Chitosan Derivatives: Introducing New Functionalities with a Controlled Molecular Architecture for Innovative Materials

An insight into chemically modified chitosan and their biological, pharmaceutical, and medical applications: A review

Quaternized chitosan derivatives demonstrated improved antimicrobial activity. Carboxy chitosan derivatives, resulting from carboxylation with glyoxylic acid or chloroalkanoic acid, enhance solubility and are utilized in wound healing and antitumor therapies. Modifications like acylation of chitosan alter hydrophobicity, affecting biocompatibility and drug delivery efficiency. Thiolated chitosan derivatives, with enhanced mucoadhesive properties, are advantageous for mucosal drug delivery. Sulfated chitosan derivatives mimic heparin's functions, showcasing anticoagulant, anti-sclerosis, and antiviral properties. Phosphorylated chitosan derivatives find utility in orthopedics due to their cation-exchange abilities. Heterocyclic chitosan derivatives exhibit antibacterial properties, while Schiff's base and epoxy Schiff's base chitosan derivatives display antimicrobial enhancements and improved drug delivery profiles. Aminosalicylhydrazide cross-linked Schiff's base chitosan derivatives exhibit versatility with heightened antimicrobial and biological activities. Continually exploring novel functional groups highlights the importance of staying current with ongoing research in chitosan modification. Future research should focus on developing innovative chitosan derivatives with enhanced bioactivity, physicochemical properties, and multifunctional capabilities to improve pharmaceutical applications. Additionally, studies on scalability, commercialization, and eco-friendly production methods are essential to ensure industrial viability and sustainability.

Metal nanoparticles incorporated chitosan-based electrospun nanofibre mats for wound dressing applications: A review

Wound healing is a dynamic physiological process essential for regenerating skin and maintaining coherence in hypodermic tissues. Chitosan-based electrospun nanofibre wound dressings show great promise for expediting the integration of skin and tissues due to their nano-topographic, biodegradable, biocompatible, and antimicrobial properties. However, their moderate bactericidal efficacy and limited mechanical strength hinder their widespread clinical application. The incorporation of specific metal nanoparticles (MNPs) and the functionalization of chitosan have brought attention to their crucial role in wound healing applications, yielding promising results by enhancing antibacterial properties, cell proliferation, cell signaling, and the mechanical robustness of the materials. Chitosan naturally mitigates the cytotoxicity of the incorporated metal nanoparticles within the nanofibers. Chitosan and modified chitosan-based electrospun mats incorporated with metal nanoparticles demonstrate substantial potential for expediting wound healing. This review offers a comprehensive overview of recent advancements in electrospun chitosan-based mats containing MNPs aimed at enhancing wound healing. It covers various aspects, including modification techniques, fabrication methods, wound closure mechanisms, MNP release profiles, histological considerations, addresses existing challenges, and outlines potential future developments.

The latest research progress on polysaccharides-based biosensors for food packaging: A review

In recent years, polysaccharide-based biosensors have emerged as promising technologies for intelligent food packaging, offering innovative solutions to enhance food quality and safety. This review highlights advancements in designing, developing, and applying these biosensors, particularly those utilizing polysaccharides such as chitosan, cellulose and alginate. Engineered with nanomaterials like ZnO, silver, and carbon nano-tubes demonstrated high sensitivity in real-time monitoring of food spoilage indicators, including pH changes, volatile nitrogen compounds and microbial activity. We discuss the electrochemical properties of these biosensors, highlighting how the integration of electrochemical methods significantly improves their detection capabilities within packaging environments, leading to sensor sensitivity enhancement, greater accuracy, and spoilage detection, ultimately extending the shelf life of perishable food products. Additionally, the review addresses the practical challenges of industrial implementation and explores future research directions for optimizing sensor functionality and scalability. The findings underscore the potential of polysaccharide-based intelligent packaging as a sustainable and effective alternative to conventional methods, paving the way for broader commercial adoption.

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.

Recent advances of chitosan-based composite hydrogel materials in application of bone tissue engineering

Bone defects, stemming from trauma, tumors, infections, and congenital conditions, pose significant challenges in orthopedics. Although the body possesses innate mechanisms for bone self-repairing, factors such as aging, disease, and injury can impair these processes, jeopardizing skeletal integrity. Addressing substantial bone defects remains a global orthopedic concern, with variables like gender, lifestyle and preexisting conditions influencing fracture risk and complication rates. Traditional repair methods, mainly bone transplantation including autografts, allografts and xenografts, have shown effectiveness but also present limitations. Autologous bone grafts, highly valued for their osteogenic properties, require additional surgeries with extended hospitalization, and carry risks associated with the donor site. The development of advanced biomaterials offers promising new avenues for bone repair. An ideal material should exhibit a combination of biocompatibility, biodegradability, bone conduction, porosity, strength, and the ability to stimulate bone formation. Chitosan (CS), derived from chitin, stands out due to its biocompatibility, biodegradability, low immunogenicity, non-toxicity, and a wide range of biological activities, including antioxidant, anti-tumor, anti-inflammatory, antimicrobial, and immunomodulatory properties. Notably, CS has shown the properties to promote bone regeneration, increase bone density, and accelerate fracture healing. This review provides a comprehensive examination of CS-based hydrogels for bone repair aiming to inspire researchers by presenting new ideas for innovative CS-based solutions, thereby advancing their potential applications in the field of bone repair.

Recent advances in chitosan-based smart hydrogel for drug delivery systems

Achieving sustainable and controllable drug delivery is a highly effective disease treatment approach. Chitosan hydrogels, with their unique three-dimensional (3D) porous structures, offer tunable capacity, controllable degradation, various stimuli sensitivities, and the ability to encapsulate therapeutic agents. These characteristics provide chitosan hydrogels with inherent advantages as vehicles for drug delivery systems. In recent years, there has been a notable shift toward embracing the "back-to-nature" ethos, with biomass materials emerging as promising candidates for constructing chitosan hydrogels used in controlled drug release applications. This trend is sustained by their biodegradability, biocompatibility, and non-toxic properties, emphasizing their unique benefits and innovative features. These hydrogels exhibit sensitivity to various factors such as temperature, pH, ion concentration, light, magnetic fields, redox, ultrasound, and multi-responsiveness, offering opportunities for finely tuned drug release mechanisms. This review comprehensively outlines fabrication methods, properties, and biocompatibility of chitosan hydrogel, as well as modification strategies and stimuli-responsive mechanisms. Furthermore, their potential applications in subcutaneous (wound dressing), parental (transdermal drug delivery), oral (gastrointestinal tract), and facial (ophthalmic and brain) drug delivery are briefly discussed. The challenges in clinical application and the future outlook of chitosan-based smart hydrogel are also highlighted.

Clicking gallic acid into chitosan prolongs its antioxidant activity and produces intracellular Ca2+ responses in rat brain cells

Gallic acid is a vegetable-derived and highly bioactive phenolic acid, but its antioxidant capacity is sensitive to environmental conditions. Chitosan is a biopolymer capable of exerting significant protection to various molecules, including phenolic compounds. A chitosan derivative that extends the antioxidant activity of gallic acid was synthesized by click chemistry and characterized by FT-IR, 1H NMR, and antioxidant capacity assays. Our results show that synthesized polymeric solutions and nanoparticles of N-(gallic acid) chitosan were both internalized by rat brain cells, processes that were modulated by extracellular Ca2+ and Na+. Their internalization was supported by dynamic light scattering and ζ-potential analyses, while Ca2+ imaging recordings performed in brain cells revealed the potential biological effect of N-(gallic acid) chitosan. We conclude that the synthesis of an N-(gallic acid) chitosan derivative through click chemistry is viable and may serve as strategy to prolong its antioxidant activity and to study its biological effects in vivo.

Investigation of pH-dependent Paclitaxel delivery mechanism employing Chitosan-Eudragit bioresponsive nanocarriers: a molecular dynamics simulation

Before embarking on any experimental research endeavor, it is advisable to do a mathematical computation and thoroughly examine the methodology. Despite the use of polymeric nanocarriers, the regulation of bioavailability and drug release at the disease site remains insufficient. Several effective methods have been devised to address this issue, including the creation of polymeric nanocarriers that can react to stimuli such as redox potential, temperature, pH, and light. The present study has been utilized all-atom molecular dynamics (AA-MD) and coarse-grained molecular dynamics (CG-MD) methods and illustrated the drug release mechanism, which is influenced by pH, for Chitosan-Eudragit bioresponsive nanocarriers. The aim of current work is to study the molecular mechanism and atomistic interactions of PAX delivery using a Chitosan-Eudragit carrier. The ability of Eudragit polymers to dissolve in various organic solvents employed in the process of solvent evaporation is a crucial benefit in enhancing the solubility of pharmaceuticals. This study investigated the use of Chitosan-Eudragit nanocarriers for delivering an anti-tumor drug, namely Paclitaxel (PAX). Upon analyzing several significant factors affecting the stability of the drug and nanocarrier, it has been shown that the level of stability is more significant in the neutral state than the acidic state. Furthermore, the system exhibits higher stability in the neutral state. The used Chitosan-Eudragit nanocarriers exhibit a stable structure under alkaline conditions, but undergo deformation and release their payloads under acidic conditions. It was demonstrated that the in silico analysis of anti-tumor drugs and carriers' integration could be quantified and validated by experimental results (from previous works) at an acceptable level.

Fabrication and optimization of chitosan-g-m-PEG-NH2 copolymer for advanced glioblastoma therapy using surface engineered lentinan loaded nanovesicles for nasal delivery

Glioblastoma multiforme (GBM) exhibits a high mortality with an incidence rate of 3-5 per 100,000 each year, which demands existence of newer approach for its treatment. The current study focuses on synthesis of novel lipidic nanovesicles (LNs) loaded with highly potent macromolecule Lentinan (LNT) and surface modified with methoxy poly (ethylene glycol; PEG) amine (m-PEG-NH2)-grafted-chitosan (CS) for intranasal delivery. The grafting procedure was optimized using Box Behnken design (BBD) to limit the use of organic solvents. The fabricated polymer showed enhanced aqueous solubility, biodegradability and mucoadhesion, resulting in higher nasal mucosa permeation (z = 53.52 μm). The presence of PEG enabled the sustained release of LNT till 48 h and assisted in achieving higher accumulation of LNT in CSF (41.7 ± 3.1 μg/mL) and a higher brain targeting potential of 96.3 ± 2.31 % (p < 0.05). In-vitro cellular studies showed the enhanced anti-GBM effect of LNT on U87 MG cells by reducing the cell viability (~2 times reduction in IC50 value) accompanied with large number of cells undergoing late apoptosis and death (p < 0.05) because of the higher cellular uptake (63.22 ± 3.01 ng/100 cells) of novel formulation. The copolymer comprising LNs were biocompatible, stable and can be used as an effective tool in the management of GBM.

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.

Inhibition of iRhom1 by CD44-targeting nanocarrier for improved cancer immunochemotherapy

The multifaceted chemo-immune resistance is the principal barrier to achieving cure in cancer patients. Identifying a target that is critically involved in chemo-immune-resistance represents an attractive strategy to improve cancer treatment. iRhom1 plays a role in cancer cell proliferation and its expression is negatively correlated with immune cell infiltration. Here we show that iRhom1 decreases chemotherapy sensitivity by regulating the MAPK14-HSP27 axis. In addition, iRhom1 inhibits the cytotoxic T-cell response by reducing the stability of ERAP1 protein and the ERAP1-mediated antigen processing and presentation. To facilitate the therapeutic translation of these findings, we develop a biodegradable nanocarrier that is effective in codelivery of iRhom pre-siRNA (pre-siiRhom) and chemotherapeutic drugs. This nanocarrier is effective in tumor targeting and penetration through both enhanced permeability and retention effect and CD44-mediated transcytosis in tumor endothelial cells as well as tumor cells. Inhibition of iRhom1 further facilitates tumor targeting and uptake through inhibition of CD44 cleavage. Co-delivery of pre-siiRhom and a chemotherapy agent leads to enhanced antitumor efficacy and activated tumor immune microenvironment in multiple cancer models in female mice. Targeting iRhom1 together with chemotherapy could represent a strategy to overcome chemo-immune resistance in cancer treatment.

Injectable hydrogel for sustained delivery of progranulin derivative Atsttrin in treating diabetic fracture healing

Hydrogels with long-term storage stability, controllable sustained-release properties, and biocompatibility have been garnering attention as carriers for drug/growth factor delivery in tissue engineering applications. Chitosan (CS)/Graphene Oxide (GO)/Hydroxyethyl cellulose (HEC)/β-glycerol phosphate (β-GP) hydrogel is capable of forming a 3D gel network at physiological temperature (37 °C), rendering it an excellent candidate for use as an injectable biomaterial. This work focused on an injectable thermo-responsive CS/GO/HEC/β-GP hydrogel, which was designed to deliver Atsttrin, an engineered derivative of a known chondrogenic and anti-inflammatory growth factor-like molecule progranulin. The combination of the CS/GO/HEC/β-GP hydrogel and Atsttrin provides a unique biochemical and biomechanical environment to enhance fracture healing. CS/GO/HEC/β-GP hydrogels with increased amounts of GO exhibited rapid sol-gel transition, higher viscosity, and sustained release of Atsttrin. In addition, these hydrogels exhibited a porous interconnected structure. The combination of Atsttrin and hydrogel successfully promoted chondrogenesis and osteogenesis of bone marrow mesenchymal stem cells (bmMSCs) in vitro. Furthermore, the work also presented in vivo evidence that injection of Atsttrin-loaded CS/GO/HEC/β-GP hydrogel stimulated diabetic fracture healing by simultaneously inhibiting inflammatory and stimulating cartilage regeneration and endochondral bone formation signaling pathways. Collectively, the developed injectable thermo-responsive CS/GO/HEC/βG-P hydrogel yielded to be minimally invasive, as well as capable of prolonged and sustained delivery of Atsttrin, for therapeutic application in impaired fracture healing, particularly diabetic fracture healing.

Structural and conformational changes on chitosan after green heterogeneous synthesis of phenyl derivatives

Four aromatic acid compounds: benzoic acid (Bz), 4-hydroxyphenylpropionic acid (HPPA), gallic acid (GA) and 4-aminobenzoic acid (PABA) were covalently bonded to chitosan in order to improve water solubility at neutral pH. The synthesis was performed via a radical redox reaction in heterogeneous phase by employing ascorbic acid and hydrogen peroxide (AA/H₂O₂) as radical initiators in ethanol. The analysis of chemical structure and conformational changes on acetylated chitosan was also the focus of this research. Grafted samples exhibited as high as 0.46 M degree of substitution (MS) and excellent solubility in water at neutral pH. Results showed a correlation between the disruption of C3-C5 (O3…O5) hydrogen bonds with increasing solubility in grafted samples. Spectroscopic techniques such as FT-IR and ¹H and ¹³C NMR showed modifications in both glucosamine and N-Acetyl-glucosamine units by ester and amide linkage at C2, C3 and C6 position, respectively. Finally, loss of crystalline structure of 2-helical conformation of chitosan after grafting was observed by XRD and correlated with ¹³C CP-MAS-NMR analyses.

Investigation of novel HCV therapies: Boscia angustifalia &Boscia senegalensis extracts loaded on galactosylated chitosan nanoparticles synthesized by eco-friendly method for HCV treatment

Hepatitis C virus (HCV) is a major causative agent of chronic liver diseases including chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma worldwide. Treatment of HCV has evolved from early interferon monotherapy to the current all-oral regimens using direct-acting antivirals. However, antiviral resistance has become a critical issue in the treatment of chronic hepatitis C after receiving therapy with direct-acting antivirals (DAA) with a 0.5 % chance of the hepatitis C virus recurrence, similar to other chronic viral infections. So, retreatment options following treatment failure have become crucial issues. Hence, this study aims to investigate a new promising therapy for HCV. In the field of nanomedicine, chitosan nanoparticles are well-known delivery systems that are frequently used as polymeric carriers. Galactosylated chitosan nanoparticles have been widely applied in HCV treatment. In this study, we have modified galactosylation by an eco-friendly method using l-ascorbic instead of hazardous reagents and we have loaded it with newly tested two Boscia extracts each in three different concentrations. The synthesized chitosan nanoparticles showed two dispersion peaks, at 196 ± 29 nm and 1.33 ± 0.36 μm, with a zeta potential of +3.3 ± 0.4mV with high stability in a range of 40.7 mV. The percentage of encapsulation of Boscia angustifalia extract was found to be 46.58 ± 1.33 % and for Boscia senegalensis extract was 9.77 ± 0.33 %. The release of Boscia angustifalia extract from the nanoparticles was about 40 % in acidic media after 180 min and about 60 % in normal pH. However, the release of Boscia senegalensis extract was 20 % in acidic media and 56 % in normal media after 24 h. Testing of these two newly developed composites against HCV was carried out using an in vitro system for the production of hepatitis C virus (HCV) which was established by infection of human hepatoma cells. Evidence for persistent virus production was monitored by the ELISA technique using an anti-HCV-specific antibody. Results obtained showed that all samples had an anti-HCV activity that increased by increasing concentration, and Boscia angustifalia had remarkable anti-HCV activity compared to Boscia senegalensis.

Multifunctionalized Cationic Chitosan Polymeric Micelles Polyplexed with pVGF for Noninvasive Delivery to the Mouse Brain through the Intranasal Route for Developing Therapeutics for Alzheimer's Disease

Multifunctionalized Chitosan-based polymeric micelles were used to deliver pVGF to the brain. VGF (non-acronymic) plays significant roles in neurogenesis and learning as well as synaptic and cognitive functions. Therefore, VGF gene therapy could be a better approach in developing effective therapeutics against Alzheimer's disease. Multifunctionalized chitosan polymeric micelles were developed by grafting oleic acid (OA) on the chitosan (CS) skeleton followed by penetratin (PEN) and mannose (MAN) conjugation. The OA-g-CS-PEN-MAN graft polymer formed cationic nanomicelles in an aqueous medium and polyplexed with pVGF. The polymeric micelles were nontoxic and cationic in charge and had an average hydrodynamic diameter of 199.8 ± 15.73 nm. Qualitative in vitro transfection efficiency of OA-g-CS-PEN-MAN/pGFP polyplex was investigated in bEnd.3, primary neurons, and astrocyte cells. In vivo transfection efficiency of OA-g-CS-PEN-MAN/pVGF polyplexes was analyzed in C57BL6/J mice after intranasal administration for 7 days. The VGF expression levels in primary astrocytes and neurons after OA-g-CS-PEN-MAN/pVGF treatment were 2.4 ± 0.24 and 1.49 ± 0.02 pg/μg of protein, respectively. The VGF expression in the OA-g-CS-PEN-MAN/pVGF polyplex-treated animal group was 64.9 ± 12.7 pg/mg of protein, significantly higher (p < 0.01) than that of the unmodified polymeric micelles. The in vivo transfection outcomes revealed that the developed multifunctionalized OA-g-CS-PEN-MAN polymeric micelles could effectively deliver pVGF to the brain, transfect brain cells, and express VGF in the brain after noninvasive intranasal administration.

Biopolymers as a versatile tool with special emphasis on environmental application

Water sources are becoming highly unsuited as potable sources due to the presence of impurities and hazardous chemicals. Although there are many conventional methods available, the development of innovative technologies is essential for the treating and recycling of wastewater. Owing to their unique and excellent qualities, polymers have recently seen extensive use across various industries. By joining the monomeric components covalently, biopolymers resemble a more natural alternative to synthetic polymers. The biopolymer and biopolymer composites integrate into many sections of the treatment process easily, making them effective, affordable, and environmentally beneficial. Due to their distinct features, biopolymers can replace traditional adsorbents. The biopolymers and composites discussed in this chapter are ideal adsorbent materials for eliminating contaminants from the environment. Based on their sources, methods of preparation, and uses, biopolymers, and their composites are categorized. This chapter also includes different research perspectives on biopolymers, especially from an ecological and financial standpoint.

Synthesis and antibacterial analysis of C-6 amino-functionalised chitosan derivatives

Synthesis of 6-O-(3-alkylamino-2-hydroxypropyl) derivatives of chitosan was achieved using a four-step strategy of N-protection, O-epoxide addition, epoxide ring opening using an amine and N-deprotection. Benzaldehyde and phthalic anhydride were used for the N-protection step, producing N-benzylidene and N-phthaloyl protected derivatives, respectively, resulting in two corresponding final 6-O-(3-alkylamino-2-hydroxypropyl) derivative series, BD1-BD6 and PD1-PD14. All the compounds were characterized using FTIR, XPS and PXRD studies and tested for antibacterial efficacy. The phthalimide protection strategy was found to be easier to apply and effective in terms of the synthetic process and improvement in antibacterial activity. Amongst the newly synthesized compounds, PD13 (6-O-(3-(2-(N,N-dimethylamino)ethylamino)-2-hydroxypropyl)chitosan) was the most active with eight times greater activity compared to the unmodified chitosan and, PD7 6-O-(3-(3-(N-(3-aminopropyl)propane-1,3-diamino)propylamino)-2-hydroxypropyl)chitosan) having a four-fold activity than chitosan, was found to be the second most potent derivative. This work has produced new chitosan derivatives those are more potent than chitosan itself and show promise in antimicrobial applications.

Structure-activity relationship for antibacterial chitosan carrying cationic and hydrophobic moieties

To overcome the problem of antibiotic resistance and toxicity of synthetic polymers, herein we report the synthesis of biocompatible polymers which can serve as broad spectrum antimicrobials. A regioselective synthetic method was developed to synthesize N-functionalized chitosan polymers having similar degree of substitution of cationic and hydrophobic functionality with different lipophilic chains. We obtained optimum antibacterial effect by utilizing the combination of cationic and longer lipophilic chain in the polymer, against four bacterial strains. Inhibition and killing of bacteria were more pronounced in Gram positive bacteria than in Gram negative bacteria. Growth kinetics and scanning electron microscopy imaging of the polymer treated bacterial cells confirmed the inhibition of bacterial growth, morphological changes in the structure and membrane disruption in the cells as compared to the growth control for each strain. Further investigation into the toxicity and selectivity of the polymers guided us to develop a structure-activity relationship for this class of biocompatible polymers.

DEAE/Catechol-Chitosan Conjugates as Bioactive Polymers: Synthesis, Characterization, and Potential Applications

This work provides the first description of the synthesis and characterization of water-soluble chitosan (Cs) derivatives based on the conjugation of both diethylaminoethyl (DEAE) and catechol groups onto the Cs backbone (Cs-DC) in order to obtain a Cs derivative with antioxidant and antimicrobial properties. The degree of substitution [DS (%)] was 35.46% for DEAE and 2.53% for catechol, determined by spectroscopy. Changes in the molecular packing due to the incorporation of both pendant groups were described by X-ray diffraction and thermogravimetric analysis. For Cs, the crystallinity index was 59.46% and the maximum decomposition rate appeared at 309.3 °C, while for Cs-DC, the values corresponded to 16.98% and 236.4 °C, respectively. The incorporation of DEAE and catechol groups also increases the solubility of the polymer at pH > 7 without harming the antimicrobial activity displayed by the unmodified polymer. The catecholic derivatives increase the radical scavenging activity in terms of the half-maximum effective concentration (EC₅₀). An EC₅₀ of 1.20 μg/mL was found for neat hydrocaffeic acid (HCA) solution, while for chitosan-catechol (Cs-Ca) and Cs-DC solutions, concentrations equivalent to free HCA of 0.33 and 0.41 μg/mL were required, respectively. Cell culture results show that all Cs derivatives have low cytotoxicity, and Cs-DC showed the ability to reduce the activity of reactive oxygen species by 40% at concentrations as low as 4 μg/mL. Polymeric nanoparticles of Cs derivatives with a hydrodynamic diameter (D_h) of around 200 nm, unimodal size distributions, and a negative ζ-potential were obtained by ionotropic gelation and coated with hyaluronic acid in aqueous suspension, providing the multifunctional nanoparticles with higher stability and a narrower size distribution.

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

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

Modification and Functionalization of Polymers for Targeting to Bone Cancer and Bone Regeneration

Bone is one of the most complex, inaccessible body structures, responsible for calcium storage and haematopoiesis. The second highest cause of death across the world is cancer. Amongst all the types of cancers, bone cancer treatment modalities are limited due to the structural complexity and inaccessibility of bones. The worldwide incidence of bone diseases and bone defects due to cancer, infection, trauma, age-related bone degeneration is increasing. Currently different conventional therapies are available for bone cancer such as chemotherapy, surgery and radiotherapy, but they have several disadvantages associated with them. Nanomedicine is being extensively researched as viable therapeutics to mitigate drug resistance in cancer therapy and promote bone regeneration. Several natural polymers such as chitosan, dextran, alginate, hyaluronic acid, and synthetic polymers like polyglycolic acid, poly(lactic-co-glycolic acid), polycaprolactone are investigated for their application in nanomedicine for bone cancer treatment and bone regeneration. Nanocarriers have shown promising results in preclinical experimental studies. However, they still face a major drawback of inadequate targetability. The paper summarizes the status of research and the progress made so far in modifications and functionalization of natural polymers for improving their site specificity and targeting for effective treatment of bone cancer and enhancing bone regeneration.

Chitosan–Hydroxycinnamic Acids Conjugates: Emerging Biomaterials with Rising Applications in Biomedicine

Over the past thirty years, research has shown the huge potential of chitosan in biomedical applications such as drug delivery, tissue engineering and regeneration, cancer therapy, and antimicrobial treatments, among others. One of the major advantages of this interesting polysaccharide is its modifiability, which facilitates its use in tailor-made applications. In this way, the molecular structure of chitosan has been conjugated with multiple molecules to modify its mechanical, biological, or chemical properties. Here, we review the conjugation of chitosan with some bioactive molecules: hydroxycinnamic acids (HCAs); since these derivatives have been probed to enhance some of the biological effects of chitosan and to fine-tune its characteristics for its application in the biomedical field. First, the main characteristics of chitosan and HCAs are presented; then, the currently employed conjugation strategies between chitosan and HCAs are described; and, finally, the studied biomedical applications of these derivatives are discussed to present their limitations and advantages, which could lead to proximal therapeutic uses.

Review on biopolymers and composites - Evolving material as adsorbents in removal of environmental pollutants

The presence of pollutants and toxic contaminants in water sources makes it unfit to run through. Though various conventional techniques are on deck, development of new technologies are vital for wastewater treatment and recycling. Polymers have been intensively utilized recently in many industries owing to their unique characteristics. Biopolymers resembles natural alternative to synthetic polymers that can be prepared by linking the monomeric units covalently. Despite the obvious advantages of biopolymers, few reviews have been conducted. This review focuses on biopolymers and composites as suitable adsorbent material for removing pollutants present in environment. The classification of biopolymers and their composites based on the sources, methods of preparation and their potential applications are discussed in detail. Biopolymers have the potentiality of substituting conventional adsorbents due to its unique characteristics. Biopolymer based membranes and effective methods of utilization of biopolymers as suitable adsorbent materials are also briefly elaborated. The mechanism of biopolymers and their membrane-based adsorption has been briefly reviewed. In addition, the methods of regeneration and reuse of used biopolymer based adsorbents are highlighted. The comprehensive content on fate of biopolymer after adsorption is given in brief. Finally, this review concludes the future investigations in recent trends in application of biopolymer in various fields in view of eco-friendly and economic perspectives.

Novel bioactive adhesive dressing based on gelatin/ chitosan cross-linked cactus mucilage for wound healing

The development of natural-based wound dressings is of great interest in the field of skin tissue engineering. Herein, different bioactive molecules such as gelatin (GEL), chitosan (CH) and mucilage (MU) were used to prepare a wound dressing. The physico-chemical and biological characterizations occurring after γ-irradiation were investigated. Results showed that Electron Paramagnetic Resonance (EPR) spectroscopy of un-irradiated GEL-CH-MU biomaterial showed two paramagnetic centers which correspond to g = 1.89 and g = 2.033. A generated new active center appeared at g = 2.003 at 25 kGy due to the interactions of gamma rays with the polymer chain creating signals at the absorbing functional groups. X-ray diffraction (XRD) spectra preserved the semi-crystalline structures between a range of 2θ (5° and 45°). Fourier Transform Infrared spectroscopy (FTIR) revealed that the initiation of cross linking phenomena. Moreover, γ-rays significantly increased antioxidant activity (9.1 ± 0.07%, p < 0.05) and exhibited a high anti-inflammatory activity (70%) at 25 kGy. Significant antibacterial activities in vitro liquid medium was observed. In addition GEL-CH-MU dressing exhibited high hemocompatibility. Conducted investigations state that such innovative dressing natural-based polymers for advanced wound care may be considered as useful for biomedical purposes.

Progress in the Degradability of Biodegradable Film Materials for Packaging

In today’s world, the problem of “white pollution” is becoming more and more serious, and many countries have paid special attention to this problem, and it has become one of the most important tasks to reduce polymer waste and to protect the environment. Due to the degradability, safety, economy and practicality of biodegradable packaging film materials, biodegradable packaging film materials have become a major trend in the packaging industry to replace traditional packaging film materials, provided that the packaging performance requirements are met. This paper reviews the degradation mechanisms and performance characteristics of biodegradable packaging film materials, such as photodegradation, hydrodegradation, thermo-oxidative degradation and biodegradation, focuses on the research progress of the modification of biodegradable packaging film materials, and summarizes some challenges and bottlenecks of current biodegradable packaging film materials.

Modified Poly(Lactic Acid) Epoxy Resin Using Chitosan for Reactive Blending with Epoxidized Natural Rubber: Analysis of Annealing Time

Poly(lactic acid) was melt-blended with epoxy resin without hardener and chitosan (CTS) to prepare modified PLA (PLAEC). Epoxy resin 5% and CTS 1–20% (wt/wt) were incorporated into PLA during melt mixing. PLAEC was melt-blended with an epoxidized natural rubber (ENR) 80/20 wt. The PLAEC CTS 1% blended with ENR (PLAEC1/ENR) showed a high tensile strength (30 MPa) and elongation at break (7%). The annealing process at 80 °C for 0–15 min maintained a tensile strength of approximately 30 MPa. SEM images of the PLAE/ENR blend showed phase inversion from co-continuous to ENR particle dispersion in the PLA matrix with the addition of CTS, whereas the annealing time reduced the hole sizes of the extracted ENR phase due to the shrinkage of PLA by crystallization. Thermal properties were observed by DSC and a Vicat softening test. The annealing process increased the crystallinity and Vicat softening temperature of the PLAEC1/ENR blend. Reactions of −COOH/epoxy groups and epoxy/−NH₂ groups occurred during PLAE and PLAEC preparation, respectively. FTIR confirmed the reaction between the −NH₂ groups of CTS in PLAEC and the epoxy groups of ENR. This reaction increased the mechanical properties, while the annealing process improved the morphology and thermal properties of the blend.

Non-Viral Vectors for Delivery of Nucleic Acid Therapies for Cancer

The research and development of non-viral gene therapy has been extensive over the past decade and has received a big push thanks to the recent successful approval of non-viral nucleic acid therapy products. Despite these developments, nucleic acid therapy applications in cancer have been limited. One of the main causes of this has been the imbalance in development of delivery vectors as compared with sophisticated nucleic acid payloads, such as siRNA, mRNA, etc. This paper reviews non-viral vectors that can be used to deliver nucleic acids for cancer treatment. It discusses various types of vectors and highlights their current applications. Additionally, it discusses a perspective on the current regulatory landscape to facilitate the commercial translation of gene therapy.

Single-Chain Mechanical Properties of Gelatin: A Single-Molecule Study

Gelatin is an important natural biological resource with a wide range of applications in the pharmaceutical, industrial and food industries. We investigated the single-chain behaviors of gelatin by atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS), and found that gelatin exists as long chains by fitting with the M-FJC model. By comparing the single-chain elasticity in a nonpolar organic solvent (nonane) and DI water, it was surprising to find that there was almost no difference in the single-chain elasticity of gelatin in nonane and DI water. Considering the specificity of gelatin solubility and the solvent size effect of nonane molecules, when a single gelatin chain is pulled into loose nonane, dehydration does not occur due to strong binding water interactions. Gelatin chains can only interact with water molecules at high temperatures; therefore, no further interaction of single gelatin chains with water molecules occurred at the experimental temperature. This eventually led to almost no difference in the single-chain F-E curves under the two conditions. It is expected that our study will enable the deep exploration of the interaction between water molecules and gelatin and provide a theoretical basis and experimental foundation for the design of gelatin-based materials with more functionalities.

Chitosan Nanoparticle-Based System: A New Insight into the Promising Controlled Release System for Lung Cancer Treatment

Lung cancer has been recognized as one of the most often diagnosed and perhaps most lethal cancer diseases worldwide. Conventional chemotherapy for lung cancer-related diseases has bumped into various limitations and challenges, including non-targeted drug delivery, short drug retention period, low therapeutic efficacy, and multidrug resistance (MDR). Chitosan (CS), a natural polymer derived from deacetylation of chitin, and comprised of arbitrarily distributed β-(1-4)-linked d-glucosamine (deacetylated unit) and N-acetyl-d-glucosamine (acetylated unit) that exhibits magnificent characteristics, including being mucoadhesive, biodegradable, and biocompatible, has emerged as an essential element for the development of a nano-particulate delivery vehicle. Additionally, the flexibility of CS structure due to the free protonable amino groups in the CS backbone has made it easy for the modification and functionalization of CS to be developed into a nanoparticle system with high adaptability in lung cancer treatment. In this review, the current state of chitosan nanoparticle (CNP) systems, including the advantages, challenges, and opportunities, will be discussed, followed by drug release mechanisms and mathematical kinetic models. Subsequently, various modification routes of CNP for improved and enhanced therapeutic efficacy, as well as other restrictions of conventional drug administration for lung cancer treatment, are covered.

Antimicrobial efficacy of triple antibiotic-loaded chitosan nanoparticles activated with photochemical disinfection: A microbiological and confocal microscopic analysis

Introduction

This in-vitro study comprises Antimicrobial and Confocal Microscopic analysis of the efficacy of Triple Antibiotic and Toluidine Blue (TBO) loaded chitosan nanoparticles (chnp) activated with photodynamic therapy (PDT) against Enterococcus faecalis (Ef).

Methodology

105 single-rooted extracted teeth were decoronated, cleaned and shaped, and incubated with Ef. The roots were randomly divided into three groups: Group I-Control, Group II-Triple Antibiotic Paste (TAP), Group III: Triple antibiotic-loaded chitosan nanoparticles (tachnp), and Group IV: Tachnp and TBO loaded chnp activated with PDT. Ten specimens from all the groups were subjected to antimicrobial analysis and five specimens were observed under the confocal microscope after 24 h and 7 days. Group IV was additionally analyzed after 24 h and 7 days of laser activation.

Results

Group IV C showed the least colony-forming units followed by Group IVB, Group IIIB, Group IVA, and Group IIIA. Group II showed more colony-forming units. On intergroup comparison of mean colony count in control and experimental groups at 24 h and 7 days using one-way ANOVA F test was highly significant P < 0.001. The confocal microscopic images of IV C showed the increased intensity of fluorescent red indicating dead bacteria.

Conclusion

Within the limitations of this study, TAP loaded chitosan nanoparticles activated with PDT showed a significant reduction in colony count.

The Water-Soluble Chitosan Derivative, N-Methylene Phosphonic Chitosan, Is an Effective Fungicide against the Phytopathogen Fusarium eumartii

Chitosan has been considered an environmental-friendly polymer. However, its use in agriculture has not been extended yet due to its relatively low solubility in water. N-Methylene phosphonic chitosan (NMPC) is a water-soluble derivative prepared by adding a phosphonic group to chitosan. This study demonstrates that NMPC has a fungicidal effect on the phytopathogenic fungus Fusarium solani f. sp. eumartii (F. eumartii) judged by the inhibition of F. eumartti mycelial growth and spore germination. NMPC affected fungal membrane permeability, reactive oxygen species production, and cell death. Also, this chitosan-derivative exerted antifungal effects against two other phytopathogens, Botrytis cinerea, and Phytophthora infestans. NMPC did not affect tomato cell viability at the same doses applied to these phytopathogens to exert fungicide action. In addition to water solubility, the selective biological cytotoxicity of NMPC adds value in its application as an antimicrobial agent in agriculture.

Complementary experimental/docking approach for determining chitosan and carboxymethylchitosan ability for the formation of active polymer-β-galactosidase adducts

The spontaneous aggregation of chitosan and carboxymethylchitosan polymers can be advantageous for the enzyme confinement on these colloidal systems during immobilization processes. The initial crucial step involves the polymer-enzyme adduct formation. The objective here is to determine the interactions that drive the adduct formation between these polymers and β-galactosidase from Bacillus circulans. The chemical characterization of chitosan and its carboxymethyl-derivate allowed to explain their colloidal behavior and design the four-unit fragments ligands used for the docking study. The deacetylation degree (0.6 times lower), isoelectric point (5.2 instead 6.4) and substitution degree (DS_O = 1.779 and DS_2N = 0.441) of carboxymenthylchitosan are due to the hydroxide concentration (>25%) and 30 °C modification conditions. Favorable Van der Waals and H-bond interactions between chitosan-β-galactosidase and contribution of electrostatic attraction mediated by calcium ions for carboxymethylchitosan-β-galactosidase explained the zeta potential and dynamic light scattering results at pH 7.0. These interactions occur onto the external surface of this galactosidase, without affecting the catalytic activity. A cross-linked enzyme aggregates-type model was proposed for the formation of the adducts, based on the complementary experimental-docking results. They contribute understanding the behavior of polyelectrolyte chitosan-derived matrices for enzyme immobilization.

Differential anti-inflammatory properties of chitosan-based cryogel scaffolds depending on chitosan/gelatin ratio

Chitosan/gelatine-based materials have been widely used as biocompatible scaffolds in the tissue engineering field. Chitosan suppresses the inflammatory activities of macrophages whereas gelatine induces inflammatory cytokine production by these cells. Cryogel form of the scaffolds created an effect that was mostly dominated by chitosan activity. Since independent of chitosan to gelatine ratio, the cryogels eliminated the inflammatory cytokine production by the activated macrophages. This will enable suppression of inflammatory reactions by macrophages during implant procedure while enabling a nest of the matrix for the macrophages to reside. Determining the immunomodulatory effect of these materials during the decay is crucial to assess their biocompatibility and safety. Our results suggest that when the chitosan ratio was higher than that of gelatine the materials had anti-inflammatory activity in their powder forms based on TNFα production levels by LPS activated macrophages, whereas higher gelatine to chitosan ratio eliminated this effect. To our knowledge, this is the first study to assess the powder vs. gel forms of the chitosan/gelatine-based materials for their immunomodulatory potentials as well as how the ratio of chitosan to gelatine might affect these materials immunomodulatory effects on the activated macrophages.HIGHLIGHTSChitosan/gelatin composite cryogels have anti-inflammatory activities.Different ratios of chitosan to gelatin content altered the immunomodulatory activities.They can be safely and effectively used as implant materials for tissue engineering applications.They will also reduce the use of anti-inflammatory drugs during implantation.

Recent Applications of Dual-Stimuli Responsive Chitosan Hydrogel Nanocomposites as Drug Delivery Tools

Polysaccharides are a versatile class of macromolecules that are involved in many biological interactions critical to life. They can be further modified for added functionality. Once derivatized, these polymers can exhibit new chemical properties that can be further optimized for applications in drug delivery, wound healing, sensor development and others. Chitosan, derived from the N-deacetylation of chitin, is one example of a polysaccharide that has been functionalized and used as a major component of polysaccharide biomaterials. In this brief review, we focus on one aspect of chitosan's utility, namely we discuss recent advances in dual-responsive chitosan hydrogel nanomaterials.

Formation of Amphiphilic Molecules from the Most Common Marine Polysaccharides, toward a Sustainable Alternative?

Marine polysaccharides are part of the huge seaweeds resources and present many applications for several industries. In order to widen their potential as additives or bioactive compounds, some structural modifications have been studied. Among them, simple hydrophobization reactions have been developed in order to yield to grafted polysaccharides bearing acyl-, aryl-, alkyl-, and alkenyl-groups or fatty acid chains. The resulting polymers are able to present modified physicochemical and/or biological properties of interest in the current pharmaceutical, cosmetics, or food fields. This review covers the chemical structures of the main marine polysaccharides, and then focuses on their structural modifications, and especially on hydrophobization reactions mainly esterification, acylation, alkylation, amidation, or even cross-linking reaction on native hydroxyl-, amine, or carboxylic acid functions. Finally, the question of the necessary requirement for more sustainable processes around these structural modulations of marine polysaccharides is addressed, considering the development of greener technologies applied to traditional polysaccharides.

One pot synthesis of new cross-linked chitosan-Schiff' base: Characterization, and anti-proliferative activities

Four novel chitosan hydrogels were successfully synthesized through the cross-linking reaction of chitosan with different concentrations of ethyl 5-(3,5-dihydroxy-1,4-dioxan-2-yl)-2-methylfuran-3-carboxylate. Their structures were confirmed by Fourier transform infrared spectroscopy (FT-IR), ¹³C Cross polarization magic angle spinning nuclear magnetic resonance spectroscopy (CP/MAS ¹³C NMR), ultraviolet-visible spectroscopy, thermogravimetric analysis (TGA, DTA), and X-ray diffraction (XRD). Cytotoxicity on hepatocellular carcinoma (HepG-2) cell line and a normal African green monkey kidney (Vero) cell line were studied using the MTT assay. The resultant hydrogels showed a good inhibitory effect comparing to the un-modified parent; the hydrogels with the lowest degree cross-linking (0.125 and 0.25 mol cross-linker per one chitosan residue) showed potent anticancer activity in the HepG2 cells with IC₅₀ of 57.9 and 80.9 μg/ml, respectively. These results show that the newly synthesized cross-linked chitosan derivatives demonstrated more selectivity to the HepG2 than the Vero cells, indicating its potential for Investigation in the cure of hepatocellular carcinoma.

Advances in chitooligosaccharides chemical modifications

Chitooligosaccharides (COS) differ from chitosan by their molar mass: those of COS are defined to be lower than 20 kg mol^-1 . Their functionalization is widely described in the literature and leads to the introduction of new properties that broaden their application fields. Like chitosan, COS modification sites are mainly primary amine and hydroxyl groups. Among their chemical modification, one can find amidation or esterification, epoxy-amine/hydroxyl coupling, Schiff base formation, and Michael addition. When depolymerized through nitrous deamination, COS bear an aldehyde at the chain end that can open the way to other chemical reactions and lead to the synthesis of new interesting amphiphilic structures. This article details the recent developments in COS functionalization, primarily focusing on amine and hydroxyl groups and aldehyde-chain end reactions, as well as paying considerable attention to other types of modification. We also describe and compare the different functionalization protocols found in the literature while highlighting potential mistakes made in the chemical structures accompanied with suggestions. Such chemical modification can lead to new materials that are generally nontoxic, biobased, biodegradable, and usable in various applications.

Degradation Behavior, Biocompatibility, Electrochemical Performance, and Circularity Potential of Transient Batteries

Transient technology seeks the development of materials, devices, or systems that undergo controlled degradation processes after a stable operation period, leaving behind harmless residues. To enable externally powered fully transient devices operating for longer periods compared to passive devices, transient batteries are needed. Albeit transient batteries are initially intended for biomedical applications, they represent an effective solution to circumvent the current contaminant leakage into the environment. Transient technology enables a more efficient recycling as it enhances material retrieval rates, limiting both human and environmental exposures to the hazardous pollutants present in conventional batteries. Little efforts are focused to catalog and understand the degradation characteristics of transient batteries. As the energy field is a property-driven science, not only electrochemical performance but also their degradation behavior plays a pivotal role in defining the specific end-use applications. The state-of-the-art transient batteries are critically reviewed with special emphasis on the degradation mechanisms, transiency time, and biocompatibility of the released degradation products. The potential of transient batteries to change the current paradigm that considers batteries as harmful waste is highlighted. Overall, transient batteries are ready for takeoff and hold a promising future to be a frontrunner in the uptake of circular economy concepts.

Physico-Chemical Properties of a Hybrid Biomaterial (PVA/Chitosan) Reinforced with Conductive Fillers

In this study, a novel hybrid material based on Polyvinyl Alcohol-Chitosan (PVA-Chi) was made, reinforced with conductive fillers such as the polypyrrole (PPy), Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT: PSS), carbon black (CB), and multi-wall carbon nanotube (MWCNT). In order to observe the mechanical and electrical responses of this composite material, for obtaining composite materials, and to characterize them for the development of applications in engineering, FTIR analysis made clear the different functional groups present in the matrix and the fillers used. Using quaternary mixtures (4 fillers) increased the contact angle, which increased hydrophobicity of the biocomposite. The Nyquist diagram of the analyzed samples showed a decrease in resistance and energy diffusion; the latter because of transferring electrons caused by the conductive polymers CB and the MWCNT. In the mechanical tension tests, Young’s modulus values of 18.386 MPa were obtained, in contrast with the material matrix of PVA-Chi, which showed values of 11.628 MPa. Morphological analysis by SEM showed the materials got were homogeneous. The materials got showed higher electrical conductivity in the OH’s presence and NH2 groups, which could have possible applications in biopolymer electrodes.

Chitosan and Derivatives: Bioactivities and Application in Foods

Chitosan is a biodegradable, biocompatible, and nontoxic aminopolysaccharide. This review summarizes and discusses the structural modifications, including substitution, grafting copolymerization, cross-linking, and hydrolysis, utilized to improve the physicochemical properties and enhance the bioactivity and functionality of chitosan and related materials. This manuscript also reviews the current progress and potential of chitosan and its derivatives in body-weight management and antihyperlipidemic, antihyperglycemic, antihypertensive, antimicrobial antioxidant, anti-inflammatory, and immunostimulatory activities as well as their ability to interact with gut microbiota. In addition, the potential of chitosan and its derivatives as functional ingredients in food systems, such as film and coating materials, and delivery systems is discussed. This manuscript aims to provide up-to-date information to stimulate future discussion and research to promote the value-added utilization of chitosan in improving the safety, quality, nutritional value and health benefits, and sustainability of our food system while reducing the environmental hazards.

A Review on the Synthesis, Characterization, and Modeling of Polymer Grafting

A critical review on the synthesis, characterization, and modeling of polymer grafting is presented. Although the motivation stemmed from grafting synthetic polymers onto lignocellulosic biopolymers, a comprehensive overview is also provided on the chemical grafting, characterization, and processing of grafted materials of different types, including synthetic backbones. Although polymer grafting has been studied for many decades—and so has the modeling of polymer branching and crosslinking for that matter, thereby reaching a good level of understanding in order to describe existing branching/crosslinking systems—polymer grafting has remained behind in modeling efforts. Areas of opportunity for further study are suggested within this review.