Antimicrobial Activities of Chitosan Derivatives

Quaternary ammonium salts of chitosan containing aromatic ring: Synthesis, characterization, antimicrobial, antioxidant and cytotoxicity

Quaternary ammonium salts of chitosan have been widely used in the development of anti-microbial biomaterials for their important role in inhibiting the growth of microorganisms. However, it is important to modify its structure to obtain more efficient and biologically active derivatives. Herein, a series of chitosan derivatives with antibacterial, antifungal, antioxidant, and non-cytotoxic properties was synthesized. These four quaternary ammonium salts of chitosan were prepared by incorporating 2-thiophenecarboxaldehyde, 2-furancarboxaldehyde, 2-pyridinecarboxaldehyde and benzaldehyde to form Schiff bases, followed by a reductive amination to obtain the chitosan N-derivatives, and quaternized by iodomethane. The inhibition rate of thiophenecarboxaldehyde chitosan trimethyl ammonium iodide (TpTMC) to B. cinerea could reach 93.78 % and the inhibition ability of pyridinecarboxaldehyde chitosan trimethyl ammonium iodide (PyTMC) to F. graminearum could reach 98.08 % at the concentration of 1.0 mg/mL. Furthermore, furancarboxaldehyde chitosan trimethyl ammonium iodide (FrTMC) exhibited a strong ability to scavenge hydroxyl radicals and DPPH radicals, especially the DPPH radicals scavenging ability was comparable to that of l-ascorbic acid at the concentration of 1.6 mg/mL. The B3LYP/6-311++G (d,p) basis set was employed to determine electronic properties, including HOMO-LUMO energies, and to analyze the chemical reactivity of the compounds. L929 cells were used to evaluate the cytotoxicity of the compounds at different concentrations (1-1000 μg/mL). The results demonstrated the diverse applications of aromatic ring-modified quaternary ammonium salts of chitosan, along with their significant antioxidant and antifungal effects against plant fungi. Therefore, these compounds have potential applications in the preparation of agricultural, biological, and medical materials.

Electrospun Chitosan/Polylactic Acid Nanofibers with Silver Nanoparticles: Structure, Antibacterial, and Cytotoxic Properties

Electrospinning, a technique for creating fabric materials from polymer solutions, is widely used in various fields, including biomedicine. The unique properties of electrospun fibrous membranes, such as large surface area, compositional versatility, and customizable porous structure, make them ideal for advanced biomedical applications like tissue engineering and wound healing. By considering the high biocompatibility and well-known regenerative potential of polylactic acid (PLA) and chitosan (CH), as well as the versatile antibacterial effect of silver nanoparticles (AgNPs), this study explores the antibacterial efficacy, adhesive properties, and cytotoxicity of electrospun chitosan membranes with a unique nanofibrous structure and varying concentrations of AgNPs. Silver nanoparticles incorporated at concentrations of 25-50 μg/mL or above significantly enhanced the antibacterial effectiveness, especially against Staphylococcus aureus and Escherichia coli. Biocompatibility assessments using umbilical cord mesenchymal stem cells demonstrated the nontoxic nature of the membranes with an AgNP concentration of 12.5 μg/mL, underscoring their potential for biomedical applications. This study provides valuable insights into developing electrospun chitosan membranes as effective antimicrobial coatings for various biomedical uses, including wound healing patches and tissue engineering constructs for soft tissue replacement.

Chitosan and its derivatives: A novel approach to gut microbiota modulation and immune system enhancement

Chitosan, a biopolymer derived from the deacetylation of chitin found in crustacean shells and certain fungi, has attracted considerable attention for its promising health benefits, particularly in gut microbiota maintenance and immune system modulation. This review critically examines chitosan's multifaceted role in supporting gut health and enhancing immunity, beginning with a comprehensive overview of its sources, chemical structure, and its dual function as a dietary supplement and biomaterial. Chitosan's prebiotic effects are highlighted, with a focus on its ability to selectively stimulate beneficial gut bacteria, such as Bifidobacteria and Lactobacillus, while enhancing gut barrier integrity and inhibiting the growth of pathogenic microorganisms. The review delves deeply into chitosan's immunomodulatory mechanisms, including its impact on antigen-presenting cells, cytokine profiles, and systemic immune responses. A detailed comparative analysis assesses chitosan's efficacy relative to other prebiotics and immunomodulatory agents, examining challenges related to bioavailability and metabolic activity. Beyond its role in gut health, this review explores chitosan's potential as a dual-action agent that not only supports gut microbiota but also fortifies immune resilience. It introduces emerging research on novel chitosan derivatives, such as chitooligosaccharides, and evaluates their enhanced bioactivity for functional food applications. Special attention is given to sustainability, with an exploration of alternative, plant-based sources of chitosan and their implications for both health and environmental stewardship. Also, the review identifies new research avenues, such as the growing interest in chitosan's role in the gut-brain axis and its potential mental health benefits through microbial interactions. By addressing these innovative areas, the review aims to shift the focus from basic health effects to chitosan's broader impact on public health. The findings encourage further exploration, particularly through human trials, and emphasize chitosan's untapped potential in revolutionizing health and disease management.

Bifunctional Electrospun Nanocomposite Dressing: Integrating Antibacterial Efficacy and Controllable Antioxidant Properties for Expedited Wound Healing

Current wound dressings are insufficient in simultaneously addressing bacterial infections and oxidative stress, which severely affects wound healing outcomes. To solve this problem, we introduced poly(ionic liquid) (PIL) with strong antibacterial properties and cerium oxide nanoparticles (CeO2NPs) with excellent antioxidant capabilities into polyacrylonitrile (PAN) nanofiber membranes to prepare a novel composite dressing. The PIL-CeO2NPs-PAN nanofiber membrane provides sustained antibacterial activity through stably embedded PIL, while the uniformly distributed CeO2NPs achieve controlled release, avoiding safety issues caused by the rapid release of active substances. In vitro and in vivo experiments demonstrated that the membrane exhibits outstanding biocompatibility, significant antibacterial effects (inhibition rates of 88.3% against Escherichia coli and 93.2% against Staphylococcus aureus), and excellent antioxidant performance (64.7% reactive oxygen species scavenging rate). More importantly, PIL-CeO2NPs-PAN achieved a 94.1% wound healing rate within 14 days, significantly superior to traditional treatment methods. The results indicate that this composite membrane significantly improves wound healing by simultaneously resisting infection and oxidative stress, providing a safe and effective new option for clinical applications. Our work offers an innovative design strategy that combines antibacterial and antioxidant mechanisms for wound care.

Advances in proteins, polysaccharides, and composite biomaterials for enhanced wound healing via microenvironment management: A review

Wound management is crucial yet imposes substantial social and economic burdens on patients and healthcare systems. The recent rapid advancements in biomaterials and manufacturing technology have created favorable conditions for expediting wound healing. This review examines the latest developments in biomacromolecule-based wound dressings, with a particular focus on proteins and polysaccharides, and their role in modulating the wound microenvironment. The importance of extracellular matrix (ECM)-inspired materials, such as hydrogels and biomimetic dressings, is emphasized. Additionally, this review explores the functionalization of wound dressings, emphasizing properties such as hemostatic capabilities, pain relief, antimicrobial activity, and innovative smart functions like electroceuticals and wound condition monitoring. The study integrates discussions on both the macroscopic healing outcomes and the microscopic pathophysiological mechanisms, highlighting recent advances in managing wound environments to expedite healing. Finally, the review critically assesses the challenges associated with the clinical translation of these wound-healing materials in the future.

Factors influencing the antimicrobial mechanism of chitosan action and its derivatives: A review

Chitosan, a versatile amino polysaccharide biopolymer derived from chitin, exhibits broad-spectrum antimicrobial activity against various pathogenic microorganisms, including gram-negative and gram-positive bacteria, as well as fungi. Due to its ubiquitous use in medications, food, cosmetics, chemicals, and crops, it is an effective antibacterial agent. However, the antimicrobial performance of chitosan is influenced by multiple factors, which have been extensively investigated and reported in the literature. The goal of this review paper is to present a thorough grasp of the mechanisms of action and determining variables of chitosan and its derivatives' antibacterial activity. The article begins by providing a brief background on chitosan and its antimicrobial properties, followed by the importance of understanding the mechanism of action and factors influencing its activity".

Research and Application of Chitosan Nanoparticles in Orthopedic Infections

Orthopedic infection is one of the most intractable orthopedic problems. Bacteria resistant to antibiotics also develop gradually. Chitosan is widely used in the Biomedical field because of its high biocompatibility, biodegradability, and antibacterial activity. Chitosan-based drug delivery systems are frequently utilized to produce controlled medication release. When combined with antibiotics, synergistic antibacterial effects can be achieved. Chitosan-based nanoparticles are one of the most widely used applications in drug delivery systems. The focus of this review is to provide information on new methods being developed for chitosan-based nanoparticles in the field of bone infection treatment, including chitosan nanoparticles for antibacterial purposes, Ch-loaded with antibiotics, Ch-loaded with metal, and used as immune adjuvants. It may Provide ideas for the fundamental research and the prospects of future clinical applications of orthopedic infections.

Antibacterial Potential and Biocompatibility of Chitosan/Polycaprolactone Nanofibrous Membranes Incorporated with Silver Nanoparticles

This study addresses the need for enhanced antimicrobial properties of electrospun membranes, either through surface modifications or the incorporation of antimicrobial agents, which are crucial for improved clinical outcomes. In this context, chitosan-a biopolymer lauded for its biocompatibility and extracellular matrix-mimicking properties-emerges as an excellent candidate for tissue regeneration. However, fabricating chitosan nanofibers via electrospinning often challenges the preservation of their structural integrity. This research innovatively develops a chitosan/polycaprolactone (CH/PCL) composite nanofibrous membrane by employing a layer-by-layer electrospinning technique, enhanced with silver nanoparticles (AgNPs) synthesized through a wet chemical process. The antibacterial efficacy, adhesive properties, and cytotoxicity of electrospun chitosan membranes were evaluated, while also analyzing their hydrophilicity and nanofibrous structure using SEM. The resulting CH/PCL-AgNPs composite membranes retain a porous framework, achieve balanced hydrophilicity, display commendable biocompatibility, and exert broad-spectrum antibacterial activity against both Gram-negative and Gram-positive bacteria, with their efficacy correlating to the AgNP concentration. Furthermore, our data suggest that the antimicrobial efficiency of these membranes is influenced by the timed release of silver ions during the incubation period. Membranes incorporated starting with AgNPs at a concentration of 50 µg/mL effectively suppressed the growth of both microorganisms during the early stages up to 8 h of incubation. These insights underscore the potential of the developed electrospun composite membranes, with their superior antibacterial qualities, to serve as innovative solutions in the field of tissue engineering.

Biopolymer Drug Delivery Systems for Oromucosal Application: Recent Trends in Pharmaceutical R&D

Oromucosal drug delivery, both local and transmucosal (buccal), is an effective alternative to traditional oral and parenteral dosage forms because it increases drug bioavailability and reduces systemic drug toxicity. The oral mucosa has a good blood supply, which ensures that drug molecules enter the systemic circulation directly, avoiding drug metabolism during the first passage through the liver. At the same time, the mucosa has a number of barriers, including mucus, epithelium, enzymes, and immunocompetent cells, that are designed to prevent the entry of foreign substances into the body, which also complicates the absorption of drugs. The development of oromucosal drug delivery systems based on mucoadhesive biopolymers and their derivatives (especially thiolated and catecholated derivatives) is a promising strategy for the pharmaceutical development of safe and effective dosage forms. Solid, semi-solid and liquid pharmaceutical formulations based on biopolymers have several advantageous properties, such as prolonged residence time on the mucosa due to high mucoadhesion, unidirectional and modified drug release capabilities, and enhanced drug permeability. Biopolymers are non-toxic, biocompatible, biodegradable and may possess intrinsic bioactivity. A rational approach to the design of oromucosal delivery systems requires an understanding of both the anatomy/physiology of the oral mucosa and the physicochemical and biopharmaceutical properties of the drug molecule/biopolymer, as presented in this review. This review summarizes the advances in the pharmaceutical development of mucoadhesive oromucosal dosage forms (e.g., patches, buccal tablets, and hydrogel systems), including nanotechnology-based biopolymer nanoparticle delivery systems (e.g., solid lipid particles, liposomes, biopolymer polyelectrolyte particles, hybrid nanoparticles, etc.).

A spherical adsorbent produced from a bagasse biochar chitosan assembly for selective adsorption of platinum-group metals from wastewater

This study addresses the challenge of platinum-group metal scarcity by exploring the adsorption of these metals from industrial wastewater. An inexpensive adsorbent with selective platinum-group metal adsorption capacity, named chitosan/citric acid@diatomaceous earth-sugarcane bagasse (CTS/CA@DE-SBS), was newly synthesized. The material features a double coating of chitosan and diatomite on bagasse biochar, and it exhibits an excellent adsorption performance for platinum-group metals due to the synergistic effects of the biochar and chitosan-diatomaceous earth intercross-linked coatings. CTS/CA@DE-SBS achieved an 81 % adsorption efficiency and a static saturated adsorption capacity of 217 mg/g for Pt (IV) in water. Notably, the material exhibited selective adsorption properties for platinum-group metals dissolved in diverse aqueous solutions. The potential for the secondary recovery of platinum-group metals in complex aqueous bodies further underscores the significance of this adsorbent. In conclusion, this research introduces a promising solution for platinum-group metal shortages, offering a cost-effective and selective adsorbent with potential applications in the secondary recovery of these metals from industrial wastewater.

Antibacterial Activity of Zinc Oxide Nanoparticles Loaded with Essential Oils

One major problem with the overuse of antibiotics is that the microorganisms acquire resistance; thus the dose must be increased unsustainably. To overcome this problem, researchers from around the world are actively investigating new types of antimicrobials. Zinc oxide (ZnO) nanoparticles (NPs) have been proven to exhibit strong antimicrobial effects; moreover, the Food and Drugs Administration (FDA) considers ZnO as GRAS (generally recognized as safe). Many essential oils have antimicrobial activity and their components do not generate resistance over time. One of the drawbacks is the high volatility of some components, which diminishes the antimicrobial action as they are eliminated. The combination of ZnO NPs and essential oils can synergistically produce a stronger antimicrobial effect, and some of the volatile compounds can be retained on the nanoparticles' surface, ensuring a better-lasting antimicrobial effect. The samples were characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), and thermal analysis (TG-DSC) coupled with analysis of evolved gases using FTIR. The ZnO NPs, with a size of ~35 nm, exhibited a loading between 1.44% and 15.62%-the lower values were specific for limonene-containing oils (e.g., orange, grapefruit, bergamot, or limette), while high values were obtained from cinnamon, minzol, thyme, citronella, and lavender oils-highlighting differences among non-polar terpenes and alcohol or aldehyde derivatives. The antibacterial assay indicated the existence of a synergic action among components and a high dependency on the percentage of loaded oil. Loaded nanoparticles offer immense potential for the development of materials with specific applications, such as wound dressings or food packaging. These nanoparticles can be utilized in scenarios where burst delivery is desired or when prolonged antibacterial activity is sought.

Influence of the Alcohols on the ZnO Synthesis and Its Properties: The Photocatalytic and Antimicrobial Activities

Zinc oxide (ZnO) nanomaterials are used in various health-related applications, from antimicrobial textiles to wound dressing composites and from sunscreens to antimicrobial packaging. Purity, surface defects, size, and morphology of the nanoparticles are the main factors that influence the antimicrobial properties. In this study, we are comparing the properties of the ZnO nanoparticles obtained by solvolysis using a series of alcohols: primary from methanol to 1-hexanol, secondary (2-propanol and 2-butanol), and tertiary (tert-butanol). While the synthesis of ZnO nanoparticles is successfully accomplished in all primary alcohols, the use of secondary or tertiary alcohols does not lead to ZnO as final product, underlining the importance of the used solvent. The shape of the obtained nanoparticles depends on the alcohol used, from quasi-spherical to rods, and consequently, different properties are reported, including photocatalytic and antimicrobial activities. In the photocatalytic study, the ZnO obtained in 1-butanol exhibited the best performance against methylene blue (MB) dye solution, attaining a degradation efficiency of 98.24%. The comparative study among a series of usual model dyes revealed that triarylmethane dyes are less susceptible to photo-degradation. The obtained ZnO nanoparticles present a strong antimicrobial activity on a broad range of microorganisms (bacterial and fungal strains), the size and shape being the important factors. This permits further tailoring for use in medical applications.

Symmetry between Structure–Antibacterial Effect of Polymers Functionalized with Phosphonium Salts

In actual context, when the terms of biomass and bioenergy are extensively used, it becomes clear that the comparative study of some biopolymers, such as cellulose and chitosan, can offer a large usage range, based on the scientific progress obtained in the biomaterials field. Starting from the structural similarity of these two polymers, we synthesized composite materials by grafting on their surface biocide substances (phosphonium salts). After testing the biocidal effect, we can conclude that the antibacterial effect depends on the ratio of support to phosphonium salt, influenced by the interaction between the cationic component of the biocides and by the anionic component of the bacterial cellular membrane. It was also observed that for the materials obtained by cellulose functionalization with tri-n-butyl-hexadecyl phosphonium bromide, the bacterial effect on E. coli strain was much better when chitosan was used as the support material.

Antimicrobial Activity of Cellulose Based Materials

Biomaterials available for a wide range of applications are generally polysaccharides. They may have inherent antimicrobial activity in the case of chitosan. However, in order to have specific functionalities, bioactive compounds must be immobilized or incorporated into the polymer matrix, as in the case of cellulose. We studied materials obtained by functionalizing cellulose with quaternary ammonium salts: dodecyl-trimethyl-ammonium bromide (DDTMABr), tetradecyl-trimethyl-ammonium bromide (TDTMABr), hexadecyl-trimethyl ammonium chloride (HDTMACl), some phosphonium salts: dodecyl-triphenyl phosphonium bromide (DDTPPBr) and tri n-butyl-hexadecyl phosphonium bromide (HDTBPBr) and extractants containing sulphur: 2-mercaptobenzothiazole (MBT) and thiourea (THIO). Cel-TDTMABr material, whose alkyl substituent chain conformation was shortest, showed the best antimicrobial activity for which, even at the lowest functionalization ratio, 1:0.012 (w:w), the microbial inhibition rate is 100% for Staphylococcus aureus, Escherichia coli, and Candida albicans. Among the materials obtained by phosphonium salt functionalization, Cel-DDTPPBr showed a significant bactericidal effect compared to Cel-HDTBPBr. For instance, to the same functionalization ratio = 1:0.1, the inhibition microbial growth rate is maximum in the case of Cel-DDTPPBr for Staphylococcus aureus, Escherichia coli, and Candida albicans. At the same time, for the Cel-HDTBPBr material, the total bactericidal effect is not reached even at the functionalization ratio 1:0.5. This behavior is based on the hydrophobicity difference between the two extractants, DDTPPBr and HDTBPBr. Cel-MBT material has a maximum antimicrobial effect upon Staphylococcus aureus, Escherichia coli, and Candida albicans at functionalized ratio = 1:0.5. Cel-THIO material showed a bacteriostatic and fungistatic effect, the inhibition of microbial growth being a maximum of 76% for Staphylococcus aureus at the functionalized ratio = 1:0.5. From this perspective, biomaterials obtained by SIR impregnation of cellulose can be considered a benefit to be used to obtain biomass-derived materials having superior antimicrobial properties versus the non-functional support.

The Expanded Role of Chitosan in Localized Antimicrobial Therapy

Chitosan is one of the most studied natural origin polymers for biomedical applications. This review focuses on the potential of chitosan in localized antimicrobial therapy to address the challenges of current rising antimicrobial resistance. Due to its mucoadhesiveness, chitosan offers the opportunity to prolong the formulation residence time at mucosal sites; its wound healing properties open possibilities to utilize chitosan as wound dressings with multitargeted activities and more. We provide an unbiased overview of the state-of-the-art chitosan-based delivery systems categorized by the administration site, addressing the site-related challenges and evaluating the representative formulations. Specifically, we offer an in-depth analysis of the current challenges of the chitosan-based novel delivery systems for skin and vaginal infections, including its formulations optimizations and limitations. A brief overview of chitosan's potential in treating ocular, buccal and dental, and nasal infections is included. We close the review with remarks on toxicity issues and remaining challenges and perspectives.