Synthesis and antimicrobial properties of new chitosan derivatives containing guanidinium groups

Development of anti-bacterial adhesion and antibacterial sulfobetaines modified chitosan/polyvinyl alcohol composite films as packaging materials

Chitosan exhibits a wide source, non-toxic and biodegradable, and is the optimal functional raw material for preparing food packaging materials. However, the pure chitosan film has some disadvantages such as limited antibacterial activity and weak mechanical properties. In this study, sulfobetaines modified chitosan (CS-SBMA) was synthesized by grafting copolymerized betaine methacrylate sulfonate onto the chain of chitosan to improve the anti-bacterial adhesion and antibacterial properties of chitosan, aiming to develop antibacterial and anti-bacterial adhesion films based on CS-SBMA and polyvinyl alcohol (PVA) by the casting method. The structure of CS-SBMA was characterized by 1H NMR and FTIR. The appropriate proportion of CS-SBMA/PVA was determined to be 1/1 and 1/2, by characterizing the composite films with FTIR, XRD, SEM, mechanical, optical, and water resistance behaviors. In addition, CS-SBMA/PVA films showed excellent antibacterial, anti-bacterial adhesion and biofilm control function. The colonies number of E. coli and S. aureus on the surface of CS-SBMA/PVA 1/1 film decreased 94.15 % and 94.27 %, respectively, and 92.93 % of S. aureus and 94.87 % of E. coli colonies were inactivated within 60 min contact. These results indicate that CS-SBMA/PVA film exhibits potential antibacterial and anti-bacterial adhesion properties, which is suitable for food packaging materials.

Biogenic selenium nanoparticles and selenium/chitosan-Nanoconjugate biosynthesized by Streptomyces parvulus MAR4 with antimicrobial and anticancer potential

BACKGROUND

As antibiotics and chemotherapeutics are no longer as efficient as they once were, multidrug resistant (MDR) pathogens and cancer are presently considered as two of the most dangerous threats to human life. In this study, Selenium nanoparticles (SeNPs) biosynthesized by Streptomyces parvulus MAR4, nano-chitosan (NCh), and their nanoconjugate (Se/Ch-nanoconjugate) were suggested to be efficacious antimicrobial and anticancer agents.

RESULTS

SeNPs biosynthesized by Streptomyces parvulus MAR4 and NCh were successfully achieved and conjugated. The biosynthesized SeNPs were spherical with a mean diameter of 94.2 nm and high stability. Yet, Se/Ch-nanoconjugate was semispherical with a 74.9 nm mean diameter and much higher stability. The SeNPs, NCh, and Se/Ch-nanoconjugate showed significant antimicrobial activity against various microbial pathogens with strong inhibitory effect on their tested metabolic key enzymes [phosphoglucose isomerase (PGI), pyruvate dehydrogenase (PDH), glucose-6-phosphate dehydrogenase (G6PDH) and nitrate reductase (NR)]; Se/Ch-nanoconjugate was the most powerful agent. Furthermore, SeNPs revealed strong cytotoxicity against HepG2 (IC50 = 13.04 μg/ml) and moderate toxicity against Caki-1 (HTB-46) tumor cell lines (IC50 = 21.35 μg/ml) but low cytotoxicity against WI-38 normal cell line (IC50 = 85.69 μg/ml). Nevertheless, Se/Ch-nanoconjugate displayed substantial cytotoxicity against HepG2 and Caki-1 (HTB-46) with IC50 values of 11.82 and 7.83 μg/ml, respectively. Consequently, Se/Ch-nanoconjugate may be more easily absorbed by both tumor cell lines. However, it exhibited very low cytotoxicity on WI-38 with IC50 of 153.3 μg/ml. Therefore, Se/Ch-nanoconjugate presented the most anticancer activity.

CONCLUSION

The biosynthesized SeNPs and Se/Ch-nanoconjugate are convincingly recommended to be used in biomedical applications as versatile and potent antimicrobial and anticancer agents ensuring notable levels of biosafety, environmental compatibility, and efficacy.

Chitosan-gentamicin conjugate attenuates heat stress-induced intestinal barrier injury via the TLR4/STAT6/MYLK signaling pathway: In vitro and in vivo studies

Heat stress (HS) has a negative impact on animal health. A modified chitosan-gentamicin conjugate (CS-GT) was prepared to investigate its potential protective effects and mechanism of action on heat stress-induced intestinal mucosa injury in IPEC-J2 cells and mouse 3D intestinal organs in a mouse model. CS-GT significantly (P < 0.01) reversed the decline in transmembrane resistance and increased the FITC-dextran permeability of the IPEC-J2 monolayer fusion epithelium caused by heat stress. Heat stress decreased the expression of the tight binding proteins occludin, claudin1, and claudin2. However, pretreatment with CS-GT significantly increased (P < 0.01) the expression of these tight binding proteins. Mechanistically, CS-GT inhibited the activation of the TLR4/STAT6/MYLK signaling pathway induced by heat stress. Molecular docking showed that CS-GT can bind effectively with TLR4. In conclusion, CS-GT alleviates heat stress-induced intestinal mucosal damage both in vitro and in vivo. This effect is mediated, at least partly, by the inhibition of the TLR4/STAT6/MYLK signaling pathway and upregulation of tight junction proteins. These findings suggest that CS-GT may have therapeutic potential in the prevention and treatment of heat stress-related intestinal injury.

Strategies for the Preparation of Chitosan Derivatives for Antimicrobial, Drug Delivery, and Agricultural Applications: A Review

Chitosan has received much attention for its role in designing and developing novel derivatives as well as its applications across a broad spectrum of biological and physiological activities, owing to its desirable characteristics such as being biodegradable, being a biopolymer, and its overall eco-friendliness. The main objective of this review is to explore the recent chemical modifications of chitosan that have been achieved through various synthetic methods. These chitosan derivatives are categorized based on their synthetic pathways or the presence of common functional groups, which include alkylated, acylated, Schiff base, quaternary ammonia, guanidine, and heterocyclic rings. We have also described the recent applications of chitosan and its derivatives, along with nanomaterials, their mechanisms, and prospective challenges, especially in areas such as antimicrobial activities, targeted drug delivery for various diseases, and plant agricultural domains. The accumulation of these recent findings has the potential to offer insight not only into innovative approaches for the preparation of chitosan derivatives but also into their diverse applications. These insights may spark novel ideas for drug development or drug carriers, particularly in the antimicrobial, medicinal, and plant agricultural fields.

Water-soluble fluorine-functionalized chitooligosaccharide derivatives: Synthesis, characterization and antimicrobial activity

In this work, a series of water-soluble fluorine-functionalized chitooligosaccharide derivatives were synthesized by conjugating nicotinic acid to chitooligosaccharide via nicotinylation reaction, followed by nucleophilic reaction with ethyl bromide, benzyl bromide and fluorobenzyl bromides. Synthesized derivatives were identified structurally by Fourier Transform Infrared Spectroscopy and Nuclear Magnetic Resonance. In addition, the antibacterial activities of chitooligosaccharide derivatives against several disease-causing bacteria were assessed by the broth dilution method and Kirby-Bauer method, the mycelium growth rate method was used to assessing the antifungal properties of samples against three plant-threatening fungi. Among the chitooligosaccharide derivatives, those containing benzyl or fluorobenzyl exhibited noteworthy antimicrobial activity. Specifically, the chitooligosaccharide derivative containing 2,3,4-trifluorobenzyl displayed remarkable antimicrobial activity, with an inhibition index of 84.35% against Botryis cinerea at a concentration of 1.0 mg/mL. Additionally, its MIC value against Staphylococcus aureus was found to be 0.03125 mg/mL, while the MBC value was determined to be 0.0625 mg/mL. The findings of the study revealed that the incorporation of pyridinium cations and fluorine into the chitooligosaccharide backbone may play a critical role in strengthening its ability to combat harmful microorganisms. Furthermore, the cytotoxicities of chitooligosaccharide derivatives against Huvec cells were evaluated through MTT assay, and all samples were not toxic. As a consequence, the water-soluble fluorine-functionalized chitooligosaccharide derivatives possessed rapid microbicidal properties and good biocompatibility, which provided promising prospects for the development of a more effective and environmentally friendly antimicrobial agent.

Synthesis and Characterization of Antibacterial Chitosan Films with Ciprofloxacin in Acidic Conditions

This work presents the results of research on obtaining chitosan (CS) films containing on their surface ciprofloxacin (CIP). A unique structure was obtained that not only gives new properties to the films, but also changes the way of coverage and structure of the surface. The spectroscopic test showed that in the process of application of CIP on the surface of CS film, CIP was converted from its crystalline form to an amorphic one, hence improving its bioavailability. This improved its scope of microbiological effect. The research was carried out on the reduction of CIP concentration during the process of CIP adhesion to the surface of chitosan films. The antibacterial activity of the CS films with and without the drug was evaluated in relation to Escherichia coli and Staphylococcus aureus, as well as Candida albicans and Penicillium expansum. Changes in the morphology and roughness of membrane surfaces after the antibacterial molecule adhesion process were tested with atomic force microscopy (AFM) and scanning electron microscopy (SEM). Structural analysis of CS and its modifications were confirmed with Fourier-transform spectroscopy in the infrared by an attenuated total reflectance of IR radiation (FTIR-ATR) and solid-state nuclear magnetic resonance (NMR).

Synthesis, characterization, and antimicrobial activities of a starch-based polymer

Due to the rise of nosocomial infections and the increasing threat of antibiotic resistance, new techniques are required to combat bacteria and fungi. Functional antimicrobial biodegradable materials developed from low-cost renewable resources like polysaccharides would enable greater applications in this regard. Our group has developed and characterized a new antimicrobial polymer using commercially available N-ethyl piperazine and starch via simple one-pot method. The prepared antimicrobial polymer was characterized by FTIR and NMR. In addition, the thermal properties of the synthesized antimicrobial polymer were examined through TGA and DSC. The antimicrobial potential of the prepared material was investigated using the bacteria, Staphylococcus aureus, Escherichia coli, and Mycobacterium smegmatis and a fungi Candida albicans. The result indicates that, as the amount of polymer increases, the antimicrobial activity also increases. SA-E-NPz exhibited a zone of inhibition in the range of 8-13 mm, and the MIC was found to be < 0.625 mg against all four microbes. The antimicrobial activity of polymer coated on fabric was also studied. Furthermore, the cytotoxicity studied against human fibroblast cell lines showed that the prepared polymer is non-toxic to the cells. The study concluded that the synthesized polymer shows good antimicrobial activity, is non-toxic to human fibroblast cells, and thus can be used for wound dressing or textile applications.

Edible chitosan-alginate based coatings enriched with turmeric and oregano additives: Formulation, antimicrobial and non-cytotoxic properties

In our study we developed the edible chitosan and alginate coatings with turmeric or oregano additives. The objective of the research was to evaluate the dose-dependent cytotoxicity of films. In cell line studies on HepG2 and BJ cells, they were shown to be non-cytotoxic materials (IC50% was not reached). For HepG2 increase in cell proliferation was observed for 3, 4, and 7 mg/mL of OS3 (124,79±9,21; 162,4±10,46; 165,37±18,44) after 72 h. In BJ cells, no significant decrease in proliferation was noted after 24- and 48-hour exposure to OS0 and OS1 (1-7 mg/ml). The addition of oregano (1% v/v) resulted in films with higher elongation at break and 40% higher tensile strength compared to the base (OS0) film. Use of additives significantly increased the thermal stability of the complexes (by an average of 10 °C). Coatings were tested on tofu and had proven potent antimicrobial properties.

Totally-green cellulosic fiber with prominent sustained antibacterial and antiviral properties for potential use in spunlaced non-woven fabric production

The worldwide spread of COVID-19 has put a higher requirement for personal medical protective clothing, developing protective clothing with sustained antibacterial and antiviral performance is the priority for safe and sustaining application. For this purpose, we develop a novel cellulose based material with sustained antibacterial and antiviral properties. In the proposed method, the chitosan oligosaccharide (COS) was subjected to a guanylation reaction with dicyandiamide in the presence of Scandium (III) triflate; because of the relatively lower molecular weight and water solubility of the COS, GCOS (guanylated chitosan oligosaccharide) with high substitution degree (DS) could be successfully synthetized without acid application. In this instance, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the GCOS were only 1/8 and 1/4 of that of COS. The introduction of GCOS onto the fiber endowed the fiber with extremely high antibacterial and antiviral performance, showing 100% bacteriostatic rate against Staphylococcus aureus and Escherichia coli and 99.48% virus load reduction of bacteriophage MS2. More importantly, the GCOS modified cellulosic fibers (GCOS-CFs) exhibit excellent sustained antibacterial and antiviral properties; namely, 30 washing cycles had negligible effect on the bacteriostatic rate (100%) and inhibition rate of bacteriophage MS2 (99.0%). Moreover, the paper prepared from the GCOS-CFs still exhibited prominent antibacterial and antiviral activity; inferring that the sheeting forming, press, and drying process have almost no effect on the antibacterial and antiviral performances. The insensitive of antibacterial and antiviral activity to water washing (spunlace) and heat (drying) make the GCOS-CFs a potential material applicable in the spunlaced non-woven fabric production.

Isopropoxy Benzene Guanidine Ameliorates Streptococcus suis Infection In Vivo and In Vitro

Streptococcus suis, an encapsulated zoonotic pathogen, has been reported to cause a variety of infectious diseases, such as meningitis and streptococcal-toxic-shock-like syndrome. Increasing antimicrobial resistance has triggered the need for new treatments. In the present study, we found that isopropoxy benzene guanidine (IBG) significantly attenuated the effects caused by S. suis infection, in vivo and in vitro, by killing S. suis and reducing S. suis pathogenicity. Further studies showed that IBG disrupted the integrity of S. suis cell membranes and increased the permeability of S. suis cell membranes, leading to an imbalance in proton motive force and the accumulation of intracellular ATP. Meanwhile, IBG antagonized the hemolysis activity of suilysin and decreased the expression of Sly gene. In vivo, IBG improved the viability of S. suis SS3-infected mice by reducing tissue bacterial load. In conclusion, IBG is a promising compound for the treatment of S. suis infections, given its antibacterial and anti-hemolysis activity.

Development of lipidated polycarbonates with broad-spectrum antimicrobial activity

Antimicrobial resistance is a global challenge owing to the lack of discovering effective antibiotic agents. Antimicrobial polymers containing the cationic groups and hydrophobic groups which mimic natural host-defense peptides (HDPs) show great promise in combating bacteria. Herein, we report the synthesis of lipidated polycarbonates bearing primary amino groups and hydrophobic moieties (including both the terminal long alkyl chain and hydrophobic groups in the sequences) by ring-opening polymerization. The hydrophobic/hydrophilic group ratios were adjusted deliberately and the lengths of the alkyl chains at the end of the polymers were modified to achieve the optimized combination for the lead polymers, which exhibited potent and broad-spectrum bactericidal activity against a panel of Gram-positive and Gram-negative bacteria. The polymers only showed very limited hemolytic activity, demonstrating their excellent selectivity. Comprehensive analyses using biochemical and biophysical assays revealed the strong interaction between the polymers and bacteria membranes. Moreover, the polymers also showed strong biofilm inhibition activity and did not readily induce antibiotic resistance. Our results suggest that lipidated polycarbonates could be a new class of antimicrobial agents.

Polysaccharide-based C-dots and polysaccharide/C-dot nanocomposites: fabrication strategies and applications

C-dots are a new class of materials with vast applications. The synthesis of bio-based C-dots has attracted increasing attention in recent years. Polysaccharides being the most abundant natural materials with high biodegradability and no toxicity have been the focus of researchers for the synthesis of C-dots. C-dots obtained from polysaccharides are generally fabricated via thermal procedures, carbonization, and microwave pyrolysis. Small size, photo-induced electron transfer (PET), and highly adjustable luminosity behavior are the most important physical and chemical properties of C-dots. However, C-dot/polysaccharide composites can be introduced as a new generation of composites that combine the features of both C-dots and polysaccharides having a wide range of applications in biomedicines, biosensors, drug delivery systems, etc. This review demonstrates the features, raw materials, and methods used for the fabrication of C-dots derived from different polysaccharides. Furthermore, the properties, applications, and synthesis conditions of various C-dot/polysaccharide composites are discussed in detail.

Bacterial Cellulose/Cellulose Imidazolium Bio-Hybrid Membranes for In Vitro and Antimicrobial Applications

In biomedical applications, bacterial cellulose (BC) is widely used because of its cytocompatibility, high mechanical properties, and ultrafine nanofibrillar structure. However, biomedical use of neat BC is often limited due to its lack of antimicrobial properties. In the current article, we proposed a novel technique for preparing cationic BC hydrogel through in situ incorporation of cationic water-soluble cellulose derivative, cellulose bearing imidazolium tosylate function group (Cell-IMD), in the media used for BC preparation. Different concentrations of cationic cellulose derivative (2, 4, and 6%) were embedded into a highly inter-twined BC nanofibrillar network through the in situ biosynthesis until forming cationic cellulose gels. Cationic functionalization was deeply examined by the Fourier transform infrared (FT-IR), NMR spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) methods. In vitro studies with L929 cells confirmed a good cytocompatibility of BC/cationic cellulose derivatives, and a significant increase in cell proliferation after 7 days, in the case of BC/Cell-IMD3 groups. Finally, antimicrobial assessment against Staphylococcus aureus, Streptococcus mutans, and Candida albicans was assessed, recording a good sensitivity in the case of the higher concentration of the cationic cellulose derivative. All the results suggest a promising use of cationic hybrid materials for biomedical and bio-sustainable applications (i.e., food packaging).

Cationic Chitooligosaccharide Derivatives Bearing Pyridinium and Trialkyl Ammonium: Preparation, Characterization and Antimicrobial Activities

In this study, chitooligosaccharide-niacin acid conjugate was designed and synthesized through the reaction of chitooligosaccharide and nicotinic acid with the aid of N,N'-carbonyldiimidazole. Its cationic derivatives were prepared by the further nucleophilic substitution reaction between the chitooligosaccharide-niacin acid conjugate and bromopropyl trialkyl ammonium bromide with different alkyl chain lengths. The specific structural characterization of all derivatives was identified using Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR), and the degree of substitution was obtained using the integral area ratio of the hydrogen signals. Specifically, the antibacterial activities against Escherichia coli, Staphylococcus aureus, Pseudoalteromonas citrea and Vibrio harveyi were evaluated using broth dilution methods. In addition, their antifungal activities, including Botrytis cinerea, Glomerella cingulate and Fusarium oxysporum f. sp. cubense were assayed in vitro using the mycelium growth rate method. Experimental data proved that the samples showed antibacterial activity against four pathogenic bacteria (MIC = 1-0.125 mg/mL, MBC = 8-0.5 mg/mL) and enhanced antifungal activity (50.30-68.48% at 1.0 mg/mL) against Botrytis cinerea. In particular, of all chitooligosaccharide derivatives, the chitooligosaccharide derivative containing pyridinium and tri-n-butylamine showed the strongest antibacterial capacity against all of the test pathogenic bacteria; the MIC against Vibrio harveyi was 0.125 mg/mL and the MBC was 1 mg/mL. The experimental results above showed that the introduction of pyridinium salt and quaternary ammonium salt bearing trialkyl enhanced the antimicrobial activity. In addition, the cytotoxicity against L929 cells of the chitooligosaccharide derivatives was evaluated, and the compounds exhibited slight cytotoxicity. Specifically, the cell viability was greater than 91.80% at all test concentrations. The results suggested that the cationic chitooligosaccharide derivatives bearing pyridinium and trialkyl ammonium possessed better antimicrobial activity than pure chitooligosaccharide, indicating their potential as antimicrobial agents in food, medicine, cosmetics and other fields.

Ionic Liquid-Based Polymer Nanocomposites for Sensors, Energy, Biomedicine, and Environmental Applications: Roadmap to the Future

Current interest toward ionic liquids (ILs) stems from some of their novel characteristics, like low vapor pressure, thermal stability, and nonflammability, integrated through high ionic conductivity and broad range of electrochemical strength. Nowadays, ionic liquids represent a new category of chemical-based compounds for developing superior and multifunctional substances with potential in several fields. ILs can be used in solvents such as salt electrolyte and additional materials. By adding functional physiochemical characteristics, a variety of IL-based electrolytes can also be used for energy storage purposes. It is hoped that the present review will supply guidance for future research focused on IL-based polymer nanocomposites electrolytes for sensors, high performance, biomedicine, and environmental applications. Additionally, a comprehensive overview about the polymer-based composites' ILs components, including a classification of the types of polymer matrix available is provided in this review. More focus is placed upon ILs-based polymeric nanocomposites used in multiple applications such as electrochemical biosensors, energy-related materials, biomedicine, actuators, environmental, and the aviation and aerospace industries. At last, existing challenges and prospects in this field are discussed and concluding remarks are provided.

Multifunctional chitosan/gelatin@tannic acid cryogels decorated with in situ reduced silver nanoparticles for wound healing

Background

Most traditional wound dressings only partially meet the needs of wound healing because of their single function. Patients usually suffer from the increasing cost of treatment and pain resulting from the frequent changing of wound dressings. Herein, we have developed a mutifunctional cryogel to promote bacterial infected wound healing based on a biocompatible polysaccharide.

Methods

The multifunctional cryogel is made up of a compositive scaffold of chitosan (CS), gelatin (Gel) and tannic acid (TA) and in situ formed silver nanoparticles (Ag NPs). A liver bleeding rat model was used to evaluate the dynamic hemostasis performance of the various cryogels. In order to evaluate the antibacterial properties of the prepared cryogels, gram-positive bacterium Staphylococcus aureus (S. aureus) and gram-negative bacterium Escherichia coli (E. coli) were cultured with the cryogels for 12 h. Meanwhile, S. aureus was introduced to cause bacterial infection in vivo. After treatment for 2 days, the exudates from wound sites were dipped for bacterial colony culture. Subsequently, the anti-inflammatory effect of the various cryogels was evaluated by western blotting and enzyme-linked immunosorbent assay. Finally, full-thickness skin defect models on the back of SD rats were established to assess the wound healing performances of the cryogels.

Results

Due to its porous structure, the multifunctional cryogel showed fast liver hemostasis. The introduced Ag NPs endowed the cryogel with an antibacterial efficiency of >99.9% against both S. aureus and E. coli. Benefited from the polyphenol groups of TA, the cryogel could inhibit nuclear factor-κB nuclear translocation and down-regulate inflammatory cytokines for an anti-inflammatory effect. Meanwhile, excessive reactive oxygen species could also be scavenged effectively. Despite the presence of Ag NPs, the cryogel did not show cytotoxicity and hemolysis. Moreover, in vivo experiments demonstrated that the biocompatible cryogel displayed effective bacterial disinfection and accelerated wound healing.

Conclusions

The multifunctional cryogel, with fast hemostasis, antibacterial and anti-inflammation properties and the ability to promote cell proliferation could be widely applied as a wound dressing for bacterial infected wound healing.

Manipulating Bacterial Biofilms Using Materiobiology and Synthetic Biology Approaches

Bacteria form biofilms on material surfaces within hours. Biofilms are often considered problematic substances in the fields such as biomedical devices and the food industry; however, they are beneficial in other fields such as fermentation, water remediation, and civil engineering. Biofilm properties depend on their genome and the extracellular environment, including pH, shear stress, and matrices topography, stiffness, wettability, and charges during biofilm formation. These surface properties have feedback effects on biofilm formation at different stages. Due to emerging technology such as synthetic biology and genome editing, many studies have focused on functionalizing biofilm for specific applications. Nevertheless, few studies combine these two approaches to produce or modify biofilms. This review summarizes up-to-date materials science and synthetic biology approaches to controlling biofilms. The review proposed a potential research direction in the future that can gain better control of bacteria and biofilms.

Antimicrobial properties of chitosan from different developmental stages of the bioconverter insect Hermetia illucens

Growing antimicrobial resistance has prompted researchers to identify new natural molecules with antimicrobial potential. In this perspective, attention has been focused on biopolymers that could also be functional in the medical field. Chitin is the second most abundant biopolymer on Earth and with its deacetylated derivative, chitosan, has several applications in biomedical and pharmaceutical fields. Currently, the main source of chitin is the crustacean exoskeleton, but the growing demand for these polymers on the market has led to search for alternative sources. Among these, insects, and in particular the bioconverter Hermetia illucens, is one of the most bred. Chitin can be extracted from larvae, pupal exuviae and dead adults of H. illucens, by applying chemical methods, and converted into chitosan. Fourier-transformed infrared spectroscopy confirmed the identity of the chitosan produced from H. illucens and its structural similarity to commercial polymer. Recently, studies showed that chitosan has intrinsic antimicrobial activity. This is the first research that investigated the antibacterial activity of chitosan produced from the three developmental stages of H. illucens through qualitative and quantitative analysis, agar diffusion tests and microdilution assays, respectively. Our results showed the antimicrobial capacity of chitosan of H. illucens, opening new perspectives for its use in the biological area.

Novel Chitosan Derivatives and Their Multifaceted Biological Applications

Chitosan is a rather attractive material, especially because of its bio-origins as well as generation from exoskeletal waste. As the mantle has been effectively transferred from chitin to chitosan, so has it been extrapolated to in-house synthesized novel chitosan derivatives. This review comprehensively lists the available novel chitosan derivatives (ChDs) and summarizes their biological applications. The fact that chitosan derivatives do comprise multifaceted biological applications is attested by the voluminous reports on their varied contributions. However, this review points out to the fact that there has been selective focus on bio functions such as antifungal, antioxidant, antibacterial, whereas other biomedical applications and antiviral applications remain relatively less explored. With their current functionality record, there is definitely no doubt that the plethora of synthesized ChDs will have a profound impact on the unexplored biological aspects. This review points out this lacuna as room for future exploration.

Novel design of bandages using cotton pads, doped with chitosan, glycogen and ZnO nanoparticles, having enhanced antimicrobial and wounds healing effects

In this present work, a new design for antimicrobial wound bandages is presented. The wound dressings were prepared using cotton fibers reinforced with elastic compression straps and secured with a polyester fabric of tight mesh size. The cotton pads were doped with a wound healing biocomposite, composed of chitosan, glycogen, and ZnO nanoparticles (CG@ZnONPs) previously formulated through a green process. The size of ZnONPs in the prepared CG@ZnONPs was 30-80 nm. The cotton pads impregnated with the CG@ZnONPs nanocomposite were characterized using FTIR, SEM, EDX, TGA, and DTGA methods. Moreover, the prepared dressings were tested on a number of intentionally injured rats. In this experiment, the % contraction of the treated wounds was monitored and compared to that of a control group of wounded rats, to which only sterile gauzes were applied. The results showed a much faster and an almost complete healing of rats treated with the synthesized dressings and the results were further confirmed by histopathological examination. The dressings were also found to exert a significant antimicrobial activity against a number of pathogenic microorganisms, generally encountered in common wounds, and could therefore be recommended to be a novel biomedical application for a fast, successful, and flawless wounds healing process.

Current trends in chitosan based nanopharmaceuticals for topical vaginal therapies

Large surface area, rich vascularisation, well defined mucous membrane, balanced pH and relatively low enzymatic activity makes vagina a suitable site for drugs associated with women's health issues like Urinary tract infection (UTI) and vaginal infections. Therapeutic performance of intravaginal dosage forms largely depends on the properties of polymers and drugs. Chitosan (CS) because of its unique physical, chemical, pharmaceutical and biopharmaceutical properties have received a great deal of attention as an essential component in vaginal drug delivery systems. Further the presence of free amino and hydroxyl groups on the chitosan skeleton allows easy derivatization under mild conditions to meet specific application requirements. Moreover, CS-based nanopharmaceuticals like nanoparticles, nanofiber, nanogel, nanofilm, liposomes and micelles are widely studied to improve therapeutic performance of vaginal formulations. However, susceptibility of CS to the acidic pH of vagina, poor loading of hydrophobic drugs, rapid mucosal turn over are the key issues need to be addressed for successful outcomes. In this review, we have discussed the application of CS and CS derivatives in vaginal drug delivery and also highlight the recent progress in chitosan based nanocarrier platforms in terms of their limitations and potentials.

Rationally engineered chitin deacetylase from Arthrobacter sp. AW19M34-1 with improved catalytic activity toward crystalline chitin

Chitin and its derivatives have anticoagulant, antimicrobial, and antioxidant properties, but the poor solubility of chitin limits its application in different fields. In this study, site-directed mutagenesis was performed to enhance the deacetylation activity of chitin deacetylases CDA from Arthrobacter (ArCE4). The mutant Mut-2-8 with Y172E/E200S/Y201W showed a 2.84- fold and 1.39-fold increase in catalytic efficiency (kcat/Km) for the deacetylation of (GluNAc)₅ and α-chitin, respectively. These results demonstrated that the mutations significantly improved the activation of ArCE4 on crystalline chitin. The molecular docking study confirmed that the enhancement of catalytic efficiency is due to the extra two hydrogen bonds and one acetyl group. In summary, the activity of Mut-2-8 to insoluble chitin was significantly improved by reactional design, which is beneficial to resolve the issues of the expensive cost of the enzymes and low efficiency. Mut-2-8 exhibits potential applications in the chitosan industry.

Antimicrobial and antiviral activities with molecular docking study of chitosan/carrageenan@clove oil beads

BACKGROUND

Biopolymers are promising candidates that can be fabricated into hydrophilic matrices and used for many applications due to their distinctive properties such as non-toxic, biodegradable, biocompatibility, and low cost. A promising composite of chitosan and carrageenan with self-crosslinking has been prepared.

METHODS AND RESULTS

In this study, a rigorous approach for an inexpensive and non-toxic combination of different amounts of clove oil with two polyelectrolytes including chitosan and carrageenan in the form of beads have been prepared. The structure and the surface morphology of the beads were investigated using FTIR, XRD, and SEM. Moreover, antimicrobial, antiviral activity, and molecular docking were evaluated. Antibacterial results revealed that chitosan/carrageenan@clove oil beads have antimicrobial activity as well as chitosan/carrageenan without clove oil against Escherichia colia ATCC25922, Pseudomonas aeruginosa aATCC27853, Staphylococcus aureus ATCC25923, Bacillus subtilisaATCC6051 and Candida albicanssATCC90028. Furthermore, maximum non-toxic concentration (MNTC) of chitosan/carrageenan@clove oil beads was (31.25 μg/mL) which exhibited promising antiviral activity against Herpes simplex virus-1 (HSV-1), and was significantly higher than chitosan/carrageenan without clove oil, where antiviral activity was 82.94 and 57.64% respectively. Eventually, docking study and computational calculation have been used to show the reactivity of the molecules.

CONCLUSIONS

The developed chitosan/carrageenan@clove oil beads have shown promising properties to be used as carriers of drug delivery, tissue engineering, and regenerative medicine. This article is protected by copyright. All rights reserved.

A new approach for antimicrobial and antiviral activities of biocompatible nanocomposite based on cellulose, amino acid and graphene oxide

In this work, biocompatible, antimicrobial, and antiviral nanocomposites were prepared through two steps. In the first step, periodate oxidation of cellulose was performed to get dialdehyde cellulose (DAC). The second step included the reaction of DAC with sulfur-containing amino acids included Cysteine (Cys) and Methionine (Meth) in the presence of graphene oxide (GO). The prepared nanocomposites were characterized via FT-IR, SEM, TEM, and TGA. Antimicrobial and antiviral activities for all designed nanocomposites besides DAC were carried out. Both DAC/GO/Cys and DAC/GO/Meth exhibited a promising antimicrobial activity against Gram-negative (E. coli and P. aeruginosa), Gram-positive (B. subtilis and S. aureus), and unicellular fungi (C. Albicans and C. neoformans), while the DAC/GO/Cys/Meth nanocomposite was the lowest. Moreover, all designed nanocomposites have a strong antiviral activity against Herpes simplex virus 1(HSV-1) at minimum nontoxic concentration. Additionally, Computational procedures and Molecular docking showed the reactivity and stability of the molecules that have biological activity against Gram-positive, Gram-negative, and HSV-1. As well as DAC incorporation with amino acid enhanced their reactivity and their interaction.

Therapeutic effect and immune mechanism of chitosan-gentamicin conjugate on Pacific white shrimp (Litopenaeus vannamei) infected with Vibrio parahaemolyticus

To explore the disease resistance mechanism of chitosan conjugates, chitosan-gentamicin conjugate (CS-GT) was synthesized and systematically characterized, the immune mechanism of CS-GT on Litopenaeus vannamei infected with Vibrio parahaemolyticus was further explored. The results showed that imine groups in CS-GT were effectively reduced. Dietary supplementation of CS-GT can significantly increase the survival rate, total hemocyte counts, the antioxidant and immune related enzyme activity levels of shrimps (P < 0.05), which are all dose-dependent under the experimental conditions. In addition, CS-GT can protect the hepatopancreas from invading bacteria and alleviate inflammation. Particularly, CS-GT promotes the expressions of legumain (LGMN), lysosomal acid lipase (LIPA) and Niemann-Pick type C2 (NPC2) up-regulated. It is speculated that CS-GT may stimulate the lysosome to phagocytose pathogens more effectively. In conclusions, shrimps fed with CS-GT can produce immune response via lysosome and greatly improve the disease resistance to Vibrio parahaemolyticus.

Anticancer, Enhanced Antibacterial, and Free Radical Scavenging Potential of Fucoidan- (Fucus vesiculosus Source) Mediated Silver Nanoparticles

The present research displays the green synthesis of stable silver nanoparticles (AgNPs). The aqueous solution of Fucoidan from Fucus vesiculosus source (brown marine algae) is used as a reducing and capping agent. UV-Vis spectroscopy, XRD, FT-IR, SEM, EDX, and TEM with selected area electron diffraction are used to characterize the synthesized silver nanoparticles (AgNPs). The synthesized AgNPs exhibit a surface plasmon resonance at 430 nm after 24 h. The characterization results showed that AgNPs are crystalline in nature and exhibit mostly spherical shapes with an average diameter of 4-45 nm. Silver nanoparticles showed effective antibacterial activity against representative pathogens of bacteria. The activities of commercial antibiotics were enhanced by impregnation with the synthesized AgNPs. It also shows good fungicidal and anticancer activity against liver and lung cell lines and shows significant antioxidant efficacy (84%) at 10 μg/ml AgNP concentration against DPPH. The utilization of environmentally synthesized AgNPs offers numerous benefits of ecofriendliness and compatibility for biomedical applications.

Antimicrobial and Antiviral Activities of Durable Cotton Fabrics Treated with Nanocomposite Based on Zinc Oxide Nanoparticles, Acyclovir, Nanochitosan, and Clove Oil

In this study, cotton fabrics based on zinc oxide nanoparticles in situ synthesis, acyclovir, nanochitosan, and clove oil were treated. The treated cotton fabrics were examined by FTIR, HR-TEM, FE-SEM, EDAX, and the surface roughness processing of FE-SEM images. The obtained characterization data emphasized the nano-size of nanocomposite with high homogeneity of particles in spherical shape as well as affirmed the deposition of nanocomposite onto the textile fibers with concluded that the deposition of nanocomposite was increased parallel with sonication time. Antimicrobial and antiviral activities of treated cotton fabrics were evaluated. Results revealed that treated cotton fabrics exhibited promising antibacterial activity toward Gram-positive higher than Gram-negative bacteria. Likewise, treated cotton fabrics are still effective as antibacterial after washing for 100 cycles. Moreover, treated cotton fabrics exhibited potential antifungal activity against Candida albicans, Aspergillus niger, and Aspergillus fumigatus. The antiviral activity significantly depended on the type of virus. The treated cotton fabrics showed antiviral activity against tested viral particles (HSV-1, Adeno, and CoxB2) with viral inhibition of 95.9, 76.4, and 86.9% respectively, while in the case of coated cotton textile with acyclovir, it only exhibited viral inhibition of 49.9, 41, and 22.3% respectively.

Ionic Liquid-Based Materials for Biomedical Applications

Ionic liquids (ILs) have been extensively explored and implemented in different areas, ranging from sensors and actuators to the biomedical field. The increasing attention devoted to ILs centers on their unique properties and possible combination of different cations and anions, allowing the development of materials with specific functionalities and requirements for applications. Particularly for biomedical applications, ILs have been used for biomaterials preparation, improving dissolution and processability, and have been combined with natural and synthetic polymer matrixes to develop IL-polymer hybrid materials to be employed in different fields of the biomedical area. This review focus on recent advances concerning the role of ILs in the development of biomaterials and their combination with natural and synthetic polymers for different biomedical areas, including drug delivery, cancer therapy, tissue engineering, antimicrobial and antifungal agents, and biosensing.

Ionic chitosan/silica nanocomposite as efficient adsorbent for organic dyes

A new adsorbent from chitosan and anionic silica was prepared by ionic interaction followed by sol-gel process. The obtained nanocomposite was characterized by different techniques: FTIR, XRD, SEM/EDX, TGA, and TEM. The results showed that silica precursor interacts with chitosan and deposits as regular spherical nanoparticles. The methylene blue (MB) adsorption by chitosan/silica nanocomposite achieved the adsorption equilibrium within 60 min. The adsorption method is fitted to the pseudo-second-order kinetic model and the Langmuir adsorption model with a maximum adsorption capacity of 847.5 mg/g at slight alkaline solution. Chitosan/silica composite displayed high regeneration capability and recovery of MB up to five cycles without the loss of the adsorption efficiency. The current study showed that as-prepared chitosan/silica nanocomposite is an appropriate material for the adsorption of organic pollutants from wastewater.

Development of Antimicrobial Laser-Induced Photodynamic Therapy Based on Ethylcellulose/Chitosan Nanocomposite with 5,10,15,20-Tetrakis(m-Hydroxyphenyl)porphyrin

The development of new antimicrobial strategies that act more efficiently than traditional antibiotics is becoming a necessity to combat multidrug-resistant pathogens. Here we report the efficacy of laser-light-irradiated 5,10,15,20-tetrakis(m-hydroxyphenyl)porphyrin (mTHPP) loaded onto an ethylcellulose (EC)/chitosan (Chs) nanocomposite in eradicating multi-drug resistant Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans. Surface loading of the ethylcelllose/chitosan composite with mTHPP was carried out and the resulting nanocomposite was fully characterized. The results indicate that the prepared nanocomposite incorporates mTHPP inside, and that the composite acquired an overall positive charge. The incorporation of mTHPP into the nanocomposite enhanced the photo- and thermal stability. Different laser wavelengths (458; 476; 488; 515; 635 nm), powers (5-70 mW), and exposure times (15-45 min) were investigated in the antimicrobial photodynamic therapy (aPDT) experiments, with the best inhibition observed using 635 nm with the mTHPP EC/Chs nanocomposite for C. albicans (59 ± 0.21%), P. aeruginosa (71.7 ± 1.72%), and S. aureus (74.2 ± 1.26%) with illumination of only 15 min. Utilization of higher doses (70 mW) for longer periods achieved more eradication of microbial growth.

Antimicrobial Polymer-Based Assemblies: A Review

An antimicrobial supramolecular assembly (ASA) is conspicuous in biomedical applications. Among the alternatives to overcome microbial resistance to antibiotics and drugs, ASAs, including antimicrobial peptides (AMPs) and polymers (APs), provide formulations with optimal antimicrobial activity and acceptable toxicity. AMPs and APs have been delivered by a variety of carriers such as nanoparticles, coatings, multilayers, hydrogels, liposomes, nanodisks, lyotropic lipid phases, nanostructured lipid carriers, etc. They have similar mechanisms of action involving adsorption to the cell wall, penetration across the cell membrane, and microbe lysis. APs, however, offer the advantage of cheap synthetic procedures, chemical stability, and improved adsorption (due to multipoint attachment to microbes), as compared to the expensive synthetic routes, poor yield, and subpar in vivo stability seen in AMPs. We review recent advances in polymer-based antimicrobial assemblies involving AMPs and APs.

Does polysaccharide quaternization improve biological activity?

The natural polysaccharides, due to their structural diversity, commonly present very distinct solubility and physical chemical properties and additionally have intrinsic biological activities that, gene-rally, reveal themselves in a light way. The chemical modification of the molecular structure can improve these parameters. In this review, original articles that approached the quaternization of polysaccharides for purposes of biological application were selected, without limitation of year of publication, in the databases Scopus, Web of Science and PubMed. The results obtained from the bibliographic survey indicate that the increase in positive charges caused by quaternization improves the interaction between modified polysaccharides and structures that have negative charges on their surface, such as the cell wall of microorganisms and some cells in the human body, such as the DNA. This greater interaction is reflected as an increase in the biological activity of all polysaccharides broached in this study. Another important data obtained was the fact that the chemical changes did not affect or irrelevantly affect the toxicity of almost all of the polysaccharides that were quaternized. Therefore, polysaccharide quaternization is a safe and effective way to obtain improvements in the biological behavior of these macromolecules.

Synthesis and antimicrobial activities of chitosan/polypropylene carbonate-based nanoparticles

Antibiotic resistance is an emerging threat to public health. The development of a new generation of antimicrobial compounds is therefore currently required. Here we report a novel antimicrobial polymer of chitosan/polypropylene carbonate nanoparticles (CS/PPC NPs). These were designed and synthesized from readily available chitosan and a reactive oligomer polypropylene carbonate (PPC)-derived epoxy intermediate. By employing a simple and efficient functionalized strategy, a series of micelle-like chitosan-graft-polypropylene carbonate (CS-g-PPC) polymers and chitosan-polypropylene carbonate (CS-PPC) microgels were prepared by reacting mono-/bis-epoxy capped PPC with chitosan. The chemical structure, particle size, and surface charge of the newly synthesized polymers were characterized by infrared (IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, dynamic light scattering (DLS), and zeta potential measurements. The antimicrobial activities of these nanoparticles were determined in both Gram-positive bacteria (S. aureus) and Gram-negative bacteria (E. coli). Minimum inhibitory concentration (MIC), the nanoparticle concentration needed to completely inhibit the bacterial growth, was found at 128 μg mL-1 to 1024 μg mL-1, strongly depending both on the nature of the epoxy-imine network formed from the functional groups (mono- or bis-capped epoxy groups reacting with amine groups) and the feed ratio of the functional groups (-epoxy/-NH2) between the functionalized PPC and chitosan. No hemolysis was observed at concentrations well in excess of the effective bacteria-inhibiting concentrations. These findings provide a novel strategy to fabricate a new type of nanoantibiotic for antimicrobial applications.

Antifungal activity of double Schiff bases of chitosan derivatives bearing active halogeno-benzenes

In this study, a series of chitosan derivatives bearing active halogenated aromatic imines were successfully synthesized via Schiff bases with the high degrees of substitution. Detailed structural characterization was carried out using Fourier transform infrared (FTIR) spectroscopy, solid-state ¹³C nuclear magnetic resonance (NMR) spectroscopy, and elemental analysis. Besides, the antifungal activity against three common plant pathogenic fungi, including Botrytis cinerea, Fusarium oxysporum f. sp. cucumerinum, and Fusarium oxysporum f. sp. niveum, was investigated using in vitro hyphal measurements. The results showed that double Schiff bases of chitosan derivatives exhibited enhanced antifungal activity compared with chitosan, especially at 1.0 mg/mL. The double Schiff bases of chitosan bearing halogeno-benzenes showed >95% inhibitory indices at 1.0 mg/mL against Botrytis cinereal since halogens had the stronger electron-withdrawing property. The higher degree of substitution was another positive effect to improve the antifungal activity. This study provides a practical strategy to synthesize new double Schiff bases of chitosan derivatives bearing halogeno-benzenes, which could be developed into stronger antifungal agents.

Enhancing the Antifungal Activity of Griseofulvin by Incorporation a Green Biopolymer-Based Nanocomposite

Fungal biofilms have caused several medical problems, resulting in significant morbidity and mortality as well as poor response to antifungal drugs. The current study was designed to evaluate the enhancement of antifungal and anti-biofilm activity of Griseofulvin-loaded green nanocomposite-based biopolymers (Ge-Nco) of glycogen and gelatin against different strains of pathogenic Candida species. The prepared Ge-Nco was characterized using Fourier-transform infrared (FT-IR), X-ray diffraction pattern (XRD), scanning electron microscopy-energy dispersive X-ray (SEM-EDX) and transmission electron microscope (TEM). In addition, the morphology of the mature biofilm and the inhibition of biofilm was monitored and visualized using confocal laser scanning microscopy (CLSM). The minimal inhibitory concentrations (MIC) and (IC50) of Griseofulvin alone and the prepared Ge-Nco against three different strains of Candida sp. were determined according to Clinical and Laboratory Standards Institute (CLSI) method. The effects of Griseofulvin alone and Ge-Nco on the tested Candida sp. biofilm formation were determined by the crystal-violet staining protocol. The biofilm inhibition potential of Ge-Nco against the tested Candida sp. was detected and depicted under CLSM (2.5 D view). The findings depicted that Ge-Nco was prepared in nanometer size (10–23 nm). The observed minimum inhibitory concentration (MIC) of Griseofulvin alone and Ge-Nco against three different Candida sp. were found to be in range 49.9–99.8 μg/mL and 6.24–12.48 μg/mL, respectively. These results provide evidence for implementing efficient antivirulence approaches against three different Candida sp. that would be less likely to foster the emergence of resistance.

Ecofriendly novel synthesis of tertiary composite based on cellulose and myco-synthesized selenium nanoparticles: Characterization, antibiofilm and biocompatibility

Microbial infections are considered common and dangerous for humans among other infections; therefore the synthesis of high efficacy antimicrobial and anti-biofilm composites is continuous to fight microbial resistance. In our study, a new and novel tertiary composite (TC) was synthesized, it composed of TEMPO cellulose (TOC), chitosan, starch, and myco-synthesized Se-NPs. Myco-synthesized Se-NPs and TC were fully characterized using UV, FT-IR, XRD, SEM with EDX, particle distribution, and mapping. The antimicrobial and anti-biofilm properties of selenium nanoparticles (Se-NPs) were effectively established for Pseudomonas aeruginosa and Staphylococcus aureus biofilms. The possible impact of myco-synthesized novel cellulose-based selenium nanoparticles tertiary composite on the biofilm formation of P. aeruginosa, S. aureus, and Candida albicans was evaluated in this study. TC exhibited constant biofilm inhibition against P. aeruginosa, S. aureus, and C. albicans, while the results obtained from cytotoxicity of Se-NPs and TC showed that, alteration occurred in the normal cell line of lung fibroblast cells (Wi-38) was shown as loss of their typical cell shape, granulation, loss of monolayer, shrinking or rounding of Wi-38 cell with an IC₅₀ value of where 461 and 550 ppm respectively.