Imination of Microporous Chitosan Fibers-A Route to Biomaterials with "On Demand" Antimicrobial Activity and Biodegradation for Wound Dressings

Chitosan-Electrospun Fibers Encapsulating Norfloxacin: The Impact on the Biochemical, Oxidative and Immunological Profile in a Rats Burn Model

This study investigates the impact of chitosan-based nanofibers on burn wound healing in a rat model. Two formulations of chitosan nanofibers were prepared through electrospinning. The formulations were then incorporated with different amounts of norfloxacin and underwent surface modifications with 2-formylphenylboronic acid. The burn model was applied to Wistar male rats by the contact method, using a heated steel rod attached to a thermocouple. The effectiveness of the nanofibers was tested against a negative control group and a standard commercial dressing (Atrauman Ag) on the described model and evaluated by wound diameter, histological analysis and biochemical profiling of systemic inflammatory markers. The results showed that chitosan-based dressings significantly accelerated burn healing compared to the control treatments. The high-concentration norfloxacin-infused chitosan coated with 2-formylphenylboronic acid' groups exhibited significant improvements in wound closure and reduced inflammation compared to the other groups; antioxidant enzymes SOD and GPx expression was significantly higher, p < 0.05, whereas pro-oxidative markers such as cortisol were lower (p < 0.05). Macroscopically, the wound area itself was significantly diminished in the chitosan-treated groups (p < 0.05). Furthermore, a histological evaluation indicated enhanced epithelialization and granulation tissue formation within the experiment time frame, while the biochemical panel revealed lower levels of inflammatory cytokines and lower leukocyte counts in the treated groups. These findings highlight the potential of the studied chitosan nanofibers as novel nanosystems for next-generation wound therapies, as well as the clinical utility of the novel chitosan fibers obtained by electrospinning technique.

Capparis sepiaria-Loaded Sodium Alginate Single- and Double-Layer Membrane Composites for Wound Healing

Background: Effective wound dressing is the key solution to combating the increased death rate and prolonged hospital stay common to patients with wounds. Methods: Sodium alginate-based single- and double-layer membranes incorporated with Capparis sepiaria root extract were designed using the solvent-casting method from a combination of polyvinyl alcohol (PVA), Pluronic F127 (PF127), and gum acacia. Results: The successful preparation of the membranes and loading of the extract were confirmed using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The prepared membranes were biodegradable and non-toxic to human skin cells (HaCaT), with high biocompatibility of 92 to 112% cell viability and good hemocompatibility with absorbance ranging from 0.17 to 0.30. The membrane's highest water vapor transmission rate was 1654.7333 ± 0.736 g/m2/day and the highest % porosity was 76%. The membranes supported cellular adhesion and migration, with the highest closure being 68% after 4 days compared with the commercial wound dressings. This membrane exhibited enhanced antimicrobial activity against the pathogens responsible for wound infections. Conclusions: The distinct features of the membranes make them promising wound dressings for treating infected wounds.

Preparation and characterization of structural and antifouling properties of chitosan/polyethylene oxide membranes

It aims to prepare the chitosan (CS) and polyethylene oxide (PEO) hydrogel membranes with different CS/PEO blend ratios (100:0, 95:5, 90:10, 80:20 and 70:30) via solvent casting. The physicochemical properties of these membranes were investigated using various characterization techniques: Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray (EDX), contact angle, and tensile testing. The interaction of PEO and chitosan was investigated by DSC in terms of freezing bound, freezing free, and non-freezing PEO fraction. The cross-sectional surface morphology of membranes displayed a smoother surface with increasing PEO content up to 20 %, beyond which nonhomogeneity on the surface was visible. The antifouling behavior of membranes was investigated by bacterial adherence study, which showed an enhanced antifouling nature of membranes with the increase in the PEO content. The peeling strength of the membranes was measured using a 90° angle peeling test, and it was found that 20 % and more PEO content promotes easy removal from the gelatin slab. In addition to this, live/ dead assay of the CS was performed to visualize the presence of live and dead bacteria on the surface. The CS/PEO blend with 20 % PEO content has properties makes it suitable for use as a protective layer on wound dressings to prevent bacterial growth. It's use in wound dressings has the potential to reduce the pain during the time of dressing removal and improve patient outcomes. The present investigation leads to the development of a CS hydrogel matrix which exhibits very interesting interaction with the PEO moiety along with its innovative feature of antifouling and antimicrobial nature.

The impact of copper nanoparticles surfactant on the structural and biological properties of chitosan/sodium alginate wound dressings

Multifunctional wound dressings based on hydrogels are an efficacious and practicable strategy in therapeutic processes and accelerated chronic wound healing. Here, copper (Cu) nanoparticles were added to chitosan/sodium alginate (CS/SA) hydrogels to improve the antibacterial properties of the prepared wound dressings. Due to the super-hydrophobicity of Cu nanoparticles, polyethylene glycol (PEG) was used as a surfactant, and then added to the CS/SA-based hydrogels. The CS/SA/Cu hydrogels were synthesized with 0, 2, 3.5, and 5 wt% Cu nanoparticles. The structural and morphological properties in presence of PEG were evaluated using Fourier-transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), and field emission scanning electron microscopy (FESEM). The biodegradation and swelling properties of the hydrogels were investigated in phosphate buffer saline (PBS) at 37 °C for up to 30 days. Cell viability and adhesion, as well as antibacterial behavior, were investigated via MTT assay, FESEM, and disk diffusion method, respectively. The obtained results showed that PEG provided new intra- and intermolecular bonds that affected significantly the hydrogels' degradation and swelling ratio, which increased up to ~1200 %. Cell viability reached ~110 % and all samples showed remarkable antibacterial behavior when CS/SA/Cu containing 2 wt% was introduced. This study provided new insights regarding the use of PEG as a surfactant for Cu nanoparticles in CS/SA hydrogel wound dressing, ultimately affecting the chemical bonding and various properties of the prepared hydrogels.

Polyphenolic Nanomedicine Regulating Mitochondria REDOX for Innovative Cancer Treatment

Cancer remains a highly lethal disease globally. The approach centered on REDOX-targeted mitochondrial therapy for cancer has displayed notable benefits. Plant polyphenols exhibit strong REDOX and anticancer properties, particularly by affecting mitochondrial function, yet their structural instability and low bioavailability hinder their utility. To overcome this challenge, researchers have utilized the inherent physical and chemical characteristics of polyphenols and their derivatives to develop innovative nanomedicines for targeting mitochondria. This review examines the construction strategies and anticancer properties of various types of polyphenol-based biological nanomedicine for regulating mitochondria in recent years, such as polyphenol self-assembly, metal-phenol network, polyphenol-protein, polyphenol-hydrogel, polyphenol-chitosan, and polyphenol-liposome. These polyphenolic nanomedicines incorporate enhanced features such as improved solubility, efficient photothermal conversion capability, regulation of mitochondrial homeostasis, and ion adsorption through diverse construction strategies. The focus is on how these polyphenol nanomedicines promote ROS production and their mechanism of targeting mitochondria to inhibit cancer. Furthermore, it delves into the benefits and applications of polyphenolic nanomedicine in cancer treatments, as well as the challenges for future research.

Trends in the Incorporation of Antiseptics into Natural Polymer-Based Nanofibrous Mats

Nanofibrous materials represent a very promising form of advanced carrier systems that can be used industrially, especially in regenerative medicine as highly functional bandages, or advanced wound dressings. By incorporation of antimicrobial additives directly into the structure of the nanofiber carrier, the functionality of the layer is upgraded, depending on the final requirement-bactericidal, bacteriostatic, antiseptic, or a generally antimicrobial effect. Such highly functional nanofibrous layers can be prepared mostly by electrospinning technology from both synthetic and natural polymers. The presence of a natural polymer in the composition is very advantageous. Especially in medical applications where, due to the presence of the material close to the human body, the healing process is more efficient and without the occurrence of an unwanted inflammatory response. However, converting natural polymers into nanofibrous form, with a homogeneously distributed and stable additive, is a great challenge. Thus, a combination of natural and synthetic materials is often used. This review clearly summarizes the issue of the incorporation and effectiveness of different types of antimicrobial substances, such as nanoparticles, antibiotics, common antiseptics, or substances of natural origin, into electrospun nanofibrous layers made of mostly natural polymer materials. A section describing the problematic aspects of antimicrobial polymers is also included.

Theoretical-Experimental Approach of Chitosan/Quaternized Chitosan Nanofibers' Behavior in Wound Exudate Media

This study aimed to investigate the behavior of chitosan/quaternized chitosan fibers in media mimicking wound exudates to understand their capacities as wound dressing. Fiber analysis of the fibers using dynamic vapor sorption proved their ability to adsorb moisture up to 60% and then to desorb it as a function of humidity, indicating their outstanding breathability. Dissolution analyses showed that quaternized chitosan leached from the fibers in water and PBS, whereas only small portions of chitosan were solubilized in water. In media containing lysozyme, the fibers degraded with a rate determined by their composition and pH, reaching a mass loss of up to 47% in media of physiologic pH. Notably, in media mimicking the wound exudate during healing, they adsorbed moisture even when their mass loss due to biodegradation was high, whereas they were completely degraded in the media of normal tissues, indicating bioabsorbable dressing capacities. A mathematical model was constructed, which characterized the degradation rate and morphology changes of chitosan/quaternized chitosan fibers through analyses of dynamics in scale space, using the Theory of Scale Relativity. The model was validated using experimental data, making it possible to generalize it to the degradation of other biopolymeric systems that address wound healing.

Mesoporous chitosan nanofibers loaded with norfloxacin and coated with phenylboronic acid perform as bioabsorbable active dressings to accelerate the healing of burn wounds

The paper reports new chitosan-based nanofibers, designed to address the healing of burn wounds. To this aim, mesoporous chitosan fiber mats were prepared by electrospinning using poly(ethylene oxide) as sacrificial additive, followed by loading with norfloxacin and coating with an antifungal agent via dynamic imine bonds. Dynamic vapor sorption experiment proved intra-fiber mesopores around 2.7 nm, and UV-vis, FTIR, and NMR spectroscopy confirmed the norfloxacin embedding and the imination reaction. SEM, AFM and POM techniques displayed semicrystalline nanofibers with average diameter around 170 nm entangled into a non-woven mat. Their mesoporous nature favored a rapid adsorption of fluids up to 17 g/g, and a biodegradation rate fitting the wound healing rate, i.e. up to 30 % mass loss in media of pH characteristic to wound exudate and total degradation in that characteristic to normal dermis. The composite fibers released the NFX and 2FPBA in a controlled manner, and showed antimicrobial activity against gram positive, gram negative and fungal strains. They had no cytotoxic effect on normal human dermal fibroblasts, and showed biocompatibility on experimental rats. The investigation of wound healing ability on second/third-degree burn model in rats revealed wound closure and total restoration of the fully functional dermis and epidermis.

Biodegradable trimethyl chitosan nanofiber mats by electrospinning as bioabsorbable dressings for wound closure and healing

The paper aimed to prepare quaternary chitosan-based nanofibers as bioabsorbable wound dressings. To this aim, fully biodegradable chitosan/N,N,N-trimethyl chitosan (TMC) nanofibers were designed and prepared via electrospinning, using poly(ethylene glycol) as sacrificial additive. The new biomaterials were structurally and morphologically characterized by FTIR and NMR spectroscopy, thermogravimetric analysis, X-ray diffraction and scanning electron microscopy, and their properties required for wound dressings application were investigated and discussed in detail. Thus, the nanofiber behavior was investigated by swelling, dynamic vapor sorption, and in vitro biodegradation in media mimicking the wound exudate. The mechanical properties were analysed from the stress-strain curves, the bioadhesivity from the texture analysis and the mucoadhesivity from the Zeta potential and transmittance measurements. The antimicrobial activity was assessed against S. aureus and E. coli strains, and the biocompatibility was tested in vitro on normal human dermal fibroblasts, and in vivo on rats. The application of the fiber mats with the best balance of properties as dressings on deep burn wound models in rats showed wound closure and active healing, with fully restoration of epithelia. It was concluded that the combination of chitosan with TMC into nanofibers provides new potential bioabsorbable wound dressing, opening new perspectives in regenerative medicine.

Quaternized chitosan (nano)fibers: A journey from preparation to high performance applications

The industrial production of chitosan, initiated over 50 years ago, has transformed its application across diverse industries, agriculture, and medicine. To enhance its properties, numerous chitosan derivatives have been synthesized. The quaternization of chitosan has proven beneficial, as it not only enhances its properties but also imparts water solubility, expanding its potential for a wider range of applications. Specifically, the utilization of quaternized chitosan-based nanofibers has leveraged the synergistic benefits of quaternized chitosan (including hydrophilicity, bioadhesiveness, antimicrobial, antioxidant, hemostatic, and antiviral activities, as well as ionic conductivity) in combination with the distinctive characteristics of nanofibers (such as a high aspect ratio and 3D architecture). This combination has permitted numerous possibilities, spanning from wound dressings, air and water filters, drug delivery scaffolds, antimicrobial textiles, to energy storage systems and alkaline fuel cells. In this comprehensive review, we examine the preparation methods, properties, and applications of various composite fibers containing quaternized chitosan. The advantages and disadvantages of each method and composition are meticulously summarized, while relevant diagrams and figures illustrate the key findings.

Quaternized chitosan/chitosan nanofibrous mats: An approach toward bioactive materials for tissue engineering and regenerative medicine

Chitosan based nanofibers are emerging biomaterials with a plethora of applications, especially in medicine and healthcare. Herein, binary quaternized chitosan/chitosan fibers are reported for the first time. Their preparation strategy consisted in the electrospinning of ternary chitosan/quaternized chitosan/poly(ethylene oxide) solutions followed by the selective removal of poly(ethylene oxide). Their morphology and performances were systematically investigated and discussed in detail. It was found that the fibers had reversible water vapor adsorption/desorption and showed swelling degrees similar to commercial wound dressings. They presented good mechanical properties and the content of quaternized chitosan modulated their bioadhesion, mucoadhesion and biodegradation rate and conferred them strong antimicrobial activity. Tests on normal human fibroblasts confirmed their safely use in contact with tissues and the biocompatibility investigation on rats showed no harmful effect when subcutaneous implanted. All these proved the binary quaternized chitosan/chitosan fibers as bioactive materials suitable for tissue regeneration, wound healing and drug delivery systems.

Electrospinning of Potential Medical Devices (Wound Dressings, Tissue Engineering Scaffolds, Face Masks) and Their Regulatory Approach

Electrospinning is the simplest and most widely used technology for producing ultra-thin fibers. During electrospinning, the high voltage causes a thin jet to be launched from the liquid polymer and then deposited onto the grounded collector. Depending on the type of the fluid, solution and melt electrospinning are distinguished. The morphology and physicochemical properties of the produced fibers depend on many factors, which can be categorized into three groups: process parameters, material properties, and ambient parameters. In the biomedical field, electrospun nanofibers have a wide variety of applications ranging from medication delivery systems to tissue engineering scaffolds and soft electronics. Many of these showed promising results for potential use as medical devices in the future. Medical devices are used to cure, prevent, or diagnose diseases without the presence of any active pharmaceutical ingredients. The regulation of conventional medical devices is strict and carefully controlled; however, it is not yet properly defined in the case of nanotechnology-made devices. This review is divided into two parts. The first part provides an overview on electrospinning through several examples, while the second part focuses on developments in the field of electrospun medical devices. Additionally, the relevant regulatory framework is summarized at the end of this paper.

TEGylated Phenothiazine-Imine-Chitosan Materials as a Promising Framework for Mercury Recovery

This paper reports new solid materials based on TEGylated phenothiazine and chitosan, with a high capacity to recover mercury ions from aqueous solutions. They were prepared by hydrogelation of chitosan with a formyl derivative of TEGylated phenothiazine, followed by lyophilization. Their structural and supramolecular characterization was carried out by 1H-NMR and FTIR spectroscopy, as well as X-ray diffraction and polarized light microscopy. Their morphology was investigated by scanning electron microscopy and their photophysical behaviour was examined by UV/Vis and emission spectroscopy. Swelling evaluation in different aqueous media indicated the key role played by the supramolecular organization for their hydrolytic stability. Mercury recovery experiments and the analysis of the resulting materials by X-ray diffraction and FTIR spectroscopy showed a high ability of the studied materials to bind mercury ions by coordination with the sulfur atom of phenothiazine, imine linkage, and amine units of chitosan.

Chitosan versus Carboxymethyl Chitosan Cryogels: Bacterial Colonization, Human Embryonic Kidney 293T Cell Culturing and Co-Culturing

The potential of chitosan and carboxymethyl chitosan (CMC) cryogels cross-linked with diglycidyl ether of 1,4-butandiol (BDDGE) and poly(ethylene glycol) (PEGDGE) have been compared in terms of 3D culturing HEK-293T cell line and preventing the bacterial colonization of the scaffolds. The first attempts to apply cryogels for the 3D co-culturing of bacteria and human cells have been undertaken toward the development of new models of host-pathogen interactions and bioimplant-associated infections. Using a combination of scanning electron microscopy, confocal laser scanning microscopy, and flow cytometry, we have demonstrated that CMC cryogels provided microenvironment stimulating cell-cell interactions and the growth of tightly packed multicellular spheroids, while cell-substrate interactions dominated in both chitosan cryogels, despite a significant difference in swelling capacities and Young's modulus of BDDGE- and PEGDGE-cross-linked scaffolds. Chitosan cryogels demonstrated only mild antimicrobial properties against Pseudomonas fluorescence, and could not prevent the formation of Staphylococcus aureus biofilm in DMEM media. CMC cryogels were more efficient in preventing the adhesion and colonization of both P. fluorescence and S. aureus on the surface, demonstrating antifouling properties rather than the ability to kill bacteria. The application of CMC cryogels to 3D co-culture HEK-293T spheroids with P. fluorescence revealed a higher resistance of human cells to bacterial toxins than in the 2D co-culture.

Erythromycin Formulations—A Journey to Advanced Drug Delivery

Erythromycin (ERY) is a macrolide compound with a broad antimicrobial spectrum which is currently being used to treat a large number of bacterial infections affecting the skin, respiratory tract, intestines, bones and other systems, proving great value from a clinical point of view. It became popular immediately after its discovery in 1952, due to its therapeutic effect against pathogens resistant to other drugs. Despite this major advantage, ERY exhibits several drawbacks, raising serious clinical challenges. Among them, the very low solubility in water and instability under acidic conditions cause a limited efficacy and bioavailability. Apart from this, higher doses promote drug resistance and undesirable effects. In order to overcome these disadvantages, during the past decades, a large variety of ERY formulations, including nanoparticles, have emerged. Despite the interest in ERY-(nano)formulations, a review on them is lacking. Therefore, this work was aimed at reviewing all efforts made to encapsulate ERY in formulations of various chemical compositions, sizes and morphologies. In addition, their preparation/synthesis, physico-chemical properties and performances were carefully analysed. Limitations of these studies, particularly the quantification of ERY, are discussed as well.

Self-Healing Chitosan Hydrogels: Preparation and Rheological Characterization

The paper aims at the preparation of chitosan self-healing hydrogels, designed as carriers for local drug delivery by parenteral administration. To this aim, 30 hydrogels were prepared using chitosan and pyridoxal 5-phosphate (P5P), the active form of vitamin B6 as precursors, by varying the ratio of glucosamine units and aldehyde on the one hand and the water content on the other hand. The driving forces of hydrogelation were investigated by nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction, and polarized light microscopy (POM) measurements. NMR technique was also used to investigate the stability of hydrogels over time, and their morphological particularities were assessed by scanning electron microscopy (SEM). Degradability of the hydrogels was studied in media of four different pH, and preliminary self-healing ability was visually established by injection through a syringe needle. In-depth rheological investigation was conducted in order to monitor the storage and loss moduli, linear viscoelastic regime, and structural recovery capacity. It was concluded that chitosan crosslinking with pyridoxal 5-phosphate is a suitable route to reach self-healing hydrogels with a good balance of mechanical properties/structural recovery, good stability over time, and degradability controlled by pH.

Infectious Inflammatory Processes and the Role of Bioactive Agent Released from Imino-Chitosan Derivatives Experimental and Theoretical Aspects

The paper focuses on the development of a multifractal theoretical model for explaining drug release dynamics (drug release laws and drug release mechanisms of cellular and channel-type) through scale transitions in scale space correlated with experimental data. The mathematical model has been developed for a hydrogel system prepared from chitosan and an antimicrobial aldehyde via covalent imine bonds. The reversible nature of the imine linkage points for a progressive release of the antimicrobial aldehyde is controlled by the reaction equilibrium shifting to the reagents, which in turn is triggered by aldehyde consumption in the inhibition of the microbial growth. The development of the mathematical model considers the release dynamic of the aldehyde in the scale space. Because the release behavior is dictated by the intrinsic properties of the polymer–drug complex system, they were explained in scale space, showing that various drug release dynamics laws can be associated with scale transitions. Moreover, the functionality of a Schrödinger-type differential equation in the same scale space reveals drug release mechanisms of channels and cellular types. These mechanisms are conditioned by the intensity of the polymer–drug interactions. It was demonstrated that the proposed mathematical model confirmed a prolonged release of the aldehyde, respecting the trend established by in vitro release experiments. At the same time, the properties of the hydrogel recommend its application in patients with intrauterine adhesions (IUAs) complicated by chronic endometritis as an alternative to the traditional antibiotics or antifungals.

Chitosan crosslinking with a vanillin isomer toward self-healing hydrogels with antifungal activity

The purpose of the study was to develop new antimicrobial hydrogels from natural resources that may promote wound healing and prevent bacterial skin infection. The new hydrogels were synthesized by crosslinking chitosan with a vanillin isomer, 5-methoxysalicylaldehyde, by a friendly and easy method. To characterize these hydrogels, their structural and morphological properties were explored by FTIR, ¹H NMR, SEM, POM, and TGA. In view of the targeted application, swelling behavior, biodegradability, antimicrobial activity and biocompatibility were investigated in vitro. Structural and morphological studies confirmed the formation of new hydrogels via the imination reaction concomitant with the supramolecular organization. The hydrogels were highly porous with the average pore diameter around 80 μm, and a swelling rate controlled by the crosslinking density and medium pH. The hydrogels showed a progressive weight loss in the presence of lysozyme up to 35%, during 21 days of testing. They proved non-cytotoxic effect on Normal Human Dermal Fibroblasts using MTS test and powerful antifungal activity against Candida Albicans, as determined by disk diffusion assay. All these properties indicate the new hydrogels as a promising option for the treatment of various skin lesions.

Biocompatible Chitosan-Based Hydrogels for Bioabsorbable Wound Dressings

Supramolecular hydrogels based on chitosan and monoaldehydes are biomaterials with high potential for a multitude of bioapplications. This is due to the proper choice of the monoaldehyde that can tune the hydrogel properties for specific practices. In this conceptual framework, the present paper deals with the investigation of a hydrogel as bioabsorbable wound dressing. To this aim, chitosan was cross-linked with 2-formylphenylboronic acid to yield a hydrogel with antimicrobial activity. FTIR, NMR, and POM procedures have characterized the hydrogel from a structural and supramolecular point of view. At the same time, its biocompatibility and antimicrobial properties were also determined in vitro. Furthermore, in order to assess the bioabsorbable character, its biodegradation was investigated in vitro in the presence of lysosome in media of different pH, mimicking the wound exudate at different stages of healing. The biodegradation was monitored by gravimetrical measurements, SEM microscopy and fractal analyses of the images. The fractal dimension values and the lacunarity of SEM pictures were accurately calculated. All these successful investigations led to the conclusion that the tested materials are at the expected high standards.