Development of a fluid-absorptive alginate-chitosan bioplatform for potential application as a wound dressing

Functional network copolymeric hydrogels derived from moringa gum: Physiochemical, drug delivery and biomedical properties

The article explores the synthesis of network hydrogels derived from moringa gum (MG) through a grafting reaction with poly (vinylsulfonic acid) and carbopol. These hydrogels are designed for use in drug delivery (DD) and wound hydrogels dressing (HYDR) applications. The copolymers were characterized by FESEM, EDX, AFM, FTIR, 13C NMR, XRD and DSC. Tetracycline release from hydrogel occurred gradually with a non-Fickian diffusion and was best described by the Hixson-Crowell kinetic model in artificial wound fluid. The HYDR demonstrated compatibility with blood, exhibited antioxidant properties and possessed tensile strength, in addition to their mucoadhesive characteristics. The copolymer dressings absorbed approximately 7 g of simulated fluid. The copolymers exhibited significant antioxidant activity, measuring at 84 % free radicals scavenging, during DPPH assay. These dressings demonstrated permeability to H2O and O2,. The hydrogel alone did not reveal antibacterial activities; however, when combined with antibiotic drug tetracycline, the dressings revealed notable antibacterial activities against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. The observed biomedical properties suggested that these hydrogels could serve as promising materials for drug delivery HYDR applications.

A universal solvent-replacement strategy to convert alginate hydrogels into mechanically strong and transparent alginate eutectogels for sensitive strain sensors

Eutectogels based on natural polymers have attracted significant attention as an alternative to easily dehydrated hydrogels and expensive ionogels in the development of flexible strain sensors. The feasibility of employing eutectogels derived from pure natural polymers could be greatly enhanced if their mechanical properties satisfy the requirements of applications. Herein, alginate eutectogels (AEs) with high mechanical properties (tensile strain 217 % and strength 2.26 MPa at fracture), and excellent transparency (over 90 %) are acquired via CaCl2 inducing ionic crosslinking and subsequent deep eutectic solvents (DESs, composed of glycerol and choline chloride) initiating physical crosslinking with a universal solvent- replacement strategy. Among them, sodium alginate, a natural polysaccharide polymer, is selected as representative supporting scaffolds and forms water-insoluble alginate hydrogels (AHs) in CaCl2 coagulation bath. The exchange of DESs with water of AHs not only restrengthens the polymer network by physical crosslinking, but also endows the obtained AEs with long-term solvent retention and high temperature resistance. In addition, the AEs not only have high reliability but also exhibit better linear sensitivity in a wide strain range (0-200 %). In particular, the AEs display multiple sensitivity to stretching, bending, and human motions, demonstrating feasibility as sensitive strain sensors.

Recent Advances in Topical Hemostatic Materials

Untimely or improper treatment of traumatic bleeding may cause secondary injuries and even death. The traditional hemostatic modes can no longer meet requirements of coping with complicated bleeding emergencies. With scientific and technological advancements, a variety of topical hemostatic materials have been investigated involving inorganic, biological, polysaccharide, and carbon-based hemostatic materials. These materials have their respective merits and defects. In this work, the application and mechanism of the major hemostatic materials, especially some hemostatic nanomaterials with excellent adhesion, good biocompatibility, low toxicity, and high adsorption capacity, are summarized. In the future, it is the prospect to develop multifunctional hemostatic materials with hemostasis and antibacterial and anti-inflammatory properties for promoting wound healing.

The characterization and analysis of the compound hemostatic cotton based on Ca2+/poly (vinyl alcohol)/soluble starch-fish skin collagen

Accidental bleeding is an unavoidable problem in daily life. To avoid the risk of excessive blood loss, it is urgent to design a functional material that can quickly stop bleeding. In this study, an efficient wound dressing for hemostasis was investigated. Based on the characteristics that Ca2+ and fish skin collagen (FSC) could activate the coagulation mechanism, hemostatic cotton was prepared by solvent replacement method using CaCl2, FSC, soluble starch (SS), and polyvinyl alcohol (PVA) as raw materials. The cytotoxicity test showed the Ca2+PVA/FSC-SS hemostatic cottons had good biocompatibility. The activated partial thromboplastin time (APTT) of Ca2+PVA/FSC-SS(4) was 35.34 s, which was 22.07 s faster than that of PVA/FSC-SS, indicating Ca2+PVA/FSC-SS mediated the endogenous coagulation system. In vitro coagulation test, Ca2+PVA/FSC-SS(4) could stop bleeding rapidly within 39.60 ± 5.16 s, and the ability of wound healing was higher than commercial product (Celox). This study developed a rapid procoagulant and hemostatic material, which had a promising application in a variety of environments.

Hydrogel-mediated extracellular vesicles for enhanced wound healing: the latest progress, and their prospects for 3D bioprinting

Extracellular vesicles have shown promising tissue recovery-promoting effects, making them increasingly sought-after for their therapeutic potential in wound treatment. However, traditional extracellular vesicle applications suffer from limitations such as rapid degradation and short maintenance during wound administration. To address these challenges, a growing body of research highlights the role of hydrogels as effective carriers for sustained extracellular vesicle release, thereby facilitating wound healing. The combination of extracellular vesicles with hydrogels and the development of 3D bioprinting create composite hydrogel systems boasting excellent mechanical properties and biological activity, presenting a novel approach to wound healing and skin dressing. This comprehensive review explores the remarkable mechanical properties of hydrogels, specifically suited for loading extracellular vesicles. We delve into the diverse sources of extracellular vesicles and hydrogels, analyzing their integration within composite hydrogel formulations for wound treatment. Different composite methods as well as 3D bioprinting, adapted to varying conditions and construction strategies, are examined for their roles in promoting wound healing. The results highlight the potential of extracellular vesicle-laden hydrogels as advanced therapeutic tools in the field of wound treatment, offering both mechanical support and bioactive functions. By providing an in-depth examination of the various roles that these composite hydrogels can play in wound healing, this review sheds light on the promising directions for further research and development. Finally, we address the challenges associated with the application of composite hydrogels, along with emerging trends of 3D bioprinting in this domain. The discussion covers issues such as scalability, regulatory considerations, and the translation of this technology into practical clinical settings. In conclusion, this review underlines the significant contributions of hydrogel-mediated extracellular vesicle therapy to the field of 3D bioprinting and wound healing and tissue regeneration. It serves as a valuable resource for researchers and practitioners alike, fostering a deeper understanding of the potential benefits, applications, and challenges involved in utilizing composite hydrogels for wound treatment.

A novel hydrogel containing 4-methylcatechol for skin regeneration: in vitro and in vivo study

Skin damages are usual physical injuries and different studies have been done to improve wound healing. Hydrogel due to its properties like a moist environment and cooling wound site is a good option for wound treatment. In this study, we evaluated the consequence of using alginate/chitosan hydrogel contained various dosages of 4-Methylcatechol (0, 0.1, 1% (W/W)) on wound healing. After hydrogel fabrication, different tests like SEM, swelling, release, weight loss, and hemo- and cytocompatibility were done to characterize fabricated hydrogels. Finally, the rat model was used to assess Alginate/Chitosan hydrogel's therapeutic function containing 0.1 and 1% of 4-Methylcatechol. The pore size of hydrogel was between 24.5 ± 9 and 62.1 ± 11.63 µm and about 90% of hydrogel was lost after 14 days in the weight loss test. Blood compatibility and MTT assay showed that hydrogels were nontoxic and improved cell proliferation. In vivo test showed that Alginate/Chitosan/0.1%4-Methylcatechol improved wound healing and the results were significantly better than the gauze-treated wound. Our results showed dose depending effect of 4-Methylcatechol on wound healing. This study shows the treatment effect of 4-Methylcatechol on wound healing and the possibility of using it for treating skin injuries.

Development and Evaluation of Cross-Linked Alginate-Chitosan-Abscisic Acid Blend Gel

Abscisic acid (ABA) has been proposed to play a significant role in the ripening of nonclimacteric fruit, stomatal opening, and response to abiotic stresses in plants, which can adversely affect crop growth and productivity. The biological effects of ABA are dependent on its concentration and signal transduction pathways. However, due to its susceptibility to the environment, it is essential to find a suitable biotechnological approach to coat ABA for its application. One promising approach is to utilize alginate and chitosan, two natural polysaccharides known for their strong affinity for water and their ability to act as coating agents. In this study, an alginate-chitosan blend was employed to develop an ABA cover. To achieve this, an alginate-chitosan-abscisic acid (ALG-CS-ABA) blend was prepared by forming ionic bonds or complexes with calcium ions, or through dual cross-linking. This was done by dripping a homogeneous solution of alginate-chitosan and ABA into a calcium chloride solution, resulting in the formation of the blend. By combining the unique properties of alginate, chitosan, and ABA, the resulting ALG-CS-ABA blend can potentially offer enhanced stability, controlled release, and improved protection of ABA. These characteristics make it a promising biotechnological approach for various applications, including the targeted delivery of ABA in agricultural practices or in the development of innovative plant-based products. Further evaluation and characterization of the ALG-CS-ABA blend will provide valuable insights into its potential applications in the fields of biomedicine, agriculture, and 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.

Microwave-Assisted Incorporation of AgNP into Chitosan-Alginate Hydrogels for Antimicrobial Applications

Herein, improving the antibacterial activity of a hydrogel system of sodium alginate (SA) and basic chitosan (CS) using sodium hydrogen carbonate by adding AgNPs was investigated. SA-coated AgNPs produced by ascorbic acid or microwave heating were evaluated for their antimicrobial activity. Unlike ascorbic acid, the microwave-assisted method produced uniform and stable SA-AgNPs with an optimal reaction time of 8 min. Transmission electron microscopy (TEM) confirmed the formation of SA-AgNPs with an average particle size of 9 ± 2 nm. Moreover, UV-vis spectroscopy confirmed the optimal conditions for SA-AgNP synthesis (0.5% SA, 50 mM AgNO₃, and pH 9 at 80 °C). Fourier transform infrared (FTIR) spectroscopy confirmed that the -COO^- group of SA electrostatically interacted with either the Ag⁺ or -NH₃⁺ of CS. Adding glucono-δ-lactone (GDL) to the mixture of SA-AgNPs/CS resulted in a low pH (below the pKa of CS). An SA-AgNPs/CS gel was formed successfully and retained its shape. This hydrogel exhibited 25 ± 2 mm and 21 ± 1 mm inhibition zones against E. coli and B. subtilis and showed low cytotoxicity. Additionally, the SA-AgNP/CS gel showed higher mechanical strength than SA/CS gels, possibly due to the higher crosslink density. In this work, a novel antibacterial hydrogel system was synthesized via 8 min of microwave heating.

Development of alginate-based hydrogels: Crosslinking strategies and biomedical applications

Natural polysaccharide-based hydrogels have drawn much concern in the biomedical fields. Among them, alginate, a natural polyanionic polysaccharide, has become one of the research hotspots, because of its abundant source, biodegradability, biocompatibility, solubility, modification flexibility, and other characteristics or physiological functions. Recently, through adopting various physical or chemical crosslinking strategies, selecting suitable crosslinking or modification reagents, precisely controlling the reaction conditions, or introducing organic or inorganic functional materials, a variety of alginate-based hydrogels with excellent performance have been continuously developed, considerably expanding the breadth and depth of their applications. Here, various crosslinking strategies in the preparation of alginate-based hydrogels are comprehensively introduced. The representative application progress of alginate-based hydrogels in drug carrier, wound dressing and tissue engineering is also summarized. Meanwhile, the application prospects, challenges and development trends of alginate-based hydrogels are discussed. It is expected to provide guidance and reference for the further development of alginate-based hydrogels.

Bibliometric analysis of the use of calcium alginate for wound dressing applications: A review

Wounds can cause many disorders and affect the quality of health, so it is necessary to develop wound dressings that have a role in accelerating the healing process. Wound dressings have evolved over time, and today there are many types of wound dressings that can suit the type of wound the patient has. This review discusses the development, types, and research directions of wound dressings from calcium alginate (CaAlg), using bibliometric analysis with time intervals from 1982 to 2021. It was found that, in the late 1990s, research related to this matter began to increase. United Kingdom, United States, China, Japan, and Italy are the five most influential countries. And from the results of the keyword analysis, it was found that, in addition to studying the general properties of wound dressings, currently there are many developments related to the structure of the material as well as the effect of adding drugs to wound dressings, so that the current study also displays various characterizations.

Chitosan - dextran phosphate carbamate hydrogels for locally controlled co-delivery of doxorubicin and indomethacin: From computation study to in vivo pharmacokinetics

The development of synergistic drug combinations is a promising strategy for effective cancer suppression. Here, we report all-polysaccharide biodegradable polyelectrolyte complex hydrogels (DPCS) based on dextran phosphate carbamate (DP) and chitosan (CS) for controlled co-delivery of the anticancer drug doxorubicin (DOX) and the non-steroidal anti-inflammatory drug indomethacin (IND). IND can induce more apoptosis in tumor cells by reducing the level of multidrug resistance-associated protein 1. Based on calculations using density functional theory and zeta potential analysis data, carriers with high drug loading were obtained. The release profile of both drugs from the hydrogels was tuned by changing the molecular weight and functional groups content of the polysaccharides. The optimized DPCS showed a steady release of DOX both in vitro and in vivo, and a gradual release of IND, which constantly induced the action of DOX. Considering all of these benefits, DOX- and IND-loaded DPCS offer a promising long-acting polysaccharide-based antitumor platform.

Wound microenvironment self-adaptive hydrogel with efficient angiogenesis for promoting diabetic wound healing

Neovascularization is critical to improve the diabetic microenvironment, deliver abundant nutrients to the wound and promote wound closure. However, the excess of oxidative stress impedes the healing process. Herein, a self-adaptive multifunctional hydrogel with self-healing property and injectability is fabricated through a boronic ester-based reaction between the phenylboronic acid groups of the 3-carboxyl-4-fluorophenylboronic acid -grafted quaternized chitosan and the hydroxyl groups of the polyvinyl alcohol, in which pro-angiogenic drug of desferrioxamine (DFO) is loaded in the form of gelatin microspheres (DFO@G). The boronic ester bonds of the hydrogel can self-adaptively react with hyperglycemic and hydrogen peroxide to alleviate oxidative stress and release DFO@G in the early phase of wound healing. A sustained release of DFO is then realized by responding to overexpressed matrix metalloproteinases. In a full-thickness diabetic wound model, the DFO@G loaded hydrogel accelerates angiogenesis by upregulating expression of hypoxia-inducible factor-1 and angiogenic growth factors, resulting in collagen deposition and rapid wound closure. This multifunctional hydrogel can not only self-adaptively change the microenvironment to a pro-healing state by decreasing oxidative stress, but also respond to matrix metalloproteinases to release DFO. The self-adaptive multifunctional hydrogel has a potential for treating diabetic wounds.

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Injectable self-healing hydrogel was prepared based on boronic ester-based reaction.

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The hydrogel could self-adaptively regulate the microenvironment to a pro-healing state.

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The hydrogel could efficiently promoting diabetic wound healing by accelerating angiogenesis.

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.

Biopolymer-Based Wound Dressings with Biochemical Cues for Cell-Instructive Wound Repair

Regenerative medicine is an active research sphere that focuses on the repair, regeneration, and replacement of damaged tissues and organs. A plethora of innovative wound dressings and skin substitutes have been developed to treat cutaneous wounds and are aimed at reducing the length or need for a hospital stay. The inception of biomaterials with the ability to interact with cells and direct them toward desired lineages has brought about innovative designs in wound healing and tissue engineering. This cellular engagement is achieved by cell cues that can be biochemical or biophysical in nature. In effect, these cues seep into innate repair pathways, cause downstream cell behaviours and, ultimately, lead to advantageous healing. This review will focus on biomolecules with encoded biomimetic, instructive prompts that elicit desired cellular domino effects to achieve advanced wound repair. The wound healing dressings covered in this review are based on functionalized biopolymeric materials. While both biophysical and biochemical cues are vital for advanced wound healing applications, focus will be placed on biochemical cues and in vivo or clinical trial applications. The biochemical cues aforementioned will include peptide therapy, collagen matrices, cell-based therapy, decellularized matrices, platelet-rich plasma, and biometals.

In Situ Forming Chitosan-Alginate Interpolymer Complex Bioplatform for Wound Healing and Regeneration

Cytocompatibility, biocompatibility, and biodegradability are amongst the most desirable qualities of wound dressings and can be tuned during the bioplatform fabrication steps to enhance wound healing capabilities. A three-stepped approach (partial-crosslinking, freeze-drying, and pulverisation) was employed in fabricating a particulate, partially crosslinked (PC), and transferulic acid (TFA)-loaded chitosan-alginate (CS-Alg) interpolymer complex (IPC) with enhanced wound healing capabilities. The PC TFA-CS-Alg IPC bioplatform displayed fluid uptake of 3102% in 24 h and a stepwise degradation up to 53.5% in 14 days. The PC TFA-CS-Alg bioplatform was used as a bioactive delivery system with an encapsulation efficiency of 65.6%, bioactive loading of 9.4%, burst release of 58.27%, and a steady release of 1.91% per day. PC TFA-CS-Alg displayed a shift in cytocompatibility from slightly cytotoxic (60-90% cell viability) to nontoxic (> 90% cell viability) over a 72-h period in NIH-3T3 cells. The wound closure and histological evaluations of the lesions indicated better wound healing performance in lesions treated with PC TFA-CS-Alg and PC CS-Alg compared to those treated with the commercial product and the control. Application of the particulate bioplatform on the wound via sprinkles, the in situ hydrogel formation under fluid exposure, and the accelerated wound healing performances of the bioplatforms make it a good candidate for bioactive delivery system and skin tissue regeneration.

Highly efficient adsorption of chromium on N, S-codoped porous carbon materials derived from paper sludge

The synergistic effect of heteroatoms is a viable method to enhance the adsorption performance of heavy metal onto carbon-based materials. However, the high cost, complex operation and a lot of pollution from the synthesis process have limited its development. Herein, a facile two-step pyrolysis method is used to prepare in situ N and S doped porous biochar from paper mill sludge for the removal of Cr(VI) from aqueous environment. The NSC-450 sample prepared under the optimum conditions has a large specific surface area of 3336.7 m² g^-1, an average pore size of 2.56 nm and a total pore volume of 2.10 cm³ g^-1, manifesting the excellent adsorption capacity of 356.25 mg g^-1 for Cr(VI). The adsorption of Cr(VI) by NSC-450 is consistent with the Langmuir isotherm and pseudo-second-order model, suggesting a spontaneous and endothermic chemisorption process. The analysis results show that the NH, graphitic nitrogen and thiophene structures have a positive effect on converting a large amount of Cr(VI) to Cr(III) by synergistic reduction, indicating obviously facilitating Cr(VI) removal compared to other sites. Therefore, in this material, the strong adsorption mechanism is mainly reductive complexation. Moreover, the effects of real water quality, anions, cations and fulvic acid on the adsorption behavior of Cr(VI) onto the NSC-450 were further investigated. The results demonstrate that the chromium removal rate remains above 82% even in actual electroplating wastewater, suggesting NSC-450 has great practical application prospect. This work offered a feasible method for high-value utilization of sludge, but also provided a novel perspective for the future design of heteroatom-doped carbon materials for promoting to eliminate hexavalent chromium from water environment.

Algal Polysaccharides-Based Hydrogels: Extraction, Synthesis, Characterization, and Applications

Hydrogels are three-dimensional crosslinked hydrophilic polymer networks with great potential in drug delivery, tissue engineering, wound dressing, agrochemicals application, food packaging, and cosmetics. However, conventional synthetic polymer hydrogels may be hazardous and have poor biocompatibility and biodegradability. Algal polysaccharides are abundant natural products with biocompatible and biodegradable properties. Polysaccharides and their derivatives also possess unique features such as physicochemical properties, hydrophilicity, mechanical strength, and tunable functionality. As such, algal polysaccharides have been widely exploited as building blocks in the fabrication of polysaccharide-based hydrogels through physical and/or chemical crosslinking. In this review, we discuss the extraction and characterization of polysaccharides derived from algae. This review focuses on recent advances in synthesis and applications of algal polysaccharides-based hydrogels. Additionally, we discuss the techno-economic analyses of chitosan and acrylic acid-based hydrogels, drawing attention to the importance of such analyses for hydrogels. Finally, the future prospects of algal polysaccharides-based hydrogels are outlined.

Recent Advances in Bioengineered Scaffolds for Cutaneous Wound Healing

Wound healing is an evolved dynamic biological process. Though many research and clinical approaches have been explored to restore damaged or diseased skin, the current treatment for deep cutaneous injuries is far from being perfect, and the ideal regenerative therapy remains a significant challenge. Of all treatments, bioengineered scaffolds play a key role and represent great progress in wound repair and skin regeneration. In this review, we focus on the latest advancement in biomaterial scaffolds for wound healing. We discuss the emerging philosophy of designing biomaterial scaffolds, followed by precursor development. We pay particular attention to the therapeutic interventions of bioengineered scaffolds for cutaneous wound healing, and their dual effects while conjugating with bioactive molecules, stem cells, and even immunomodulation. As we review the advancement and the challenges of the current strategies, we also discuss the prospects of scaffold development for wound healing.

Influence of replacing oregano essential oil by ground oregano leaves on chitosan/alginate-based dressings properties

Biopolymers, as chitosan and alginate, have gained prominence in the biomedical area, mainly for application in wound dressings, as partial replacements for synthetic polymers. The present work aimed to compare the influence of the antimicrobial agent incorporation form on the properties of films prepared by casting. The chitosan/alginate-based films were manufactured containing oregano essential oil (OEO) or ground oregano leaves (OR). The OEO was chosen due to its excellent pharmacological properties, and the substitution by OR can represent an advantageous alternative for minimizing the final cost of the product, by removing the oil extraction step. The films, with different amounts of OEO and OR, were characterized in terms of their morphological, physicochemical, mechanical and antimicrobial properties. The films had properties according to desirable for wound dressing application: water vapor flux less than 35 g m^-2 h^-1, moderate liquid absorption capacity, and similar mechanical properties to human skin. All developed films showed antimicrobial activity against the bacteria Escherichia coli and Staphylococcus aureus. Formulations containing OEO presented the largest inhibition zones, although OR showed high potential for the proposed use. These results suggest that films developed, with both OEO and ground oregano leaves, are promising for use as dressings.

Alginate-gum acacia based sponges as potential wound dressings for exuding and bleeding wounds

The improper management of wound exudates can expose the wound to bacterial invasion, skin maceration etc. thereby resulting in prolonged wound healing. Biopolymers are characterized by hydrophilic functional groups which when employed for the development of wound dressings promote the wound dressings capability to absorb a high amount of wound exudates. Alginate-gum acacia sponges were prepared from a combination of biopolymers such as sodium alginate and gum acacia in varying amounts with carbopol via crosslinking with 1 and 2% CaCl₂. The prepared sponges were loaded with a combination of ampicillin and norfloxacin. In vitro antibacterial analysis revealed that the antibacterial activity of the loaded antibiotics was retained and the sponges were effective against gram-positive and gram-negative bacteria. The sponges displayed rapid and high absorption capability in the range of 1022-2419% at pH 5.5 simulating wound exudates, and 2268-5042% at pH 7.4 simulating blood within a period of 1-3 h. Furthermore, the whole blood clotting studies further revealed low absorbance values when compared to the control revealing the good clotting capability of the sponges. The unique features of the sponges revealed their potential application for the management of infected, high exuding and bleeding wounds.

Chitosan-covered liposomes as a promising drug transporter: nanoscale investigations

Liposomes are small artificial vesicles spherical shaped of 50-1000 nm in diameter. They are created from natural non-toxic phospholipids membranes. Externally, they are decorated with biocompatible polymers. Chitosan, a natural polymer, demonstrates exceptional advantages in drug delivery, in particular, as liposome cover. In this paper, Molecular Dynamics simulations (MD) are performed in the coupled NPT-NPH and NVT-NVE statistical ensembles to study the static and dynamic properties of DPPC membrane-bilayer with grafted cationic chitosan chains, with added Cl- anions to neutralize the environment, using the Martini coarse-grained force-field. From the NPT-NPH MD simulations we found a chitosan layer L DM ranging from 3.2 to 6.6 nm for graft chains of a degree of polymerization n p = 45 and different grafting molar fractions X p = 0.005, X p = 0.014 and X p = 0.1. Also, the chitosan chains showed three essential grafting regimes: mushroom, critic, and brush depending on X p. The DPPC bilayer thickness D B and the area per lipid A l increased proportionally to X p. From the NVT-NVE MD simulations, the analysis of the radial distribution function showed that the increase of X p gives a more close-packed and rigid liposome. The analysis of the mean square displacement revealed that the diffusion of lipids is anomalous. In contrast, the diffusion of chitosan chains showed a normal diffusion, just after 100 ps. The diffusion regime of ions is found to be normal and independent of time. For the three identified regimes, the chitosan showed a tendency to adhere to the membrane surface and therefore affect the properties of the liposomal membrane.

Biodegradable polyelectrolyte complexes of chitosan and partially crosslinked dextran phosphate with potential for biomedical applications

Polyelectrolyte complexes (PECs) are spontaneously formed by mixing oppositely charged polyelectrolyte solutions without the use of organic solvents and chemical crosslinkers are great candidate carriers for drug delivery. Herein, biodegradable antimicrobial polyelectrolyte complexes of chitosan - dextran phosphate (DPCS) containing cefazolin were developed and characterized in order to assess their suitability for biomedical applications. For this purpose, the simultaneous partial crosslinking and functionalization of dextran with phosphoric acid in a urea melt under reduced pressure were studied. The functional group content and molecular weight of dextran phosphate were varied in order to establish their influence on gel fraction yield, thermal properties and morphologies of the hydrogels. The stoichiometric PECs of DPCS showed good in vitro biocompatibility, pH sensitivity and biodegradability depending on the hydrogel composition. The release of drug from cefazolin-loaded DPCS hydrogels was through non-Fickian diffusion and displayed long sustained-release time. The drug-loaded hydrogels showed antimicrobial activity against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. The tunable degradation behavior under physiological conditions in combination with biocompatibility of the pristine DPCS and high antibacterial efficacy drug-loaded hydrogels may render the presented materials interesting for biomedical applications.

New Opportunity to Formulate Intranasal Vaccines and Drug Delivery Systems Based on Chitosan

In an attempt to develop drug delivery systems that bypass the blood–brain barrier (BBB) and prevent liver and intestinal degradation, it was concluded that nasal medication meets these criteria and can be used for drugs that have these drawbacks. The aim of this review is to present the influence of the properties of chitosan and its derivatives (mucoadhesion, permeability enhancement, surface tension, and zeta potential) on the development of suitable nasal drug delivery systems and on the nasal bioavailability of various active pharmaceutical ingredients. Interactions between chitosan and proteins, lipids, antigens, and other molecules lead to complexes that have their own applications or to changing characteristics of the substances involved in the bond (conformational changes, increased stability or solubility, etc.). Chitosan and its derivatives have their own actions (antibacterial, antifungal, immunostimulant, antioxidant, etc.) and can be used as such or in combination with other molecules from the same class to achieve a synergistic effect. The applicability of the properties is set out in the second part of the paper, where nasal formulations based on chitosan are described (vaccines, hydrogels, nanoparticles, nanostructured lipid carriers (NLC), powders, emulsions, etc.).

Preparation and evaluation of curcumin grafted hyaluronic acid modified pullulan polymers as a functional wound dressing material

Curcumin grafted hyaluronic acid modified pullulan polymers (Cur-HA-SPu) by chemical conjugation was designed and prepared, and its film may be used to accelerate wound healing and help to fight infection. The synthesis of Cur-HA-SPu polymer was characterized by FT-IR, ¹H NMR and DSC. Cur-HA-SPu film has a higher swelling ratio than that of HA-SPu film. Moreover, the good biocompatibility of Cur-HA-SPu polymer was confirmed by skin irritation, cytotoxicity and hemolysis tests. Compared to Cur, the MTT and proliferation test carried out in L929 cells revealed that Cur-HA-SPu polymer showed no cytotoxicity and enhanced cell proliferation. Cur-HA-SPu polymer exhibited a certain bactericidal activity against E. coli and S. aureus. Furthermore, the materials showed antioxidant activity when DPPH method determined. Wound healing study using wistar rat model demonstrated that Cur-HA-SPu film obtained better wound healing result than that of HA-SPu film or natural healing. The above results suggest that Cur-HA-SPu film is a promising and safety formulation for accelerating skin wound healing.

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.

Role of rheological properties on physical chitosan aerogels obtained by supercritical drying

Chitosan aerogels were obtained after using supercritical carbon dioxide to dry physical hydrogels, studying the effect of the rheological behavior of hydrogels and solutions on the final aerogels properties. An increase on the solutions pseudoplasticity increased the subsequent hydrogels physical entanglement, without showing a significant effect on aerogels morphology (nanoporous) and textural properties (pores of about 10 nm). However, an increase of hydrogel physical entanglement promoted the formation of aerogels with a higher compressive strength (from 0.2 to 0.80 MPa) and higher thermal decomposition range, while decreasing the porosity (from 90 % to 94 %). Aerogels stress-strain responses were also successfully fitted using a hyperelastic equation with three adjustable parameters (Yeoh), showing that this type of models must be taken into account when large stresses are studied.

Bioplatform Fabrication Approaches Affecting Chitosan-Based Interpolymer Complex Properties and Performance as Wound Dressings

Chitosan can form interpolymer complexes (IPCs) with anionic polymers to form biomedical platforms (BMPs) for wound dressing/healing applications. This has resulted in its application in various BMPs such as gauze, nano/microparticles, hydrogels, scaffolds, and films. Notably, wound healing has been highlighted as a noteworthy application due to the remarkable physical, chemical, and mechanical properties enabled though the interaction of these polyelectrolytes. The interaction of chitosan and anionic polymers can improve the properties and performance of BMPs. To this end, the approaches employed in fabricating wound dressings was evaluated for their effect on the property-performance factors contributing to BMP suitability in wound dressing. The use of chitosan in wound dressing applications has had much attention due to its compatible biological properties. Recent advancement includes the control of the degree of crosslinking and incorporation of bioactives in an attempt to enhance the physicochemical and physicomechanical properties of wound dressing BMPs. A critical issue with polyelectrolyte-based BMPs is that their effective translation to wound dressing platforms has yet to be realised due to the unmet challenges faced when mimicking the complex and dynamic wound environment. Novel BMPs stemming from the IPCs of chitosan are discussed in this review to offer new insight into the tailoring of physical, chemical, and mechanical properties via fabrication approaches to develop effective wound dressing candidates. These BMPs may pave the way to new therapeutic developments for improved patient outcomes.

Leucine-activated nanohybrid biofilm for skin regeneration via improving cell affinity and neovascularization capacity

Nanohybrids containing amino acid are doped into biodegradable nanofibrous membranes, which improves the cell affinity, the migration and growth of fibroblasts, and the neovascularization capacity, comprehensively accelerating a rapid wound healing.