pH Effects on solubility, zeta potential, and correlation between antibacterial activity and molecular weight of chitosan

Intravitreal CBD-loaded niosomes enhance retinal neuroprotection in ischemic injury

Cannabidiol (CBD) has emerged as a promising treatment for conditions like retinal ischemia, characterized by reduced blood flow to the retina and significant vision loss. Despite its therapeutic potential, CBD's clinical application could be limited by due to its low bioavailability. This study investigates the efficacy of CBD-loaded niosomes as a neuroprotective formulation for the use in ocular therapies related to retinal ischemia. We investigated the neuroprotective effects of CBD using a nanodispersed system (niosomes) administered via intravitreal injection in rats' eyes. Niosomes underwent characterization for size, distribution, zeta potential, morphology, and encapsulation efficiency. Safety and neuroprotective activity were assessed by electroretinography (ERG), confocal and transmission microscopy and histology. Niosomes exhibited nanometric size (100-400 nm) and stability, showing good tolerance in animals. ERG results demonstrated higher b-wave amplitudes in animals pre-treated with niosomes + CBD compared to the control group following ischemic injury induced by a sudden increase in IOP. Histological and confocal microscopy analyses of retinas from the niosomes + CBD group showed preserved structure compared to the ischemic control group, suggesting significant retinal protection by intravitreally injected niosomes + CBD before ischemia. CBD-loaded niosomes effectively preserved retinal function, highlighting the neuroprotective potential of CBD against retinal ischemia. This formulation presents a promising and innovative treatment for ischemic retinal diseases.

Recent Progress in Chitosan-Based Nanoparticles for Drug Delivery: A Review on Modifications and Therapeutic Potential

Chitosan, obtained from chitin by deacetylation, is a versatile biopolymer known for its biocompatibility, biodegradability, and environmental friendliness. Combined with its chemical and physical modifiability, these properties have made chitosan an important material in biomedical and pharmaceutical fields, especially in drug delivery systems. Chitosan-based nanomaterials exhibit enhanced functions through various chemical modifications such as thiolation, acetylation, carboxylation, and phosphorylation, as well as through physical and enzymatic approaches. These modifications address inherent limitations such as poor solubility, limited acid resistance, and insufficient mechanical strength, expanding the applications of chitosan in tissue engineering, gene therapy, vaccine delivery, wound healing, and bioimaging.This review provides an in-depth analysis of the chemical structure, physicochemical properties and modification strategies of chitosan. It also explores current methodologies for preparing chitosan nanoparticles, along with drug loading and release techniques. Various targeting strategies employed in chitosan-based delivery systems are examined in detail. To illustrate the clinical relevance of these approaches, representative examples from recent therapeutic studies are included. Moreover, it highlights future research directions and the innovation potential of chitosan-based materials.

Enhancing Bioactivity of Titanium-Based Materials Through Chitosan Based Coating and Calcitriol Functionalization

Titanium (Ti)-based materials are favored for hard tissue applications, yet their bioinertness limits their success. This study hypothesizes that functionalizing Ti materials with chitosan nano/microspheres and calcitriol (VD) will enhance their bioactivity by improving cellular activities and mineralization. To test this, chitosan particles were applied uniformly onto Ti surfaces using electrophoretic deposition (EPD) at 20 V for 3 minutes. VD was then loaded onto the coated surfaces, and the release profile of VD was monitored. Human fetal osteoblastic cells (hFOB) were cultured on the VD-loaded Ti surfaces. Cellular activities such as proliferation, Alkaline phosphatase (ALP) activity, osteogenic gene expression (runt-related transcription factor 2 (Runx2), collagen type 1 (Col I), osteocalcin ( OCn), osteopontin (OP)), and mineralization were assessed. Von Kossa staining was performed to analyze mineralization, and the expression of cell adhesion proteins (N-cadherin (NC), integrin alpha V (IaV), integrin beta 3, (Ib3)) was measured. The results showed that approximately 50% of the VD released over 50 hours. The chitosan coating increased surface roughness three-fold, and this, combined with VD release, resulted in reduced cell proliferation but increased ALP activity, suggesting enhanced differentiation. VD-functionalized Ti surfaces showed statistically significant differences in osteogenic gene expressions, particularly on rougher surfaces. Additionally, the expression of cell adhesion proteins (NC, IaV, Ib3) was upregulated on VD-containing coated surfaces. Von Kossa analysis revealed that surface roughness significantly enhanced mineralization, particularly on VD-free surfaces by day 7, while mineralization on VD-containing bare surfaces started on day 14. These findings demonstrate that VD-loaded chitosan coatings significantly enhance the biocompatibility and bioactivity of Ti-based materials, highlighting their potential for applications in bone regeneration.

Viability and Surface Morphology of Human Erythrocytes upon Interaction with Chitosan Derivatives

The viability and surface morphology of human erythrocytes upon interaction with oligochitosan (OCH), having a molecular weight (MW) of 6.2-15.4 kDa and a degree of acetylation (DA) of 1-2%, and interaction with N-reacetylated OCH (ROCH) with a 6.4-14.3 kDa MW and 24-30% DA were studied in isotonic saline phosphate buffer with pH 7.4. It was shown that the use of OCH caused high hemolysis and irreversible transformation of the erythrocytes. Thus, OCH having a 6.2 kDa MW and 1% DA, used at a 0.01% concentration, induced high hemolysis of erythrocytes, and their viability did not exceed the maximal value of 60%. Among the nonhemolyzed erythrocytes, about 20% reversibly transformed erythrocytes and about 20% irreversibly transformed erythrocytes were observed in comparison with the control experiments. For the first time, it was shown that ROCHs had a much lower impact on the cells. Thus, about 82% of the erythrocytes had a discoid form, while 12% and ∼6% of the cells underwent reversible and irreversible transformations, respectively, in the presence of ROCH (MW 6.4, DA 24%), used at a 0.01% concentration. It was observed that an increase in the MW and concentration of chitosan derivatives led to a decrease in the cell viability. It was supposed that the complexation of chitosan derivatives with phosphate counterions in the buffer might reduce the impact of chitosan derivatives on the viability and surface morphology of erythrocytes due to a reduction in the average zeta-potential of chitosan derivative/phosphate complexes from positive to negative values. These results supported the suggestion that reacetylation and reduction of the overall charge of chitosan molecules could improve the compatibility of chitosan derivatives with erythrocytes. This finding opens an opportunity for the construction of chitosan derivatives and their complexes that are compatible with other blood forming elements.

Quaternary ammonium chitosan-functionalized mesoporous silica nanoparticles: A promising targeted drug delivery system for the treatment of intracellular MRSA infection

The limited membrane permeability and bacterial resistance pose significant challenges in the management of intracellular drug-resistant bacterial infections. To overcome this issue, we developed a bacterial-targeted drug delivery system based on quaternary ammonium chitosan-modified mesoporous silica nanoparticles (MSN-NH2-CFP@HACC) for the treatment of intracellular Methicillin-resistant Staphylococcus aureus (MRSA) infections. This system utilizes amino-functionalized mesoporous silica nanoparticles to efficiently load cefoperazone (CFP), and the nanoparticles' surface is coated with 2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC) to target bacteria and enhance macrophage uptake. The findings indicate that MSN-NH2-CFP@HACC nanoparticles are efficiently internalized by macrophages, demonstrate accelerated drug release in acidic environments, and exhibit enhanced antibacterial properties, effectively suppressing the proliferation and intracellular escape of MRSA. Moreover, HACC enhances the bacterial capture ability of the nanoparticles and reduces resistance by disrupting bacterial membrane structures and inhibiting bacterial β-lactamase activity. In a murine model of MRSA bacteremia, MSN-NH2-CFP@HACC exhibited remarkable antibacterial efficacy and significantly attenuated severe inflammatory responses. In conclusion, MSN-NH2-CFP@HACC represent a promising antibiotic delivery system with exceptional antibacterial efficacy and favorable biocompatibility, thus presenting a novel strategy for addressing intracellular drug-resistant bacterial infections and demonstrating significant potential for clinical application.

Physicochemical characteristics of chitosan molecules: Modeling and experiments

Chitosan, a biocompatible polysaccharide, finds a wide range of applications, inter alia as an antimicrobial agent, stabilizer of food products, cosmetics, and in the targeted delivery of drugs and stem cells. This work represents a comprehensive review of the properties of chitosan molecule and its aqueous solutions uniquely combining theoretical modeling and experimental results. The emphasis is on physicochemical aspects which were sparsely considered in previous reviews. Accordingly, in the first part, the explicit solvent molecular dynamics (MD) modeling results characterizing the conformations of chitosan molecule, the contour length, the chain diameter and the density are discussed. These MD data are used to calculate several parameters for larger chitosan molecules using a hybrid approach based on continuous hydrodynamics. The dependencies of hydrodynamic diameter, frictional ratio, radius of gyration, and intrinsic viscosity on the molar mass of molecules are presented and discussed. These theoretical predictions, comprising useful analytical solutions, are used to interpret and rationalize the extensive experimental data acquired by advanced experimental techniques. In the final part, the molecule charge, acid-base, and electrokinetic properties, comprising the electrophoretic mobility and the zeta potential, are reviewed. Future research directions are defined and discussed.

Controlled-Release Phosphorus Fertilizers Manufactured with Chitosan Derivatives: An Effective Alternative for Enhanced Plant Development

In modern agriculture, fertilizers are commonly used to increase crop yields; however, their negligent use can lead to environmental pollution and the waste of essential nutrients such as inorganic phosphate (Pi). Encapsulated fertilizers are a feasible alternative that could prevent these issues, as they can protect Pi from leaching and extend the interval between applications. In this study, we developed and tested innovative fertilizers (IFs) manufactured with KH2PO4, encapsulated with chitosan modified via high-frequency ultrasound treatment. The characterization of these fertilizers consisted of Fourier-transform infrared spectroscopy analysis and scanning transmission electron microscopy to determine their sizes and forms. In addition, we evaluated the phosphate release profile using electrical conductivity. The IFs were spheroidal microcapsules with an average diameter of 0.5-2 μM and showed slow-release behavior. Their efficacy was assessed via in vivo and in vitro assays, using Arabidopsis thaliana as a study model. As expected, the IFs promoted the growth of seedlings. One of the IFs showed enhanced growth promotion, contrasting with the control. This phenotype was likely promoted by this fertilizer due to the synergistic effect of Pi and the modified chitosan used as an encapsulant matrix. Our results highlight the potential of these formulations, which have unique properties and could be used on a large scale.

Strong Hydrophobic Interaction of High Molecular Weight Chitosan in Aqueous Solution

Chitosan is a versatile bioactive polysaccharide in various industries, such as pharmaceuticals and environmental applications, owing to its abundance, biodegradability, biocompatibility, and antibacterial properties. To effectively harness its potential for various purposes, it is crucial to understand the mechanisms of its interaction in water. This study investigates the interactions between high molecular weight (HMW, >150 kDa) chitosan and four different functionalized self-assembled monolayers (SAMs) at three different pHs (3.0, 6.5, and 8.5) using a surface forces apparatus (SFA). We report that HMW chitosan exhibits the strongest adhesion to methyl-terminated SAM (CH3-SAM) at all pHs, showing potential for strong hydrophobic interactions against other molecules containing hydrophobic moieties. Noting that hydrogen bonding has been considered the dominating interaction mechanism of chitosan, the consequence of this study provides valuable insights into its applications in developing chitosan-based eco-friendly materials.

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.

Waste-to-resource: Extraction and transformation of aquatic biomaterials for regenerative medicine

The fisheries and aquaculture industry are known for generating substantial waste or by-products, often underutilized, or relegated to low-value purposes. However, this overlooked segment harbors a rich repository of valuable bioactive materials of which have a broad-spectrum of high-value applications. As the blue economy gains momentum and fisheries expand, sustainable exploitation of these aquatic resources is increasingly prioritized. In this review, we present a comprehensive overview of technology-enabled methods for extracting and transforming aquatic waste into valuable biomaterials and their recent advances in regenerative medicine applications, focusing on marine collagen, chitin/chitosan, calcium phosphate and bioactive-peptides. We discuss the inherent bioactive qualities of these "waste-to-resource" aquatic biomaterials and identify opportunities for their use in regenerative medicine to advance healthcare while achieving the Sustainable Development Goals.

Carboxymethyl cellulose-chitosan edible films for food packaging: A review of recent advances

Polysaccharide-based edible films have been widely developed as food packaging materials in response to the rising environmental concerns caused by the extensive use of plastic packaging. In recent years, the integration of carboxymethyl cellulose (CMC) and chitosan (CS) for a binary edible film has received considerable interest because this binary edible film can retain the advantages of both constituents (e.g., the great oxygen barrier ability of CMC and moderate antimicrobial activity of CS) while mitigating their respective disadvantages (e.g., the low water resistance of CMC and poor mechanical strength of CS). This review aims to present the latest advancements in CMC-CS edible films. The preparation methods and properties of CMC-CS edible films are comprehensively introduced. Potential additives and technologies utilized to enhance the properties are discussed. The applications of CMC-CS edible films on food products are summarized. Literature shows that the current preparation methods for CMC-CS edible film are solvent-casting (main) and thermo-mechanical methods. The CMC-CS binary films have superior properties compared to films made from a single constituent. Moreover, some properties, such as physical strength, antibacterial ability, and antioxidant activity, can be greatly enhanced via the incorporation of some bioactive substances (e.g. essential oils and nanomaterials). To date, several applications of CMC-CS edible films in vegetables, fruits, dry foods, dairy products, and meats have been studied. Overall, CMC-CS edible films are highly promising as food packaging materials.

Natural polysaccharides combined with mussel-inspired adhesion for multifunctional hydrogels in wound hemostasis and healing: A review

As naturally derived macromolecular polymers, polysaccharides have garnered significant attention in recent years as promising candidates for fabricating multifunctional hydrogels, particularly for wound healing applications, owing to their inherent biocompatibility, biodegradability, and structural diversity. However, the inherently weak skin adhesion of natural polysaccharide hydrogels has motivated the exploration of mussel-inspired catechol-based adhesion strategies to overcome this limitation. Incorporating mussel-inspired modifications into natural polysaccharides can imbue them with unique properties such as enhanced adhesion, antioxidant activity, antibacterial properties, and chelation capabilities, considerably broadening their potential for wound hemostasis and healing applications. This review comprehensively overviews recent advances in mussel-inspired polysaccharide hydrogels, focusing on the combination of natural polysaccharides, including chitosan, alginate, hyaluronic acid, cellulose, and dextran, with mussel-inspired catechol. We delve into their fabrication strategies and highlight their promising biomedical applications, with a particular emphasis on wound hemostasis and diverse wound healing processes. Mussel-inspired modification strategies for polysaccharide hydrogels are expected to remain a focal point within the fields of wound hemostasis and healing, paving the way for more impactful research endeavors.

Evaluation of polymer combinations in vaginal mucoadhesive tablets for the extended release of acyclovir

Genital herpes, caused by herpes simplex virus type 2 (HSV-2), affects nearly 500 million people, mostly women. Since the main route of transmission is sexual contact, the development of an acyclovir extended-release vaginal microbicide would be a suitable tool for the prevention of virus transmission. In this work, we evaluated the potential of three polymers with different characteristics (chitosan, xanthan gum and ethyl cellulose) for obtaining acyclovir extended-release vaginal tablets. By combining the polymers, certain useful synergies were observed to modify their mucoadhesive capacity and control drug release. In the swelling studies, it observed that a polyelectrolyte complex with more moderate swelling and sustained gelation was formed between chitosan and xanthan gum exclusively in acidic medium (simulated vaginal fluid). This complex allowed prolonging the mucoadhesion of the tablets in ex vivo studies performed with vaginal mucosa, which would translate into better retention in the vagina after administration. In addition, the combination of chitosan and xanthan gum allowed obtaining a controlled release of acyclovir for 5 days, regardless of the pH of the medium, which would guarantee that drug release continues even in the presence of seminal fluid.

Functionalisation of chitosan with methacryloyl and crotonoyl groups as a strategy to enhance its mucoadhesive properties

Mucoadhesive polymers are crucial for prolonging drug retention on mucosal surfaces. This study focuses on synthesising and characterising novel derivatives by reacting chitosan with crotonic and methacrylic anhydrides. The structure of the resulting derivatives was confirmed using proton-nuclear magnetic resonance spectroscopy and Fourier-transform infrared spectroscopy. It was established that the degree of substitution plays a crucial role in the pH-dependent solubility profiles and electrophoretic mobility of the chitosan derivatives. Spray-drying chitosan solutions enabled preparation of microparticles, whose mucoadhesive properties were evaluated using fluorescence flow-through studies and tensile test, demonstrating improved retention on sheep nasal mucosa for modified derivatives. Acute toxicity studies conducted in vivo using planaria and in vitro using MTT assay with the Caco-2 cell line, a model of the mucosal epithelium in vitro, showed that the novel derivatives are not cytotoxic. These findings emphasise the potential of tailored chitosan chemical modifications for enhancing transmucosal drug delivery.

Interaction between reacetylated chitosan and albumin in alcalescent media

Interaction of chitosan and its derivatives with proteins of animal blood at blood pH relevant conditions is of a particular interest for construction of antimicrobial chitosan/protein-based drug delivery systems. In this work, the interaction of a series of N-reacetylated oligochitosans (RA-CHI) having Mw of 10-12 kDa and differing in the degree of acetylation (DA 19, 24, and 40 %) with bovine serum albumin (BSA) in alkalescent media is described in first. It is shown that RA-CHI forms soluble complexes with BSA in solutions with pH 7.4 and a low ionic strength. Light scattering study shows that soluble RA-CHI complexes have spherical form with the radius of about 100 nm. Circular dichroism, fluorescent spectroscopy, and micro-IR spectroscopy studies show that the secondary structure of BSA in soluble complexes remain intact. Isothermal titration calorimetry of RA-CHI with DA 24 % and BSA mixing in the buffers with different ionization heats reveals a significant contribution of electrostatic forces to the binding process and an additional ionization of chitosan due to the proton transfer from the buffer substance. An increase of ionic strength to the blood relevant value 0.15 M suppresses the binding. It is shown that application of RA-CHI with higher DA value leads to a decrease in the affinity of RA-CHI to BSA and an alteration of the interaction mechanism. The finding opens an opportunity to the application of N-reacetylated chitosan derivatives in the complex systems compatible with blood plasma proteins.

Mussel-inspired chitosan and its applications in the biomedical field

Chitosan (CS) has physicochemical properties including solubility, crystallinity, swellability, viscosity, and cohesion, along with biological properties like biocompatibility, biodegradation, antioxidant, antibacterial, and antitumor effects. However, these characteristics of CS are greatly affected by its degree of deacetylation, molecular weight, pH and other factors, which limits the application of CS in biomedicine. The modification of CS with catechol-containing substances inspired by mussels can not only improve these properties of CS, but also endow it with self-healing property, providing an environmentally friendly and sustainable way to promote the application of CS in biomedicine. In this paper, the properties of CS and its limitation in the biomedical filed are introduced in detail. Then, the modification methods and properties of substances with catechol groups inspired by mussels on CS are reviewed. Finally, the applications of modified CS in the biomedical field of wound healing, drug delivery, anticancer therapy, biosensor and 3D printing are further discussed. This review can provide valuable information for the design and exploitation of mussel-inspired CS in the biomedical field.

Contributions of Surface Oxidizing Species and Cu+ to the Antibacterial Activities of Cu2O with Different Crystalline Structures

Although precise regulation of the crystalline structures of metal oxides is an effective method to improve their antibacterial activities, the corresponding mechanisms involved in this process are still unclear. In this study, three kinds of cuprous oxide (Cu2O) samples with different structures of cubes, octahedra, and rhombic dodecahedra (c-Cu2O, o-Cu2O, and r-Cu2O) have been successfully synthesized and their antibacterial activities are compared. The antibacterial activities follow the order of r-Cu2O > o-Cu2O > c-Cu2O, revealing the significant dependence of the antibacterial activities on the crystalline structures of Cu2O. Quenching experiments, as well as the NBT and DPD experiments indicate that ≡CuII─OO• superoxo and ≡CuII─OOH peroxo, instead of •OH, O2•-, and H2O2, are the primary oxidizing species in the oxidative damage to E. coli. Raman analysis further confirms the presence of both ≡CuII─OO• superoxo and ≡CuII─OOH peroxo on the surface of r-Cu2O. On the other hand, the NCP experiment reveals that Cu+, instead of Cu2+, also contributes to the antibacterial process. This study provides new insight into the antibacterial mechanisms of Cu2O.

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.

Biomimetic Antifungal Materials: Countering the Challenge of Multidrug-Resistant Fungi

In light of rising public health threats like antifungal and antimicrobial resistance, alongside the slowdown in new antimicrobial development, biomimetics have shown promise as therapeutic agents. Multidrug-resistant fungi pose significant challenges as they quickly develop resistance, making traditional antifungals less effective. Developing new antifungals is also complicated by the need to target eukaryotic cells without harming the host. This review examines biomimetic antifungal materials that mimic natural biological mechanisms for targeted and efficient action. It covers a range of agents, including antifungal peptides, alginate-based antifungals, chitosan derivatives, nanoparticles, plant-derived polyphenols, and probiotic bacteria. These agents work through mechanisms such as disrupting cell membranes, generating reactive oxygen species, and inhibiting essential fungal processes. Despite their potential, challenges remain in terms of ensuring biocompatibility, optimizing delivery, and overcoming potential resistance. Production scalability and economic viability are also concerns. Future research should enhance the stability and efficacy of these materials, integrate multifunctional approaches, and develop sophisticated delivery systems. Interdisciplinary efforts are needed to understand interactions between these materials, fungal cells, and the host environment. Long-term health and environmental impacts, fungal resistance mechanisms, and standardized testing protocols require further study. In conclusion, while biomimetic antifungal materials represent a revolutionary approach to combating multidrug-resistant fungi, extensive research and development are needed to fully realize their potential.

Enhancing Wastewater Depollution: Sustainable Biosorption Using Chemically Modified Chitosan Derivatives for Efficient Removal of Heavy Metals and Dyes

Driven by concerns over polluted industrial wastewater, particularly heavy metals and dyes, this study explores biosorption using chemically cross-link chitosan derivatives as a sustainable and cost-effective depollution method. Chitosan cross-linking employs either water-soluble polymers and agents like glutaraldehyde or copolymerization of hydrophilic monomers with a cross-linker. Chemical cross-linking of polymers has emerged as a promising approach to enhance the wet-strength properties of materials. The chitosan thus extracted, as powder or gel, was used to adsorb heavy metals (lead (Pb2+) and copper (Cu2+)) and dyes (methylene blue (MB) and crystal violet (CV)). Extensive analysis of the physicochemical properties of both the powder and hydrogel adsorbents was conducted using a range of analytical techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and scanning electron microscopy (SEM), as well as 1H and 13C nuclear magnetic resonance (NMR). To gain a comprehensive understanding of the sorption process, the effect of contact time, pH, concentration, and temperature was investigated. The adsorption capacity of chitosan powder for Cu(II), Pb(II), methylene blue (MB), and crystal violet (CV) was subsequently determined as follows: 99, 75, 98, and 80%, respectively. In addition, the adsorption capacity of chitosan hydrogel for Cu(II), Pb(II), MB, and CV was as follows: 85, 95, 85, and 98%, respectively. The experimental data obtained were analyzed using the Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models. The isotherm study revealed that the adsorption equilibrium is well fitted to the Freundlich isotherm (R2 = 0.998), and the sorption capacity of both chitosan powder and hydrogel was found to be exceptionally high (approximately 98%) with the adsorbent favoring multilayer adsorption. Besides, Dubinin has given an indication that the sorption process was dominated by Van der Waals physical forces at all studied temperatures.

Citrus flavonoids-loaded chitosan derivatives-route nanofilm as drug delivery systems for cutaneous wound healing

This study focuses on creating new forms of biomimetic nanofiber composites by combining copolymerizing and electrospinning approaches in the field of nanomedicine. The process involved utilizing the melt polymerization of proline (Pr) and hydroxyl proline (Hyp) to synthesize polymers based on Pr (PPE) and Hyp (PHPE). These polymers were then used in a grafting copolymerization process with chitosan (CS) to produce PHPC (1560 ± 81.08 KDa). A novel electrospun nanofiber scaffold was then produced using PHPC and/or CS, hyaluronic acid, polyvinyl alcohol, and naringenin (NR) as a loading drug. Finally, Mouse Dermal Fibroblast (MDF) cells were introduced to the wound dressing and assessed their therapeutic potential for wound healing in rats. The scaffolds were characterized by FTIR, NMR, DSC, and SEM analysis, which confirmed the amino acid grafting, loading drug, and porous and nanofibrous structures (>225 nm). The results showed that the PHPC-based scaffolds were more effective for swelling/absorption of wound secretions, had more elasticity/elongation, faster drug release, more MDF-cytocompatibility, and antibacterial activity against multidrug-resistant S. aureus compared to CS-based scaffolds. The in vivo studies showed that NR in combination with MDF can accelerate cell migration/proliferation, and remodeling phases of wound healing in both PHPC/CS-based scaffolds. Moreover, PHPC-based scaffolds promote collagen content, and better wound contraction, epithelialization, and neovascularization than CS-based, showing potential as wound-dressing.

Environmental Sustainability and Physicochemical Property Screening of Chitin and Chitin-Glucan from 22 Fungal Species

Thanks to its biobased character with embedded biogenic carbon, chitin can aid in the transition to a sustainable circular economy by replacing fossil carbon from the geosphere. However, meeting current demands for material availability and environmental sustainability requires alternative methods limiting conventional chemical and energy-consuming chitin extraction from crustaceans. To assist future chitinous bioproduct development, this work analyzes the physicochemical properties and potential environmental sustainability of fungal chitin-glucan complexes. A conventional isolation procedure using sodium hydroxide, a weak acid, and short reaction times are applied to the fruiting body of 22 fungal species. Besides, the valorization of underutilized waste streams including Agaricus bisporus and Agaricus brunnescens stipes is investigated. The carbohydrate analysis renders chitin fractions in the range of 9.5-63.5 wt %, while yields vary from 4.2 to 29.9%, and the N-acetylation degree in found in between 53.0 and 98.7%. The sustainability of the process is analyzed using life cycle assessment (LCA), providing impact quantification for global warming potential, terrestrial acidification, freshwater eutrophication, and water use. With 87.5-589.3 kg·CO2-equiv per kilo, potentially lower global warming potential values in comparison to crustacean chitin are achieved. The crystallinity degree ranged from 28 to 78%, while the apparent chitin crystalline size (L020) is between 2.3 and 5.4 nm. Ten of the species yield α-chitin coexisting with semicrystalline glucans. Zwitterionic properties are observed in aqueous solutions, shifting from cationic to anionic at pH 4.5. With its renewable carbon content, fungal chitin is an environmentally sustainable alternative for high-value applications due to its balance of minimal treatment, low carbon footprint, material renewability, ease of isolation, thermal stability, zwitterionic behavior, biodegradability, and noncytotoxicity.

Analysis of molecular structure and topological properties of chitosan isolated from crab shell and mushroom

This investigation aimed to scrutinize the chemical and structural analogies between chitosan extracted from crab exoskeleton (High Molecular Weight Chitosan, HMWC) and chitosan obtained from mushrooms (Mushroom-derived Chitosan, MRC), and to assess their biological functionalities. The resulting hydrolysates from the hydrolysis of HMWC by chitosanase were categorized as chitosan oligosaccharides (csCOS), while those from MRC were denoted as mrCOS. The molecular weights (MW) of csCOS and mrCOS were determined using Matrix-Assisted Laser Desorption Ionization Time-of-Flight (MALDI-TOF) mass spectrometry. Furthermore, structural resemblances of csCOS and mrCOS were assessed utilizing X-ray powder diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. Intriguingly, no apparent structural disparity between csCOS and mrCOS was noted in terms of the glucosamine (GlcN) and N-acetylglucosamine (GlcNAc) composition ratios. Consequently, the enzymatic activities of chitosanase for HMWC and MRC exhibited remarkable similarity. A topological examination was performed between the enzyme and the substrate to deduce the alteration in MW of COSs following enzymatic hydrolysis. Moreover, the evaluation of antioxidant activity for each COS revealed insignificance in the structural disparity between HMWC and MRC. In summary, grounded on the chemical structural similarity of HMWC and MRC, we propose the potential substitution of HMWC with MRC, incorporating diverse biological functionalities.

Biomimetic zwitterionic copolymerized chitosan as an articular lubricant

Restoration of the lubrication functions of articular cartilage is an effective treatment to alleviate the progression of osteoarthritis (OA). Herein, we fabricated chitosan-block-poly(sulfobetaine methacrylate) (CS-b-pSBMA) copolymer via a free radical polymerization of sulfobetaine methacrylate onto activated chitosan segment, structurally mimicking the lubricating biomolecules on cartilage. The successful copolymerization of CS-b-pSBMA was verified by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and 1H nuclear magnetic resonance. Friction test confirmed that the CS-b-pSBMA copolymer could achieve an excellent lubrication effect on artificial joint materials such as Ti6Al4V alloy with a coefficient of friction as low as 0.008, and on OA-simulated cartilage, better than the conventional lubricant hyaluronic acid, and the adsorption effect of lubricant on cartilage surface was proved by a fluorescence labeling experiment. In addition, CS-b-pSBMA lubricant possessed an outstanding stability, which can withstand enzymatic degradation and even a long-term storage up to 4 weeks. In vitro studies showed that CS-b-pSBMA lubricant had a favorable antibacterial activity and good biocompatibility. In vivo studies confirmed that the CS-b-pSBMA lubricant was stable and could alleviate the degradation process of cartilage in OA mice. This biomimetic lubricant is a promising articular joint lubricant for the treatment of OA and cartilage restoration.

Gums as Macromolecular Crowding Agents in Human Skin Fibroblast Cultures

Even though tissue-engineered medicines are under intense academic, clinical, and commercial investigation, only a handful of products have been commercialised, primarily due to the costs associated with their prolonged manufacturing. While macromolecular crowding has been shown to enhance and accelerate extracellular matrix deposition in eukaryotic cell culture, possibly offering a solution in this procrastinating tissue-engineered medicine development, there is still no widely accepted macromolecular crowding agent. With these in mind, we herein assessed the potential of gum Arabic, gum gellan, gum karaya, and gum xanthan as macromolecular crowding agents in WS1 skin fibroblast cultures (no macromolecular crowding and carrageenan were used as a control). Dynamic light scattering analysis revealed that all macromolecules had negative charge and were polydispersed. None of the macromolecules affected basic cellular function. At day 7 (the longest time point assessed), gel electrophoresis analysis revealed that all macromolecules significantly increased collagen type I deposition in comparison to the non-macromolecular crowding group. Also at day 7, immunofluorescence analysis revealed that carrageenan; the 50 µg/mL, 75 µg/mL, and 100 µg/mL gum gellan; and the 500 µg/mL and 1000 µg/mL gum xanthan significantly increased both collagen type I and collagen type III deposition and only carrageenan significantly increased collagen type V deposition, all in comparison to the non-macromolecular crowding group at the respective time point. This preliminary study demonstrates the potential of gums as macromolecular crowding agents, but more detailed biological studies are needed to fully exploit their potential in the development of tissue-engineered medicines.

Antibacterial effects of various molecular weight chitosans against Alicyclobacillus acidoterrestris in orange juice

Alicyclobacillus acidoterrestris has been gaining attention due to its unique thermo-acidophilic properties and being associated with the deterioration of pasteurized beverages. The objective of this study was to evaluate the antibacterial activity of chitosan with various molecular weights (MWs) (164, 85, 29.2, and 7.1 kDa) and concentrations (0-100 μg/mL) against A. acidoterrestris and its effect on guaiacol production. Various chitosan MWs were co-incubated for 7 days, and the bacterial growth, guaiacol, and vanillic acid contents during storage were determined. The chitosans performed antibacterial effects against A. acidoterrestris. Further, 164 kDa chitosan showed excellent results in controlling the growth and guaiacol formation in A. acidoterrestris. These findings demonstrated the efficacy of chitosan antibacterial activity against A. acidoterrestris and mitigating the guaiacol formation. Chitosan's antibacterial properties are attributed to the elimination of cells and suppression of guaiacol production. This study introduces a new approach for reducing A. acidoterrestris contamination in fruit juices, with potential product quality and safety advantages.

The Preparation and Characterization of Chitosan/Calcium Phosphate Composite Microspheres for Biomedical Applications

In this study, we successfully prepared porous composite microspheres composed of hydroxyapatite (HAp), di-calcium phosphate di-hydrated (DCPD), and chitosan through the hydrothermal method. The chitosan played a crucial role as a chelating agent to facilitate the growth of related calcium phosphates. The synthesized porous composite microspheres exhibit a specific surface area of 38.16 m2/g and a pore volume of 0.24 cm3/g, with the pore size ranging from 4 to 100 nm. Given the unique properties of chitosan and the exceptional porosity of these composite microspheres, they may serve as carriers for pharmaceuticals. After being annealed, the chitosan transforms into a condensed form and the DCPD transforms into Ca2P2O7 at 300 °C. Then, the Ca2P2O7 initially combines with HAp to transform into β tricalcium phosphate (β-TCP) at 500 °C where the chitosan is also completely combusted. Finally, the microspheres are composed of Ca2P2O7, β-TCP, and HAp, also making them suitable for applications such as injectable bone graft materials.

Chitosan, chitosan derivatives, and chitosan-based nanocomposites: eco-friendly materials for advanced applications (a review)

For many years, chitosan has been widely regarded as a promising eco-friendly polymer thanks to its renewability, biocompatibility, biodegradability, non-toxicity, and ease of modification, giving it enormous potential for future development. As a cationic polysaccharide, chitosan exhibits specific physicochemical, biological, and mechanical properties that depend on factors such as its molecular weight and degree of deacetylation. Recently, there has been renewed interest surrounding chitosan derivatives and chitosan-based nanocomposites. This heightened attention is driven by the pursuit of enhancing efficiency and expanding the spectrum of chitosan applications. Chitosan's adaptability and unique properties make it a game-changer, promising significant contributions to industries ranging from healthcare to environmental remediation. This review presents an up-to-date overview of chitosan production sources and extraction methods, focusing on chitosan's physicochemical properties, including molecular weight, degree of deacetylation and solubility, as well as its antibacterial, antifungal and antioxidant activities. In addition, we highlight the advantages of chitosan derivatives and biopolymer modification methods, with recent advances in the preparation of chitosan-based nanocomposites. Finally, the versatile applications of chitosan, whether in its native state, derived or incorporated into nanocomposites in various fields, such as the food industry, agriculture, the cosmetics industry, the pharmaceutical industry, medicine, and wastewater treatment, were discussed.

Quality evaluation and storage test for capsaicin-fortified yogurt based on the multilayer nanoemulsion system

Capsaicin has many benefits, such as pain relief, cancer prevention, and weight reduction. However, the application of capsaicin has been limited in the food industry due to its strong pungency, odor, and low solubility in water. Therefore, a multilayer nanoemulsion with chitosan and hyaluronic acid was developed for masking its odor and taste and improving the physicochemical stability against the surrounding environment. The capsaicin-fortified yogurts were prepared by blending various concentration levels of multilayer nanoemulsion (0-15%, w/v). The quality of yogurt was determined as a function of pH, acidity, viscosity, and total lactic acid bacteria population in an extended storage period (21 days). The multivariate statistical analysis was used to compare the quality of yogurts supplemented with capsaicin nanoemulsion. As a result, this study demonstrated the potential of capsaicin-loaded multilayer emulsion-supplemented yogurt as a novel nutrition-fortified food.

Action of chitosan-based solutions against a model four-species biofilm formed on cobalt-chromium and acrylic resin surfaces

OBJECTIVE

To evaluate the anti-biofilm action of chitosan, nanoparticulate chitosan, and denture cleanser Nitradine™ against biofilms comprising Candida albicans, Candida glabrata, Staphylococcus aureus, and Streptococcus mutans.

BACKGROUND

Biofilm removal from removable partial dentures (RPD) is important for success in prosthetic rehabilitation.

MATERIALS AND METHODS

The anti-biofilm action of the experimental chitosan-based solutions and Nitradine™ was evaluated on acrylic resin and cobalt-chromium alloy through assessing cell viability, cell metabolism, residual aggregated biofilm, and extracellular polymeric substance and biofilm morphology.

RESULTS

Only chitosan reduced the viability of C. albicans on cobalt-chromium alloy surface, by 98% (a 1.7 log10 reduction in cfu). Chitosan-based solutions neither promoted substantial alteration of the metabolic activity of the four-species biofilm nor reduced the amount of the aggregated biofilm. After immersion in chitosan and nanoparticulate chitosan, viable microorganisms and extracellular polymeric substances distributed over the entire specimens' surfaces were observed. Nitradine™ reduced the viability and metabolic activity of biofilm grown on both surfaces, but it did not remove all aggregated biofilm and extracellular polymeric substances. After immersion in Nitradine™, approximately 35% of the specimens' surfaces remained covered by aggregated biofilm, mainly composed of dead cells.

CONCLUSION

Although chitosan and Nitradine™ promoted changes in the viability of microorganisms, neither solution completely removed the four-species biofilm from the Co-Cr and acrylic resin surfaces. Thus, isolated use of hygiene solutions is not indicated for biofilm control on RPDs; this requires complementary mechanical removal.

Recent advances in chitosan-based materials; The synthesis, modifications and biomedical applications

The attention to polymer-based biomaterials, for instance, chitosan and its derivatives, as well as the techniques for using them in numerous scientific domains, is continuously rising. Chitosan is a decomposable naturally occurring polymeric material that is mostly obtained from seafood waste. Because of its special ecofriendly, biocompatible, non- toxic nature as well as antimicrobial properties, chitosan-based materials have received a lot of interest in the field of biomedical applications. The reactivity of chitosan is mainly because of the amino and hydroxyl groups in its composition, which makes it further fascinating for various uses, including biosensing, textile finishing, antimicrobial wound dressing, tissue engineering, bioimaging, gene, DNA and drug delivery and as a coating material for medical implants. This study is an overview of the different types of chitosan-based materials which now a days have been fabricated by applying different techniques and modifications that include etherification, esterification, crosslinking, graft copolymerization and o-acetylation etc. for hydroxyl groups' processes and acetylation, quaternization, Schiff's base reaction, and grafting for amino groups' reactions. Furthermore, this overview summarizes the literature from recent years related to the important applications of chitosan-based materials (i.e., thin films, nanocomposites or nanoparticles, sponges and hydrogels) in different biomedical applications.

Polyphenol-mediated sandwich-like coating promotes endothelialization and vascular healing

Drug-eluting stents have become one of the most effective methods to treat cardiovascular diseases. However, this therapeutic strategy may lead to thrombosis, stent restenosis, and intimal hyperplasia and prevent re-endothelialization. In this study, we selected 3-aminophenylboronic acid-modified hyaluronic acid and carboxylate chitosan as polyelectrolyte layers and embedded an epigallocatechin-3-gallate-tanshinone IIA sulfonic sodium (EGCG-TSS) complex to develop a sandwich-like layer-by-layer coating. The introduction of a functional molecular EGCG-TSS complex improved not only the biocompatibility of the coating but also its stability by enriching the interaction between the polyelectrolyte coatings through electrostatic interactions, hydrogen bonding, π-π stacking, and covalent bonding. We further elucidated the effectiveness of sandwich-like coatings in regulating the inflammatory response, smooth muscle cell growth behavior, stent thrombosis and restenosis suppression, and vessel re-endothelialization acceleration via in vivo and in vitro. Conclusively, we demonstrated that sandwich-like coating assisted by an EGCG-TSS complex may be an effective surface modification strategy for cardiovascular therapeutic applications.

The influence of ionic polysaccharides on the physicochemical and techno-functional properties of soy proteins; a comprehensive review

Since the world's population has surged in recent decades, the need for sustainable as well as environmentally friendly protein sources is growing. However, there are daunting challenges in utilizing these protein sources in the food industry due to their poor techno-functional properties compared with animal proteins. Numerous procedures have been introduced to improve plant protein functionalities with related pros and cons. Among them, complexation with polysaccharides is considered a safe and effective process for modulating plant proteins' technological and industrial applications. Notwithstanding the nutritional value of soy protein (SP) as a "complete protein," it is a crucial protein commercially because of its rank as the highest-traded plant-based protein worldwide. The current review deals with SP complexation with ionic polysaccharides, including chitosan, alginate, carrageenan, and xanthan gum, and their effects on the physicochemical and techno-functional properties of SP. Accordingly, the structure of SP and the abovementioned polysaccharides have been considered for a better understanding of the possible interactions. Then, the changes in the physicochemical and functional properties of SP and their potential applications in the formulation of plant-based food products have been discussed. Overall, ionic polysaccharides at optimum conditions would improve the functional properties of SP by altering its secondary structure, making it suitable for a wide range of applications in the food industry.

Comparative Study of Adsorption of Methylene Blue and Basic Red 9 Using Rice Husks of Different Origins

Methylene blue (MB) and basic red 9 (BR9) are cationic dyes that are commonly used in the dye industry and negatively affect humans and other living organisms. This study compares the performance of Indonesian rice husk (IRH) and Hungarian rice husk (HRH) as bio-adsorbents for removing MB and BR9 from aqueous solutions. Chemical content, zeta potential, and Fourier-transform infrared spectroscopy analyses were used to characterize the rice husks (RHs). Adsorption studies were performed through batch experiments involving several parameters, namely, pH, adsorbent dose, initial dye concentration, contact time, and temperature to observe the self-association (aggregation) of MB and BR9. Adsorption kinetic studies showed that maximum dye removal was achieved at a contact time of 120 min. MB and BR9 adsorption followed a pseudo-second order kinetic model, and the BET multilayer isotherm model provided a better fit to the experimental data of MB and BR9 adsorption. The IRH adsorption capacities were 15.0 mg/g for MB and 7.2 mg/g for BR9, whereas those of HRH were 24.4 mg/g for MB and 8.3 mg/g for BR9. Therefore, these RHs are potential bio-adsorbents for removing MB and BR9 from aqueous solutions.

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.

Cost-effective removal of toxic methylene blue dye from textile effluents by new integrated crosslinked chitosan/aspartic acid hydrogels

Chitosan/aspartic acid hydrogels were synthesized for MB dye removal from textile aqueous effluents with different ratios by gelation of chitosan with non-toxic gelling agent, crosslinker, glutaraldehyde (Glu). The obtained hydrogels were characterized by spectral and morphological techniques. The characterization techniques confirmed successful preparations and MB dye adsorption. Batch experiments were done to investigate the effects of adsorbent dose, pH, contact time, temperature, and initial MB dye concentration. The optimum conditions were: adsorbent dose 0.1 g, pH 5, contact time 30 min, and temperature 25 °C for Chitosan-Aspartic Acid Hydrogel 1 (CSAA-HG1) and adsorbent dose 0.4 g, pH 2, contact time 60 min, temperature 25 °C for Chitosan-Aspartic Acid Hydrogel 2 (CSAA-HG2). Adsorption capacity of newly hydrogels CSAA-HG1,2 was compared with each other. Adsorption efficiencies reached 99.85 % for CSAA-HG1 and 99.88 % for CSAA-HG2. MB dye adsorption on CSAA-HG1,2 followed Freundlich isotherm model (R2 = 0.94 and 0.92, respectively). Both adsorbents exhibited pseudo-second-order kinetics for MB dye adsorption (R2 = 1). The negative ΔHo indicated that the MB dye adsorption was exothermic, negative ΔGo confirmed that MB dye adsorption process was spontaneous and low values of ∆So indicated low degree of freedom, ordered MB dye molecules on CSAA-HG1,2 surfaces.

A curcumin-crosslinked bilayer film of soy protein isolate and chitosan with enhanced antibacterial property for beef preservation and freshness monitoring

In this study, antibacterial and antioxidant bilayer films were prepared by using curcumin (Cur) crosslinked soy rotein isolate (SPI) and chitosan (CS). Molecular docking simulations and multispectral analysis revealed that hydrogen bonding and hydrophobic interactions were the primary driving forces that promoted the self-assembly of the bilayer films. The tensile strength, the UV-blocking properties and the hydrophobicity was greatly improved of the bilayer antimicrobial films. Moreover, water vapor permeability, thermal shrinkage and opacity were all reduced significantly. In addition, the composite films with curcumin demonstrated effective antioxidant activity and a slow release characteristic. Morphology observation of the bacteria by AFM revealed that the antibacterial bilayer film had a significant damaging effect on the cell structures of S. aureus and E. coli due to the dual antibacterial effect of curcumin and chitosan. SPI + Cur-CS antimicrobial bilayer film effectively inhibited the growth of bacteria and extended the shelf life of beef. According to the findings, SPI + Cur-CS antimicrobial bilayer film can be used as an active package material for beef preservation and freshness monitoring.

Synthesis and characterization of n-phosphonium chitosan and its virucidal activity evaluation against coronavirus

Despite the worldwide vaccination effort against COVID-19, the demand for biocidal materials has increased. One promising solution is the chemical modification of polysaccharides, such as chitosan, which can provide antiviral activity through the insertion of cationic terminals. In this study, chitosan was modified with (4-carboxybutyl) triphenylphosphonium bromide to create N-phosphonium chitosan (NPCS), a quaternized derivative. The resulting NPCS samples with three degrees of substitution (15.6 %, 19.8 % and 24.2 %) were characterized and found to have improved solubility in water and alkaline solutions but reduced thermal stability. The particles zeta potential exhibits positive charges and is directly correlated with the degree of substitution of the derivative. In virucidal assays, all NPCS samples were able to inhibit 99.999 % of the MHV-3 coronavirus within 5 min at low concentrations of 0.1 mg/mL, while maintaining low cytotoxicity to L929 cells. In addition to its potential application against current coronavirus strains, NPCS could also be valuable in combating future pandemics caused by other viral pathogens. The antiviral properties of NPCS make it a promising material for use in coating surface and personal protective equipment to limit the spread of disease-causing viruses.

Recent Advances in Sustainable Antimicrobial Food Packaging: Insights into Release Mechanisms, Design Strategies, and Applications in the Food Industry

In response to the issues of foodborne microbial contamination and carbon neutrality goals, sustainable antimicrobial food packaging (SAFP) composed of renewable or biodegradable biopolymer matrices with ecofriendly antimicrobial agents has emerged. SAFP offers longer effectiveness, wider coverage, more controllability, and better environmental performance. Analyzing SAFP information, including the release profile of each antimicrobial agent for each food, the interaction of each biomass matrix with each food, the material size, form, and preparation methods, and its service quality in real foods, is crucial. While encouraging reports exist, a comprehensive review summarizing these developments is lacking. Therefore, this review critically examines recent release-antimicrobial mechanisms, kinetics models, preparation methods, and key regulatory parameters for SAFPs based on slow- or controlled-release theory. Furthermore, it discusses fundamental physicochemical characteristics, effective concentrations, advantages, release approaches, and antimicrobial and preservative effects of various materials in food simulants or actual food. Lastly, inadequacies and future trends are explored, providing practical references to regulate the movement of active substances in different media, reduce the reliance on petrochemical-based materials, and advance food packaging and preservation technologies.

Grafted chitosan thin films of various degrees of acetylation as a reusable platform for the investigation of biological interactions

Surface treatment by adhesive polymers is a promising solution to immobilize and study bacteria cells through microscopic assays and, for example, control their growth or determine their susceptibility to antibiotic treatment. The stability of such functional films in wet conditions is crucial, as the film degradation would compromise a persistent use of the coated devices. In this work, low roughness chitosan thin films of degrees of acetylation (DA) ranging from 0.5 % to 49 % were chemically grafted onto silicon and glass substrates and we have demonstrated how the physicochemical properties of the surfaces and the bacterial response were DA-dependent. A fully deacetylated chitosan film presented an anhydrous crystalline structure while the hydrated crystalline allomorph was the preferred structure at higher DA. Moreover, their hydrophilicity increased at higher DA, leading to higher film swelling. Low DA chitosan-grafted substrate favored bacterial growth away from the surface and could be envisioned as bacteriostatic surfaces. Contrarily, an optimum of Escherichia coli adhesion was found for substrates modified with chitosan of DA = 35 %: these surfaces are adapted for the study of bacterial growth and antibiotic testing, with the possibility of reusing the substrates without affecting the grafted film - ideal for limiting single-use devices.

Chitosan-Based Composite Membranes with Different Biocompatible Metal Oxide Nanoparticles: Physicochemical Properties and Drug-Release Study

Chitosan (CS) composite membranes were prepared using different biocompatible metal oxide nanoparticles (NPs): titanium dioxide (TiO₂); iron oxide (Fe₃O₄); and aluminum oxide (Al₂O₃). For each nanoparticle, the CS-based composite membranes were prepared with two NPs contents in the CS solution, high (H) and low (L) NPs concentrations. To establish both concentrations, the NPs saturation point in the CS polymeric matrix was determined. The influence of NP concentrations on the physicochemical properties of the CS films was assessed. The prepared CS membranes were characterized with different techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and zeta potential. It was found that the addition of NPs in the CS matrix improved both swelling and mechanical properties. Nanocomposite CS membranes could be prepared using Al₂O₃ NPs. Swelling experiments revealed different pH-sensitive mechanisms, which might be beneficial in biomedical applications since solute permeation through CS-based composite membranes could be controlled by adjusting environmental conditions. When aspirin transport (ASA) through the prepared membranes was carried out in different release media, SGF (simulating gastric fluid) and SIF (simulating intestinal fluid without enzymes), it was observed that the Fickian diffusion coefficient (D) was conditioned by the pH of the release solution. In SGIT (simulating gastrointestinal transit) medium, a transition time (t_trans) was detected due to the shrinkage of the CS polymeric chains, and the drug release depended not only on the Fickian's diffusion but also on the shrinkage of the biopolymer, obeying Peppas and Sahlin equation.

Evaluation of the In Vitro Antimicrobial Efficacy against Staphylococcus aureus and epidermidis of a Novel 3D-Printed Degradable Drug Delivery System Based on Polycaprolactone/Chitosan/Vancomycin-Preclinical Study

Acute and chronic bone infections, especially those caused by methicillin-resistant Staphylococcus aureus (MRSA), remains a major complication and therapeutic challenge. It is documented that local administration of vancomycin offers better results than the usual routes of administration (e.g., intravenous) when ischemic areas are present. In this work, we evaluate the antimicrobial efficacy against S. aureus and S. epidermidis of a novel hybrid 3D-printed scaffold based on polycaprolactone (PCL) and a chitosan (CS) hydrogel loaded with different vancomycin (Van) concentrations (1, 5, 10, 20%). Two cold plasma treatments were used to improve the adhesion of CS hydrogels to the PCL scaffolds by decreasing PCL hydrophobicity. Vancomycin release was measured by means of HPLC, and the biological response of ah-BM-MSCs growing in the presence of the scaffolds was evaluated in terms of cytotoxicity, proliferation, and osteogenic differentiation. The PCL/CS/Van scaffolds tested were found to be biocompatible, bioactive, and bactericide, as demonstrated by no cytotoxicity (LDH activity) or functional alteration (ALP activity, alizarin red staining) of the cultured cells and by bacterial inhibition. Our results suggest that the scaffolds developed would be excellent candidates for use in a wide range of biomedical fields such as drug delivery systems or tissue engineering applications.

Contribution of non-ionic interactions on bile salt sequestration by chitooligosaccharides: Potential hypocholesterolemic activity

Chitooligosaccharides have been suggested as cholesterol reducing ingredients mostly due to their ability to sequestrate bile salts. The nature of the chitooligosaccharides-bile salts binding is usually linked with the ionic interaction. However, at physiological intestinal pH range (6.4 to 7.4) and considering chitooligosaccharides pKa, they should be mostly uncharged. This highlights that other type of interaction might be of relevance. In this work, aqueous solutions of chitooligosaccharides with an average degree of polymerization of 10 and 90 % deacetylated, were characterized regarding their effect on bile salt sequestration and cholesterol accessibility. Chitooligosaccharides were shown to bind bile salts to a similar extent as the cationic resin colestipol, both decreasing cholesterol accessibility as measured by NMR at pH 7.4. A decrease in the ionic strength leads to an increase in the binding capacity of chitooligosaccharides, in agreement with the involvement of ionic interactions. However, when the pH is decreased to 6.4, the increase in charge of chitooligosaccharides is not followed by a significant increase in bile salt sequestration. This corroborates the involvement of non-ionic interactions, which was further supported by NMR chemical shift analysis and by the negative electrophoretic mobility attained for the bile salt-chitooligosaccharide aggregates at high bile salt concentrations. These results highlight that chitooligosaccharides non-ionic character is a relevant structural feature to aid in the development of hypocholesterolemic ingredients.

Food matrix design can influence the antimicrobial activity in the food systems: A narrative review

Antimicrobial agents are safe preservatives having the ability to protect foods from microbial spoilage and extend their shelf life. Many factors, including antimicrobials' chemical features, storage environments, delivery methods, and diffusion in foods, can affect their antimicrobial activities. The physical-chemical characteristics of the food itself play an important role in determining the efficacy of antimicrobial agents in foods; however the mechanisms behind it have not been fully explored. This review provides new insights and comprehensive knowledge regarding the impacts of the food matrix, including the food components and food (micro)structures, on the activities of antimicrobial agents. Studies of the last 10 years regarding the influences of the food structure on the effects of antimicrobial agents against the microorganisms' growth were summarized. The mechanisms underpinning the loss of the antimicrobial agents' activity in foods are proposed. Finally, some strategies/technologies to improve the protection of antimicrobial agents in specific food categories are discussed.

Synthesis of chitosan succinate-g-amine functionalized mesoporous silica: Inorganic-organic nanohybrid for antibacterial assessment, antioxidant activity and pH-controlled drug delivery

An innovative and proficient inorganic-organic nanohybrid was synthesized by using amine modified MCM-41 as an inorganic precursor combined with organic moiety, a derivative of chitosan i.e. chitosan succinate through amide bond. These nanohybrids can be used in diverse applications due to potential combination of desired properties of inorganic and organic components. The nanohybrid was characterized by FTIR, TGA, small angle powder XRD, zeta potential, particle size distribution, BET, proton NMR and ¹³C NMR techniques to confirm its formation. The synthesized hybrid was loaded with curcumin drug to check its potential application for controlled drug release, showing 80 % drug release in acidic medium (i.e. pH -5.0), while physiological pH -7.4 shows only 25 % release. The encapsulation efficiency of nanohybrid is 87.24 %. The results of antibacterial performances are demonstrated in terms of ZOI (zone of inhibition) which depicts that hybrid material shows better ZOI in gram negative (E. coli) than for gram positive (B. subtilis) bacteria. Nanohybrid was also tested for the antioxidant activity by using two different methods (DPPH and ABTS) radical scavenging methods. The ability of nano-hybrid to scavenge DPPH radicals was found 65 %, and ability to scavenge ABTS radicals was 62.47 %.

Carboxymethyl chitosan-glycerol multi-aldehyde based self-healing hydrogel system

The superiority of self-healing hydrogel systems with dynamic covalent chemistry is the ability to establish the gel network structure despite changes in ambient conditions such as pH, temperature, and ion concentrations. The Schiff base reaction, which occurs through aldehyde and amine groups, allows dynamic covalent bonds at physiological pH and temperature. In this study, gelation kinetics between glycerol multi-aldehyde (GMA) and water-soluble form of chitosan, carboxymethyl chitosan (CMCS), has been investigated, and the self-healing ability has been evaluated in detail. Macroscopic and electron microscope-based visual inspection and rheological tests showed that the hydrogels exhibit the highest self-healing capacity at 3-4 % CMCS and 0.5-1 % GMA concentrations. Hydrogel samples were subjected to alternating high and low strains to deteriorate and rebuild the elastic network structure. The results showed that hydrogels could restore their physical integrity after applying 200 % strains. In addition, direct cell encapsulation and double staining tests showed that the samples do not possess any acute cytotoxicity on mammalian cells; hence, hydrogels could potentially be used in tissue engineering applications for soft tissues.

Post grafted gallic acid to chitosan-Ag hybrid nanoparticles via free radical-induced grafting reactions

The present study proposes two unique systems using free radical-induced grafting reactions to combine Ag, chitosan (CS) and gallic acid (GA) into a single particulate nanostructure. GA-grafted-CS (GA-g-CS) was used to reduce Ag⁺ to Ag⁰, and producing Ag-GA-g-CSNPs (hybrid NPs I). Also, GA was grafted into CS-AgNPs, to form GA-g-CS AgNPs (hybrid NPs II). Although there were previous attempts to graft GA into CS, this is first time to graft GA into CS-AgNPs. The study aimed to enhance biocompatibility, antibacterial and antioxidant properties of CS-AgNPs via grafted GA. Grafting GA into CS-AgNPs was confirmed by UV-Vis, DLS, DSC/TGA, XRD, EDX and FTIR. The morphology and size of NPs were studied by TEM and SEM. The decrease of ζ-potential from +50 mV in CS-Ag NPs to +33 and + 29 mV, in the presented 2 nanoforms hybrid NPs I and II, respectively, is an indication for the successful GA graft. Among all samples, hybrid NPs II showed lower toxicity, higher antioxidant and antibacterial activity. The obtained results revealed that grafting GA to CS-AgNPs, as a new method to combine Ag, CS and GA in a uniparticulate structure, is a unique process which may deserve a more future consideration.

Carbohydrate polymer-based nanocomposites for breast cancer treatment

Breast cancer is known as the most common invasive malignancy in women with the highest mortality rate worldwide. This concerning disease may be presented in situ (relatively easier treatment) or be invasive, especially invasive ductal carcinoma which is highly worrisome nowadays. Among several strategies used in breast cancer treatment, nanotechnology-based targeted therapy is currently being investigated, as it depicts advanced technological features able of preventing drugs' side effects on normal cells while effectively acting on tumor cells. In this context, carbohydrate polymer-based nanocomposites have gained particular interest among the biomedical community for breast cancer therapy applications due to their advantage features, including abundance in nature, biocompatibility, straightforward fabrication methods, and good physicochemical properties. In this review, the physicochemical properties and biological activities of carbohydrate polymers and their derivate nanocomposites were discussed. Then, various methods for the fabrication of carbohydrate polymer-based nanocomposites as well as their application in breast cancer therapy and future perspectives were discussed.

Engineering chitosan into fully bio-sourced, water-soluble and enhanced antibacterial poly(aprotic/protic ionic liquid)s packaging membrane

The design and facile preparation of water-soluble and eco-friendly polymer packaging membrane materials is a fascinating research topic, particularly in terms of the increasing concerns on potential microplastics pollution in ecosystem. In this study, taking advantages of the structural features of chitosan (CS) and betaine hydrochloride (BHC), fully bio-sourced and water-soluble poly(aprotic/protic ionic liquid)s (PAPILs) were successfully designed and prepared through the reaction of the amino groups in CS and carboxyl groups in BHC. The structure and thermo-properties of the PAPILs were elucidated by a series of characteristic methods. The rheological properties of the PAPILs aqueous solutions were also investigated. Moreover, water-soluble PAPILs membrane with a smooth surface morphology and a tensile strength of 62.9 MPa was successfully prepared. The PAPILs membrane also exhibited satisfactory biocompatibility, excellent antibacterial activities and high oxygen barrier property. Together with these outstanding material performance and functionality, as a "proof of concept", the potential use of the PAPILs membrane as water-soluble packaging material for laundry detergent capsule and pesticide was preliminarily demonstrated. These findings provide significant insights for the design of sustainable and functional packaging materials by using natural resources.