thus promoting infected full-thickness wound healing without obvious scar formation. Overall, the functionalized collagen-based nanocomposite dressings have great potential in the clinical treatment against bacteria-associated wound infection.