Chitosan disrupts the barrier properties of the outer membrane of gram-negative bacteria

Advanced healing potential of simple natural hydrogel loaded with sildenafil in combating infectious wounds

Infected wounds are common clinical injuries that often complicated by inflammation and oxidative stress due to bacterial invasion. These wounds typically suffer from impaired vascularization, which delays healing and increases the risk of complications such as sepsis and chronic wounds. Therefore, developing an effective treatment for infected wounds is highly necessary. Egg white can promote cell regeneration and repair, while chitosan is effective in resisting bacterial invasion. Sildenafil is believed to have the potential to promote angiogenesis. Based on these properties, we have prepared a new type of hydrogel using egg white and chitosan as the framework, loaded with sildenafil (CEHS). The hydrogel combines the benefits of its components, exhibiting good biocompatibility and promoting the proliferation and migration of NIH 3T3 (3T3) cells and human umbilical vein endothelial cells (HUVEC), as well as the angiogenesis in HUVEC. It also exhibits significant antioxidant, anti-inflammatory, and antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Additionally, in a mouse model of infected wounds, the CEHS effectively promoted wound healing through its excellent antioxidant and anti-inflammatory properties, antibacterial activity, and pro-angiogenic effects. In summary, this simple-to-prepare, multifunctional natural hydrogel shows great promise for the treatment of infected wounds.

Obtention and Characterization of Chitosan from Exuviae of Tenebrio molitor and Sphenarium purpurascens

Chitosan is a versatile biopolymer with applications in various industries due to its biocompatibility and biodegradability. While crustacean shells are the primary source of chitosan, the extraction process can be environmentally taxing. This study focuses on evaluating chitosan from Tenebrio molitor and Sphenarium purpurascens, two insect species that offer a more sustainable alternative and require fewer resources for cultivation and produce large amounts of chitin-rich biomass. The acid-alkali method was applied using three experimental conditions (M1, M2, and M3) that involved modification in the demineralization, deproteinization, and deacetylation steps. The chitosan samples were characterized by determining the degree of deacetylation, solubility, molecular weight, antimicrobial activity, and swelling capacity and furthermore by measuring deproteinization and impurity content. Also, Fourier-transform infrared spectroscopy (FTIR) analysis was also performed on the chitosan samples. Samples M3 from the exuvia of T. molitor (DD 55.62% ± 0.79 and solubility 24.13% ± 2.07) and M1 from S. purpurascens (DD 61.86% ± 4.98 and solubility 27.31% ± 1.87) presented the best performance. The molecular weight was calculated between 75 kDa and 118 kDa. On the other hand, data obtained for swelling tests suggested that the film obtained from sample M1 (T. molitor, 5.07% ± 0.11) proved to be more resistant to degradation in an aqueous environment, suggesting that this chitosan could be used for designing a film with high resistance. By exploring these insect sources, this research aims to contribute to the development of chitosan production practices, with potential applications in water treatment, biomedicine, and food packaging, thereby expanding the availability and uses of this valuable biopolymer.

Effects of ruminal infusion of unsaturated fatty acids on digestive parameters, milk fatty acids and ruminal kinetics in Jersey cows supplemented with chitosan

This study aimed to evaluate the effects of ruminal infusion of unsaturated fatty acids on digestive parameters, milk fatty acids, and ruminal kinetics in Jersey cows supplemented (CHI) or not supplements (CON) with chitosan. Four multiparous Jersey cows cannulated in the rumen were used (DIM 150 ± 45, daily milk production 22.2 ± 4.5 kg). A crossover design was used, with two experimental periods of 17 days, seven days of adaptation, and 10 days of data collection. With a washout (buffer period) of five days between periods. Cows in the CHI group received 0.2% chitosan in the DM total of diet or 4g/kg of DMI. On day 17, 300 g of soybean oil were infused to evaluate the effect of chitosan's interaction on linoleic acid's biohydrogenation. No differences in dry matter intake and digestibility of nutrients, milk production, and composition were observed with the inclusion of 0.2% of CHI in the DM total of diet. CHI did not alter the fatty acid profile of milk, except for C18:1 cis-11 (P=0.02), which decreased with CHI supplementation. Diets did not influence any variables of energy balance, rumen characterization, omasal flow of nutrients, and rumen kinetics. Including chitosan in diets for lactating Jersey cows did not promote production and composition changes. Likewise, chitosan at the evaluated level does not influence rumen kinetics, omasal flow of nutrients, and energy balance.

Understanding antimicrobial activity of biogenic selenium nanoparticles and selenium/chitosan nano-incorporates via studying their inhibition activity against key metabolic enzymes

Microbial metabolic enzymes play a crucial role in several biological processes that have a significant impact on growth and proliferation. Therefore, inhibiting specific key metabolic enzymes can be an applicable approach for developing antimicrobial agents that selectively target pathogens. In the current study, selenium nanoparticles (Se NPs) extracellularly biosynthesized by Nocardiopsis sp. MAR13 and Se NPs incorporated with nano-chitosan (NCh) (Se/Ch-nano-incorporate) were evaluated for their antimicrobial activity against various microbial pathogens such as Salmonella typhi, Proteus vulgaris, Staphylococcus aureus, Escherichia coli, Aspergillus flavus, Aspergillus niger, Rhizoctonia sp., Candida albicans ATCC10231. The synthesized Se NPs, and Se/Ch-nano-incorporate were characterized by UV-Vis., FTIR, HRTEM, SEM, EDX, DLS, Zeta potential, and XRD. Additionally, their inhibition activity against microbial metabolic key enzymes, including phosphoglucose isomerase (PGI), pyruvate dehydrogenase (PDH), glucose-6-phosphate dehydrogenase (G6PDH), and nitrate reductase (NR), was assessed. The impact on protein leakage from bacterial cell membranes was also evaluated as a potential mechanism of antimicrobial action. On the other hand, MCF-7 and A549 tumor cell lines, as well as WI-38 normal cell lines, were used to assess their cytotoxic activity. It was found that Se NPs were spherical with a diameter range of 60.2 to 120.2 nm. In contrast, Se/Ch-nano-incorporate had a roughly spherical shape with a diameter range of 21.4 to 32.7 nm and substantially higher stability. Both synthesized agents exhibited strong antimicrobial activity against the most tested microbial pathogens with substantial inhibitory effect on the tested enzymes and notable protein leakage. Furthermore, they showed potent anticancer activity against both tumor cell lines with low cytotoxicity against WI-38 normal cell line. Consequently, Se NPs and Se/Ch-nano-incorporate are highly recommended to be employed as antimicrobial and anticancer agents with promised biosafety, eco-friendliness, and efficacy.

New advances in biological preservation technology for aquatic products

Aquatic products, characterized by their high moisture content, abundant nutrients, and neutral pH, create an optimal environment for the rapid proliferation of spoilage organisms, lipid oxidation, and autolytic degradation. These factors collectively expedite the spoilage and deterioration of aquatic products during storage and transportation within the supply chain. To maintain the quality and extend the shelf-life of aquatic products, appropriate preservation methods must be implemented. The growing consumer preference for bio-preservatives, is primarily driven by consumer demands for naturalness and concerns about environmental sustainability. The present review discusses commonly employed bio-preservatives derived from plants, animals, and microorganisms and their utilization in the preservation of aquatic products. Moreover, the preservation mechanisms of bio-preservatives, including antioxidant activity, inhibition of spoilage bacteria and enzyme activity, and the formation of protective films are reviewed. Integration of bio-preservation techniques with other methods, such as nanotechnology, ozone technology, and coating technology that enhance the fresh-keeping effect are discussed. Importantly, the principal issues in the application of bio-preservation technology for aquatic products and their countermeasures are presented. Further studies and the identification of new bio-preservatives that preserve the safety and quality of aquatic products should continue.

Cellulose Acetate Membranes: Antibacterial Strategy and Application-A Review

Developing antibacterial and biodegradable cellulose acetate (CA) membrane materials is one of the main challenges in multiple application fields. CA membrane materials are widely used in gas purification, water purification, and biomedical fields due to their environmental friendliness, high chemical and mechanical stability, excellent processability, and low cost. However, antibacterial modification of CA membrane materials to enhance their utilization value in the application process has always been the direction of researchers' efforts. This review focuses on the preparation and application of antibacterial CA and its derivatives membranes, especially the types and introduction methods of antibacterial agents. First, a brief introduction of CA-based polymer membranes is presented, followed by an overview of the antibacterial agent types and their introduction methods, and antibacterial mechanisms. After that, various membranes prepared using CA-based polymers as the main matrix or as additives are discussed. Then, specific applications of antibacterial CA-based membrane materials in water purification, gas purification, biomedical, food packaging, and other fields are outlined.

Antibacterial chitosan/organic rectorite nanocomposite-conjugated gelatin/β-cyclodextrin hydrogels with improved hemostasis performance for wound repair

Bacterial infections and severe bleeding continue to pose significant challenges in wound repair. There is an urgent need for innovative, nature-inspired hydrogel dressings with antibacterial and hemostatic properties. A Ge-β-CD-CS-OREC conjugate hydrogel was developed by grafting β-CD and CS-OREC nanocomposites into a Ge matrix using EDC/NHS crosslinking, as confirmed by FT-IR and EDX analyses. Compared to single Ge-β-CD cross-linked hydrogels, the addition of CS-OREC enhanced the hydrogel's properties, including increased pore size (60 ± 14 μm), improved wettability (WCA = 28.82 ± 0.6°), enhanced tensile strength (41.3 ± 3.56 KPa), and strong tissue adhesion. Furthermore, this hydrogel demonstrated excellent cytocompatibility when co-cultured with keratinocytes (Kcs) and vascular endothelial cells (VECs). The incorporation of CS chains into OREC interlayers allowed the hydrogel to specifically target bacteria and increase membrane permeability in Pseudomonas aeruginosa (PA), Klebsiella pneumoniae (KP), and Staphylococcus aureus (SA), effectively reducing the bacterial load in infected wounds by 50.24-73.92 % compared to controls in vivo. Further, the hydrogel exhibited superior hemostatic efficiency (78 ± 10 s) over commercial gauze and other gels by enhancing platelet activation and coagulation factor secretion. The hydrogel accelerated tissue regeneration by promoting epithelial maturation and blood vessel regeneration, indicating its clinical potential as promising wound dressing.

Exploring the Potential of Chitosan-Phytochemical Composites in Preventing the Contamination of Antibiotic-Resistant Bacteria on Food Surfaces: A Review

The escalating presence of antibiotic-resistant bacteria (ARB) in food systems presents a pressing challenge, particularly in preventing contamination and ensuring food safety. Traditional sanitation methods, such as cooking and chemical disinfectants, provide effective means to reduce ARB, yet there is a growing need for additional preventive measures directly on food surfaces. This review explores the potential of chitosan-phytochemical composites (CPCs) as surface coatings to prevent the initial contamination of food by ARB, thereby offering a novel complementary approach to conventional food safety practices. Chitosan, combined with active plant-derived metabolites (phytochemicals), forms composites with notable antibacterial and antioxidant properties that enhance its protective effects. We examine CPC synthesis methodologies, including chemical modifications, free radical-induced grafting, and enzyme-mediated techniques, which enhance the stability and activity of CPCs against ARB. Highlighting recent findings on CPCs' antibacterial efficacy through minimum inhibitory concentrations (MIC) and zones of inhibition, this review underscores its potential to reduce ARB contamination risks on food surfaces, particularly in seafood, meat, and postharvest products. The insights provided here aim to encourage future strategies leveraging CPCs as a preventative surface treatment to mitigate ARB in food production and processing environments.

Chitosan and Its Nanoparticles: A Multifaceted Approach to Antibacterial Applications

Chitosan, a multifaceted amino polysaccharide biopolymer derived from chitin, has extensive antibacterial efficacy against diverse pathogenic microorganisms, including both Gram-negative and Gram-positive bacteria, in addition to fungi. Over the course of the last several decades, chitosan nanoparticles (NPs), which are polymeric and bio-based, have garnered a great deal of interest as efficient antibacterial agents. This is mostly due to the fact that they are used in a wide variety of applications, including medical treatments, food, chemicals, and agricultural products. Within the context of the antibacterial mechanism of chitosan and chitosan NPs, we present a review that provides an overview of the synthesis methods, including novel procedures, and compiles the applications that have been developed in the field of biomedicine. These applications include wound healing, drug delivery, dental treatment, water purification, agriculture, and food preservation. In addition to this, we focus on the mechanisms of action and the factors that determine the antibacterial activity of chitosan and its derivatives. In conjunction with this line of inquiry, researchers are strongly urged to concentrate their efforts on developing novel and ground-breaking applications of chitosan NPs.

Potential of natural polysaccharide for ovarian cancer therapy

Ovarian cancer, characterized by high lethality, presents a significant clinical challenge. The standard first-line treatment is surgery and chemotherapy; however, postoperative chemotherapy is often ineffective and associated with severe side effects and the development of drug resistance. Consequently, there is an urgent need for innovative drug delivery strategies to enhance therapeutic efficacy. Natural polysaccharide polymers with high bioactivity have been extensively investigated for use alone or as adjuvants to chemotherapy and radiotherapy, and also for the preparation of efficient delivery systems for ovarian cancer therapy. This paper aims to review recent advances in the application of natural polysaccharides, including hyaluronic acid, chitosan, alginate, and cellulose, in the therapy of ovarian cancer. This paper primarily discusses the anti-tumor properties inherent to these natural polysaccharide polymers and offers a summary of their role in delivery systems used in ovarian cancer therapy.

Antimicrobial and Remineralization of Carboxymethyl Chitosan and Xylitol Functionalized Carbon Dots Coating on Orthodontic Brackets

Purpose

During fixed orthodontic treatment, oral hygiene is difficult to ensure and can easily lead to an imbalance in the oral micro-ecological balance. In this study, based on the adhesive properties of polydopamine (PDA) and the good antimicrobial and remineralization properties of carboxymethyl chitosan (CMC) and xylitol (Xy), new nanocomposites with both antimicrobial and remineralization capabilities were prepared to coat on orthodontic brackets.

Methods

Composite carbon dots (CDs) were synthesized using carboxymethyl chitosan and xylitol, we characterized them and the antimicrobial properties of the CMC-Xy-CDs were investigated by co-cultivation with S. mutans in vitro and in vivo. The composite coating was then adhered to the brackets. After the characterization measurements, antibacterial properties against S. mutans and the ability to promote remineralization of isolated teeth were investigated.

Results

Biological studies demonstrated that L929 cells co-cultured with CMC-Xy-CDs did not observe significant cytotoxicity and CMC-Xy-CDs have good biocompatibility. In the adhesive action of PDA, various characterizations have proved that CDs are modified on the brackets surface. In the antibacterial experiment, CMC-Xy-CDs and the adhesive coating on the brackets were found to have better antibacterial performance than the control group, with an antibacterial rate of up to 80%. In the animal experiment, the results of CMC-Xy-CDs promoting the healing of S. mutans infection wound models showed that there was a significant difference at 7d (P < 0.001), indicating that the experimental group had good antibacterial effects. The SEM of teeth after CMC-Xy-CDs promoted remineralization showed that the structure of the tooth surface became dense and some precipitation appeared, and the surface hardness measurement was significantly increased (p<0.0001).

Conclusion

Our study revealed that new nanocomposites with both antimicrobial and remineralization capabilities coated on orthodontic brackets provide a good basis for future clinical applications.

Garlic and Chitosan Improve the Microbial Quality of Hummus and Reduce Lipid Oxidation

This study investigated the antimicrobial and antioxidant effects of garlic and chitosan on hummus. Hummus was prepared by using 0.5% or 1% (w/w) chitosan, with or without 1% (w/w) garlic, and samples were stored at 4, 10, or 25 °C for 28, 21, or 7 d, respectively. The behavior of lactic acid bacteria (LAB), Pseudomonas spp., aerobic bacteria, and yeasts and molds was then investigated. Color, pH, TBARS, and rheological properties were also measured. In hummus, both with and without garlic, chitosan added at 0.5% and 1% w/w significantly (p < 0.05) decreased LAB, aerobic bacteria, yeasts, and molds, and Pseudomonas spp., at 4 °C. However, at 10 °C, adding chitosan at 1% w/w significantly reduced only aerobic bacteria (2.2 log cfu/g) and Pseudomonas spp. (1.0 log cfu/g). The pH values (regardless of treatment) decreased upon storage. The addition of garlic or chitosan did not significantly affect the lightness (L*) or yellowness (b*). However, garlic, regardless of chitosan concentration, notably reduced lipid oxidation (0.8-1.4 MDA Eq/kg of sample) and had a greater impact on the sensory properties compared to chitosan. The results of this study will encourage producers to produce hummus that has a better flavor due to garlic with enhanced microbial quality.

Chitosan-based dressing for management of palatal donor site: A randomized clinical trial

AIMS

This study aimed to evaluate the effectiveness of a chitosan-based dressing (CD) in achieving early wound healing and hemostasis at palatal donor sites in patients undergoing free gingival graft (FGG) surgery.

METHODS

Thirty-two patients requiring FGG were treated in this randomized controlled clinical trial. Complete epithelialization (CE) and color match (CM) at donor sites were assessed by a blinded examiner on postoperative days 7, 14, 21, and 28. Donor sites were compressed for 2 min with wet gauze (WG) alone in control group (CG) or WG + CD in test group (TG) immediately after graft harvesting, and immediate bleeding (IB) was recorded (yes/no). Delayed bleeding (DB) (for 1 week), and number of analgesic tablets consumed, and VAS scores for pain (for 2 weeks) were recorded by patient every day.

RESULTS

Twenty-eight patients (14 in each group) were included in final analysis. The prevalence of CE (at weeks 2 and 3) and VAS scores for CM scores were higher in TG but the intergroup differences were statistically significant only for CM (at week 4). Number of patients exhibiting IB and DB was significantly fewer in the TG (p < .05). Although average pain scores and analgesic consumption were higher in TG up to 5 days, differences between two groups were not statistically significant at any time point.

CONCLUSION

Our data suggests that the application of CD increased re-epithelialization and accelerated wound healing process, although it did not reach statistical significance. Moreover, CD was found to significantly reduce bleeding complications, but it did not decrease the pain levels.

Novel pectin-carboxymethylcellulose-based double-layered mucin/chitosan microcomposites successfully protect the next-generation probiotic Akkermansia muciniphila through simulated gastrointestinal transit and alter microbial communities within colonic ex vivo bioreactors

The rapid acceleration of microbiome research has identified many potential Next Generation Probiotics (NGPs). Conventional formulation processing methods are non-compatible, leading to reduced viability and unconfirmed incorporation into intestinal microbial communities; consequently, demand for more bespoke formulation strategies of such NGPs is apparent. In this study, Akkermansia muciniphila (A.muciniphila) as a candidate NGP was investigated for its growth and metabolism properties, based on which a novel microcomposite-based oral formulation was formed. Initially, a chitosan-based microcomposite was coated with mucin to establish a surface culture of A.muciniphila. This was followed by 'double encapsulation' with pectin (PEC) using a novel Entrapment Deposition by Prilling method to create core-shell double-encapsulated microcapsules. The formulation of A.muciniphila was verified to require no oxygen-restriction properties, and additionally, biopolymers were selected, including carboxymethylcellulose (CMC), that support and enhance its growth; consequently, a high viability (6 log CFU/g) of A.muciniphila microencapsulated in PEC-CMC double-encapsulates was obtained. Subsequently, the high stability of the PEC-CMC double-encapsulates was verified in simulated gastric fluid, successfully protecting and then releasing the A.muciniphila under intestinal conditions. Finally, employing a model of gastrointestinal transit and faecal-inoculated colonic bioreactors, significant alterations in microbial communities following administration and successful establishment of A.muciniphila were demonstrated.

Gelatin-chitosan interactions in edible films and coatings doped with plant extracts for biopreservation of fresh tuna fish products: A review

The preservation of tuna fish products, which are extremely perishable seafood items, is a substantial challenge due to their instantaneous spoilage caused by microbial development and oxidative degradation. The current review explores the potential of employing chitosan-gelatin-based edible films and coatings, which are enriched with plant extracts, as a sustainable method to prolong the shelf life of tuna fish products. The article provides a comprehensive overview of the physicochemical properties of chitosan and gelatin, emphasizing the molecular interactions that underpin the formation and functionality of these biopolymer-based films and coatings. The synergistic effects of combining chitosan and gelatin are explored, particularly in terms of improving the mechanical strength, barrier properties, and bioactivity of the films. Furthermore, the application of botanical extracts, which include high levels of antioxidants and antibacterial compounds, is being investigated in terms of their capacity to augment the protective characteristics of the films. The study also emphasizes current advancements in utilizing these composite films and coatings for tuna fish products, with a specific focus on their effectiveness in preventing microbiological spoilage, decreasing lipid oxidation, and maintaining sensory qualities throughout storage. Moreover, the current investigation explores the molecular interactions associated with chitosan-gelatin packaging systems enriched with plant extracts, offering valuable insights for improving the design of edible films and coatings and suggesting future research directions to enhance their effectiveness in seafood preservation. Ultimately, the review underscores the potential of chitosan-gelatin-based films and coatings as a promising, eco-friendly alternative to conventional packaging methods, contributing to the sustainability of the seafood industry.

Enhancement of antibacterial activity in electrospun fibrous membranes based on quaternized chitosan with caffeic acid and berberine chloride for wound dressing applications

Electrospun nanofibers made from chitosan are promising materials for surgical wound dressings due to their non-toxicity and biocompatibility. However, the antibacterial activity of chitosan is limited by its poor water solubility under physiological conditions. This study addresses this issue by producing electrospun nanofibers mainly from natural compounds, including chitosan and quaternized chitosan, which enhance both its solubility for electrospinning and the antibacterial activity of the resulting electrospun nanofibers. Additionally, antimicrobial agents like caffeic acid or berberine chloride were incorporated. The glutaraldehyde-treated nanofibers showed improved mechanical properties, with an average tensile strength exceeding 2.7 MPa, comparable to other chitosan-based wound dressings. They also demonstrated enhanced water stability, retaining over 50% of their original weight after one week in phosphate-buffered saline (PBS) at 37 °C. The morphology and performance of these nanofibers were thoroughly examined and discussed. Furthermore, these membranes displayed rapid drug release, indicating potential for inhibiting bacterial growth. Antibacterial assays revealed that S2-CX nanofibers containing caffeic acid were most effective against E. coli and S. aureus, reducing their survival rates to nearly 0%. Similarly, berberine chloride-containing S4-BX nanofibers reduced the survival rates of E. coli and S. aureus to 19.82% and 0%, respectively. These findings suggest that electrospun membranes incorporating chitosan and caffeic acid hold significant potential for use in antibacterial wound dressings and drug delivery applications.

Physical, antibacterial, blood coagulation, and healing promotion evaluations of chitosan derivative-based composite films

Chitosan is a potentially suitable material for wound dressing, but is undesirably water-insoluble. Although chitosan can be modified to produce water-soluble derivatives, the best chitosan derivative for wound dressings remains unclear. The present study introduced three water-soluble chitosan derivatives, namely, carboxymethyl chitosan, quaternized chitosan (QCS), and carboxymethyl quaternized chitosan, and explored the physical properties, biochemical properties, and wound care effectiveness of films of these derivatives. The QCS-based film exhibited higher absorption ability, mechanical properties, water-vapor permeability, electroconductivity, and antioxidant capacity than the other films. Most importantly, the cationic quaternary ammonium groups facilitated the antibacterial activity (>95 %) and blood coagulant capacity of the QCS-based film. As this film also promoted wound healing, it presented as an ideal candidate for wound dressings.

Designing antibacterial materials through simulation and theory

Antibacterial materials have a wide range of potential applications in bio-antimicrobial, environmental antimicrobial, and food antimicrobial fields due to their intrinsic antimicrobial properties, which can circumvent the development of drug resistance in bacteria. Understanding the intricate mechanisms and intrinsic nature of diverse antibacterial materials is significant for the formulation of guidelines for the design of materials with rapid and efficacious antimicrobial action and a high degree of biomedical material safety. Herein, this review highlights the recent advances in investigating antimicrobial mechanisms of different antibacterial materials with a particular focus on tailored computer simulations and theoretical analysis. From the view of structure and function, we summarize the characteristics and mechanisms of different antibacterial materials, introduce the latest advances of new antibacterial materials, and discuss the design concept and development direction of new materials. In addition, we underscore the significance of employing simulation and theoretical methodologies to elucidate the intrinsic antimicrobial mechanisms, which is crucial for a comprehensive comprehension of the control strategies, safer biomedical applications, and the management of health and environmental concerns associated with antibacterial materials. This review could potentially stimulate further endeavors in fundamental research and facilitate the extensive utilization of computational and theoretical approaches in the design of novel functional nanomaterials.

Effect of feeding chitosan and blend of essential organic acids on growth performance, haematological parameters and innate immunity in early aged male layer chicks

The use of antibiotics as conventional feed additives in poultry operations have proven useful, however resulted serious health concerns to consumer due to their bio-accumulation, besides rising problem of antimicrobial resistance in microbes, thus, an alternative to antibiotic growth promoter have called for. One of the aim of the experiment was to assess the lone and combined effects of feeding of chitosan oligosaccharide (COS) and blend of organic acids and short chain fatty acids in essential oils on growth performance, haematological parameters, relative lymphoid organ weight and innate immunity in early aged layer chick (male birds). A total of ninety, day-old chicks were randomly allotted into five groups: CO, Control group fed only poultry feed ; AGP, antibiotic growth promoter fed Avilomycin at the dose of 200 mg/kg of poultry feed; CH, chitosan oligosaccharide fed at the rate of 100 mg/kg feed; OE, blend of organic acids and short chain fatty acids in essential oils contained 1000 to 2000 mg/kg feed in a graded dose per week and CH + OE, chitosan oligosaccharide plus blend of organic acids and short chain fatty acids in essential oils at consistent rate and manner as followed for each of given feed additives when fed individually. Data on growth performance, samples for haematological parameters and innate immunity were measured and assayed on 7th, 21st and 42nd day post feeding (dpf) respectively. The results showed that compared with the control group; there is a marginal gain in body weight at 7th and 21st dpf in CH group and the corresponding CH + OE group. Feed conversion ratio in CH group was remarkably good at 7th and 21st dpf. No significant difference was observed in relative organ weights of thymus, spleen and Bursa of Fabricius in treatment groups as compared to control birds; however a significant rise in splenic weight index in OE fed birds at 42nd dpf noted. Haematological changes were inconsequential in treatment groups with an exception to enhancement of heterophil to lymphocyte ratio (H:L ratio) in CH group at 42nd dpf. Serum lysozyme activity proportionately elevated in CH + OE group on 21st and 42nd dpf when measured against control group; on the other hand no detectable augmentation of gut lysozyme activity observed. Both serum bactericidal and gut bactericidal activity boosted in combinatorial group at 42nd dpf. These results indicated that early age feeding of chitosan individually or combination with organic acids and short chain fatty acids in layer chick is beneficial, as it has the potential to enhance body weight gain to some extent and improves systemic and localized innate immunity to offer protection against infectious assaults thus may avoid early chick mortality in farms.

Applications of chitosan in the agri-food sector: A review

Chitosan is a natural and renewable polysaccharide that can form biopolymers. It is derived from the deacetylation of chitin mainly from crustaceans' shells, but also from fungi and insects. Thanks to unique characteristics such as antimicrobial effects, antioxidant properties or film forming capacities, it has triggered an important amount of research in the last decade about possible applications in industrial fields. The main application field of chitosan is the food industry where it can be used for preservation purposes and shelf-life improvement for fresh food products such as fruits or meat. For beverages, it is used for clarification and fining as well as elimination of spoilage flora in beverages like fruit juices or wine. And in agriculture, it can be used as a plant protection product through different mechanisms like the elicitation of plant defences. The mechanisms of action of chitosan on microorganisms are multiple and complex but revolve mostly around the disturbance of microorganisms' membranes and cell walls resulting in the leakage of cell material. The use of chitosan is still minor but is promising in finding environmentally friendly alternatives to synthetic chemicals and plastics. Therefore, its characterization is primordial for the future of sustainable production and preservation processes.

Preparation of Phosphorylated Chitosan From the Cuttlebone of Sepia pharaonis and the Effect of Concentration on Oral Clinical Pathogens

BACKGROUND

Chitosan, a biopolymer derived from chitin, has attracted scholarly interest because of its antibacterial, biocompatible, and biodegradable characteristics. We can phosphorylate the cuttlebone of Sepia pharaonis, a natural source of chitin, to enhance its antimicrobial properties. Phosphorylated chitosan is promising for treating oral infections, which are the causative agents of a variety of dental disorders.

OBJECTIVES

The goal of this study is to look into how to make phosphorylated chitosan from cuttlebone and what effect different concentrations have on killing oral clinical pathogens like Streptococcus mutans, Pseudomonas aeruginosa, Escherichia coli, and Candida tropicalis.

MATERIALS AND METHODS

We extracted chitin and chitosan from the cuttlebone of a specimen of S. pharaonis. We then synthesized phosphorylated chitosan by phosphorylating chitosan. We then assessed the antimicrobial activities of phosphorylated chitosan using the well diffusion method. We characterized and evaluated it using Fourier transform infrared spectroscopy (FTIR), Fourier emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD).

RESULTS

Phosphorylated chitosan, in 100% concentration, had the highest inhibition zone of 14 ± 0.82 mm against P. aeruginosa and E. coli (14 ± 0.75). However, the two different concentrations studied showed no activity against both Candida tropicalis and S. mutans.

CONCLUSION

This work successfully used the cuttlebone of S. pharaonis to yield phosphorylated chitosan, subsequently demonstrating its antimicrobial potential against dental clinical pathogens. Different concentrations of phosphorylated chitosan strongly controlled its antimicrobial activity, with larger concentrations exhibiting stronger inhibitory effects. According to these findings, phosphorylated chitosan appears to be a promising material for dental care solutions that target clinical bacteria in the mouth.

Cascaded Nanozyme Based pH-Responsive Oxygenation for Targeted Eradication of Resistant Helicobacter Pylori

Nanozymes, as substitutes for natural enzymes, are constructed as cascade catalysis systems for biomedical applications due to their inherent catalytic properties, high stability, tunable physicochemical properties, and environmental responsiveness. Herein, a multifunctional nanozyme is reported to initiate cascade enzymatic reactions specific in acidic environments for resistant Helicobacter pylori (H. pylori) targeting eradication. The cobalt-coated Prussian blue analog based FPB-Co-Ch NPs displays oxidase-, superoxide dismutase-, peroxidase-, and catalase- mimicking activities that trigger •O 2 - ${\mathrm{O}}_2^ - {\bm{\ }}$ and H2O2 to supply O2, thereby killing H. pylori in the stomach. To this end, chitosan is modified on the surface to exert bacterial targeted adhesion and improve the biocompatibility of the composite. In the intestinal environment, the cascade enzymatic activities are significantly inhibited, ensuring the biosafety of the treatment. In vitro, sensitive and resistant strains of H. pylori are cultured and the antibacterial activity is evaluated. In vivo, murine infection models are developed and its success is confirmed by gastric mucosal reculturing, Gram staining, H&E staining, and Giemsa staining. Additionally, the antibacterial capacity, anti-inflammation, repair effects, and biosafety of FPB-Co-Ch NPs are comprehensively investigated. This strategy renders a drug-free approach that specifically targets and kills H. pylori, restoring the damaged gastric mucosa while relieving inflammation.

Dencichine/palygorskite nanocomposite incorporated chitosan/polyvinylpyrrolidone film for accelerating wound hemostasis

The development of efficient, safe, environmentally friendly, and user-friendly hemostatic dressings remains a great challenge for researchers. A variety of clay minerals and plant extracts have garnered considerable attention due to their outstanding hemostatic efficacy and favorable biosafety. In this study, a facile solution casting strategy was employed to prepare nanocomposite films by incorporating natural nanorod-like palygorskite (Pal) and herb-derived hemostat dencichine (DC) based on chitosan and polyvinylpyrrolidone. The dynamic blood clotting index demonstrated that the nanocomposite film with a DC addition of 1.0 wt% exhibited significantly superior hemostatic properties compared to both pure DC powder or commercial hemostatic agent Yunnan Baiyao. This improvement was primarily attributed to proper blood affinity, increased porosity, enhanced adhesion of platelets and erythrocytes, as well as the accelerated activation of coagulation factors and platelets. Under the synergistic effect of Pal and DC, the nanocomposite film displayed suitable tensile strength (20.58 MPa) and elongation at break (47.29 %), which may be due to the strong intermolecular hydrogen bonding and electrostatic interaction between Pal/DC and macropolymers. Notably, the nanocomposite film exhibited remarkable antibacterial effectiveness and desirable cytocompatibility, as well as the capability of promoting wound healing in vitro. Taken together, the nanocomposite film synergized with Pal and DC is expected to be an efficacious and suitable wound dressing.

The quantitative molecular weight-antimicrobial activity relationship for chitosan polymers, oligomers, and derivatives

Chitosan and chitosan derivatives can kill pathogenic microorganisms including bacteria and fungi. The antimicrobial activity is dependent on the degree of acetylation, substituent structure, and molecular weight. Over the past four decades, numerous studies have endeavored to elucidate the relationship between molecular weight and the activity against microorganisms. However, investigators have reported divergent and, at times, conflicting conclusions. Here a bilinear equation is proposed, delineating the relationship between antimicrobial activity, defined as log (1/MIC), and the molecular weight of chitosan and chitosan derivatives. Three constants AMin, AMax, and CMW govern the shape of the curve determined by the equation. The constant AMin denotes the minimal activity expected as the molecular weight tends towards zero while AMax represents the maximal activity observed for molecular weights exceeding CMW, the critical molecular weight required for max activity. This equation was applied to analyze data from seven studies conducted between 1984 and 2019, which reported MIC (Minimum Inhibitory Concentration) values against bacteria and fungi for various molecular weights of chitosan and its derivatives. All the 29 datasets exhibited a good fit (R2 ≥ 0.5) and half excellent (R2 ≥ 0.95) fit to the equation. The CMW generally ranged from 4 to 10 KD for datasets with an excellent fit to the equation.

A randomized, placebo-controlled study of chitosan gel for the treatment of chronic diabetic foot ulcers (the CHITOWOUND study)

INTRODUCTION

To assess the efficacy of a chitosan-based gel (ChitoCare) for the treatment of non-healing diabetic foot ulcers (DFUs).

RESEARCH DESIGN AND METHODS

Forty-two patients with chronic DFUs were randomized to the ChitoCare or placebo gel for a 10-week treatment period and 4-week follow-up. The primary study end point was the rate of complete wound closure at week 10, presented as relative rate.

RESULTS

Thirty patients completed the 10-week treatment and 28 completed the 4-week follow-up. The ChitoCare arm achieved 16.7% complete wound closure at week 10 vs 4.2% in the placebo arm (p=0.297), 92.0% vs 37.0% median relative reduction in wound surface area from baseline at week 10 (p=0.008), and 4.62-fold higher likelihood of achieving 75% wound closure at week 10 (p=0.012). Based on the results of the Bates-Jensen Wound Assessment Tool, the wound state at week 10 and the relative improvement from the baseline were significantly better (median 20 vs 24 points, p=0.018, and median 29.8% vs 3.6%, p=0.010, respectively).

CONCLUSIONS

ChitoCare gel increased the rate of the DFU healing process. Several secondary end points significantly favored ChitoCare gel.

TRIAL REGISTRATION NUMBER

NCT04178525.

Poly(Lysine)-Derived Carbon Quantum Dots Conquer Enterococcus faecalis Biofilm-Induced Persistent Endodontic Infections

Introduction

Persistent endodontic infections (PEIs) mediated by bacterial biofilm mainly cause persistent periapical inflammation, resulting in recurrent periapical abscesses and progressive bone destruction. However, conventional root canal disinfectants are highly damaging to the tooth and periodontal tissue and ineffective in treating persistent root canal infections. Antimicrobial materials that are biocompatible with apical tissues and can eliminate PEIs-associated bacteria are urgently needed.

Methods

Here, ε-poly (L-lysine) derived carbon quantum dots (PL-CQDs) are fabricated using pyrolysis to remove PEIs-associated bacterial biofilms.

Results

Due to their ultra-small size, high positive charge, and active reactive oxygen species (ROS) generation capacity, PL-CQDs exhibit highly effective antibacterial activity against Enterococcus faecalis (E. faecalis), which is greatly dependent on PL-CQDs concentrations. 100 µg/mL PL-CQDs could kill E. faecalis in 5 min. Importantly, PL-CQDs effectively achieved a reduction of biofilms in the isolated teeth model, disrupting the dense structure of biofilms. PL-CQDs have acceptable cytocompatibility and hemocompatibility in vitro and good biosafety in vivo.

Discussion

Thus, PL-CQDs provide a new strategy for treating E. faecalis-associated PEIs.

Organoclay-assisted disperse dyeing of polypropylene nanocomposite fabrics in supercritical carbon dioxide

Dyeing using supercritical carbon dioxide (SC-CO2) is carried out on the polypropylene (PP) nanocomposite fabrics with model disperse dye compared with their regular fabric at various dyeing temperatures and pressures. The results are compared with those obtained in aqueous dyeing method. The PP nanocompsite fabrics dyed in SC-CO2 medium exhibited higher colour strength (K/S) values compared with their PP regular fabric. The PP nanocompsite fabrics and their regular fabric dyed in SC-CO2 medium have higher K/S values than those dyed in aqueous medium. The color coordinates of all PP fabrics dyed in SC-CO2 and aqueous medium were positive with respect to a* and b* coordinates depending on the disperse red dye uptake. The PP nanocomposite fabrics dyed in SC-CO2 and aqueous medium exhibited higher antibacterial properties than their regular fabrics. All PP fabrics dyed in SC-CO2 and aqueous medium present very good washing, perspiration and light fastness.

Chitosan nanocomposites as a nano-bio tool in phytopathogen control

Chitosan, an economically viable and versatile biopolymer, exhibits a wide array of advantageous physicochemical and biological properties. Chitosan nanocomposites, formed by the amalgamation of chitosan or chitosan nanoparticles with other nanoparticles or materials, have garnered extensive attention across agricultural, pharmaceutical, and biomedical domains. These nanocomposites have been rigorously investigated due to their diverse applications, notably in combatting plant pathogens. Their remarkable efficacy against phytopathogens has positioned them as a promising alternative to conventional chemical-based methods in phytopathogen control, thus exploring interest in sustainable agricultural practices with reduced reliance on chemical interventions. This review aims to highlight the anti-phytopathogenic activity of chitosan nanocomposites, emphasizing their potential in mitigating plant diseases. Additionally, it explores various synthesis methods for chitosan nanoparticles to enhance readers' understanding. Furthermore, the analysis delves into elucidating the intricate mechanisms governing the antimicrobial effectiveness of these composites against bacterial and fungal phytopathogens.

Marine polysaccharides: Biological activities and applications in drug delivery systems

The ocean is the common home of a large number of marine organisms, including plants, animals, and microorganisms. Researchers can extract thousands of important bioactive components from the oceans and use them extensively to treat and prevent diseases. In contrast, marine polysaccharide macromolecules such as alginate, carrageenan, Laminarin, fucoidan, chitosan, and hyaluronic acid have excellent physicochemical properties, good biocompatibility, and high bioactivity, which ensures their wide applications and strong therapeutic potentials in drug delivery. Drug delivery systems (DDS) based on marine polysaccharides and modified marine polysaccharide molecules have emerged as an innovative technology for controlling drug distribution on temporal, spatial, and dosage scales. They can detect and respond to external stimuli such as pH, temperature, and electric fields. These properties have led to their wide application in the design of novel drug delivery systems such as hydrogels, polymeric micelles, liposomes, microneedles, microspheres, etc. In addition, marine polysaccharide-based DDS not only have smart response properties but also can combine with the unique biological properties of the marine polysaccharide base to exert synergistic therapeutic effects. The biological activities of marine polysaccharides and the design of marine polysaccharide-based DDS are reviewed. Marine polysaccharide-based responsive DDS are expected to provide new strategies and solutions for disease treatment.

Facile fabrication of adenosine triphosphate/chitosan/polyethyleneimine coating for high flame-retardant lyocell fabrics with outstanding antibacteria

Addressing highly flammable and easily breeding bacteria property via environmentally friendly approach was critical for the large-scale application of lyocell fibers. Herein, a bio-based coating constructed by layer-by-layer deposition of adenosine triphosphate (ATP), chitosan (CS), and polyethyleneimine (PEI) was successfully fabricated to obtain excellent fire-resistant and antimicrobial lyocell fabrics (LBL/Lyocell). The resulted fabrics with add-on of 11.5 wt% achieved the limiting oxygen index (LOI) of 32.0 %. Meanwhile, compared with the pure lyocell fabrics, the peak of heat release rate (PHRR), total heat release (THR), and fire growth rate (FIGRA) of LBL/Lyocell fabrics decreased by 75.2 %, 61.0 % and 69.8 % in cone calorimetric test (CCT), respectively. By characterizing the gaseous products and solid residues, the presence of the ATP/CS/PEI coating could not only quickly form the dense expanded carbon layer by itself, but also promote the conversion of cellulose into thermal-stability residues, thus reducing the release of combustible substances during combustion and protecting the lyocell fabrics. In addition, LBL/Lyocell showed excellent antimicrobial properties with 99.99 % antibacterial rates against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). This bio-based coating was a promising candidate for efficiently flame-retardant cellulose fibers with excellent antibacteria.

Design and characterization of edible chitooligosaccharide/fish skin gelatin nanofiber-based hydrogel with antibacterial and antioxidant characteristics

Antibacterial and active packaging materials have gained significant research attention in response to the growing interest in food packaging. In this investigation, we developed hydrogel packaging materials with antibacterial and antioxidant properties by incorporating chitooligosaccharide (COS) and fish skin gelatin (FSG) nanofiber membranes, which readily absorbed water and exhibited swelling characteristics. The nanofiber membranes were fabricated by electrospinning technology, embedding COS within FSG, and subsequently crosslinked through the Maillard reaction facilitated by the addition of glucose. The behavior of conductivity, viscosity, and surface tension in the spinning solutions was analyzed to understand their variation patterns. Scanning electron microscopy (SEM) results revealed that the crosslinked COS/FSG nanofiber membranes possessed a uniform yet disordered fiber structure, with the diameter of the nanofibers increasing as the COS content increased. Remarkably, when the COS content reached 25 %, the COS/FSG nanofiber membranes (CF-C-25) exhibited a suitable fiber diameter of 437.16 ± 63.20 nm. Furthermore, the thermal crosslinking process involving glucose supplementation enhanced the hydrophobicity of CF-C-25. Upon hydration, the CF-H-25 hydrogel displayed a distinctive porous structure, exhibiting a remarkable swelling rate of 954 %. Notably, the inclusion of COS significantly augmented the antibacterial and antioxidant properties of the hydrogel-based nanofiber membranes. CF-H-25 demonstrated an impressive growth inhibition of 90.56 ± 5.91 % against E. coli, coupled with excellent antioxidant capabilities. In continuation, we performed a comprehensive analysis of the total colony count, pH, TVB-N, and TBA of crucian carp. The CF-H-25 hydrogel proved highly effective in extending the shelf life of crucian carp by 2-4 days, suggesting its potential application as an edible membrane for aquatic product packaging.

Polyelectrolyte Complex Hydrogels from Controlled Kneading and Annealing-Induced Tightly Wound and Highly Entangled Natural Polysaccharides

Hydrogels usually are fabricated by using monomers or preexisting polymers in precursor solutions. Here, a polyelectrolyte complex biohydrogel (Bio-PEC hydrogel) made from a precursor dough, by kneading, annealing, and crosslinking the dough of two oppositely charged polysaccharides, cationic chitosan quaternary ammonium salt (HACC) and anionic sodium hyaluronate (HA), photoinitiator (α-ketoglutaric acid), crosslinker glycidyl methacrylate (GMA), and water of very small quantity is reported. Controlled kneading and annealing homogenized the dough with respect to transforming randomly distributed, individual polymer chains into tightly wound double-stranded structures, which, upon UV irradiation, covalently sparsely crosslinked into a highly entangled network and subsequently, upon fully swollen in water, results in Bio-PEC hydrogel, HACC/HA, exhibiting near-perfect elasticity, high tensile strength, and high swelling resistance. Via the same kneading and annealing, tetracarboxyphenylporphyrin iron (Fe-TCPP) metal nanoclusters are incorporated into HACC/HA to obtain photocatalytic, antibacterial, and biocompatible Bio-PEC hydrogel composite, Fe-TCPP@HACC/HA. Using SD rat models, the efficacy of Fe-TCPP@HACC/HA in inhibiting Escherichia coli (E. coli) growth in vitro and the ability to promote wound healing and scar-free skin regeneration in vivo, or its high potential as a wound dressing material for biomedical applications are demonstrated.

2D Nanomaterials and Their Drug Conjugates for Phototherapy and Magnetic Hyperthermia Therapy of Cancer and Infections

Photothermal therapy (PTT) and magnetic hyperthermia therapy (MHT) using 2D nanomaterials (2DnMat) have recently emerged as promising alternative treatments for cancer and bacterial infections, both important global health challenges. The present review intends to provide not only a comprehensive overview, but also an integrative approach of the state-of-the-art knowledge on 2DnMat for PTT and MHT of cancer and infections. High surface area, high extinction coefficient in near-infra-red (NIR) region, responsiveness to external stimuli like magnetic fields, and the endless possibilities of surface functionalization, make 2DnMat ideal platforms for PTT and MHT. Most of these materials are biocompatible with mammalian cells, presenting some cytotoxicity against bacteria. However, each material must be comprehensively characterized physiochemically and biologically, since small variations can have significant biological impact. Highly efficient and selective in vitro and in vivo PTTs for the treatment of cancer and infections are reported, using a wide range of 2DnMat concentrations and incubation times. MHT is described to be more effective against bacterial infections than against cancer therapy. Despite the promising results attained, some challenges remain, such as improving 2DnMat conjugation with drugs, understanding their in vivo biodegradation, and refining the evaluation criteria to measure PTT or MHT effects.

A natural biogenic fluorapatite as a new biomaterial for orthopedics and dentistry: antibacterial activity of lingula seashell and its use for nanostructured biomimetic coatings

Calcium phosphates are widely studied in orthopedics and dentistry, to obtain biomimetic and antibacterial implants. However, the multi-substituted composition of mineralized tissues is not fully reproducible from synthetic procedures. Here, for the first time, we investigate the possible use of a natural, fluorapatite-based material, i.e., Lingula anatina seashell, resembling the composition of bone and enamel, as a biomaterial source for orthopedics and dentistry. Indeed, thanks to its unique mineralization process and conditions, L. anatina seashell is among the few natural apatite-based shells, and naturally contains ions having possible antibacterial efficacy, i.e., fluorine and zinc. After characterization, we explore its deposition by ionized jet deposition (IJD), to obtain nanostructured coatings for implantable devices. For the first time, we demonstrate that L. anatina seashells have strong antibacterial properties. Indeed, they significantly inhibit planktonic growth and cell adhesion of both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. The two strains show different susceptibility to the mineral and organic parts of the seashells, the first being more susceptible to zinc and fluorine in the mineral part, and the second to the organic (chitin-based) component. Upon deposition by IJD, all films exhibit a nanostructured morphology and sub-micrometric thickness. The multi-doped, complex composition of the target is maintained in the coating, demonstrating the feasibility of deposition of coatings starting from biogenic precursors (seashells). In conclusion, Lingula seashell-based coatings are non-cytotoxic with strong antimicrobial capability, especially against Gram-positive strains, consistently with their higher susceptibility to fluorine and zinc. Importantly, these properties are improved compared to synthetic fluorapatite, showing that the films are promising for antimicrobial applications.

In vitro and in vivo studies of Dragon's blood plant (D. cinnabari)-loaded electrospun chitosan/PCL nanofibers: Cytotoxicity, antibacterial, and wound healing activities

The D. cinnabari plant was loaded into the chitosan (Chn)/polycaprolactone (PCL) nanofibers in two forms: resin (D. cinnabari) and its ethyl acetate fraction. The Chn/PCL, Chn/PCL/D. cinnabari (CPD, 1, 3, and 5 %), and Chn/PCL/ethyl acetate extract D. cinnabari (CPED, 1, 3, and 5 %) showed no toxicity against human dermal fibroblast cells. The lactate dehydrogenase assay results indicated that the toxicity of pour, coated D. cinnabari, and CPED nanofibers were lower than 10 and 15 % after 1 and 3 days, respectively. The antibacterial results showed the inhibition zone for ethyl acetate extract D. cinnabari (ED-3 %), the Chn/PCL-2, and CPED3% nanofibers was 8.1, 7.4, 4.2, 5.1 mm, 12.8, 12.4, 21.7, 17.2 mm, and 24.7, 22.9, 37.1, 30.2 mm against S. aureus, B. subtilis, E. coli, and P. aeruginosa, respectively. The antibacterial activity results showed synergistic effect between the Chn/PCL and ethyl acetate extract D. cinnabari occurred. The diameter of wounds (1.50 × 1.50 cm diameter) made on the dorsal surface of rabbits reduced to 1.50 × 0.70, 0.50 × 0.30, 1.00 × 1.00, 0.60 × 0.50, 0.20 × 0.05, and 0.00 × 0.00 cm in the presence of ordinary gauze dressing, silver sulfadiazine, ED-3 %, Chn/PCL-2, CPD3%, and CPED3%nanofibers, respectively, after 14 days.

The impact of chitosan in experimental resin with different photoinitiator systems

OBJECTIVE

to investigate the effect of different concentrations of chitosan added to experimental resins containing either BAPO or camphorquinone (CQ) as photoinitiators, regarding degree of conversion (DC), flexural strength (FS), flexural elastic modulus (E), Knoop microhardness (KHN), cytotoxicity, genotoxicity and antimicrobial activity.

METHODS

Experimental resins with polymeric matrix of BisGMA and TEGDMA was added either 0.5 wt% BAPO or 0.5 wt% camphorquinone/0.2% amine along with and chitosan concentrations of 0.5%; 1.0% or 2.0%. Degree of conversion was measured using Fourier transformed infrared spectroscopy. Flexural strength and elastic modulus were obtained through three-point bending test and Knoop microhardness was measured in a microidenter. Direct cytotoxicity was performed in human keratinocytes and genotoxicity test was done in murine macrophages cells. Antimicrobial activity was acessed against Staphylococcus aureus and Streptococcus mutans through the inhibition halo. Data were analyzed using two-way ANOVA and Tukey teste (α = 0.05).

RESULTS

The materials containing photoinitiator BAPO showed higher values of DC, FS, E, and KHN compared to resins with CQ. The addition of chitosan did not affect the properties of these materials. However, in resins containing CQ, the addition of chitosan improve these properties compared to control group. For the groups containing BAPO the chitosan reduced cytotoxicity and genotoxicity compared to materials with camphorquinone. The materials with 1.0% and 2.0% chitosan showed increased antibacterial activity in the materials containing BAPO as photoinitiator for both bacteria.

SIGNIFICANCE

The alternative photoinitiator BAPO and chitosan can improve physical and biological properties of photoactivated resins when compared with the materials with photoinitiator camphorquinone.

Preparation and evaluation in vitro release of sodium alginate/chitosan polyelectrolyte microparticles containing rifampicin and theoretical study using DFT methods

In this work, rifampicin-loaded sodium alginate/chitosan polyelectrolyte microparticles were prepared by the ionotropic gelation technique using CaCl2 as a cross-linking agent. The influence of different sodium alginate and chitosan concentrations on particle size, surface properties, and in vitro release behavior was studied. An infrared spectroscopy investigation verified the lack of any drug-polymer interaction. The microparticles prepared using (30, 50) mg of sodium alginate were spherical while when using 75 mg of sodium alginate, vesicles with round heads and tapered tails were formed. The results showed that the microparticle diameters were between (11.872-35.3645) µm. The amount of rifampicin released and the kinetics of drug release from microparticles were studied, and the results showed that by increasing the concentration of the polymer, the release of the rifampicin from the microparticles decreased. The findings showed that rifampicin release followed zero-order kinetics and that drug release from these particles is frequently influenced by diffusion. The electronic structure and characteristics of the conjugated polymers (sodium alginate/Chitosan) were examined using density functional theory (DFT) and PM3 calculations with Gaussian 9, using the B3LYP, and electronic structure calculations using 6-311 G (d,p). The HOMO and LUMO energy levels are determined as the HOMO's maximum and the LUMO's minimum, respectively.Communicated by Ramaswamy H. Sarma.

High molecular/low acetylated chitosans reduce adhesion of Campylobacter jejuni to host cells by blocking JlpA

Infections caused by Campylobacter spp. are a major cause of severe enteritis worldwide. Multifactorial prevention strategies are necessary to reduce the prevalence of Campylobacter. In particular, antiadhesive strategies with specific inhibitors of early host-pathogen interaction are promising approaches to reduce the bacterial load. An in vitro flow cytometric adhesion assay was established to study the influence of carbohydrates on the adhesion of C. jejuni to Caco-2 cells. Chitosans with a high degree of polymerization and low degree of acetylation were identified as potent antiadhesive compounds, exerting significant reduction of C. jejuni adhesion to Caco-2 cells at non-toxic concentrations. Antiadhesive and also anti-invasive effects were verified by confocal laser scanning microscopy. For target identification, C. jejuni adhesins FlpA and JlpA were expressed in Escherichia coli ArcticExpress, and the influence of chitosan on binding to fibronectin and HSP90α, respectively, was investigated. While no effects on FlpA binding were found, a strong inhibition of JlpA-HSP90α binding was observed. To simulate real-life conditions, chicken meat was inoculated with C. jejuni, treated with antiadhesive chitosan, and the bacterial load was quantified. A strong reduction of C. jejuni load was observed. Atomic force microscopy revealed morphological changes of C. jejuni after 2 h of chitosan treatment, indicating disturbance of the cell wall and sacculi formation by electrostatic interaction of positively charged chitosan with the negatively charged cell surface. In conclusion, our data indicate promising antiadhesive and anti-invasive potential of high molecular weight, strongly de-acetylated chitosans for reducing C. jejuni load in livestock and food production. KEY POINTS: • Antiadhesive effects of chitosan with high DP/low DA against C. jejuni to host cells • Specific targeting of JlpA/Hsp90α interaction by chitosan • Meat treatment with chitosan reduces C. jejuni load.

The impact of exogenous vasoactive intestinal polypeptide on inflammatory responses and mRNA expression of tight junction genes in lambs fed a high-grain diet

This study assessed the impact of administering vasoactive intestinal polypeptide (VIP) on inflammation and intestinal VIP and tight junction mRNA expression in lambs fed grain-based finishing diets. Sixteen wether lambs (69.6 ± 1.9 kg) were individually housed, adapted to a corn-based diet containing no forage, and randomly assigned to 2 treatment groups. Lambs were intraperitoneally injected every other day for 28 d with either saline (0.9% NaCl) with no VIP (n = 8; control) or saline with VIP (n = 8; 1.3 nmol/kg BW). Blood samples were collected weekly for analysis of cytokine concentrations, and on days 0 and 28 for lipopolysaccharide (LPS), and LPS-binding protein (LBP) concentrations. Upon completion of the treatment period, lambs were euthanized and gastrointestinal tissues, including rumen, jejunum, cecum, and colon samples, were collected for analysis of the expression of tight junction mRNA (claudin-1, claudin-4, occludin, and ZO-1), endogenous VIP, and VIP receptor (VPAC-1). No treatment effects (P ≥ 0.38) were observed for VIP and VPAC-1 mRNA expression in the colon. Supplementation with VIP did not influence (P ≥ 0.28) the expression of claudin-1, claudin-4, occludin, and ZO-1 tight junction mRNA in the rumen, jejunum, cecum, and colon. Lambs treated with VIP had greater (P ≤ 0.01) plasma concentrations of the anti-inflammatory cytokines, IL-10 and IL-36RA. There were treatment-by-day interactions observed (P ≤ 0.02) for concentrations of the pro-inflammatory cytokines, MIP-1α and MIP-1β. Lambs that did not receive VIP had greater serum concentrations of LPS (P = 0.05) than the lambs receiving VIP. These data suggest that VIP administration may not influence tight junction mRNA expression but may decrease LPS concentrations and thus inflammation in lambs fed a grain-based diet.

Release studies of the anticancer drug 5-fluorouracil from chitosan-banana peel extract films

5-F-lourouracil is an anticancer drug used for the treatment of different types of cancers. 5-flourouracil loaded chitosan-banana peel extract films were prepared for the in vitro drug release studies. Solvent casting technique was employed to prepare the films. The structure and morphology of the prepared films were analysed by FTIR, XRD and SEM methods and confirmed the presence of drug in the films. The drug loaded films show excellent thermal stability and good shelf life. Studies revealed that the percentage of banana peel extract influences the swelling properties of the film, thickness of the films and release of the drug from the films. Increase in the concentration of chitosan and banana peel extract decreases the swelling properties of the film and rate of release of the drug from the film. The release rate of 5-fluorouracil from the drug loaded chitosan-banana peel extract films were followed spectrophotometrically at λmax 266 nm and the film derived from 1 % chitosan solution and 1 mL aqueous banana peel extract (saturated) exhibited maximum drug release. Cytotoxicity studies proved that the films are non-toxic in nature and augurs well for their applications as excellent drug delivery systems. Antimicrobial studies show that the drug loaded chitosan-banana peel extract films were found to be active against microbes E. coli, Streptococcus mutans, Staphylococcus aureus, Candida albicans and Aspergillus niger and inactive against Pseudomonas aeruginosa.

Recent findings in molecular reactions of E. coli as exposed to alkylated, nano- and ordinary chitosans

The antibacterial effects of chitosan have been widely studied, but the underlying molecular mechanisms are not fully understood. We investigated the molecular responses of Escherichia coli MG1655 cell, a model gram-negative bacterium, upon exposure to chitosan (Cs), alkylated Cs (AlkCs), and chitosan nanoparticles (CsNPs). Nine target genes involved in relevant signaling pathways (ompF, ompC, ompA, mrcA, mrcB, mgtA, glnA, kdpA, lptA) were selected for analysis. A significant reduction in the expression of mrcA, mgtA, glnA, and lptA genes was observed in the cells treated with Cs. Those treated with Cs, AlkCs, and CsNPs revealed an increase in ompF gene expression, but the expression level was lower in the cells treated with AlkCs and CsNPs compared to Cs. This increase in porin expression suggests compromised membrane integrity and disrupted nutrient transport. In addition, the changes in the expression of mgtA, kdpA, and glnA are related to different effects on membrane permeability. The higher expression in the genes mrcA and mrcB is associated with morphological changes of cells treated with AlkCs and CsNPs. These findings contribute to our understanding of the molecular mechanisms underlying chitosan-induced stress responses and provide insights for the development of safer antimicrobial compounds in the future.

Oxidized of chitosan with different molecular weights for potential antifungal and plant growth regulator applications

The application of Chitosan (CS) in drug delivery systems, plant growth promotion, antibacterial potentiality and plant defense is significantly limited by its inability to dissolve in neutral solutions. In this work, CS with different molecular weights (Mw) has been oxidized, yielding five kinds of oxidized chitosan (OCS 1-5) with solubilities in neutral solutions. The results obtained from Fourier Transform Infrared Spectroscopy clearly showed the successful oxidation of the hydroxyl group to form aldehyde and carboxyl groups. And the CS derivatives showed the wrinkled and lamellar structures on the surface of OCS. The results of antifungal activity against Fusarium graminearum showed that the OCS dissolved in 2 % (V/V) acetic acid exhibited better performance of almost complete inhibition of mycelial growth compared with CS at the concentration of 500 μg/mL. Among the five OCS, OCS-4 exhibited the best antifungal effect and had the lowest EC50 value of 581.68 μg/mL in samples. OCS-4 displayed superior promoting effect on seed germination with a germination potential of 62.2 % at a concentration of 3 g/L and a germination rate of 74.5 %. Additionally, the other four OCS also showed excellent antifungal activity with dose-dependent manners. These results indicated that the OCS had excellent antifungal potential in agricultural production.

An influence of molecular weight, deacetylation degree of chitosan xerogels on their antimicrobial activity and cytotoxicity. Comparison of chitosan materials obtained using lactic acid and CO2 saturation

This paper presents a comparison of the antimicrobial activity and cytotoxicity against L929 cells of chitosan xerogels prepared by dissolving the polymer in a solution of lactic acid (LA) or carbonic acid (CO2) and then freeze-drying. There was no simple relationship between the antimicrobial activity and cytotoxicity of the samples obtained using both techniques (LA and CO2). Chitosan materials obtained by the LA method in a 1:1 dilution were characterized by the highest cytotoxicity against L929 cells (∼20%). For the same diluted samples prepared using the CO2 saturation method, the viability of L929 cells was approximately 2.5 times greater. Some of the tested chitosan materials obtained by the innovative method were characterized by significantly lower antimicrobial activity, for example, reduction of E. coli bacteria for MMW-LA and MMW-CO2 samples by 6.00 and 0.75 logarithmic order, respectively. This clearly indicates that in many applications, the presence of the acid necessary to dissolve chitosan is responsible for the antimicrobial activity of the polymer solution and its products.

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.

Factors affecting production and effectiveness, performance improvement and mechanisms of action of bacteriocins as food preservative

Modern society is increasingly attracted with safe, natural, and additive-free food products, that gives preference to bacteriocins produced by General Recognized as Safe bacteria as a food preservative. Bacteriocins have been reported to be effective in extending shelf life of diverse foods such as meats, dairy products, wine, juice, and fruits and vegetables, whereas commercialized bacteriocins remain only nisin, pediocin, and Micocin. It is important that commercialized preservatives undergo an easy-to-handle manufacturing while maintaining high efficacy. Limited application of bacteriocins is most often caused by the absence of legislatives for use, low production, high cost and complicated purification process, reduced efficiency in the complex food matrix and insufficiently defined mechanism of action. Accordingly, this review provides an overview of bacteriocins, in relation to production stimulation, general purification scheme, impact of food matrix on bacteriocin effectiveness, and collaborative technology to improve bacteriocin performances. It is worth to note that purification and performance improvement technology remain the two challenging tasks in promoting bacteriocins as a widely used bio-preservative. Furthermore, this review for the first time divides bacteriocin receptors into specific classes (class I, II, III) and nonspecific class, to provide a basis for an in-depth understanding of the mechanism of action.

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

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

Nature to Nurture: Chitosan nanopowder a natural carbohydrate polymer choice of egg parasitoid, Trichogramma Japonicum Ashmead

Chitosan is a naturally occurring linear biopolymer made of partially deacetylated acetyl and N-acetyl glucosamine. Its biocompatible physiochemical and biochemical properties are unmatched. Chitosan is transformed to nanopowder for use in agriculture and associated industries as nanocarriers for existing agrochemicals, ensuring the delayed release of chemicals with better solubility. Chitosan nanopowder applied to leaves or soil can activate a plant's natural defences against insects and pathogens. These studies were carried out because there is a potential for toxicological risk linked with products created utilizing nanotechnology, such as chitosan nanopowder, and therefore researchers felt the need to investigate this. The egg parasitoides Trichogramma Japonicum Ashmead was used as a low-cost biomarker to determine the potential toxicity of chitosan nanopowder. This study looked into the possibility that the adult stage of the egg parasitoids, Trichogramma Japonicum Ashmead might be negatively impacted by chitosan nanopowder (80-100 nm). Unpaired t-test statistical analysis has been carried out. According to the statistical analysis, host eggs exposed to chitosan nanopowder showed noticeably greater parasitization than the control group. As a natural supply of carbohydrate polymers chitosan nanopowder promotes the parasitization of T. Japonicum. The findings showed that T. Japonicum favoured chitosan nanopowder. Through Y dual choice, eight-arm multiple choice, and no-choice olfactometer experiments, as well as images from a stereozoom microscope and a scanning electron microscope (SEM), the data was thoroughly supported. Future agricultural applications of chitosan nanopowder will benefit from a deeper understanding of our findings.

An aminocaproic acid-grafted chitosan derivative with superior antibacterial and hemostatic properties for the prevention of secondary bleeding

Uncontrolled bleeding is one of the leading causes of human mortality. Existing hemostatic materials or techniques cannot meet the clinical requirements for safe and effective hemostasis. The development of novel hemostatic materials has always been of great interest. Chitosan hydrochloride (CSH), a derivative of chitin, is extensively used on wounds as an antibacterial and hemostatic agent. However, the formation of intra- or intermolecular hydrogen bonds between hydroxyl and amino groups limits its water solubility and dissolution rate and affects its effectiveness in promoting coagulation. Herein, we covalently grafted aminocaproic acid (AA) to the hydroxyl and amino groups of CSH via ester and amide bonds, respectively. The solubility of CSH in water (25 °C) was 11.39 ± 0.98 % (w/v), whereas the AA-grafted CSH (CSH-AA) reached 32.34 ± 1.23 % (w/v). Moreover, the dissolution rate of CSH-AA in water was 6.46 times higher than that of CSH. Subsequent studies proved that CSH-AA is non-toxic, biodegradable, and has superior antibacterial and hemostatic properties to CSH. Additionally, anti-plasmin activity can be exerted by the dissociated AA from the CSH-AA backbone, which can help to lessen secondary bleeding.

3D printing of chitooligosaccharide-polyethylene glycol diacrylate hydrogel inks for bone tissue regeneration

To date, lack of functional hydrogel inks has limited 3D printing applications in tissue engineering. This study developed a series of photocurable hydrogel inks based on chitooligosaccharide (COS)-polyethylene glycol diacrylate (PEGDA) for extrusion-based 3D printing of bone tissue scaffolds. The scaffolds were prepared by aza-Michael addition of COS and PEGDA followed by photopolymerisation of unreacted PEGDA. The hydrogel inks showed sufficient shear thinning properties required for extrusion 3D printing. The printed scaffolds exhibited excellent shape fidelity and fine microstructure with a resolution of 250 μm. By increasing the COS content, the swelling ratio of the scaffolds decreased, while the compressive strength increased. 3D printed COS-PEGDA scaffolds showed high viability of human bone mesenchymal stem cells in vitro. In addition, scaffolds containing 2 wt% COS showed significantly higher alkaline phosphatase activity, calcium deposition, and bioactivity in simulated body fluid compared to the control (PEGDA). Altogether, 3D printed COS-PEGDA scaffolds represent promising candidates for bone tissue regeneration.