Application status and technical analysis of chitosan-based medical dressings: a review

Chitosan-based matrix as a carrier for bacteriophages

Wound healing is a dynamic and complex process where infection prevention is essential. Chitosan, thanks to its bactericidal activity against gram-positive and gram-negative bacteria, as well as anti-inflammatory and hemostatic properties, is an excellent candidate to design dressings for difficult-to-heal wound treatment. The great advantage of this biopolymer is its capacity to be chemically modified, which allows for the production of various functional forms, depending on the needs and subsequent use. Moreover, chitosan can be an excellent polymer matrix for bacteriophage (phage) packing as a novel alternative/supportive antibacterial therapy approach. This study is focused on the preparation and characteristics of chitosan-based material in the form of a film with the addition of Pseudomonas lytic phages (KTN4, KT28, and LUZ19), which would exhibit antibacterial activity as a potential dressing that accelerates the wound healing. We investigated the method of producing a polymer based on microcrystalline chitosan (MKCh) to serve as the matrix for phage deposition. We described some important parameters such as average molar mass, swelling capacity, surface morphology, phage release profile, and antibacterial activity tested in the Pseudomonas aeruginosa bacterial model. The chitosan polysaccharide turned out to interact with phage particles immobilizing them within a material matrix. Nevertheless, with the high hydrophilicity and swelling features of the prepared material, the external solution of bacterial culture was absorbed and phages went in direct contact with bacteria causing their lysis in the polymer matrix. KEY POINTS: • A novel chitosan-based matrix with the addition of active phages was prepared • Phage interactions with the chitosan matrix were determined as electrostatic • Phages in the matrix work through direct contact with the bacterial cells.

One-pot reaction for the preparation of diatom hemostatic particles with effective hemostasis and economic benefits

Effective hemostatic materials have been in demand for rapid pre-hospital hemostasis in emergency situations, which can significantly reduce accidental deaths. The development of emergency hemostatic materials with rapid hemostasis, biosafety, and economical preparation is a great challenge. In this study, Ca(OH)2-complexed diatom powder hemostatic particles (Ca(OH)2-Php) were prepared based on a one-pot reaction by directly mixing various raw materials and by rotary granulation. High-temperature calcination was able to carbonate and consume the organic matter in the hemostatic particles. The crosslinked hydrogen bonds in those particles were converted to silica-oxygen bonds, the particles became more stable, and the porous structure of diatom biosilica (DBs) was exposed. Ca(OH)2-Php has high porosity, can quickly adsorb the water in blood (water absorption: 75.85 ± 6.93%), and exhibits rapid hemostasis capacity (clotting time was shortened by 43% compared with that of the control group), good biocompatibility (hemolysis rate <7%, no cytotoxicity), and simplicity of handling (conveniently debride, no residues, no tissue inflammation). This study provides a new idea for the preparation of emergency hemostatic materials, and Ca(OH)2-Php prepared by one-pot reaction has various high-quality characteristics including rapid hemostasis, wide applicability, economical preparation, and potential for large-scale production.

Triple-layered core-shell fiber dressings with enduring platelet conservation and sustained growth factor release abilities for chronic wound healing

Platelet-rich plasma (PRP) is one of the most popular biomaterials in regenerative medicine. However, the difficulties encountered in its preservation, and the requirement for on-demand preparation severely limit its application. In addition, its rapid degradation in the wound microenvironment makes the sustained release of growth factors impossible and finally reduces the therapeutic effect on chronic wounds. Here, a multifunctional dressing based on triple-layered core-shell fibers for loading and enduring preservation of PRP was developed using a one-step coaxial bioprinting technique combined with freeze-drying. The platelets were effectively dispersed and immobilized in the core layer of the fiber, leading to a sustained release of growth factors from the PRP. The rate of release can be controlled by adjusting the triple-layered core-shell structure. Simultaneously, the triple-layered core-shell structure can reduce the deactivation of PRP during freezing and storage. The experimental findings suggest that PRP exhibits sustained activity, facilitating the process of wound healing even after a storage period of 180 days. Furthermore, the protective mechanism of PRP by the triple-layered core-shell fiber was investigated, and the conditions for freeze-drying and storage were optimized, further enhancing the long-term storability of PRP. As a result, the multifunctional core-shell fiber dressings developed in this study offer a novel approach for sustained growth factor release and the enduring preservation of active PRP.

Biodegradable Polymers in Veterinary Medicine-A Review

During the past two decades, tremendous progress has been made in the development of biodegradable polymeric materials for various industrial applications, including human and veterinary medicine. They are promising alternatives to commonly used non-degradable polymers to combat the global plastic waste crisis. Among biodegradable polymers used, or potentially applicable to, veterinary medicine are natural polysaccharides, such as chitin, chitosan, and cellulose as well as various polyesters, including poly(ε-caprolactone), polylactic acid, poly(lactic-co-glycolic acid), and polyhydroxyalkanoates produced by bacteria. They can be used as implants, drug carriers, or biomaterials in tissue engineering and wound management. Their use in veterinary practice depends on their biocompatibility, inertness to living tissue, mechanical resistance, and sorption characteristics. They must be designed specifically to fit their purpose, whether it be: (1) facilitating new tissue growth and allowing for controlled interactions with living cells or cell-growth factors, (2) having mechanical properties that address functionality when applied as implants, or (3) having controlled degradability to deliver drugs to their targeted location when applied as drug-delivery vehicles. This paper aims to present recent developments in the research on biodegradable polymers in veterinary medicine and highlight the challenges and future perspectives in this area.

Chitosan sponges loaded with metformin and microalgae as dressing for wound healing: A study in diabetic bio-models

Among the conditions caused by diabetes, the diabetic foot is a significant public health problem due to its delayed healing process. That makes it essential to design, manufacture, and apply auxiliary dressings during healing. In this work, chitosan sponges were developed and evaluated as wound dressings. Metformin, fucoidan, and exopolysaccharide from Porphyridium purpureum algae were loaded into the sponges and studied as healing promoters. The composite sponges were physicochemically, morphologically, and thermally characterized, allowing us to determine the chemical mechanisms involved in the sponge formation. The mechanical analysis demonstrated that sponge composites have shape memory and good mechanical performance under compression stress, showing a compressive strength above 30 kPa. These results correlated with the materials' porosity, influencing the swelling capacity that reached a maximum of 70 %. The morphology of materials was observed by SEM, resulting in folded films with surface porosity. The results of the biocompatibility tests confirmed that the materials are not cytotoxic or hemolytic and have good antibacterial activity. In vivo wound healing evaluation showed that metformin-loaded chitosan sponges regenerated skin tissue after 21 days of treatment, highlighting the rate of healing provided when exopolysaccharide was added to promote tissue regeneration, which can be corroborated by histological analysis. These results make chitosan sponge compounds promising dressings for diabetic foot wound treatment.

Chitosan-Based Dressing as a Sustained Delivery System for Bioactive Cytokines

Wounds represent a common occurrence in human life. Consequently, scientific investigations are underway to advance wound healing methodologies, with a notable focus on dressings imbued with biologically active compounds capable of orchestrating the wound microenvironment through meticulously regulated release mechanisms. Among these bioactive agents are cytokines, which, when administered to the wound milieu without appropriate protection, undergo rapid loss of their functional attributes. Within the context of this research, we present a method for fabricating dressings enriched with G-CSF (granulocyte colony-stimulating factor) or GM-CSF (granulocyte-macrophage colony-stimulating factor), showcasing both biological activity and protracted release dynamics. Based on Ligasano, a commercial polyurethane foam dressing, and chitosan crosslinked with TPP (sodium tripolyphosphate), these dressings are noncytotoxic and enable cytokine incorporation. The recovery of cytokines from dressings varied based on the dressing preparation and storage techniques (without modification, drying, freeze-drying followed by storage at 4 °C or freeze-drying followed by storage at 24 °C) and cytokine type. Generally, drying reduced cytokine levels and their bioactivity, especially with G-CSF. The recovery of G-CSF from unmodified dressings was lower compared to GM-CSF (60% vs. 80%). In summary, our freeze-drying approach enables the storage of G-CSF or GM-CSF enriched dressings at 24 °C with minimal cytokine loss, preserving their biological activity and thus enhancing future clinical availability.

Preparation and comparison of two medical dressings made from the collagens from fish and bovine

Collagen is used in medical dressings because of its high hydrophilicity, low immunogenicity, excellent biocompatibility, and degradability. These features can promote cell proliferation and platelet agglomeration. Herein, we studied the preparation of gel dressing by using silver carp skin collagen and bovine collagen as raw materials. Their properties and the application effects of collagen gel dressing were evaluated and compared. The centrifugal stability, rheology, and water-loss rate of silver carp skin collagen gel (SCG) and bovine tendon collagen gel (CTG) were determined. Results showed that the two gels were stable, and SCG had better rheology and ductility than CTG. However, the denaturation temperature and water-retention rate of SCG were slightly lower than those of CTG. Two collagen gels were used in the burn-repair experiment of KM mice. Results showed that the SCG and CTG were consistent with the wound-repair effect of commercially available products for shallow II-degree scald and deep II-degree scald. In the superficial shallow II scald experiment, SCG had a faster healing rate in the first 8 days and a shorter recovery time than CTG. In the deep II-degree scald experiment, the wound-healing rate of SCG on the 14th day reached 94.24%, which was 2 days faster than the recovery time of CTG. Moreover, the skin after wound healing was shallower than the scar produced after CTG treatment. Therefore, SCG had the potential to be used as the medical dressing.

Sustainable functionalized chitosan based nano-composites for wound dressings applications: A review

Functionalized chitosan nanocomposites have been studied for wound dressing applications due to their excellent antibacterial and anti-fungal properties. Polysaccharides show excellent antibacterial and drug-release properties and can be utilized for wound healing. In this article, we comprise distinct approaches for chitosan functionalization, such as photosensitizers, dendrimers, graft copolymerization, quaternization, acylation, carboxyalkylation, phosphorylation, sulfation, and thiolation. The current review article has also discussed brief insights on chitosan nanoparticle processing for biomedical applications, including wound dressings. The chitosan nanoparticle preparation technologies have been discussed, focusing on wound dressings owing to their targeted and controlled drug release behavior. The future directions of chitosan research include; a) finding an effective solution for chronic wounds, which are unable to heal completely; b) providing effective wound healing solutions for diabetic wounds and venous leg ulcers; c) to better understanding the wound healing mechanism with such materials which can help provide the optimum solution for wound dressing; d) to provide an improved treatment option for wound healing.

The effect of different hemostatic agents following dental extraction in patients under oral antithrombotic therapy: a network meta-analysis

This network meta-analysis was done to thoroughly evaluate the available literature on the use of different hemostatic agents for dental extraction in patients under oral antithrombotic therapy, aiming to identify the agent with the best/worst performance in bleeding control. Considering that such patients have a higher risk of bleeding, choosing the right hemostatic is essential. Twenty-three randomized clinical trials articles were included after completing the literature search. Cyanoacrylate tissue adhesive showed a reduction in the odds of postoperative bleeding events compared with conventional methods (i.e., gauze/cotton pressure, sutures), with a tendency toward a statistical significance (OR 0.03, P = 0.051). Tranexamic acid was the only agent that demonstrated a significantly lower risk of developing postoperative bleeding events (OR 0.27, P = 0.007). Interestingly, chitosan dental dressing and collagen plug had the shortest time to reach hemostasis. However, they ranked last among all hemostatic agents, regarding bleeding events, revealing higher odds than conventional measures. Therefore, it is concluded that the use of cyanoacrylate tissue adhesive and tranexamic acid gives favorable results in reducing postoperative bleeding events following dental extractions. Although chitosan dental dressing and collagen exhibited a faster time to reach hemostasis, they led to a higher occurrence of bleeding events.

Application of Polymer Hydrogels in the Prevention of Postoperative Adhesion: A Review

Postoperative adhesion is a common post-surgery complication formed between the surface of the body cavity, ranging from a layer of connective tissue to a fibrous bridge containing blood vessels and nerve tissue. Despite achieving a lot of progress, the mechanisms of adhesion formation still need to be further studied. In addition, few current treatments are consistently effective in the prevention of postoperative adhesion. Hydrogel is a kind of water-expanding crosslinked hydrophilic polymer network generated by a simple reaction of one or more monomers. Due to the porous structure, hydrogels can load different drugs and control the drug release kinetics. Evidence from existing studies has confirmed the feasibility and superiority of using hydrogels to counter postoperative adhesions, primarily due to their outstanding antifouling ability. In this review, the current research status of hydrogels as anti-adhesion barriers is summarized, the character of hydrogels in the prevention of postoperative adhesion is briefly introduced, and future research directions are discussed.

Water-soluble chitosan-g-PMAm (PMAA)-Bodipy probes prepared by RAFT methods for the detection of Fe3+ ion

It is a challenge to achieve the fully water-soluble chitosan. In this work, water-soluble chitosan-based probes were obtained by the following steps: boron-dipyrrolemethene (BODIPY)-OH was synthesized, and then BODIPY-OH was halogenated to BODIPY-Br. Afterwards, BODIPY-Br reacted with carbon disulfide and mercaptopropionic acid to obtain BODIPY-disulfide. BODIPY-disulfide was introduced to chitosan via amidation reaction to obtain fluorescent chitosan-thioester (CS-CTA); it is employed as the macro-initiator. Methacrylamide (MAm) was grafted onto chitosan fluorescent thioester through reversible addition-fragmentation chain transfer (RAFT) polymerization method. Thus, a water-soluble macromolecular probe (CS-g-PMAm) with chitosan as the main chain and PMAm as long-branched chains was obtained. It greatly improved the solubility in pure water. The thermal stability was reduced slightly, and the stickiness was greatly reduced and the samples displayed the characteristics of liquid. CS-g-PMAm could detect Fe³⁺ in pure water. By the same method, CS-g-PMAA (CS-g-Polymethylacrylic acid) was synthesized and investigated as well.

Bioactivity and Thermal Stability of Collagen-Chitosan Containing Lemongrass Essential Oil for Potential Medical Applications

Bioactive collagen–chitosan–lemongrass (COL–CS–LG) membranes were prepared by casting method and analyzed for potential biomedical applications. For COL–CS–LG membranes, LG essential oil release, antioxidant properties, in vitro cytotoxicity and antimicrobial assessments were conducted, as well as free radical determination after gamma irradiation by chemiluminescence, and structural characteristics analysis through Attenuated Total Reflection–Fourier Transform Infrared Spectroscopy (ATR–FTIR) and Differential Scanning Calorimetry (DSC). The evaluation of non-isothermal chemiluminescence after gamma radiation exposure to COL–CS–LG membranes revealed a slowing down of the oxidation process at temperatures exceeding 200 °C, in correlation with antioxidant activity. Antimicrobial properties and minimum inhibitory concentrations were found to be in correlation with cytotoxicity limits, offering the optimum composition for designing new biomaterials.

Progress in the Degradability of Biodegradable Film Materials for Packaging

In today’s world, the problem of “white pollution” is becoming more and more serious, and many countries have paid special attention to this problem, and it has become one of the most important tasks to reduce polymer waste and to protect the environment. Due to the degradability, safety, economy and practicality of biodegradable packaging film materials, biodegradable packaging film materials have become a major trend in the packaging industry to replace traditional packaging film materials, provided that the packaging performance requirements are met. This paper reviews the degradation mechanisms and performance characteristics of biodegradable packaging film materials, such as photodegradation, hydrodegradation, thermo-oxidative degradation and biodegradation, focuses on the research progress of the modification of biodegradable packaging film materials, and summarizes some challenges and bottlenecks of current biodegradable packaging film materials.

Effects of Benzalkonium Chloride Contents on Structures, Properties, and Ultrafiltration Performances of Chitosan-Based Nanocomposite Membranes

The effects of benzalkonium chloride (BKC) contents on the structure, properties, and ultrafiltration performance of chitosan-based nanocomposite membranes containing poly(ethylene glycol) and multi-walled carbon nanotube (chitosan/BKC/PEG/CNT) were examined. The membranes were prepared by a mixing solution method and phase inversion before being characterized with microscopic techniques, tensile tests, thermogravimetric analysis, water contact angle, and porosity measurements. The performance of the nanocomposite membranes in regard to permeability (flux) and permselectivity (rejection) was examined. The results show that the incorporation of BKC produced nanocomposite membranes with smaller pore structures and improved physico-chemical properties, such as an increase in porosity and surface roughness (Ra = 45.15 to 145.35 nm and Rq = 53.69 to 167.44 nm), an enhancement in the elongation at break from 45 to 109%, and an enhancement in the mechanical strength from 31.2 to 45.8 MPa. In contrast, a decrease in the membrane hydrophilicity (water contact angle increased from 56.3 to 82.8°) and a decrease in the average substructure pore size from 32.64 to 10.08 nm were observed. The membrane rejection performances toward Bovine Serum Albumin (BSA) increased with the BKC composition in both dead-end and cross-flow filtration processes. The chitosan/BKC/PEG/CNT nanocomposite membranes have great potential in wastewater treatments for minimizing biofouling without reducing the water purification performance.

Application of Electrospinning in Antibacterial Field

In recent years, electrospun nanofibers have attracted extensive attention due to their large specific surface area, high porosity, and controllable shape. Among the many applications of electrospinning, electrospun nanofibers used in fields such as tissue engineering, food packaging, and air purification often require some antibacterial properties. This paper expounds the development potential of electrospinning in the antibacterial field from four aspects: fiber morphology, antibacterial materials, antibacterial mechanism, and application fields. The effects of fiber morphology and antibacterial materials on the antibacterial activity and characteristics are first presented, then followed by a discussion of the antibacterial mechanisms and influencing factors of these materials. Typical application examples of antibacterial nanofibers are presented, which show the good prospects of electrospinning in the antibacterial field.

Growth factor loading on aliphatic polyester scaffolds

Cells, scaffolds and growth factors are three elements of tissue engineering. The success of tissue engineering methods relies on precise and dynamic interactions between cells, scaffolds and growth factors. Aliphatic polyester scaffolds are promising tissue engineering scaffolds that possess good mechanical properties, low immunogenicity, non-toxicity, and adjustable degradation rates. How growth factors can be loaded onto/into aliphatic polyester scaffolds and be constantly released with the required bioactivity to regulate cell growth and promote defect tissue repair and regeneration has become the main concern of tissue engineering researchers. In this review, the existing main methods of loading growth factors on aliphatic polyester scaffolds, the release behavior of loaded growth factors and their positive effects on cell, tissue repair and regeneration are introduced. Advantages and shortcomings of each method also are mentioned. It is still a great challenge to control the release of loaded growth factors at a certain time and at a concentration simulating the biological environment of native tissue.

Paracetamol and other acetanilide analogs as inter-molecular hydrogen bonding assisted diamagnetic CEST MRI contrast agents

Paracetamol and a few other acetanilide derivatives are reported as a special class of diamagnetic Chemical Exchange Saturation Transfer (diaCEST) MRI contrast agents, that exhibit contrast only when the molecules form inter-molecular hydrogen bonding mediated molecular chains or sheets. Without the protection of the hydrogen bonding their contrast producing labile proton exchanges too quickly with the solvent to produce any appreciable contrast. Through a number of variable temperature experiments we demonstrate that under the conditions when the hydrogen bond network breaks and the high exchange returns back, the contrast drops quickly. The well-known analgesic drug paracetamol shows 12% contrast at a concentration of 15 mM at physiological conditions. With the proven safety track-record for human consumption and appreciable physiological contrast, paracetamol shows promise as a diaCEST agent for in vivo studies.

Toughened chitosan-based composite membranes with antibiofouling and antibacterial properties via incorporation of benzalkonium chloride

Biofouling due to biofilm formation is a major problem in ultrafiltration membrane applications. In this work, a potential approach to solve this issue has been developed by functionalization of chitosan-based membranes with benzalkonium chloride (BKC). The chitosan composite membranes consisting of poly(ethylene glycol) (PEG), multiwalled carbon nanotubes (MWCNT), and BKC were synthesized by mixing the membrane precursors and the antibacterial solution, and casting via an inversed phase technique. The effects of the BKC content on the morphology and performance of the membranes are investigated by varying the BKC feed compositions. The composite membranes demonstrate better antibacterial efficacy against Staphylococcus aureus than Escherichia coli. The permeability and selectivity performances of the composites as filter membranes are examined by employing a dead-end filtration system. Interestingly, enhanced toughness of the membranes is observed as a function of the BKC content. Mechanisms of the structural formation are investigated. The results from SEM, XRD, and FTIR spectroscopy revealed that MWCNT/BKC are located as nanoclusters with π–π stacking interactions, and are covered by PEG chains. The shape of the dispersed domains is spherical at low BKC contents, but becomes elongated at high BKC contents. These act as soft domains with an anisotropic shape with toughening of the brittle chitosan matrix, leading to enhanced durability of the membranes, especially in ultrafiltration applications. The composite membranes also demonstrate improved rejection in dead-end ultrafiltration systems due to high porosity, high hydrophilicity, and the positive charges of the membrane surface.

Chitosan/PEG/MWCNT/BKC membranes exhibit enhanced antibiofouling properties against S. aureus and E. coli. MWCNT/BKC are located as dispersed nano-clusters with π–π stacking interactions in the chitosan matrix, and are coved by PEG chains.

Sonophotocatalytic Degradation of Malachite Green by Nanocrystalline Chitosan-Ascorbic Acid@NiFe2O4 Spinel Ferrite

Statistics show that more than 700 thousand tons of dye are produced annually across the globe. Around 10–20% of this is used in industrial processes such as printing and dyeing, while about 50% of the dye produced is discharged into the environment without proper physicochemical treatment. Even trace amounts of dye in water can reduce oxygen solubility and have carcinogenic, mutagenic, and toxic effects on aquatic organisms. Therefore, before dye-containing wastewater is discharged into the environment, it must be properly treated. The present study investigates the green synthesis of nickel ferrite NiFe2O4 (NIFE) spinel magnetic nanoparticles (MNPs) via chemical coprecipitation of a solution of Ni2+/Fe3+ in the presence of a biopolymer blend of chitosan (CT) and ascorbic acid (AS). The magnetic nanomaterial was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy–energy dispersive X-ray analysis (SEM-EDX), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), differential scanning calorimetry (DSC), and vibrating-sample magnetometry (VSM). The material was further explored as a catalyst for the photocatalytic degradation of malachite green (MG) under visible light irradiation coupled with ultrasonic waves. The combination of 90 min of visible solar light irradiation with 6.35 W·mL−1 ultrasonic power at pH 8 resulted in 99% of the photocatalytic efficiency of chitosan-ascorbic acid@NIFE (CTAS@NIFE) catalyst for 70 mg·L−1 MG. The quenching of the photocatalytic efficiency from 98% to 64% in the presence of isopropyl alcohol (IPA) suggested the involvement of hydroxy (•OH) radicals in the mineralization process of MG. The high regression coefficients (R2) of 0.99 for 35, 55, and 70 mg·L−1 MG indicated the sonophotocatalysis of MG by CTAS@NIFE was best defined by a pseudo first-order kinetic model. The mechanism involves the adsorption of MG on the catalyst surface in the first step and thereby mineralization of the MG by the generated hydroxyl radicals (•OH) under the influence of visible radiation coupled with 6.34 W·mL−1 ultrasonic power. In the present study the application of photodegradation process with sonochemistry results in 99% of MG mineralization without effecting the material structure unlike happens in the case adsorption process. So, the secondary pollution (generally happens in case of adsorption) can be avoided by reusing the spent material for another application instead of disposing it. Thus, the ecofriendly synthesis protocol, ease in design of experimentation like use of solar irradiation instead of electric power lamps, reusability and high efficiency of the material suggested the study to be potentially economical for industrial development at pilot scale towards wastewater remediation.