Preparation of hydroxylated lecithin complexed iodine/carboxymethyl chitosan/sodium alginate composite membrane by microwave drying and its applications in infected burn wound treatment

Application of metal-organic framework materials in regenerative medicine

In the past few decades, scaffolds manufactured from composite or hybrid biomaterials of natural or synthetic origin have made great strides in enhancing wound healing and repairing fractures and pathological bone loss. However, the prevailing use of such scaffolds in tissue engineering is accompanied by numerous constraints, including low mechanical stability, poor biological activity, and impaired cell proliferation and differentiation. The performance of scaffolds in wound and bone tissue engineering may be enhanced by some modifications in the synthesis of nanoscale metal-organic framework (nano-MOF) scaffolds. Nano-MOFs have attracted researchers' attention in recent years due to their distinctive features, which include tenability, biocompatibility, good mechanical stability, and ultrahigh surface area. The biological properties of scaffolds are enhanced and tissue regeneration is facilitated by the introduction of nano-MOFs. Moreover, the physicochemical characteristics, drug loading, and ion release capacities of the scaffolds are improved by the nanoscale structure and topological features of nano-MOFs, which also control stem cell differentiation, proliferation, and attachment. This review provides further comprehensive detail about the most recent uses of nano-MOFs in tissue engineering. The distinct characteristics of nano-MOFs are explored in enhancing tissue repair, wound healing, osteoinduction, and bone conductivity. Significant attributes include high antibacterial activity, substantial drug-loading capacity, and the ability to regulate drug release. Finally, this discussion addresses the obstacles, clinical impediments, and considerations encountered in the application of these nanomaterials to diverse scaffolds, tissue-mimicking structures, dressings, fillers, and implants for bone tissue repair and wound healing.

Ganoderma lucidum polysaccharide hydrogel accelerates diabetic wound healing by regulating macrophage polarization

Impaired macrophage polarization or the high levels of reactive oxygen species (ROS) produced by high glucose conditions and bacterial infection are the primary factors that make healing diabetic wounds difficult. Here, we prepared an OGLP-CMC/SA hydrogel with a double network structure that was synthesized with oxidized Ganoderma lucidum polysaccharide (OGLP), sodium alginate (SA) and carboxymethyl chitosan (CMC) as the matrix. The results showed that the OGLP-CMC/SA hydrogel had good mechanical properties, tissue adhesion, oxidation resistance and biocompatibility. Moreover, the hydrogel could effectively improve the proliferation and migration of fibroblasts, also can enhance antibacterial properties. We found that the OGLP-CMC/SA hydrogel can promote the polarization of M1 macrophages towards the M2 and decrease intracellular ROS levels, effectively reduce the inflammatory response, and promote epidermal growth, the development of skin appendages and collagen deposition in wounds, which hasten diabetic wound healing. Therefore, using this versatile biologically active new hydrogel network constructed with OGLP provides a promising therapeutic strategy for chronic diabetic wound repair.

Chitosan‑iodine complexes: Preparation, characterization, and antibacterial activity

Bacterial infections have always been a major threat to public health, and the development of effective antibacterial substances from natural polymers is crucial. 2-Aminoisonicotinic acid (AN) was grafted onto chitosan by 1-ethyl-(3-dimethylaminopropyl)carbodiimide-mediated coupling reactions, and then modified chitosan‑iodine (CSAN-I) complexes were prepared by solvent-assisted grinding. The samples were characterized using ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, proton nuclear magnetic resonance spectroscopy, and X-ray diffraction, confirming that CSAN-I complexes had been successfully prepared. Thermogravimetric (TG) analysis indicated that the chemical modification of chitosan and iodine complexation reduced the thermal stability; X-ray photoelectron spectroscopy (XPS) analysis revealed that 81 % of the iodine in CSAN-I complex was in the form of triiodide ions. The iodine contents of three CSAN-I complexes (CSAN-I-1, CSAN-I-2 and CSAN-I-3) were 1.59 ± 0.22 %, 3.18 ± 0.26 %, and 5.56 ± 0.41 %, respectively. The antibacterial effects were evaluated in vitro, and the results indicated that CSAN-I complexes had strong antibacterial activities against both E. coli and S. aureus. In particular, CSAN-I-3 exhibited the best antibacterial effect. In addition, CSAN-I-3 was nontoxic to L929 cells with good cytocompatibility. Therefore, CSAN-I complexes can be considered as promising candidates for wound management in clinical applications.

Recent advances in chitosan-based materials; The synthesis, modifications and biomedical applications

The attention to polymer-based biomaterials, for instance, chitosan and its derivatives, as well as the techniques for using them in numerous scientific domains, is continuously rising. Chitosan is a decomposable naturally occurring polymeric material that is mostly obtained from seafood waste. Because of its special ecofriendly, biocompatible, non- toxic nature as well as antimicrobial properties, chitosan-based materials have received a lot of interest in the field of biomedical applications. The reactivity of chitosan is mainly because of the amino and hydroxyl groups in its composition, which makes it further fascinating for various uses, including biosensing, textile finishing, antimicrobial wound dressing, tissue engineering, bioimaging, gene, DNA and drug delivery and as a coating material for medical implants. This study is an overview of the different types of chitosan-based materials which now a days have been fabricated by applying different techniques and modifications that include etherification, esterification, crosslinking, graft copolymerization and o-acetylation etc. for hydroxyl groups' processes and acetylation, quaternization, Schiff's base reaction, and grafting for amino groups' reactions. Furthermore, this overview summarizes the literature from recent years related to the important applications of chitosan-based materials (i.e., thin films, nanocomposites or nanoparticles, sponges and hydrogels) in different biomedical applications.

Current application and modification strategy of marine polysaccharides in tissue regeneration: A review

Marine polysaccharides (MPs) are exceptional bioactive materials that possess unique biochemical mechanisms and pharmacological stability, making them ideal for various tissue engineering applications. Certain MPs, including agarose, alginate, carrageenan, chitosan, and glucan have been successfully employed as biological scaffolds in animal studies. As carriers of signaling molecules, scaffolds can enhance the adhesion, growth, and differentiation of somatic cells, thereby significantly improving the tissue regeneration process. However, the biological benefits of pure MPs composite scaffold are limited. Therefore, physical, chemical, enzyme modification and other methods are employed to expand its efficacy. Chemically, the structural properties of MPs scaffolds can be altered through modifications to functional groups or molecular weight reduction, thereby enhancing their biological activities. Physically, MPs hydrogels and sponges emulate the natural extracellular matrix, creating a more conducive environment for tissue repair. The porosity and high permeability of MPs membranes and nanomaterials expedite wound healing. This review explores the distinctive properties and applications of select MPs in tissue regeneration, highlighting their structural versatility and biological applicability. Additionally, we provide a brief overview of common modification strategies employed for MP scaffolds. In conclusion, MPs have significant potential and are expected to be a novel regenerative material for tissue engineering.

Alginate: Microbial production, functionalization, and biomedical applications

Alginates are natural polysaccharides widely participating in food, pharmaceutical, and environmental applications due to their excellent gelling capacity. Their excellent biocompatibility and biodegradability further extend their application to biomedical fields. The low consistency in molecular weight and composition of algae-based alginates may limit their performance in advanced biomedical applications. It makes microbial alginate production more attractive due to its potential for customizing alginate molecules with stable characteristics. Production costs remain the primary factor limiting the commercialization of microbial alginates. However, carbon-rich wastes from sugar, dairy, and biodiesel industries may serve as potential substitutes for pure sugars for microbial alginate production to reduce substrate costs. Fermentation parameter control and genetic engineering strategies may further improve the production efficiency and customize the molecular composition of microbial alginates. To meet the specific needs of biomedical applications, alginates may need functionalization, such as functional group modifications and crosslinking treatments, to achieve enhanced mechanical properties and biochemical activities. The development of alginate-based composites incorporated with other polysaccharides, gelatin, and bioactive factors can integrate the advantages of each component to meet multiple requirements in wound healing, drug delivery, and tissue engineering applications. This review provided a comprehensive insight into the sustainable production of high-value microbial alginates. It also discussed recent advances in alginate modification strategies and alginate-based composites for representative biomedical applications.

Alginate-Based Biomaterials in Tissue Engineering and Regenerative Medicine

Today, with the salient advancements of modern and smart technologies related to tissue engineering and regenerative medicine (TE-RM), the use of sustainable and biodegradable materials with biocompatibility and cost-effective advantages have been investigated more than before. Alginate as a naturally occurring anionic polymer can be obtained from brown seaweed to develop a wide variety of composites for TE, drug delivery, wound healing, and cancer therapy. This sustainable and renewable biomaterial displays several fascinating properties such as high biocompatibility, low toxicity, cost-effectiveness, and mild gelation by inserting divalent cations (e.g., Ca2+). In this context, challenges still exist in relation to the low solubility and high viscosity of high-molecular weight alginate, high density of intra- and inter-molecular hydrogen bonding, polyelectrolyte nature of the aqueous solution, and a lack of suitable organic solvents. Herein, TE-RM applications of alginate-based materials are deliberated, focusing on current trends, important challenges, and future prospects.

Development of an Fe3O4 Surface-Grafted Carboxymethyl Chitosan Molecularly Imprinted Polymer for Specific Recognition and Sustained Release of Salidroside

The choice of carrier material is critical in the study of natural drug release preparations and glycosylated magnetic molecularly imprinted materials. The stiffness and softness of the carrier material affect the efficiency of drug release and the specificity of recognition. The dual adjustable aperture-ligand in molecularly imprinted polymers (MIPs) provides the possibility of individualized design for sustained release studies. In this study, a combination of paramagnetic Fe₃O₄ and carboxymethyl chitosan (CC) was used to enhance the imprinting effect and improve drug delivery. A combination of tetrahydrofuran and ethylene glycol was used as a binary porogen to prepare MIP-doped Fe₃O₄-grafted CC (SMCMIP). Salidroside serves as the template, methacrylic acid acts as the functional monomer, and ethylene glycol dimethacrylate (EGDMA) serves as the crosslinker. Scanning and transmission electron microscopy were used to observe the micromorphology of the microspheres. The structural and morphological parameters of the SMCMIP composites were measured, including the surface area and pore diameter distribution. In an in vitro study, we found that the SMCMIP composite had a sustained release property of 50% after 6 h of release time in comparison to the control SMCNIP. The total amounts of SMCMIP released at 25 °C and 37 °C were 77% and 86%, respectively. In vitro results showed that the release of SMCMIP followed Fickian kinetics, meaning that the rate of release is dependent on the concentration gradient, with diffusion coefficients ranging from 3.07 × 10^-2 cm²/s to 5.66 × 10^-3 cm²/s. The results of cytotoxicity experiments showed that the SMCMIP composite did not have any harmful effects on cell growth. The survival rates of intestinal epithelial cells (IPEC-J2) were found to be above 98%. By using the SMCMIP composite, drugs may be delivered in a sustained manner, potentially leading to improved therapeutic outcomes and reduced side effects.

Preparation and evaluation of chitosan- and hyaluronic acid-grafted pullulan succinate films for skin wound healing

A novel wound dressing that possesses antibacterial properties and accelerates skin wound repair was developed by physically blending hyaluronic acid-grafted pullulan succinate (HA-st-Pu) with chitosan (CS). The HA-st-Pu polymer was synthesized and characterized, and then CS/HA-st-Pu film dressings were prepared by a freeze-drying method. The novel film wound dressings exhibited a three-dimensional cavity structure under scanning electron microscopy (SEM) and a better swelling ratio than CS, HA and Pu alone, absorbing a large amount of liquid and effectively maintaining the moist environment of the wound. CS/HA-st-Pu materials had no cytotoxicity and increased cell proliferation when coincubated with L929 cells. Moreover, CS/HA-st-Pu wound dressings exhibited a certain antibacterial capability against E. coli and S. aureus. In rat skin wound healing, CS/HA-st-Pu film dressings outperformed both the control and market band-aid groups with respect to the reduction of inflammation and acceleration of wound closure.

Carboxymethyl chitosan-grafted polyvinylpyrrolidone-iodine microspheres for promoting the healing of chronic wounds

Chronic wounds that fail to heal are the most common complications experienced by diabetic patients, and current treatment remains unsatisfactory, mainly due to the vulnerability of diabetic wounds to bacterial infections. Chitosan derivatives are widely used to treat chronic wounds due to their excellent hydrophilicity, biodegradability, and antimicrobial activity and substantial contribution to tissue regeneration. However, the antimicrobial effect of chitosan is not sufficient due to the complicated pathological mechanism of diabetes mellitus. Here, we prepared carboxymethyl chitosan-grafted polyvinylpyrrolidone-iodine (CMC-g-PVPI) microspheres and used them to treat chronic wounds. Carboxymethyl chitosan (CMC) was used as the skeleton and was grafted with polyvinylpyrrolidone-iodine (PVPI) to form a CMC-g-PVPI complex hydrogel and CMC-g-PVPI microspheres, which formed as a result of the high shearing dispersion of the complex hydrogel. In vivo experiments on diabetic wounds revealed significantly accelerated wound closure in the presence of the microspheres, demonstrating the excellent potential of CMC-g-PVPI to promote skin wound regeneration under diabetic conditions.

A novel multilayer thin-film membrane with high durability: preparation, characterization, performance investigation

The main aim of this research is the improvement of the performance in desalination of polyamide (PA) thin film composite nanofiltration membranes by modification of nanofibrous polyvinylidene fluoride as a support layer.

A self-healing and injectable oxidized quaternized guar gum/carboxymethyl chitosan hydrogel with efficient hemostatic and antibacterial properties for wound dressing

Multifunctional wound dressings urgently need to be developed to meet the various needs of wound healing. In this work, we first proposed a new method about modifying the guar gum (GG) by performing a quaternization graft reaction and then oxidation. The obtained oxidized quaternized guar gum (OQGG) not only has antibacterial function due to the introduction of quaternary ammonium groups, but also can become one of the components of Schiff base hydrogels due to the presence of aldehyde groups. Therefore, we used it and carboxymethyl chitosan (CMCS) to design a hydrogel with antibacterial, hemostatic, self-repairing and injectable properties. We characterized the structure of OQGG and OQGG@CMCS hydrogels, but also evaluated the performance of the hydrogels. The results showed that GG was successfully modified to OQGG and OQGG@CMCS hydrogel was successfully prepared, and the obtained OQGG@CMCS hydrogel showed excellent antibacterial and hemostatic properties, and exhibited self-healing and injectability. In addition, cytotoxicity tests demonstrated that the OQGG@CMCS hydrogels presented good cytocompatibility. Further, the OQGG@CMCS hydrogel significantly promoted wound healing in an S. aureus-infected rat wound model. Therefore, the hydrogel has the potential to be applied as a wound dressing.

Preparation, Characterization, and Biological Evaluation of Transparent Thin Carboxymethyl-Chitosan/Oxidized Carboxymethyl Cellulose Films as New Wound Dressings

Full thickness burns in which the damage penetrates deep into the skin layers and reaches underneath the muscle, compel the need for more effective cure. Herein, cross-linked carboxymethyl-chitosan (CM-chitosan) films, prepared by Schiff base association with oxidized carboxymethyl cellulose (OCMC), are investigated regarding the wound healing capacity on full thickness burn injuries in vivo. Transparent thin CM-chitosan/OCMC films are obtained with tensile strength reaching 6.11 MPa, elongation at break above 27%, and water absorption more than 800%, which operates in favor of absorbing excess exudate and monitoring the wound status. Furthermore, the nonadherent CM-chitosan/OCMC films, with satisfactory biodegradability, cell, and tissue compatibility, are readily used to the wound sites and easily removed following therapy on scalded tissue so as to alleviate the suffering from burn. The films efficiently promote epithelial and dermal regeneration compared to the control, achieving 75.9% and 94.4% wound closure, respectively, after 14 and 27 days. More importantly, CM-chitosan/OCMC films accelerate wound healing with natural mechanisms which include controlling inflammatory response, reducing apoptosis, promoting fibroblast cell proliferation, and collagen formation. In conclusion, the CM-chitosan/OCMC films elevate the repair ratio of burn injuries and have great potential for facilitating the healing process on full-thickness exuding wounds.

Design and Fabrication of Sodium Alginate/Carboxymethyl Cellulose Sodium Blend Hydrogel for Artificial Skin

Tissue-engineered skin grafts have long been considered to be the most effective treatment for large skin defects. Especially with the advent of 3D printing technology, the manufacture of artificial skin scaffold with complex shape and structure is becoming more convenient. However, the matrix material used as the bio-ink for 3D printing artificial skin is still a challenge. To address this issue, sodium alginate (SA)/carboxymethyl cellulose (CMC-Na) blend hydrogel was proposed to be the bio-ink for artificial skin fabrication, and SA/CMC-Na (SC) composite hydrogels at different compositions were investigated in terms of morphology, thermal properties, mechanical properties, and biological properties, so as to screen out the optimal composition ratio of SC for 3D printing artificial skin. Moreover, the designed SC composite hydrogel skin membranes were used for rabbit wound defeat repairing to evaluate the repair effect. Results show that SC4:1 blend hydrogel possesses the best mechanical properties, good moisturizing ability, proper degradation rate, and good biocompatibility, which is most suitable for 3D printing artificial skin. This research provides a process guidance for the design and fabrication of SA/CMC-Na composite artificial skin.

Preparation and Application of Quaternized Chitosan- and AgNPs-Base Synergistic Antibacterial Hydrogel for Burn Wound Healing

Infection is the major reason that people die from burns; however, traditional medical dressings such as gauze cannot restrain bacterial growth and enhance the healing process. Herein, an organic- and inorganic-base hydrogel with antibacterial activities was designed and prepared to treat burn wounds. Oxidized dextran (ODex) and adipic dihydrazide grafted hyaluronic acid (HA-ADH) were prepared, mixed with quaternized chitosan (HACC) and silver nanoparticles to fabricate Ag@ODex/HA-ADH/HACC hydrogel. The hydrogel, composed of nature biomaterials, has a good cytocompatibility and biodegradability. Moreover, the hydrogel has an excellent antibacterial ability and presents fast healing for burn wounds compared with commercial Ag dressings. The Ag@ODex/HA-ADH/HACC hydrogel will be a promising wound dressing to repair burn wounds and will significantly decrease the possibility of bacterial infection.

Edible Materials in Tissue Regeneration

Edible materials have attracted increasing attention because of their excellent properties including availability, biocompatibility, biological activity, and biodegradability. Natural polysaccharides, phenolic compounds, and proteins are widely used in tissue regeneration. To better characterize their healing effect, this review article describes the applications of edible materials in tissue regeneration including wound healing and bone tissue regeneration. As an introduction to the topic, their sources and main bioactive properties are discussed. Then, the mechanism by which they facilitate wound healing based on their hemostasis, antibacterial, anti-inflammatory, and antioxidant properties is systematically investigated. Moreover, a more comprehensive discussion is presented on the approaches by which edible materials can be used as scaffolds or agents for the provision of the components of natural bones for regulating the level of osteogenesis-related cytokines to enhance bone repair. Finally, the prospects of edible materials for tissue regeneration are discussed.

Polymeric Iodophors: Preparation, Properties, and Biomedical Applications

The review summarizes the data on the main chemical and physiological properties of iodine and its capability of complexation with natural and synthetic polymers. Iodine is the best known antiseptic used to prevent and treat microbial infections. Its unique capability of complexation with certain polymers opens wide opportunities for targeted and prolonged delivery to target organs. Polymeric complexes with iodine have another color, other morphology, a higher electrical conductivity, and higher biological activity as compared with initial polymers. The formation of and ions is associated with iodine-polymer complexation. Iodine-containing biocompatible adhesive controlled-release formulations are designed as part of research into iodine-polymer complexes. The field is promising in terms of treating certain diseases because tolerance to iodine compounds does not usually develop in microbial cells.

Alginate-based composite materials for wound dressing application:A mini review

Alginate biopolymer has been used in the design and development of several wound dressing materials in order to improve the efficiency of wound healing. Mainly, alginate improves the hydrophilic nature of wound dressing materials in order to create the required moist wound environment, remove wound exudate and increase the speed of skin recovery of the wound. In addition, alginate can easily cross-link with other organic and inorganic materials and they can promote wound healing in clinical applications. This review article addresses the importance of alginates and the roles of derivative polymeric materials in wound dressing biomaterials. Additionally, studies on recent alginate-based wound dressing materials are discussed.

Preparation of Antimicrobial Hyaluronic Acid/Quaternized Chitosan Hydrogels for the Promotion of Seawater-Immersion Wound Healing

Wound immersion in seawater with high salt, high sodium, and a high abundance of pathogenic bacteria, especially gram-negative bacteria, can cause serious infections and difficulties in wound repair. The present study aimed to prepare a composite hydrogel composed of hyaluronic acid (HA) and quaternized chitosan (QCS) that may promote wound healing of seawater-immersed wounds and prevent bacterial infection. Based on dynamic Schiff base linkage, hydrogel was prepared by mixing oxidized hyaluronic acid (OHA) and hyaluronic acid-hydrazide (HA-ADH) under physiological conditions. With the addition of quaternized chitosan, oxidized hyaluronic acid/hyaluronic acid-hydrazide/quaternized chitosan (OHA/HA-ADH/O-HACC and OHA/HA-ADH/N-HACC) composite hydrogels with good swelling properties and mechanical properties, appropriate water vapor transmission rates (WVTR), and excellent stability were prepared. The biocompatibility of the hydrogels was demonstrated by in vitro fibroblast L929 cell culture study. The results of in vitro and in vivo studies revealed that the prepared antibacterial hydrogels could largely inhibit bacterial growth. The in vivo study further demonstrated that the antibacterial hydrogels exhibited high repair efficiencies in a seawater-immersed wound defect model. In addition, the antibacterial hydrogels decreased pro-inflammatory factors (TNF-α, IL-1β, and IL-6) but enhanced anti-inflammatory factors (TGF-β1) in wound. This work indicates that the prepared antibacterial composite hydrogels have great potential in chronic wound healing applications, such as severe wound cure and treatment of open trauma infections.

Regulating Preparation Of Functional Alginate-Chitosan Three-Dimensional Scaffold For Skin Tissue Engineering

AIM

In this study, we attempted to regulate the preparation of Alg-CS-Flu three-dimensional scaffolds via a facile freeze-drying method combined with amidation.

MATERIALS AND METHODS

Three-dimensional porous flurbiprofen-grafted alginate (Alg)-chitosan (CS) scaffolds were successfully prepared by a facile freeze-drying method combined with amidation for skin tissue engineering applications. Alg-CS composite was first used to load flurbiprofen (Flu), which is a kind of anti-inflammatory non-steroidal molecule. The Flu-loaded Alg/CS composite solution, through freeze-drying and 1-ethyl-3(3-(dimethylamino)propyl) carbodiimide/N-hydroxysuccinimide crosslinking to form an Alg-CS-Flu scaffold, exhibited a uniform and porous morphology that was characterized using scanning electron microscopy. The Alg-CS-Flu as-prepared scaffold was also characterized using Fourier-transform infrared spectroscopy, water contact angle, thermal properties, and stress-strain testing.

RESULTS

The results reveal that Flu was successfully grafted onto the surfaces of the Alg-CS-Flu scaffold, which showed good hydrophilicity and appropriate mechanical properties. Furthermore, cell viability, cell morphology from cells cultured in vitro, and hematoxylin-eosin staining after the graft was subcutaneously embedded in mice for 7 d demonstrated that the Alg-CS-Flu scaffold had no unfavorable effects on the adhesion and proliferation of fibroblasts, as well as a good anti-inflammatory property.

CONCLUSION

The developed Alg-CS-Flu scaffold is proposed as a promising material or skin tissue engineering application.