Investigation of the properties of N-[(2-hydroxy-3-trimethylammonium) propyl] chloride chitosan derivatives

Preparation of a thermosensitive and antibacterial in situ gel using poloxamer-quaternized chitosan for sustained ocular delivery of Levofloxacin hydrochloride

In this study, a thermosensitive in situ gel with porous structure was developed using poloxamer (Po) and N-(2-hydroxy-3-trimethyl ammonium) propyl chitosan chloride (HTCC). The poloxamer-quaternized chitosan (Po-HTCC) in situ gel exhibited superior rheological property, water absorption capacity and antibacterial activity against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Streptococcus pyogenes, making it well-suited for ocular applications. Scanning electron microscope revealed a macroporous architecture with pore sizes ranging from 1 to 2 μm, suggesting that the gel has desirable breathability, corneal adhesion capability, and overall conformability. In vitro drug release assay was conducted with levofloxacin hydrochloride, demonstrating that sustained release over 48 h could be achieved at 34 °C, with approximately 80 % of the drug released within this timeframe. Computational simulations revealed substantial binding affinity between the material and the Escherichia coli outer membrane lipopolysaccharide-associated protein and corneal mucin. The protein showing the strongest binding energy to N-(2-hydroxy-3-trimethyl ammonium) propyl chitosan chloride (HTCC), as calculated by the Molecular Mechanics Generalized Born Surface Area Method (MM-GBSA), was LptD-LptE, with a binding energy of -61.14 ± 4.72 kcal/mol. These results underscore the potential of this system for effective and convenient ocular delivery with sustained drug release.

Biodegradable packaging paper derived from chitosan-based composite barrier coating for agricultural products preservation

Development of green packaging materials is essential to replace traditional plastics in fresh agricultural products preservation. Herein, a coated paper was designed by applying chitosan-based composite coating on paper substrate through a facile automatic coating method. The hydroxypropyl trimethyl ammonium chloride chitosan (HACC) was obtained by direct quaternization via the introduction of hydroxypropyl trimethyl ammonium chloride into the amino group of chitosan, then mixed with polyvinyl alcohol (PVA) to prepare the HACC/PVA coating. Accordingly, the key performance of coated paper were improved ascribed to the synergy effect of HACC/PVA coating and paper substrate. In particular, the minimum oxygen permeability of the coated paper could reach to 0.87 × 10-13 cm3·cm/cm2·s·Pa, and the optimum water vapor permeability and tensile strength of HACC/PVA coated paper was 0.75 × 10-12 g·cm/cm2·s·Pa and 6.88 kN/m, respectively. The coated paper used as packaging material not only reduced weight loss ratio of strawberry and greengrocery, but also exhibited lower chromatic aberration and better sensory evaluation, indicating a favorable effect on fruit and vegetable storage. Taken together, the designed eco-friendly coated paper has shown tremendous potential for green and biodegradable packaging material in agricultural products preservation.

Advances in the preparation, characterization, and biological functions of chitosan oligosaccharide derivatives: A review

Chitosan oligosaccharide (COS), which represent the positively charged basic amino oligosaccharide in nature, is the deacetylated and degraded products of chitin. COS has become the focus of intensive scientific investigation, with a growing body of practical and clinical studies highlighting its remarkable health-enhancing benefits. These effects encompass a wide range of properties, including antibacterial, antioxidant, anti-inflammatory, and anti-tumor activities. With the rapid advancements in chemical modification technology for oligosaccharides, many COS derivatives have been synthesized and investigated. These newly developed derivatives possess more stable chemical structures, improved biological activities, and find applications across a broader spectrum of fields. Given the recent interest in the chemical modification of COS, this comprehensive review seeks to consolidate knowledge regarding the preparation methods for COS derivatives, alongside discussions on their structural characterization. Additionally, various biological activities of COS derivatives have been discussed in detail. Lastly, the potential applications of COS derivatives in biomedicine have been reviewed and presented.

Investigation of Filtration and Shale Inhibition Characteristics of Chitosan-N-(2-hydroxyl)-propyl trimethylammonium Chloride as Drilling Fluid Additives

Hydrated shale formations often lead to severe drilling problems and may lead to wellbore instability. These instabilities can result in issues such as bit balling, borehole collapse, formation damage, stuck pipe, and low drilling rates. Keeping these fundamental issues with drilling in shale formation in mind, this study is aimed at designing a water-based drilling fluid system for effective shale inhibition, ensuring enhanced wellbore stability and drilling efficiency. The designed mud system comprises a typical base fluid along with newly synthesized chitosan derivative chitosan-N-(2-hydroxyl)-propyl trimethylammonium chloride (HACC) as an additive. This additive was found to be soluble in water and conducive for shale inhibition. The derived product was characterized by field emission scanning electron microscopy, thermogravimetric analysis, and Fourier-transform infrared spectroscopy (FTIR). Various drilling fluid tests, including filtration and rheological experiments, were conducted to evaluate its proficiency as a drilling mud additive. The results showed improvement in rheological and filtration properties after hot rolling at 100 °C in comparison to a conventional shale inhibitor, polyethylenimine. As we increase the concentration of synthesized chitosan derivative from 0.3 to 1.5 w/v%, the filtration loss is reduced from 40% to 65% as compared to the base fluids. Shale recovery tests were also conducted using shale samples from an Indian field to assess its viability for field application. The addition of 0.3 to 1.5 w/v% chitosan derivative resulted in high shale recovery above 88% to 96% at 100 °C compared to polyethylenimine, which showed a change in recovery from 62% to 73%. HACC intercalates into clay platelets, reducing the interlayer spacing between particles and preventing clay from hydrating and swelling. This mechanism of inhibition is evaluated by X-ray diffraction, FTIR, and zeta potential analysis. This bolsters the hypothesis of using the synthesized chitosan derivative as a shale inhibitor.

Dual-functional thermosensitive hydrogel for reducing infection and enhancing bone regeneration in infected bone defects

The contamination of bone defects is a serious therapeutic problem. The treatment of infected bone defects involves rigorous infection control followed by bone reconstruction. Considering these two processes, the development of biomaterials possessing antibacterial and osteogenic properties offers a promising approach for the treatment of infected bone defects. In this study, a dual-functional, thermosensitive, and injectable hydrogel composed of chitosan (CS), quaternized CS (QCS), and nano-hydroxyapatite (nHA) was designed, and the ratio of CS to QCS in the hydrogel was optimized to enhance the antibacterial efficacy of CS while reducing the cytotoxicity of QCS. In vitro studies demonstrated that the hydrogel with an 85 %:15 % ratio of CS to QCS exhibited excellent biocompatibility and antibacterial properties while also possessing suitable mechanical characteristics and degradability. The incorporation of nHA into the hydrogel enhanced MC3T3-E1 proliferation and osteogenic differentiation. Moreover, this hydrogel demonstrated superior in vivo therapeutic effectiveness in a rabbit model of infected bone defect. In summary, this study provides a promising material design and a comprehensive one-step treatment strategy for infected bone defects.

Bilayer regenerated cellulose/quaternized chitosan-hyaluronic acid/collagen electrospun scaffold for potential wound healing applications

In this study, a bilayer electrospun scaffold has been prepared using regenerated cellulose (RC)/quaternized chitosan (CS) as the primary layer and collagen/hyaluronic acid (HA) as the second layer. An approximate 48 mol% substituted (estimated from 1H NMR) quaternized CS was used in this study. Both layers were crosslinked with EDC/NHS, reflecting an increase in UTS (2.29 MPa for the bilayer scaffold compared to 1.82 MPa for the RC scaffold). Initial cell viability, cell adhesion and proliferation, FDA staining for live cells, and hydroxyproline release rate from cells were evaluated with L929 mouse fibroblast cells. Also, detailed in vitro studies were performed using HADF cells, which include MTT Assay, Live/Dead imaging, DAPI staining, gene expression of PDGF, VEGF-A, and COL1 in RT-PCR, and cell cycle analysis. The collagen/HA-based bilayer scaffold depicted a 9.76-fold increase of VEGF-A compared to a 2.1-fold increase for the RC scaffold, indicating angiogenesis and vascularization potential. In vitro scratch assay was performed to observe the migration of cells in simulated wounds. Antimicrobial, antioxidant, and protease inhibitory activity were further performed, and overall, the primary results highlighted the potential usage of bilayer scaffold in wound healing applications.

Chemical modification of chitosan for developing of new hemostatic materials: A review

Uncontrolled bleeding that occurs during surgery, trauma, and in combat conditions is critical and require immediate action. Chitosan is a polysaccharide, obtained from natural sources with unique biological properties. It is often used as basis for local hemostatic agents (LHA). We summarized the data on hemostatic properties of chitosan, commercially available chitosan-based products with focus in the field of chemical modification of chitosan. Various approaches are used to enhance hemostatic activity of chitosan-based materials. The approach with chemical modification of chitosan allows changing the properties of the polymer in order to obtain an active macromolecule that contributes to hemostasis. Ongoing research on the mechanism of interaction with blood components in the case of different chitosan derivatives will make it possible to identify promising directions for chemical modification to obtain an effective LHA.

Multifunctional ADM hydrogel containing endothelial cell-exosomes for diabetic wound healing

Non-healing wound, with limited treatment options, remains a prevalent complication of diabetes mellitus. The underlying causes wherein include oxidative stress injury, bacterial infection, cellular dysfunction, and persistent inflammation. Acellular Dermal Matrix (ADM), a wound dressing composed of natural extracellular matrix and abundant bioactive factors, has been successfully developed to treat various wounds, including burns and diabetic ulcers. Protocatechualdehyde (PA) & trivalent iron ion (Fe3+) complex (Fe3+@PA) exhibits potential antioxidant and antibacterial properties. In this study, we developed a dual hydrogel network by combining Fe3+@PA complex-modified ADM with light-cured gelatin (GelMA), supplemented with exosomes derived from human umbilical vein endothelial cells (HUVEC-Exos), to create an ADM composite hydrogel system (ADM-Fe3+@PA-Exos/GelMA) with antioxidant, antibacterial, and cell-promoting functions for diabetic wound treatment. Through in vitro experiments, we investigated the biosafety, antioxidant and antibacterial properties of ADM composite hydrogel. Furthermore, we examined the protective effects of ADM composite hydrogel on diabetic wound. The above experiments collectively demonstrate that our ADM-Fe3+@PA-Exos/GelMA hydrogel promotes diabetic wound healing by eliminating bacterial infection, reduced the reactive oxygen species (ROS) levels, protecting cells against oxidative stress damage, promotingcollagen deposition and angiogenesis, which provides a promising strategy to optimize ADM for diabetic wound treatment.

Chitosan and Its Derivatives: Preparation and Antibacterial Properties

This comprehensive review illuminates the various methods of chitosan extraction, its antibacterial properties, and its multifarious applications in diverse sectors. We delve into chemical, physical, biological, hybrid, and green extraction techniques, each of which presents unique advantages and disadvantages. The choice of method is dictated by multiple variables, including the desired properties of chitosan, resource availability, cost, and environmental footprint. We explore the intricate relationship between chitosan's antibacterial activity and its properties, such as cationic density, molecular weight, water solubility, and pH. Furthermore, we spotlight the burgeoning applications of chitosan-based materials like films, nanoparticles, nonwoven materials, and hydrogels across the food, biomedical, and agricultural sectors. The review concludes by highlighting the promising future of chitosan, underpinned by technological advancements and growing sustainability consciousness. However, the critical challenges of optimizing chitosan's production for sustainability and efficiency remain to be tackled.

Preparation of imidazole acids grafted chitosan with enhanced antioxidant, antibacterial and antitumor activities

Herein, imidazole acids grafted chitosan derivatives were synthesized, including HACC, HACC derivatives, TMC, TMC derivatives, amidated chitosan and amidated chitosan bearing imidazolium salts. The prepared chitosan derivatives were characterized by FT-IR and ¹H NMR. The tests evaluated the biological antioxidant, antibacterial, and cytotoxic activities of chitosan derivatives. The antioxidant capacity (DPPH radical, superoxide anion radical and hydroxyl radical) of chitosan derivatives was 2.4-8.3 times higher than that of chitosan. The antibacterial capacity against E. coli and S. aureus of cationic derivatives (HACC derivatives, TMC derivatives, and amidated chitosan bearing imidazolium salts) was more active than only imidazole-chitosan (amidated chitosan). In particular, the inhibition effect of HACC derivatives on E. coli was 15.625 μg/mL. Moreover, the series of chitosan derivatives bearing imidazole acids showed certain activity against MCF-7 and A549 cells. The present results suggest that the chitosan derivatives in this paper seem to be promising carrier materials for use in drug delivery systems.

New N-Methylimidazole-Functionalized Chitosan Derivatives: Hemocompatibility and Antibacterial Properties

Novel imidazole derivatives of the low molecular weight chitosan N-(2-hydroxypropyl)-1H-1,2,3-triazol-4-yl)methyl)-1-methyl-1H-imidazol-3-ium chitosan chloride (NMIC) were synthesized using copper-catalyzed azide-alkyne cycloaddition (CuAAC). The degrees of substitution (DSs) for the new derivatives were 18-76%. All chitosan derivatives (2000 µg/mL) were completely soluble in water. The antimicrobial activity of the new compounds against E. coli and S. epidermidis was studied. The effect of chitosan derivatives on blood and its components was studied. NMIC samples (DS 34-76%) at a concentration <10 μg/mL had no effect on blood and plasma coagulation. Chitosan derivatives (DS 18-76%) at concentrations of ≥83 μg/mL in blood and ≥116.3 μg/mL in plasma resulted in a prolongation of the clotting time of blood and plasma, positively related to the DS. At concentrations up to 9.1 μg/mL, NMIC did not independently provoke platelet aggregation. The degree of erythrocyte hemolysis upon contact with NMIC samples (2.5-2500 μg/mL) was below 4%. The inhibition of blood/plasma coagulation indicates the promising use of the studied samples to modify the surface of medical materials in order to achieve thromboresistance.

Preparation and characterization of antibacterial, antioxidant, and biocompatible p-coumaric acid modified quaternized chitosan nanoparticles

To fabricate multifunctional nanoparticles (NPs) based on chitosan (CS) derivative, we first prepared quaternized CS (2-hydroxypropyltrimethyl ammonium chloride CS, HTCC) via a one-step approach, then synthesized p-coumaric acid (p-CA) modified HTCC (HTCC-CA) for the first time through amide reaction, and finally fabricated a series of NPs (HTCC-CA NPs) using HTCC-CAs with different substitution degrees and sodium tripolyphosphate (TPP) by ionic gelation. Newly-prepared HTCC and HTCC-CAs were characterized by FT-IR, ¹H NMR, elemental analysis (EA), full-wavelength UV scanning, silver nitrate titration, and Folin-Ciocalteu methods. DLS and TEM results demonstrated that three selected HTCC-CA NPs had moderate size (< 350 nm), good dispersion (PDI < 0.4), and positive zeta potential (11-20 mV). The HTCC-CA NPs had high antibacterial activity against six bacterial strains, and the minimum inhibitory concentration (MIC) values were almost the same as the minimum bactericidal concentration (MBC) values (250-1000 μg/mL). Also, the HTCC-CA NPs had good antioxidation (radical scavenging ratio > 65 %) and low cytotoxicity (relative cell viability >80 %) to the tested cells. Totally, HTCC-CA NPs with high antibacterial activity, great antioxidation, and low cytotoxicity might serve as new biomedical materials for promoting skin wound healing.

Synthesis of Selenium Nanoparticles Modified by Quaternary Chitosan Covalently Bonded with Gallic Acid

Quaternary chitosan derivative with covalently bonded antioxidant (QCG) was used as media for synthesis of selenium nanoparticles (SeNPs). SeNPs were characterized using AFM, TEM, and DLS methods. The data confirmed the formation of stable nanoparticles with a positive charge (34.86-46.73 mV) and a size in the range 119.5-238.6 nm. The antibacterial and fungicidal activity of SeNPs occurred within the range of values for chitosan derivatives. In all cases, the highest activity was against C. albicans (MIC 125 µg/mL). The toxicity of the modified selenium nanoparticles to eukaryotic cells was significantly higher. Among nanoparticle samples, SeNPs that were synthesized at 55 °C demonstrated the highest toxicity against Colo357 and HaCaT cell lines. Based on these results, SeNPs loaded with doxorubicin were obtained. DOX loading efficiency was about 18%. QCG-SeNPs loaded with DOX at a concentration of 1.25 μg/mL inhibited more than 50% of hepatocarcinoma (Colo 357) cells and about 70% of keratinocytes (HaCaT).

Synthesis and characterization of thiazolium chitosan derivative with enhanced antimicrobial properties and its use as component of chitosan based films

In this work, chemical modification of chitosan using cationic thiazolium groups was investigated with the aim to improve water solubility and antimicrobial properties of chitosan. Enzymatic synthesis and ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) chemistry were employed to synthesize and attach to chitosan through the amine groups the molecule bearing thiazolium moieties, quaternized 4-(2-(4-methylthiazol-5-yl) ethoxy)-4-oxobutanoic acid (MTBAQ). On the basis of Fourier transform infrared spectroscopy (FTIR), elemental analysis and solid state nuclear magnetic resonance (ssNMR), around 95 % of the available amine groups of chitosan (of 25 % degree of acetylation) reacted. The resulting derivative was water soluble at physiological pH and exhibit excellent antimicrobial activity against Listeria innocua, Staphylococcus epidermidis, Staphylococcus aureus and Methicillin Resistant S. aureus Gram-positive bacteria (MIC = 8-32 μg/ mL), whereas its efficiency decreases against fungi Candida albicans and Eschericia coli Gram-negative bacterium. Subsequently, the thiazolium chitosan derivative was employed as antimicrobial component (up to 7 wt%) of chitosan/glycerol based films. The incorporation of the chitosan derivative does not modify significantly the characteristics of the film in terms of thermal and mechanical properties, while enhances considerably the antimicrobial activity.

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.

Preparation of composite monoliths of quaternized chitosan and diatom earth for protein separation

In this study, composite monoliths with porous structures were prepared using quaternized chitosan and diatom earth for protein separation. Quaternized chitosan (N-[(2-hydroxy-3-trimethylammonium)propyl] chitosan chloride) dissolved in water was mixed with diatom earth and crosslinked with glutaraldehyde under low-temperature conditions to form a cryogel. Interconnected porous monoliths were obtained after removing ice crystals from the cryogel. The monoliths adsorbed bovine serum albumin selectively from the solution mixture of bovine serum albumin and bovine ɤ-globulin, and bovine ɤ-globulin was recovered in the flow-through fraction. The adsorption selectivity was enhanced by changing the solution pH from 6.8 to 5.5. The adsorption of bovine serum albumin by the monolith was replicated at least five times following its washing with a buffer containing 400 mM NaCl and subsequent regeneration with a 10 mM acetate buffer. The composited monolith is a promising adsorbent for the removal of acidic proteins, such as serum albumin contamination in neutral proteins, for example, ɤ-globulins, in bioproduction processes.

Development of Quaternized Chitosan Integrated with Nanofibrous Polyacrylonitrile Mat as an Anion-Exchange Membrane

A two-phase anion-exchange membrane was prepared from quaternized chitosan (QCS) integrated with an electrospun polyacrylonitrile (PAN) scaffold by spin coating. To synthesize QCS, glycidyltrimethylammonium chloride in various amounts was introduced into the structure of CS. The characterization of the cast cross-linked QCS (CQCS) membranes by impedance spectroscopy revealed the ionic conductivity (IC) in the range of 2.8 × 10^-4 to 8.2 × 10^-4 S cm^-1 and the degree of quaternization (DQ) of 26.4-51.0%, where the CQCS film with the DQ of 51.0% showed excellent performance. When CQCS was reinforced with a PAN fiber mat, the newly developed composite membrane demonstrated the highest IC of 34 × 10^-4 S cm^-1 at 80 °C, low swelling, and an almost eightfold increase in tensile strength at a fully hydrated state compared to pristine materials. Moreover, the CQCS/PAN membrane was chemically stable and revealed increasing hydroxide transport during 1 month immersion in alkaline media.

Evaluation of quaternization effect on chitosan-HAP composite for bone tissue engineering application

This study attempts to improve the aqueous solubility of chitosan and utilizes it in the fabrication of composites with hydroxyapatite (HAP). The composites were evaluated as a curcumin delivery vehicle for bone regeneration. The chitosan was modified by quaternization, with a quaternization degree of 5 % for low quaternized chitosan (LQC) and 11 % for high quaternized chitosan (HQC). The modified chitosan, at alkaline pH 11, facilitated in situ HAP growth and formed LQC-HAP and HQC-HAP composites. The quaternization weakens intermolecular hydrogen bonds, facilitates interaction with the apatite precursor ions and promotes the growth of HAP. The modification significantly improved drug encapsulation (2.6 fold) but at the cost of a slight decrease in mechanical strength and increase in drug release. The in vitro studies with human osteoblast-like MG-63 cells established that the curcumin-loaded composites, LQC-HAP-C and HQC-HAP-C are biocompatible, encourage proliferation and promote a 2-fold increase in calcium mineralization over drug-free composites. The study exemplifies the reciprocity between quaternization degree and drug load/release properties and also illustrates that the magnitude of the latter reflects bioactivity. Thus, the quaternized chitosan-based HAP composite with tailorable bio-physicochemical properties becomes an interesting drug delivery system in bone regeneration.

Tailorable antibacterial and cytotoxic chitosan derivatives by introducing quaternary ammonium salt and sulfobetaine

Chitosan (CS) derivatives with improved water solubility, antibacterial activity and adequate biocompatibility are attracting increasingly interest in medical application. Herein, we have successfully synthesized isocyanate terminated quaternary ammonium salt (IQAS) and sulfopropylbetaine (ISB) to be readily covalently bounded to CS skeleton by selective reaction with amino and hydroxyl groups. And their molecular structures and crystallinity were confirmed by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and X-ray diffraction. The effect of the substitution degree, carbon chain length, content ratio of IQAS/ISB on their water solubility, antibacterial activity and cytotoxicity were systematically investigated, which shows that those properties of the CS derivatives can be tailored by adjusting the grafted antibacterial agents and their additive amount. The structure-property relationship of these CS derivatives may provide a solid guidance on the development of CS derivatives for more efficient practical applications.

Chitosan-Based Biomaterial Scaffolds for the Repair of Infected Bone Defects

The treatment of infected bone defects includes infection control and repair of the bone defect. The development of biomaterials with anti-infection and osteogenic ability provides a promising strategy for the repair of infected bone defects. Owing to its antibacterial properties, chitosan (an emerging natural polymer) has been widely studied in bone tissue engineering. Moreover, it has been shown that chitosan promotes the adhesion and proliferation of osteoblast-related cells, and can serve as an ideal carrier for bone-promoting substances. In this review, the specific molecular mechanisms underlying the antibacterial effects of chitosan and its ability to promote bone repair are discussed. Furthermore, the properties of several kinds of functionalized chitosan are analyzed and compared with those of pure chitosan. The latest research on the combination of chitosan with different types of functionalized materials and biomolecules for the treatment of infected bone defects is also summarized. Finally, the current shortcomings of chitosan-based biomaterials for the treatment of infected bone defects and future research directions are discussed. This review provides a theoretical basis and advanced design strategies for the use of chitosan-based biomaterials in the treatment of infected bone defects.

Supramolecular Thermo-Contracting Adhesive Hydrogel with Self-Removability Simultaneously Enhancing Noninvasive Wound Closure and MRSA-Infected Wound Healing

Conventional wound closure and dressing are two crucial, time-consuming but isolated principles in wound care. Even though tissue adhesive opens a new era for wound closure, the method and biomaterial that can simultaneously achieve noninvasive wound closure and promote wound healing are highly appreciated. Herein, a novel supramolecular poly(N-isopropylacrylamide) hybrid hydrogel dressing composed of quaternized chitosan-graft-β-cyclodextrin, adenine, and polypyrrole nanotubes via host-guest interaction and hydrogen bonds is developed. The hydrogel demonstrates thermal contraction of 47% remaining area after 2 h at 37 ℃ and tissue adhesion of 5.74 kPa, which are essential for noninvasive wound closure, and multiple mechanical and biological properties including suitable mechanical properties, self-healing, on-demand removal, antioxidant, hemostasis, and photothermal/intrinsic antibacterial activity (higher 99% killing ratio within 5 min after irradiation). In both full-thickness skin incision and excision wound models, the hydrogel reveals significant wound closure after 24 h post-surgery. In acute and methicillin-resistant Staphylococcus aureus-infected wound and photothermal/intrinsic antibacterial activity assays, wounds treated with the hydrogel demonstrate enhanced wound healing with rapid wound closure rate, mild inflammatory response, advanced angiogenesis, and well-arranged collagen fibers. Altogether, the results indicate the hydrogel is promising in synchronously noninvasive wound closure and enhanced wound healing.

Application of Chitosan and Its Derivative Polymers in Clinical Medicine and Agriculture

Chitosan is a biodegradable natural polymer derived from the exoskeleton of crustaceans. Because of its biocompatibility and non-biotoxicity, chitosan is widely used in the fields of medicine and agriculture. With the latest technology and technological progress, different active functional groups can be connected by modification, surface modification, or other configurations with various physical, chemical, and biological properties. These changes can significantly expand the application range and efficacy of chitosan polymers. This paper reviews the different uses of chitosan, such as catheter bridging to repair nerve broken ends, making wound auxiliaries, as tissue engineering repair materials for bone or cartilage, or as carriers for a variety of drugs to expand the volume or slow-release and even show potential in the fight against COVID-19. In addition, it is also discussed that chitosan in agriculture can improve the growth of crops and can be used as an antioxidant coating because its natural antibacterial properties are used alone or in conjunction with a variety of endophytic bacteria and metal ions. Generally speaking, chitosan is a kind of polymer material with excellent development prospects in medicine and agriculture.

Amphiphilic quaternized chitosan: Synthesis, characterization, and anti-cariogenic biofilm property

Hydrophobized chitosan derivatives, hexyl chitosan (HCS), dodecyl chitosan (DCS), and phthaloyl chitosan (PhCS) of approximately 30 and 50% degree of substitution (%DS) reacted with glycidyltrimethylammonium chloride (GTMAC) to incorporate hydrophilic positively charged groups of N-[(2-hydroxyl-3-trimethylammonium)propyl] and yielded amphiphilic quaternized chitosan derivatives. They can assemble into spherical nanoparticles with a hydrodynamic diameter of ~100-300 nm and positive ζ-potential values (+15 to +56). Their anti-biofilm efficacy was evaluated against the dental caries pathogen, Streptococcus mutans. Among all derivatives, the one having 30%DS of hexyl group and prepared by reacting with 1 mol equivalent of GTMAC (H₃₀CS-GTMAC) showed the best performance in terms of its aqueous solubility, the lowest minimum inhibitory concentration (138 μg/mL) and the minimum bactericidal concentration (275 μg/mL) which are superior to the unmodified chitosan. Its equivalent anti-biofilm efficacy to that of chlorhexidine suggests that it can be a greener antibacterial agent for oral care formulations.

Investigation of the Antioxidant Properties of the Quaternized Chitosan Modified with a Gallic Acid Residue Using Peroxidase that Produces Reactive Oxygen Species

Chitosan modified with a (2-hydroxy-3-trimethylammonium) propyl group and gallic acid residue, or quaternized chitosan with gallic acid (QCG), was synthesized. Antioxidant properties of the produced QCG have been investigated. Peroxidase in combination with NADH and salicyl hydroxamate (SHAM) caused consumption of oxygen and production of H2O2 in aqueous solution as a result of O2 reduction in the peroxidase-oxidase reactions. The rates of O2 consumption and H2O2 generation were reduced in the presence of QCG. The antioxidant propyl gallate (PG) and superoxide dismutase (SOD) had the same effect, but not the quaternized chitosan (QC) without gallic acid. The effect of chitosan derivatives on the production of reactive oxygen species (ROS) in the cells of pea leaf epidermis and on the cell death detected by the destruction of cell nuclei, was investigated. QCG, QC, and SOD had no effect, while PG decreased the rate of ROS generation in the cells of the epidermis, which was induced by NADH with SHAM or by menadione. QCG and QC prevented destruction of the guard cell nuclei in the pea leaf epidermis that was caused by NADH with SHAM or by KCN. SOD had no effect on the destruction of nuclei, while the effect of PG depended on the inducer of the cell death. Suppression of the destruction of guard cell nuclei by chitosan derivatives was associated not with their antioxidant effect, but with the disruption of the plasma membrane of the cells. The results obtained have shown that QCG exhibits antioxidant properties in solutions, but does not prevent generation of ROS in the plant cells. The mechanism of antioxidant effect of QCG is similar to that of PG and SOD.

Evaluation of Antibacterial and Antifungal Properties of Low Molecular Weight Chitosan Extracted from Hermetia illucens Relative to Crab Chitosan

This study shows the research on the depolymerisation of insect and crab chitosans using novel enzymes. Enzyme preparations containing recombinant chitinase Chi 418 from Trichoderma harzianum, chitinase Chi 403, and chitosanase Chi 402 from Myceliophthora thermophila, all belonging to the family GH18 of glycosyl hydrolases, were used to depolymerise a biopolymer, resulting in a range of chitosans with average molecular weights (Mw) of 6-21 kDa. The depolymerised chitosans obtained from crustaceans and insects were studied, and their antibacterial and antifungal properties were evaluated. The results proved the significance of the chitosan's origin, showing the potential of Hermetia illucens as a new source of low molecular weight chitosan with an improved biological activity.

The aqueous assembly preparation of OPs-AgNPs with phenols from olive mill wastewater and its mechanism on antimicrobial function study

To valorise olive mill wastewater phenols (OPs) potentially applied in food preservation, a novel stable and regularly spherical OPs-AgNPs (Davg = 78 nm) were successfully assembled in aqueous solution under the optimized conditions (pH 8.0, 5 mM AgNO3, 35C and 30 min). The results of antimicrobial zone diameters indicated that 50 μg/mL of promising OPs-AgNPs presented excellent antimicrobial effects. Especially, the cell wall damages of E. coli ATCC 23,815 were caused when OPs-AgNPs concentration was exceeded its MIC (8.58 μg/mL). Also, a significant down-regulating of the Ca2+-ATPase activity in E. coli was revealed, and the intracellular Ca2+ concentrations were thus decreased from 12.5 to 1.35 µg/mL after a treatment for 3 h. The apoptosis level of E. coli was significantly increased more than the control (55.13% of OPs-AgNPs vs 9.90% of control). In sum, OPs exerts enhanced antimicrobial function via penetrating cell membrane and targeting Ca2+-ATPase after chelated with AgNPs.

Collagen/Chitosan Gels Cross-Linked with Genipin for Wound Healing in Mice with Induced Diabetes

Diabetes mellitus continues to be one of the most common diseases often associated with diabetic ulcers. Chitosan is an attractive biopolymer for wound healing due to its biodegradability, biocompatibility, mucoadhesiveness, low toxicity, and hemostatic effect. A panel of hydrogels based on chitosan, collagen, and silver nanoparticels were produced to treat diabetic wounds. The antibacterial activity, cytotoxicity, swelling, rheological properties, and longitudinal sections of hydrogels were studied. The ability of the gels for wound healing was studied in CD1 mice with alloxan-induced diabetes. Application of the gels resulted in an increase in VEGF, TGF-b1, IL-1b, and TIMP1 gene expression and earlier wound closure in a comparison with control untreated wounds. All gels increased collagen deposition, hair follicle repair, and sebaceous glands formation. The results of these tests show that the obtained hydrogels have good mechanical properties and biological activity and have potential applications in the field of wound healing. However, clinical studies are required to compare the efficacy of the gels as animal models do not reproduce full diabetes pathology.

Biomedical Applications of Quaternized Chitosan

The natural polymer chitosan is the second most abundant biopolymer on earth after chitin and has been extensively explored for preparation of versatile drug delivery systems. The presence of two distinct reactive functional groups (an amino group at C2, and a primary and secondary hydroxyl group at C3 and C6) of chitosan are involved in the transformation of expedient derivatives such as acylated, alkylated, carboxylated, quaternized and esterified chitosan. Amongst these, quaternized chitosan is preferred in pharmaceutical industries owing to its prominent features including superior water solubility, augmented antimicrobial actions, modified wound healing, pH-sensitive targeting, biocompatibility, and biodegradability. It has been explored in a large realm of pharmaceuticals, cosmeceuticals, and the biomedical arena. Immense classy drug delivery systems containing quaternized chitosan have been intended for tissue engineering, wound healing, gene, and vaccine delivery. This review article outlines synthetic techniques, basic characteristics, inherent properties, biomedical applications, and ubiquitous challenges associated to quaternized chitosan.

Comparative studies of chitosan and carboxymethyl chitosan doped with nickel and copper: Characterization and antibacterial potential

The study focused on the preparation and antibacterial evaluation of chitosan (CHT), carboxymethyl chitosan (CMC) and their respective metal composites. All the samples were characterized using Fourier Transform Infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The antibacterial potentials of the samples were tested against Escherichia coli, Klebsiella sp., Pseudomonas aeruginosa A, and Pseudomonas aeruginosa B. SEM results revealed different changes in samples surfaces as a result of chemical modification. EDS revealed the presence of Ni and Cu in the composites. XRD spectra of CMC showed that the crystalline region of CHT was reduced by the modification. The antibacterial results indicated that the samples had inhibitory and bactericidal effects against Escherichia coli and Klebsiella sp. at 1000, 500, and 250 mg mL^-1. The study showed that CMC and CMC-metal composites performed better at inhibiting the growth of microorganisms than CHT and CHT-metal composites.

Antifungal action of chitosan in combination with fungicides in vitro and chitosan conjugate with gallic acid on tomatoes against Botrytis cinerea

In the present work, a positive effect was obtained by using low molecular weight chitosan compounds in combination with synthetic fungicides. Antifungal activity against Botrytis cinerea, determined by the radial growth method, was more than 75%, with a 25 × 10^- 10 g/L concentration of fludioxonil or difenoconazole in compounds. Metabolic activity of B. cinerea fungus was about 15% when using a chitosan compound containing fludioxonil at a concentration of 25 × 10^- 7 g/L. The combined action of chitosan with difenoconazole at a fungicide concentration of 25 × 10^- 4 g/L is 2-3 times more effective than the action of each component separately. Results of studies for artificially inoculated B. cinerea tomato fruit when treated with low molecular chitosan and chitosan conjugate with gallic acid reduced the frequency of rotting fruit by 50 and 83%, respectively. Chitosan-gallic acid conjugate were obtained from chitosans with Mw of 28 kDa (Ch28GA) was proved to be effective as a preventive treatment for 3 days and can potentially be used as a biofungicide against B. cinerea on tomatoes in the post-harvest period.

Dual-Dynamic-Bond Cross-Linked Antibacterial Adhesive Hydrogel Sealants with On-Demand Removability for Post-Wound-Closure and Infected Wound Healing

The design and development of a smart bioadhesive hydrogel sealant with self-healing and excellent antibacterial activity to achieve high wound closure effectiveness and post-wound-closure care is highly desirable in clinical applications. In this work, a series of adhesive antioxidant antibacterial self-healing hydrogels with promising traits were designed through dual-dynamic-bond cross-linking among ferric iron (Fe), protocatechualdehyde (PA) containing catechol and aldehyde groups and quaternized chitosan (QCS) to enable the closure of skin incisions and promotion of methicillin-resistant Staphylococcus aureus (MRSA)-infected wound healing. The dual-dynamic-bond cross-linking of a pH-sensitive coordinate bond (catechol-Fe) and dynamic Schiff base bonds with reversible breakage and re-formation equips the hydrogel with excellent autonomous healing and on-demand dissolution or removal properties. Additionally, the hydrogel presents injectability, good biocompatibility and antibacterial activity, multifunctional adhesiveness, and hemostasis as well as NIR responsiveness. The in vivo evaluation in a rat skin incision model and infected full-thickness skin wound model revealed the high wound closure effectiveness and post-wound-closure care of the smart hydrogels, demonstrating its great potential in dealing with skin incisions and infected full-thickness skin wounds.

Clotrimazole-loaded N-(2-hydroxy)-propyl-3-trimethylammonium, O-palmitoyl chitosan nanoparticles for topical treatment of vulvovaginal candidiasis

Vulvovaginal candidiasis (VVC) represents a considerable health burden for women. Despite the availability of a significant array of antifungal drugs and topical products, the management of the infection is not always effective, and new approaches are needed. Here, we explored cationic N-(2-hydroxy)-propyl-3-trimethylammonium, O-palmitoyl chitosan nanoparticles (NPs) as carriers of clotrimazole (CLT) for the topical treatment of VVC. CLT-NPs with approximately 280 nm in diameter were obtained by self-assembly in water and subsequent stabilization by ionic crosslinking with tripolyphosphate. The nanosystem featured pH-independent sustained drug release up to 24 h, which affected both in vitro anti-Candida activity and cytotoxicity. The CLT-loaded nanostructured platform yielded favorable selectivity index values for a panel of standard strains and clinical isolates of Candida spp. and female genital tract cell lines (HEC-1-A, Ca Ski and HeLa), as compared to the free drug. CLT-NPs also improved in vitro drug permeability across HEC-1-A and Ca Ski cell monolayers, thus suggesting that the nanocarrier may provide higher mucosal tissue levels of the active compound. Overall, data support that CLT-NPs may be a valuable asset for the topical treatment of VVC. STATEMENT OF SIGNIFICANCE: Topical azoles such as clotrimazole (CLT) are first line antifungal drugs for the management of vulvovaginal candidiasis (VVC), but their action may be limited by issues such as toxicity and poor capacity to penetrate the genital mucosa. Herein, we report on the ability of a new cationic N-(2‑hydroxy)-propyl-3-trimethylammonium, O-dipalmitoyl chitosan derivative (DPCat35) to yield tripolyphosphate-reinforced micelle-like nanostructures that are suitable carriers for CLT. In particular, these nanosystems were able to improve the in vitro selectivity index of the drug and to provide enhanced epithelial drug permeability when tested in cell monolayer models. These data support that CLT-loaded DPCat35 nanoparticles feature favorable properties for the development of new nanomedicines for the topical management of VVC.

Versatile Use of Chitosan and Hyaluronan in Medicine

Chitosan is industrially acquired by the alkaline N-deacetylation of chitin. Chitin belongs to the β-N-acetyl-glucosamine polymers, providing structure, contrary to α-polymers, which provide food and energy. Another β-polymer providing structure is hyaluronan. A lot of studies have been performed on chitosan to explore its industrial use. Since chitosan is biodegradable, non-toxic, bacteriostatic, and fungistatic, it has numerous applications in medicine. Hyaluronan, one of the major structural components of the extracellular matrix in vertebrate tissues, is broadly exploited in medicine as well. This review summarizes the main areas where these two biopolymers have an impact. The reviewed areas mostly cover most medical applications, along with non-medical applications, such as cosmetics.

N-(2-hydroxy)-propyl-3-trimethylammonium, O-palmitoyl chitosan: Synthesis, physicochemical and biological properties

Two samples of N-(2-hydroxy)-propyl-3-trimethylammonium, O-palmitoyl chitosan (DPCat) with different average degrees of quaternization named as DPCat35 (DQ¯ = 35%) and DPCat80 (DQ¯ = 80%), were successfully synthesized by reacting glycidyltrimethylammonium chloride (GTMAC) with O-palmitoyl chitosan (DPCh) derivative (DS¯ = 12%). Such amphiphilic derivatives of chitosan were fully water-soluble at 1.0 < pH < 12.0 and showed significant electrostatic stability enhancement of a self-assembly micellar nanostructure (100-320 nm) due to its positively-charged out-layer. In vitro mucoadhesive and cytotoxicity essays toward healthy fibroblast cells (Balb/C 3T3 clone A31 cell), human prostate cancer (DU145) and liver cancer (HepG2/C3A) cell lines revealed that the biological properties of DPCat derivatives were strongly dependent on DQ¯. Additionally, DPCat35 had better interactions with the biological tissue and with mucin glycoproteins at pH 7.4 as well as exhibited potential to be used on the development of drug delivery systems for prostate and liver cancer treatment.

An Overview of Current Knowledge on the Properties, Synthesis and Applications of Quaternary Chitosan Derivatives

Chitosan, a chitin-derivative polysaccharide, known for its non-toxicity, biocompatibility and biodegradability, presents limited applications due to its low solubility in neutral or basic pH medium. Quaternization stands out as an alternative to modify this natural polymer, aiming to improve its solubility over a wide pH range and, consequently, expand its range of applications. Quaternization occurs by introducing a quaternary ammonium moiety onto or outside the chitosan backbone, via chemical reactions with primary amino and hydroxyl groups, under vast experimental conditions. The oldest and most common forms of quaternized chitosan involve N,N,N-trimethyl chitosan (TMC) and N-[(2-hydroxy-3-trimethyl ammonium) propyl] chitosan (HTCC) and, more recently, quaternized chitosan by insertion of pyridinium or phosphonium salts. By modifying chitosan through the insertion of a quaternary moiety, permanent cationic charges on the polysaccharide backbone are achieved and properties such as water solubility, antimicrobial activity, mucoadhesiveness and permeability are significantly improved, enabling the application mainly in the biomedical and pharmaceutical areas. In this review, the main quaternized chitosan compounds are addressed in terms of their structure, properties, synthesis routes and applications. In addition, other less explored compounds are also presented, involving the main findings and future prospects regarding the field of quaternized chitosans.

Enhancement of the permeability and activities of epigallocatechin gallate by quaternary ammonium chitosan/fucoidan nanoparticles

Epigallocatechin gallate (EGCG) has many biological functions; however, the use of EGCG in biomedical and food industries was limited due to its poor oral absorption and high susceptibility to degradation. In this study, a mucoadhesive quaternary chitosan was synthesized and combined with fucoidan (FD) (or depolymerized lower molecular weight fucoidan, LMWF) to prepare EGCG-loaded nanoparticles, which extended EGCG release over 300 min and enhanced the transepithelial permeation of EGCG using Caco-2 cells as a model for intestinal absorption. The nanoparticls protected EGCG against degradation in phosphate buffer (pH 6.8) and the remaining EGCG was 1.7-folds higher than the control (EGCG alone). The additive effects of EGCG combined with FD or LMWF in the nanoparticles increased the DPPH radical scavenging activity and the enzyme inhibitory activity against α-amylase (2.82-4.92 fold increase) and α-glucosidase (1.35-1.67 fold increase), while quaternary chitosan helped to enhance the antibacterial effect of EGCG.

Antibacterial effect of chitosan and its derivative on Enterococcus faecalis associated with endodontic infection

Chitosan and its derivatives have been increasingly used for bacteriostasis. To date, the effect of chitosan and N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (HTCC) on Enterococcus faecalis (E. faecalis) associated with endodontic infection has remained to be determined. Chitosan and HTCC were serially diluted with double-distilled water (DDW) or PBS at concentrations of 20-2,500 µg/ml. Various strains of E. faecalis (American Type Tissue Collection no. 29212, as well as isolated strains P25RC and P52Sa) in plankton were adjusted to an optical density at 600 nm of 0.10 and treated with chitosan or HTCC. A colony-forming unit assay was used to determine the concentration of residual bacteria after treatment. Furthermore, E. faecalis biofilms were cultured on coverslips and treated with chitosan or HTCC. The coverslips were rinsed, stained using Live/dead^® BacLight™ bacterial viability kit and observed under an inverted fluorescence microscope. In addition, biofilms on dentine blocks were prepared and observed under a scanning electron microscope. MC3T3-E1 pre-osteoblasts were seeded on 96-well plates and treated with chitosan or HTCC at various concentrations. The cytotoxicity of chitosan and HTCC on MC3T3-E1 pre-osteoblasts was detected using a Cell Counting Kit-8 assay after 24, 48 and 72 h of treatment. The results revealed that the final minimum bactericidal concentrations (MBC) of chitosan and HTCC dissolved in DDW were 70 and 140 µg/ml, respectively. Chitosan and HTCC in DDW exerted a significantly greater antibacterial effect as compared with that in PBS (P<0.05). At the MBC, chitosan and HTCC in DDW, but particularly chitosan, had a significant antibacterial effect on E. faecalis biofilm. Chitosan exhibited no cytotoxicity to MC3T3-E1 pre-osteoblasts at a concentration of <625 µg/ml, while HTCC inhibited the proliferation of the cells in the concentration range of 39-10,000 µg/ml. In conclusion, chitosan and HTCC exhibited prominent antibacterial properties on E. faecalis in the planktonic state and as a biofilm via charge interaction, indicating their potential for application in root canal disinfection and fillings.

Chitin/Chitosan and Its Derivatives: Fundamental Problems and Practical Approaches

In this review, we present the data on the natural occurrence of chitin and its partially or fully deacetylated derivative chitosan, as well as their properties, methods of modification, and potential applications of derivatives with bactericidal, fungicidal, and antioxidant activities. The structure and physicochemical characteristics of the polymers, their functions, and features of chitin microbial synthesis and degradation, including the processes occurring in nature, are described. New data on the hydrolytic microorganisms capable of chitin degradation under extreme conditions are presented. Special attention is focused on the effect of physicochemical characteristics of chitosan, including molecular weight, degree of deacetylation, polydispersity index, and number of amino group derivatives (quaternized, succinyl, etc.) on the antimicrobial and antioxidant properties of modified polymers that can be of particular interest for biotechnology, medicine, and agriculture. Analysis of the available literature data confirms the importance of fundamental research to broaden our knowledge on the occurrence of chitin and chitosan in nature, their role in global biosphere cycles, and prospects of applied research aimed at using chitin, chitosan, and their derivatives in various aspects of human activity.

Hemocompatibility of Silver Nanoparticles Based on Conjugate of Quaternized Chitosan with Gallic Acid in In Vitro Experiments

We studied hemocompatibility of silver nanoparticles synthesized on the basis of a conjugate of quaternized chitosan with gallic acid (QChit-Gal). For the three variants of silver particles (Nos. 1, 2, and 3), the QChit-Gal:AgNO₃ ratio was 5:1, 5:3, and 1:1, respectively. Anticoagulant activity of all samples of silver nanoparticles was lower than that of the conjugate. Samples of nanoparticles Nos. 1 and 2 in a concentration of 0.0233 mg/ml did not affect plasma clotting time and can be used for intravenous administration. However, their concentration in the blood should not exceed 0.01 mg/ml, because in this concentration they do not affect erythrocyte membrane, do not induce platelet aggregation, and do not affect platelet aggregation induced by ADP.

Cationic chitosan derivatives as potential antifungals: A review of structural optimization and applications

The increasing resistance of pathogen fungi poses a global public concern. There are several limitations in current antifungals, including few available fungicides, severe toxicity of some fungicides, and drug resistance. Therefore, there is an urgent need to develop new antifungals with novel targets. Chitosan has been recognized as a potential antifungal substance due to its good biocompatibility, biodegradability, non-toxicity, and availability in abundance, but its applications are hampered by the low charge density results in low solubility at physiological pH. It is believed that enhancing the positive charge density of chitosan may be the most effective approach to improve both its solubility and antifungal activity. Hence, this review mainly focuses on the structural optimization strategy of cationic chitosan and the potential antifungal applications. This review also assesses and comments on the challenges, shortcomings, and prospect of cationic chitosan derivatives as antifungal therapy.

Antibacterial Therapeutic Agents Composed of Functional Biological Molecules

Antibacterial agents are a group of materials that selectively destroy bacteria by interfering with bacterial growth or survival. With the emergence of resistance phenomenon of bacterial pathogens to current antibiotics, new drugs are frequently entering into the market along with the existing drugs, and the alternative compounds with antibacterial functions are being explored. Due to the advantages of their inherent biochemical and biophysical properties including precise targeting ability, biocompatibility, biodegradability, long blood circulation time, and low cytotoxicity, biomolecules such as peptides, carbohydrates, and nucleic acids have huge potential for the antimicrobial application and have been extensively studied in recent years. In this review, antimicrobial therapeutic agents composed of three kinds of functional biological molecules were summarized. In addition, the research progress of antibacterial mechanism, chemical modification, and nanoparticle coupling of those biomolecules were also discussed.

Synthesis of silver nanoparticles using gallic acid-conjugated chitosan derivatives

In presented study, various chitosan derivatives containing covalently bounded gallic acid were obtained: chitosan with gallic acid (CG), quaternized chitosan with gallic acid (QCG), and succinylated chitosan with gallic acid (SCG). Chitosan derivatives were used as stabilizing and reducing agents in the synthesis of silver nanoparticles (AgNPs). The dimensional characteristics of nanomaterials were determined by transmission electron (TEM), dynamic light scattering (DLS) and atomic force (AFM) microscopy, antibacterial activity (against E. coli, S. epidermidis), cytotoxicity (HaCaT, Colo 357 cell lines) and hemocompatibility. Among all samples, QCG-AgNPs showed low toxicity in the range of studied concentrations (3.125-100 μg/ml) high stability of nanoparticle for 4 months (according to UV.spectroscopy data) the highest antibacterial activity against S. epidermidis (3.91 μg/ml). The high antibacterial activity, stability, and simplicity of the process of producing AgNPs based on the QCG derivative reveals that a new method for producing modified AgNPs deserves future consideration.