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Uncontrolled non-compressible hemorrhage, which is often accompanied by coagulopathy, is a major cause of mortality following traumatic injuries in civilian and military populations. In this study, coagulopathy-independent injectable catechol-modified chitosan (CS-HCA) hemostatic materials featuring rapid shape recovery were fabricated by combining controlled sodium tripolyphosphate-crosslinking with hydrocaffeic acid (HCA) grafting. CS-HCA exhibited robust mechanical strength and rapid blood-triggered shape recovery. Furthermore, CS-HCA demonstrated superior blood-clotting ability, enhanced blood cell adhesion and activation, and greater protein adsorption than commercial hemostatic gauze and Celox. CS-HCA showed enhanced procoagulant and hemostatic capacities in a lethal liver-perforation wound model in rabbits, particularly in heparinized rabbits. CS-HCA is suitable for mass manufacturing and shows promise as a clinically translatable hemostat. [Display omitted] [ABSTRACT FROM AUTHOR]

Chitosan chemical functionalization is a powerful tool to provide novel materials for additive manufacturing strategies. The main aim of this study was the employment of computer-aided wet spinning (CAWS) for the first time to design and fabricate carboxymethyl chitosan (CMCS) scaffolds. For this purpose, the synthesis of a chitosan derivative with a high degree of O-substitution (1.07) and water soluble in a large pH range allowed the fabrication of scaffolds with a 3D interconnected porous structure. In particular, the developed scaffolds were composed of CMCS fibers with a small diameter (< 60 μm) and a hollow structure due to a fast non solvent-induced coagulation. Zn2+ ionotropic crosslinking endowed the CMCS scaffolds with stability in aqueous solutions, pH-sensitive water uptake capability, and antimicrobial activity against Escherichia coli and Staphylococcus aureus. In addition, post-printing functionalization through collagen grafting resulted in a decreased stiffness (1.6 ± 0.3 kPa) and a higher elongation at break (101 ± 9 %) of CMCS scaffolds, as well as in their improved ability to support in vitro fibroblast viability and wound healing process. The obtained results encourage therefore further investigation of the developed scaffolds as antimicrobial wound dressing hydrogels for skin regeneration. [Display omitted] [ABSTRACT FROM AUTHOR]

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. [Display omitted] [ABSTRACT FROM AUTHOR]

Aiming at dealing with organic and inorganic pollutants dissolved in aquatic environments, we introduce self-assembled fluorescent nanocomposite hydrogel based on a binary polysaccharide network (xanthan gum/chitosan) embedding nitrogen-doped carbon quantum dots not only as a hybrid solid optical sensor for detecting Cr(VI) ions but also to remove anionically charged contaminants Cr(VI) and methyl orange (MO) by acting as an adsorbent. This fluorescent nanocomposite achieved a detection limit of 0.29 μM when used to detect Cr(VI) and demonstrated a fluorescence quantum yield of 59.7 %. Several factors contributed to the effectiveness of the adsorption of Cr(VI) and MO in batch studies, including the solution pH, dosage of the adsorbent, temperature, initial contamination level, and contact time. Experimental results showed 456 mg/g maximum adsorption capacity at pH 4 for MO compared to 291 mg/g at pH 2 for Cr(VI) at 25 °C. In addition to conforming to Langmuir's model, Cr(VI) and MO's adsorption kinetics closely matched pseudo-second-order. Using thermodynamic parameters, the results indicate that Cr(VI) and MO adsorb spontaneously and exothermically. Recycling spent adsorbent for Cr(VI) and MO using NaOH at 0.1 M was possible; the respective adsorption efficiency remained at approximately 82.2 % and 83 % after the fifth regeneration cycle. [Display omitted] [ABSTRACT FROM AUTHOR]

Burns are the fourth most common type of civilian trauma worldwide, and the management of severe irregular scald wounds remains a significant challenge. Herein, crocin-1 laden hydroxybutyl chitosan (CRO-HBC) thermosensitive hydrogel with smart anti-inflammatory performance was developed for accelerating full-thickness burn healing. The injectable and shape adaptability of the CRO-HBC gel make it a promising candidate for effectively filling scald wounds with irregular shapes, while simultaneously providing protection against external pathogens. The CRO-HBC gel network formed by hydrophobic interactions exhibited an initial burst release of crocin-1, followed by a gradual and sustained release over time. The excessive release of ROS and pro-inflammatory cytokines should be effectively regulated in the early stage of wound healing. The controlled release of crocin-1 from the CRO-HBC gel adequately addresses this requirement for wound healing. The CRO-HBC hydrogel also exhibited an excellent biocompatibility, an appropriate biodegradability, keratinocyte migration facilitation properties, and a reactive oxygen species scavenging capability. The composite CRO-HBC hydrogel intelligently mitigated inflammatory responses, promoted angiogenesis, and exhibited a commendable efficacy for tissue regeneration in a full-thickness scalding model. Overall, this innovative temperature-sensitive CRO-HBC injectable hydrogel dressing with smart anti-inflammatory performance has enormous potential for managing severe scald wounds. [Display omitted] [ABSTRACT FROM AUTHOR]

Uncontrolled hemorrhage stands as the primary cause of potentially preventable deaths following traumatic injuries in both civilian and military populations. Addressing this critical medical need requires the development of a hemostatic material with rapid hemostatic performance and biosafety. This work describes the engineering of a chitosan-based cryogel construct using thermo-assisted cross-linking with α-ketoglutaric acid after freeze-drying. The resulting cryogel exhibited a highly interconnected macro-porous structure with low thermal conductivity, exceptional mechanical properties, and great fluid absorption capacity. Notably, assessments using rabbit whole blood in vitro, as well as rat liver volume defect and femoral artery injury models simulating severe bleeding, showed the remarkable hemostatic performance of the chitosan cryogel. Among the cryogel variants with different chitosan molecular weights, the 150 kDa one demonstrated superior hemostatic efficacy, reducing blood loss and hemostasis time by approximately 73 % and 63 % in the hepatic model, and by around 60 % and 68 %, in the femoral artery model. Additionally, comprehensive in vitro and in vivo evaluations underscored the good biocompatibility of the chitosan cryogel. Taken together, these results strongly indicate that the designed chitosan cryogel configuration holds significant potential as a safe and rapid hemostatic material for managing severe hemorrhage. [Display omitted] [ABSTRACT FROM AUTHOR]

Dihydrazide (ADH) and dioxyamine (PDHA) were assessed for their efficacy in coupling chitosan and dextran via their reducing ends. Initially, the end-functionalization of the individual polysaccharide blocks was investigated. Under non-reducing conditions, chitosan with a 2,5-anhydro- D -mannose unit at its reducing end exhibited high reactivity with both PDHA and ADH. Dextran, with a normal reducing end, showed superior reactivity with PDHA compared to ADH, although complete conversion with ADH could be achieved under reductive conditions with NaBH 3 CN. Importantly, the oxime bond in PDHA conjugates exhibited greater stability against hydrolysis compared to the hydrazone bond in ADH conjugates. The optimal block coupling method consisted in reacting chitosan with an excess of dextran pre-functionalized with PDHA. The copolysaccharides could be synthesized in high yields under both reducing and non-reducing conditions. This methodology was applied to relatively long polysaccharide blocks with molecular weight up to 14,000 g/mol for chitosan and up to 40,000 g/mol for dextran. Surprisingly, block copolysaccharides did not self-assemble at neutral or basic pH; rather, they precipitated due to hydrogen bonding between neutralized amino groups of chitosan. However, nanoparticles could be obtained through a nanoprecipitation approach. [Display omitted] [ABSTRACT FROM AUTHOR]

Probiotics and polyphenols have multiple bioactivities, and developing co-encapsulated microcapsules (CM) is a novel strategy to enhance their nutritional diversity. However, the development of CMs is challenged by complicated processing, single types, and unclear in vivo effects and applications. In this study, the co -microencapsulations of polyphenol and probiotic were constructed using pectin, alginate (WGCA@LK), and Fu brick tea polysaccharides (WGCF@LK), respectively, with chitosan-whey isolate proteins by layer-by-layer coacervation reaction, and their protective effects, in vivo effectiveness, and application potential were evaluated. WGCA@LK improved the encapsulation rate of polyphenols (42.41 %), and remained high viability of probiotics after passing through gastric acidic environment (8.79 ± 0.04 log CFU/g) and storage for 4 weeks (4.59 ± 0.06 log CFU/g). WGCF@LK exhibited the highest total antioxidant activity (19.40 ± 0.25 μmol/mL) and its prebiotic activity removed the restriction on probiotic growth. WGCA@LK showed strong in vitro colonic adhesion, but WGCF@LK promoted in vivo retention of probiotics at 48 h. WGCF@LK showed excellent anti-inflammatory effects and alleviated symptoms of acute colitis in mice. These findings provide unique insights into the fortification of probiotic-polyphenol CMs by different polysaccharides and the development of novel health foods with rich functional hierarchies and superior therapeutic effects. [Display omitted] • Develop three polysaccharide-enhanced probiotic polyphenol co-delivery microcapsules. • WGCA@LK and WGCF@LK CMs improved probiotic in vitro viability and in vivo retention. • Combination of FBTP and probiotic in WGCF@LK showed enhanced alleviation in mice colitis. • WGCA@LK CM addition fortified the quality and viable bacteria counts of Kefir yogurt. [ABSTRACT FROM AUTHOR]

Bleeding and bacterial infection are common problems associated with wound treatment, while effective blood clotting and vessel regeneration promotion are the primary considerations to design the wound dressing materials. This research presents a chitosan-based hydrogel with grafted quaternary ammonium and polyphosphate (QCSP hydrogel) as the antibacterial hemostatic dressing to achieve burn wound treatment. The tissue adhesion of the hydrogel sealed the blood flow and the polyphosphate grafted to the chitosan promoted the activation of coagulation factor V to enhance the hemostasis. At the same time, the grafted quaternary ammonium enhanced the antibacterial ability of the biodegradable hydrogel wound dressing. In addition, the polydopamine as a photothermal agent was composited into the hydrogel to enhance the antibacterial and reactive oxygen scavenging performance. The in vivo hemostasis experiment proved the polyphosphate enhanced the coagulation property. Moreover, this photothermal property of the composite hydrogel enhanced the burn wound repairing rate combined with the NIR stimulus. As a result, this hydrogel could have potential application in clinic as dressing material for hemostasis and infection prone would repairing. [Display omitted] [ABSTRACT FROM AUTHOR]

The paper reports new multifunctional plant biostimulant formulations obtained via in situ hydrogelation of chitosan with salicylaldehyde in the presence of a mimetic naphthalimide-based strigolactone, in specific conditions. Various analytical techniques (FTIR, 1H NMR, SEM, POM, TGA, WRXD) were employed to understand the particularities of the hydrogelation mechanism and its consequences on the formulations' properties. Further, in order to evaluate their potential for the targeted application, the swelling in media of pH characteristic for different soils, water holding capacity, soil biodegradability, in vitro release of the strigolactone mimic and impact on tomatoes plant growth in laboratory conditions were investigated and discussed. It was found that the strigolactone mimic has the ability to bond to the chitosan matrix via physical forces, favoring a prolonged release. Moreover, the combination of chitosan with the strigolactone mimic in an optimal mass ratio triggered a synergistic effect on the plant growth, up to 4 times higher compared to the neat control soil. [Display omitted] [ABSTRACT FROM AUTHOR]

Rapid regeneration of the injured tissue or organs is necessary to achieve the usual functionalities of the damaged parts. However, bacterial infections delay the regeneration process, a severe challenge in the personalized healthcare sector. To overcome these challenges, 3D-printable multifunctional hydrogels of Zn/tannic acid-reinforced glycol functionalized chitosan for rapid wound healing were developed. Polyphenol strengthened intermolecular connections, while glutaraldehyde stabilized 3D-printed structures. The hydrogel exhibited enhanced viscoelasticity (G′; 1.96 × 104 Pa) and adhesiveness (210 kPa). The dual-crosslinked scaffolds showed remarkable antibacterial activity against Bacillus subtilis (∼81 %) and Escherichia coli (92.75 %). The hydrogels showed no adverse effects on human dermal fibroblasts (HDFs) and macrophages (RAW 264.7), indicating their superior biocompatibility. The Zn/TA-reinforced hydrogels accelerate M2 polarization of macrophages through the activation of anti-inflammatory transcription factors (Arg-1 , VEGF , CD163 , and IL-10), suggesting better immunomodulatory effects, which is favorable for rapid wound regeneration. Higher collagen deposition and rapid re-epithelialization occurred in scaffold-treated rat groups vis-à-vis controls, demonstrating superior wound healing. Taken together, the developed multifunctional hydrogels have great potential for rapidly regenerating bacteria-infected wounds in the personalized healthcare sector. [Display omitted] • Zn@TA-assisted multifunctional glycol-functionalized chitosan hydrogels were fabricated. • The hydrogels demonstrated superior printability and adhesiveness (210 kPa). • Remarkable antibacterial and antibiofilm activity against B. subtilis and E. coli. • Hydrogels accelerated M2 polarization and expression of wound healing gene markers. • Higher collagen deposition and rapid re-epithelialization in 3D printed scaffold-treated rat groups. [ABSTRACT FROM AUTHOR]

Chitosan is a promising natural polymer for coatings, it combines intrinsic antibacterial and pro-osteoblastic properties, but the literature still has a gap from the development to behavior of these coatings, so this systematic review aimed to answer, "What is the relationship between the physical and chemical properties of polymeric chitosan coatings on titanium implants on antibacterial activity and osteoblast viability?". PRISMA guidelines was followed, the search was applied into 4 databases and grey literature, without the restriction of time and language. The selection process occurred in 2 blinded steps by the authors. The criteria of eligibility were in vitro studies that evaluated the physical, chemical, microbiological, and biological properties of chitosan coatings on titanium surfaces. The risk of bias was analyzed by the specific tool. Of 734 potential articles 10 were included; all had low risk of bias. The coating was assessed according to the technique of fabrication, FT-IR, thickness, adhesion, roughness, wettability, antibacterial activity, and osteoblast viability. The analyzed coatings showed efficacy on antibacterial activity and cytocompatibility dependent on the class of material incorporated. Thus, this review motivates the development of time-dependent studies to optimize manufacturing and allow for an increase in patents and availability on the market. [Display omitted] [ABSTRACT FROM AUTHOR]

The development of thrombolytic drug carriers capable of thrombus-targeting, prolonged circulation time, intelligent responsive release, and the ability to inhibit thrombotic recurrences remains a promising but significant challenge. To tackle this, an artificial polysaccharide microvesicle drug delivery system (uPA-CS/HS@RGD-ODE) was constructed. It is composed of cationic chitosan and anionic heparin assembled in a layer by layer structure, followed by surface modification using RGD peptide and 2-(N-oxide-N,N-diethylamino) ethylmethacrylate (ODE) before encapsulation of urokinase-type plasminogen activator (uPA). The effect of chitosan on the basic performances of uPA-CS/HS@RGD-ODE was estimated. The in vitro results suggest the uPA carrier, CS/HS@RGD-ODE, displayed outstanding targeting specific to activated platelets (61 %) and microenvironment-responsiveness at pH 6.5, facilitating thrombus-targeting and a controlled drug release, respectively. Most importantly, in vivo experiment suggests ODE from uPA-CS/HS@RGD-ODE substantially extends the half-life of uPA (120 min), as uPA-CS/HS@RGD-ODE can adhere onto erythrocytes and deliver uPA under cover of erythrocytes enabling a prolonged circulation time in the bloodstream. Further tail vein and abdominal aorta thrombosis models confirmed uPA-CS/HS@RGD-ODE exhibited superior targeting and thrombolysis capabilities compared to systemic administration of free uPA. To the knowledge of authors, this may be the first study to develop new drug carriers for delivery of thrombolytic drugs under the cover of erythrocytes for extended drug half-lives. [Display omitted] [ABSTRACT FROM AUTHOR]

Ophthalmic diseases can be presented as acute diseases like allergies, ocular infections, etc. , or chronic ones that can be manifested as a result of systemic disorders, like diabetes mellitus, thyroid, rheumatic disorders, and others. Chitosan (CS) and its derivatives have been widely investigated as nanocarriers in the delivery of drugs, genes, and many biological products. The biocompatibility and biodegradability of CS made it a good candidate for ocular delivery of many ingredients, including immunomodulating agents, antibiotics, ocular hypertension medications, etc. CS-based nanosystems have been successfully reported to modulate ocular diseases by penetrating biological ocular barriers and targeting and controlling drug release. This review provides guidance to drug delivery formulators on the most recently published strategies that can enhance drug permeation to the ocular tissues in CS-based nanosystems, thus improving therapeutic effects through enhancing drug bioavailability. This review will highlight the main ocular barriers to drug delivery observed in the nano-delivery system. In addition, the CS physicochemical properties that contribute to formulation aspects are discussed. It also categorized the permeation enhancement strategies that can be optimized in CS-based nanosystems into four aspects: CS-related physicochemical properties, formulation components, fabrication conditions, and adopting a novel delivery system like implants, inserts, etc. as described in the published literature within the last ten years. Finally, challenges encountered in CS-based nanosystems and future perspectives are mentioned. [ABSTRACT FROM AUTHOR]

Thin (ca. 340 nm) chitosan coatings were deposited onto glass substrates via dip-coating, then modified with the methanol solution of decanoic anhydride (0.17–56 mM). NMR, FTIR and XPS measurements confirmed that the acylation degree increased from 18 % to 45 %, and at the highest degree, the whole layer was acylated homogeneously by the reagent molecules. The coating thickness increased (up to 60 %), and the refractive index decreased (from 1.541 to 1.532) due to the acylation, that was determined by UV–visible spectroscopy. The AFM did not reveal morphological changes, but wetting tests showed that the acylation rendered the coating hydrophobic (water contact angle increased from ca. 75° to 100°). The contact angle, however, decreased to 85° due to the development of a second molecular layer of the decanoic acid by-product at the highest (over 25 mM) reagent concentrations. XRD studies showed a self-assembling structuring of the alkyl-chains in the bulk phase, which occurred in the case of the highest degree of acylation. This also manifested itself in a significant decrease of the layer hygroscopicity: the swelling degree decreased from 40 % to 8 % in a saturated water atmosphere monitored by spectroscopic ellipsometry. [Display omitted] [ABSTRACT FROM AUTHOR]

Emulsions have extensive applications in food, cosmetics, and agriculture, while the requirements for emulsions differ in various fields. It is a challenge for one emulsion to satisfy multiple requirements in different applications. Herein, CO 2 -switchable emulsions with controllable stability and viscosity were prepared by a mixture of chitosans (CS) and CTAB. After adding low concentrations of CTAB (e.g. 0.5 mM), the viscous Pickering emulsions stabilized by CS alone were converted into moderate-viscous Pickering emulsions due to the competition adsorption between CS aggregates and CTAB at the oil-water interface. The transformation of emulsion types (such as Pickering and conventional emulsions) and the emulsion's stability and viscosity were controlled by CO 2 /N 2 trigger. Furthermore, at high CTAB concentrations (≥ 0.8 mM), a novel long-term stable conventional emulsion was obtained after the CS aggregates at the oil-water interface were entirely replaced by CTAB. Compared with other stimuli, CO 2 is recognized as a green trigger that doesn't cause contaminations in the system, which has potential applications in organic synthesis and polymerization. Our strategy provides a simple and effective method to smartly control the properties of the emulsions (such as the emulsion type, stability, and viscosity), obtaining an intelligent emulsion to meet different requirements in many applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Nature-inspired chitosan (CS) materials show a high potential for the design/fabrication of sustainable heterogeneous (nano)materials with extraordinary structural/physical features, such as superior biodegradability/biocompatibility, simplicity of chemical modification, environmental safety, high availability, cost-effectiveness, high electrochemical activity, good film-forming ability, and antioxidant, antimicrobial/antibacterial, and anticoagulant activities. Industrialization and growth of industrial wastes or by-products induce an increasing demand for the development of clean, low-cost, and renewable natural systems to minimize or eliminate the utilization of environmentally toxic compounds. The preparation of novel heterogeneous functionalized polysaccharide-inspired bio(nano)materials via chemical modifications of natural CS to improve its physicochemical/biochemical properties has recently become tremendously attractive for many researchers. The most abundantly available and cost-effective functionalized CS-inspired (nano)materials are considerably valuable in terms of the economic aspects of production of (nano)catalysts, (nano)hydrogels, (nano)composite/blend membranes, and thus their commercialization. In this respect, the preparation of functionalized CS-inspired (nano)materials containing -SO 3 H groups has been represented as a valid alternative to the homogenous unmodified biomaterials for various applications. Sulfonated derivatives of CS-inspired (nano)materials may possess huge surface areas, catalytic activity, adsorption, and biological/biomedical properties. This review article is aimed at the investigation of different methods and potential applications of sulfonated CS-inspired (nano)materials in catalysis, fuel cells, adsorption of ions, membranes, and biological applications. [Display omitted] [ABSTRACT FROM AUTHOR]

The application of novel insect proteins as future food resources in the food field has attracted more and more attention. In this study, a biodegradable antibacterial food packaging material with beneficial mechanical properties was developed using Tenebrio molitor larvae protein (TMP), chitosan (CS) and propolis ethanol extract (PEE) as raw materials. PEE was uniformly dispersed in the film matrix and the composite films showed excellent homogeneity and compatibility. There are strong intermolecular hydrogen bond interactions between CS, TMP, and PEE in the films, which exhibit the structure characteristics of amorphous materials. Compared with CS/TMP film, the addition of 3 % PEE significantly enhanced the elongation at break (34.23 %), water vapor barrier property (22.94 %), thermal stability (45.84 %), surface hydrophobicity (20.25 %), and biodegradability of the composite film. The composite film has strong antioxidant and antimicrobial properties, which were enhanced with the increase of PEE content. These biodegradable films offer an eco-friendly end-of-life option when buried in soil. Composite films can effectively delay the spoilage of strawberries and extend the shelf life of strawberries. Biodegradable active packaging film developed with insect protein and chitosan can be used as a substitute for petroleum-based packaging materials, and has broad application prospects in the field of fruits preservation. [Display omitted] • CS/TMP-based multifunctional active food packaging films were prepared for fruit preservation; • PEE can improve the mechanical properties and barrier properties of composite films; • The composite films exhibited good antioxidant activity and antibacterial activity; • The functional composite films can significantly delay the spoilage of strawberries. [ABSTRACT FROM AUTHOR]

Chitin and its deacetylated form, chitosan, have demonstrated remarkable versatility in the realm of biomaterials. Their exceptional biocompatibility, antibacterial properties, pro- and anticoagulant characteristics, robust antioxidant capacity, and anti-inflammatory potential make them highly sought-after in various applications. This review delves into the mechanisms underlying chitin/chitosan's biological activity and provides a comprehensive overview of their derivatives in fields such as tissue engineering, hemostasis, wound healing, drug delivery, and hemoperfusion. However, despite the wealth of studies on chitin/chitosan, there exists a notable trend of homogeneity in research, which could hinder the comprehensive development of these biomaterials. This review, taking a clinician's perspective, identifies current research gaps and medical challenges yet to be addressed, aiming to pave the way for a more sustainable future in chitin/chitosan research and application. [ABSTRACT FROM AUTHOR]

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. [Display omitted] [ABSTRACT FROM AUTHOR]

Nanotechnology has revolutionized the diagnosis, monitoring and treatment of biomedical diseases, in which nanocarriers have greatly improved the targeting and bioavailability of antitumor drugs. The marine natural polysaccharides fucoidan, chitosan, alginate, carrageenan and porphyran have broad-spectrum bioactivities and unique physicochemical properties such as excellent non-toxicity, biocompatibility, biodegradability and reproducibility, which have placed them as a principal focus in the nanocarrier field. Nanocarriers based on different types of marine polysaccharides are distinctive in addressing antitumor therapeutic challenges such as targeting, environmental responsiveness, drug resistance, tissue toxicity, enhancing diagnostic imaging, overcoming the first-pass effect and innovative 3D binding. Additionally, they all share the possibility of relatively easy chemical modification, while their separation into well-defined derivatives provide innovative structure-activity relationship possibilities. Liposomes, nanoparticles and polymer-micelles constructed from them can efficiently deliver drugs such as paclitaxel, gemcitabine, siRNA and others, which are widely used in radiotherapy, chemotherapy, immunotherapy, nucleic acid therapy and photothermal therapy, yet there are still infinite possibilities for innovation and exploration. This article reviews the recent advances and challenges of marine polysaccharide-based delivery systems as oncology drug nanocarriers. [Display omitted] [ABSTRACT FROM AUTHOR]

The development of tissue adhesives with good biocompatibility and potent antimicrobial properties is crucial for addressing the high incidence of surgical site infections in emergency and clinical settings. Herein, an injectable hydrogel adhesive composed of chitosan biguanidine (CSG), oxidized dextran (ODex) and tannin (TA) was synthesized primarily through Schiff-base reactions, hydrogen bonding, and electrostatic interactions. TA was introduced into the CSG/ODex hydrogel to prepare a physicochemically double cross-linked hydrogel. The hydrogel formulation incorporating 2 wt% TA (CSG/ODex-TA2) exhibited rapid gelation, moderate mechanical properties, good tissue adhesion, and sustained release behavior of TA. Both in vitro and in vivo studies demonstrated that CSG/ODex-TA2 showed significantly enhanced adhesion and antibacterial effectiveness compared to the CSG/ODex hydrogel and commercial fibrin glue. Leveraging the positive charge of CSG, the CSG/ODex-TA2 hydrogel demonstrated a strong contact antibacterial effect, while the sustained release of TA provided diffusion antibacterial capabilities. By integrating contact and diffusion antibacterial mechanisms into the hydrogel, a promising approach was developed to boost antibacterial efficiency and accelerate the healing of wounds infected with methicillin-resistant Staphylococcus aureus (MRSA). The CSG/ODex-TA2 hydrogel has excellent biocompatibility, hemostatic properties, and antibacterial capabilities, making it a promising candidate for improving in vivo wound care and combating bacterial infections. [Display omitted] [ABSTRACT FROM AUTHOR]

Diabetes-related slow healing of wounds is primarily driven by bacterial infections and angiogenesis disorder and presents a substantial hurdle in clinical treatment. To solve the above problems, an advanced multifunctional hydrogel system based on natural polymer was created here to facilitate wound healing in patients with chronic diabetes. The prepared dressing was composed of an outer hydrogel containing polyvinyl alcohol and hydroxypropyl methyl cellulose in dimethyl sulfoxide and water as binary solvents, and an inner hydrogel containing chitosan quaternary ammonium salt, flaxseed gum, and polyvinyl alcohol. Thus, a polysaccharide based bilayer hydrogel (BH) with superior mechanical strength and biocompatibility was created. This bilayer hydrogel could easily bind to dynamic tissue surfaces, thereby generating a protective barrier. Meanwhile, L-arginine-modified polyoxometalate (POM@L-Arg) nanoclusters were loaded in the inner hydrogel. They released NO when stimulated by the peroxide microenvironment of diabetic wounds. NO as a signal molecule regulated vascular tension and promoted cell proliferation and migration. Additionally, because of the synergistic effect of NO and the chitosan quaternary ammonium salt, the hydrogel system exhibited excellent antibacterial performance. The NO released reduced the levels of proinflammatory factors IL-6 and TNF-α in the diabetic wounds, which thus accelerated wound healing. In short, BH + POM@L-Arg is expected to serve as an ideal wound dressing as it exerts a good promotion effect on diabetes-related wound healing. [Display omitted] [ABSTRACT FROM AUTHOR]

The paper reports new hydrogels based on quaternary ammonium salts of chitosan designed as biocidal products. The chitosan derivative was crosslinked with salicylaldehyde via reversible imine bonds and supramolecular self-assemble to give dynamic hydrogels which respond to environmental stimuli. The crosslinking mechanism was demonstrated by 1H NMR and FTIR spectroscopy, and X-ray diffraction and polarized light microscopy. The hydrogel nature, self-healing and thixotropy were proved by rheological investigation and visual observation, and their morphology was assessed by scanning electron microscopy. The relevant properties for application as biocidal products, such as swelling, dissolution, bioadhesiveness, antimicrobial activity and ex-vivo hemocompatibility and in vivo local toxicity and biocompatibility on experimental mice were measured and analyzed in relationship with the imination degree and the influence of each component. It was found that the hydrogels are superabsorbent, have good adhesivity to skin and various surfaces and antimicrobial activity against relevant gram-positive and gram-negative bacteria, while being hemocompatible and biocompatible. Besides, the hydrogels are easily biodegraded in soil. All these properties recommend the studied hydrogels as ecofriendly biocidal agents for living tissues and surfaces, but also open the perspectives of their use as platform for in vivo applications in tissue engineering, wound healing, or drug delivery systems. [Display omitted] [ABSTRACT FROM AUTHOR]

Red fluorescent hydrogels possessing injectable and self-healing properties have widespread potential in biomedical field. It is still a challenge to achieve a biomacromolecules based dynamic hydrogels simultaneously combining with excellent red fluorescence, good mechanical properties, and biocompatibility. Here we first explore hydrophilic inclusion complex of (R-CDs@α-CD) derived from hydrophobic red fluorescent carbon dots (R-CDs) and α-cyclodextrin (α-CD), and then achieved a red fluorescent and dynamic polysaccharide R-CDs@α-CD/CEC-l-OSA hydrogel. The nanocomposite hydrogel can be fabricated through controlled doping of red fluorescent R-CDs@α-CD into dynamic polymer networks, taking reversibly crosslinked N-carboxyethyl chitosan (CEC) and oxidized sodium alginate (OSA) as an example. The versatile red fluorescent hydrogel simultaneously combines the features of injection, biocompatibility, and augmented mechanical properties and self-healing behavior, especially in rapid self-recovery even after integration. The R-CDs@α-CD uniformly dispersed into dynamic hydrogel played the role of killing two birds with one stone, that is, endowing red emission of a hydrophilic fluorescent substance, and improving mechanical and self-healing properties as a dynamic nano-crosslinker, via forming hydrogen bonds as reversible crosslinkings. The novel red fluorescent and dynamic hydrogel based on polysaccharides is promising for using as biomaterials in biomedical field. [Display omitted] [ABSTRACT FROM AUTHOR]

The complexity in structure and function of the nervous system, as well as its slow rate of regeneration, makes it more difficult to treat it compared to other tissues. Neural tissue engineering aims to create an appropriate environment for nerve cell proliferation and differentiation. Fibrous scaffolds with suitable morphology and topography and better mimicry of the extracellular matrix have been promising for the alignment and migration of neural cells. On this premise, to improve the properties of the scaffold, we combined montmorillonite (MMT) with chitosan (CS) polymer and created microfibers with variable diameters and varied concentrations of MMT using microfluidic technology and tested its suitability for the rat pheochromocytoma cell line (PC12). According to the findings, CS/MMT 0.1 % compared to CS/MMT 0 % microfibers showed a 201 MPa increase in Young's modulus, a 68 mS/m increase in conductivity, and a 1.4-fold increase in output voltage. Analysis of cell mitochondrial activity verified the non-toxicity, resulting in good cell morphology with orientation along the microfiber. Overall, the results of this project showed that with a low concentration of MMT, the properties of microfibers can be significantly improved and a suitable scaffold can be designed for neural tissue engineering. [Display omitted] [ABSTRACT FROM AUTHOR]

Antibiotic abuse is increasing the present rate of drug-resistant bacterial wound infections, producing a significant healthcare burden globally. Herein, we prepared a pH-responsive CMCS/PVP/TA (CPT) multifunctional hydrogel dressing by embedding the natural plant extract TA as a nonantibiotic and cross-linking agent in carboxymethyl chitosan (CMCS) and polyvinylpyrrolidone (PVP) to prompt wound healing. The CPT hydrogel demonstrated excellent self-healing, self-adaptive, and adhesion properties to match different wound requirements. Importantly, this hydrogel showed pH sensitivity and exhibited good activity against resistant bacteria and antioxidant activity by releasing TA in case of bacterial infection (alkaline). Furthermore, the CPT hydrogel exhibited coagulant ability and could rapidly stop bleeding within 30 s. The biocompatible hydrogel effectively accelerated wound healing in a full-thickness skin defect model by thickening granulation tissue, increasing collagen deposition, vascular proliferation, and M2-type macrophage polarization. In conclusion, this study demonstrates that multifunctional CPT hydrogel offers a candidate material with potential applications for infected skin wound healing. [Display omitted] [ABSTRACT FROM AUTHOR]

The effect of two crosslink strategies on the preparation of chitosan-based covalent hydrogels was investigated employing the widely used thiol-ene reaction. This versatile "click" chemistry can be activated either photochemically or thermochemically. Initially, well-purified chitosan (CS, DA ∼4 %, M w ∼580 kg mol−1) was separately functionalized with vinyl (CS-ene) or thiol (CS-SH) groups in aqueous media. Subsequently, two strategies were compared where thiol-ene reaction occurs respectively between: (S1) modified chitosans CS-ene and CS-SH, in a polymer – polymer strategy, and (S2) CS-ene and di(ethylene glycol) dithiol (dEG-(SH) 2), in a polymer – molecule strategy. Both crosslinking strategies were evaluated through rheological measurements, starting with entangled chitosan solutions. The difference in diffusion of functional groups, whether attached to polymer chains or to free molecules, leads to faster gelation kinetics with S2. Consequently, stronger gels were obtained with S2, where the modulus was connected with the degree of functionalization, while S1 produced weaker gels closer to the percolation point, where crosslinked density was associated with the entanglement number derived from the initial concentration. Nevertheless, networks formed by both strategies were homogenous with minimal dissipative contributions to their rheological properties, indicating that structural defects are negligible. [Display omitted] [ABSTRACT FROM AUTHOR]

Polyelectrolyte complexes (PECs) were elaborated from chitosan as cationic polymer and carboxy-methylpullulan (CMP), hyaluronic acid (HA) and their derivatives grafted with aminoguaiacol (G) with different degrees of substitution (DS GA) with the aim of obtaining nanogels for drug delivery. For each couple of polysaccharides, the charge ratios giving the smaller size with the lower PDI were selected to produce PECs. CMP_CHIT and CMP-G_CHIT PECs had smaller sizes (220–280 nm) than HA_CHIT and HA-G_CHIT PECs (280–390 nm). PECs were stable at 4 °C during 28 days at pH 5. In phosphate buffer saline (PBS) at pH 7.4, at 4 °C, a better stability of PECs based on CMP-G derivatives was observed. The hydrophobic associations between aminoguaiacol groups (highlighted by measurements of pyrene fluorescence) led to a better PECs' stabilization in PBS. The PECs' antioxidant and antibacterial activities were demonstrated and related to the DS GA. Diclofenac and curcumin were used as drug models: their loading reached 260 and 53 μg/mg PEC, respectively. The release of diclofenac in PBS at 37 °C followed a quasi-Fickian diffusion mechanism with release constant between 0.88 and 1.04 h−1. The curcumin release followed a slow linear increase in PBS/EtOH (60/40 V /V) with an effect of DS GA. [ABSTRACT FROM AUTHOR]

Using new materials to improve detection accuracy and efficiency is important to broaden the application of immunoassay sensors. Among numerous materials for improving sensors, chitosan, as a natural polysaccharide, has excellent biocompatibility, mechanical adjustability, stimulation sensitivity and porous structure, which holds significant potential for enhancing the performance of immunoassay sensors. However, at present, there are few systematic reviews on the application of chitosan in immune sensors. In this paper, the principle of immunoassay is discussed systematically, we reviewed the recent development of chitosan enhancement strategies in various immunoassay sensors, including surface plasmon resonance immunoassay sensors, colorimetric immunoassay sensors, electrochemical immunoassay sensor, electrochemical luminescence immunoassay sensors are reviewed. Focused on the theoretical basis of improving sensor performance in immunoassay by use chitosan, as well as the various functions and applications of chitosan, and discussed how to solve the challenges of immunoassay sensors by using chitosan and the future research trend. By providing a robust foundation for the development of more efficient detection platforms, it provides insights for advancing the use of chitosan in the detection of complex biological samples. This is crucial for promoting the widespread application of immunoassay sensors with high performance in clinical diagnosis, environmental monitoring and food safety. [Display omitted] [ABSTRACT FROM AUTHOR]

The development of injectable, dual-component formulations based on natural-based polysaccharides is a promising strategy for the localized treatment of rheumatoid arthritis (RA). In the present study, biomimetic formulations consisting of aldehyde-functionalized hyaluronic acid (AHA) and O -carboxymethyl chitosan (OCC) were developed, presenting rapid in situ gelation rates and finely tunable physicochemical properties. These two properties allowed for the controlled delivery of anti-inflammatory, antioxidant, and pro-regenerative agents (i.e., strontium-methotrexate (SrMTX) and europium-tannic acid nanocomplexes (EuTA NCs), making them suitable for application in in vivo RA-models. Biological analyses demonstrated the system's cytocompatibility and its ability to modulate the activity of human articular chondrocytes at the secretome level and scavenge nitric oxide (NO). Moreover, the loaded cargoes not only extended the anti-inflammatory properties of the formulation but also the radiolabeling of EuTA NCs with 68Ga allowed the visualization of the gel by positron emission tomography (PET). Overall, this work presents the design and in vitro evaluation of an easily modulable polymeric system that allows the in situ release of a multifunctional therapy with promising perspectives for RA treatment. [ABSTRACT FROM AUTHOR]

As a natural cationic polymer material, the application of chitosan hydrogel for bone tissue engineering has been greatly limited due to its poor mechanical strength. Enzymatic mineralization has drawn increased attention to effectively improve the mechanical properties of hydrogels. In this study, carboxymethyl chitosan (CMCS) hydrogels cross-linked with different concentrations of genipin (2.5 %, 5 % and 10 %) were prepared and further mineralized through enzyme-induced biomimetic mineralization. The mechanical properties of the CMCS hydrogels were significantly increased as a result of mineralization, showing improvement of 1200–1500 % on storage moduli, and even exhibiting certain tensile behavior with the elongation rate of 30–35 %, likely due to the uniform formation and small size of mineralized products. Interestingly, the cationicity of chitosan also exerted an important modulation effect and the mineralization behavior and mechanical properties of mineralized hydrogels. In addition, the enzymatic mineralized hydrogels showed enhanced biocompatibility and osteogenic differentiation in-vitro, likely due to its superior mechanical properties and the introduction of calcium phosphate biominerals. In vivo experiments further suggest excellent bone-forming activity for the enzymatic mineralized hydrogels. Overall, tuning cationicity and enzymatic mineralization provide an effective approach for the preparation of chitosan hydrogels with superior mechanical and biological properties for bone tissue engineering application. [Display omitted] [ABSTRACT FROM AUTHOR]

The industrial use of certain insects, such as the black soldier fly (BSF, Hermetia illucens), has become a burgeoning way of converting residual biomass into a valuable source of biomolecules for the feed and food industry. Here, the integration of a valuable step as an upcycling technology using biological waste from the 5th instar BSF larvae processing as a source of bioactive chitosan was explored. The goal is to pave the way for sustainable chitosan production from insect-based resources in addition to proteins, lipids, and fertilizers. The macronutrient profile of the larval waste was evaluated for chitosan extraction. After homogenization and mechanical separation of the larval pulp, enzyme-assisted extraction of chitosan from the chitin-rich matrix was performed using different combinations of commercially available proteases and lipases, followed by chemical deacetylation. The antifungal efficacy of the recovered chitosan varied depending on the extracted product and tested fungal plant pathogens. Furthermore, the plant priming effect of chitosan on Beta vulgaris promoted plant vigor and disease resistance. Seed coating resulted in improved germination and primary root growth. Thus, the extraction of chitosan from BSF larval cuticles offers an optimistic outlook for expanding the technological competence of the insect upcycling industries. [Display omitted] [ABSTRACT FROM AUTHOR]

Chitosans are versatile biopolymers with antimicrobial and plant-strengthening properties relevant to agriculture. However, a limited understanding of molecular structure-function relationships and cellular modes of action of chitosans hampers the development of effective chitosan-based agro-biologics. We partially hydrolyzed a chitosan polymer (degree of polymerization DP 800, fraction of acetylation F A 0.2) using acetic acid, a GH18 chitinase, or a GH8 chitosanase. All hydrolysates contained mixtures of chitosan oligomers and small polymers, but their composition in terms of DP, F A , and pattern of acetylation (PA) differed greatly. Importantly, chitinase products had mostly deacetylated residues at their ends, flanking mostly deacetylated residues, and vice versa for chitosanase products, while the products of acid hydrolysis had random PA. Acid hydrolysis did not significantly change antifungal and antibacterial activities. In contrast, chitinase hydrolysis slightly increased antibacterial, and chitosanase almost abolished antifungal activity. Elicitor and priming activities in the plant Arabidopsis were unchanged by acid, destroyed by chitinase, and increased by chitosanase hydrolysis. Transcriptomic analysis revealed that the chitosan polymer strongly induced genes involved in photosynthesis, while the chitosanase hydrolysate strongly induced genes involved in disease resistance. Clearly, different bioactivities require different chitosans, and enzymatic modification can fine-tune these activities as required for different agricultural products. [Display omitted] [ABSTRACT FROM AUTHOR]

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

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

Polysaccharides-based smart fertilizers are essential for promoting plant growth, yet significant challenges exist in achieving stable structures and synchronizing nutrient release and plant growth. This study developed a temperature-responsive gating chitosan-based microcapsule (CTSMC-g-PNIPAM) by grafting N-isopropyl acrylamide (NIPAM) onto chitosan microcapsules (CTSMC) via atom transfer radical polymerization (ATRP). The interfacial crosslinking of chitosan (CTS) and terephthalendehyde (TPA) formed the CTSMC matrix with a hollow chamber structure and ensured stability. CTSMC-g-PNIPAM exhibited reversible temperature-responsive gating properties and sustained release behavior, and the PNIPAM chains acted like gating switches. Below the low critical solution temperature (LCST) (25 °C), the PNIPAM chains stretched and the gating switch closed, slowing down the release rate. Above the LCST (40 °C), the PNIPAM chains contracted and the gating switch opened, accelerating the release rate. The release behaviors of CTSMC-g-PNIPAM in soil indicated that the gating microcapsule effectively prolonged the release of urea. Moreover, the cumulative release of CTSMC-g-PNIPAM at 40 °C was significantly higher than at 25 °C. The first-order kinetic and Korsmeyer-Peppas model indicate that the urea release involves concentration gradient diffusion and skeleton dissolution. Compared with pure urea, urea@(CTSMC-g-PNIPAM) increased the growth status of maize, suggesting a promising strategy for smart fertilizers. [ABSTRACT FROM AUTHOR]

Hybrid nano- and microparticles based on metal ion crosslinked biopolymers are promising carriers for the development of drug delivery systems with improved biopharmaceutical properties. In this work, dexamethasone phosphate-containing particles based on chondroitin sulfate and chitosan or diethylaminoethyl chitosan additionally crosslinked with Zn2+ were prepared. Depending on the polycation/polyanion ratio in the system, anionic and cationic polyelectrolyte complexes (PECs) were obtained. The anionic Zn2+-containing and Zn2+-free PECs had sizes of 154 and 180 nm and ζ-potentials of −22.4 and −27.5 mV, respectively. The cationic Zn2+-containing and Zn2+-free PECs had sizes of 242 and 362 nm and ζ-potentials of 22.4 and 24.7 mV, respectively. The presence of Zn2+ in the system significantly prolonged the release of dexamethasone phosphate from the hybrid polyelectrolyte particle. The resulting release profiles of dexamethasone phosphate were in agreement with the Peppas-Sahlin kinetic model, which considers the combined effects of Fickian diffusion and polymer chain relaxation on the drug release rate. It was shown that the prolongation of drug release was mainly due to swelling and relaxation of the Zn2+ crosslinked polymers. The developed particles exhibited good mucoadhesive properties and pronounced anti-inflammatory activity, making them attractive candidates for biomedical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

The characteristics and performance of chitosan-based colon delivery systems are significantly influenced by the method of preparation. Insect chitosan-melanin complex (CMC) may offer superior attributes over traditional shrimp and crab chitosan (CS) for colon-targeted administration. This study used dung beetle CMC as the carrier matrix and comprehensively examined the impact of various crosslinking techniques on the colonic drug delivery efficacy of microspheres, encompassing drug loading, swelling, drug release behavior, adhesion, enzymatic degradation, and absorption enhancement. The results indicate that F-TPPLC microspheres, crosslinked with a combination of formaldehyde and sodium tripolyphosphate, exhibit superior drug loading capabilities, optimal swelling behavior, and controlled in vitro drug release profiles in the colonic environment, along with excellent adhesion and enzymatic degradation properties within intestinal tract. Notably, these F-TPPLC microspheres increase paracellular permeability, possibly by disrupting the calcium-dependent adhesion junctions. In comparison to commercial CS, CMC demonstrates superior drug encapsulation efficiency, enhanced colonic drug release, adhesion, and absorption promotion, rendering it a favorable candidate as a carrier in colon-targeted drug delivery systems. Consequently, F-TPPLC microspheres derived from CMC are highly suitable for colon drug delivery applications and show promising potential for the oral delivery of peptide and protein-based therapeutics to the colon. [Display omitted] • Chitosan-melanin complex is more advantageous as a carrier material for colon delivery systems than chitosan. • Crosslinking agents affect the colon delivery performance of chitosan microspheres. • F-TPPLC microspheres have potential applications in oral colonic delivery of drugs. [ABSTRACT FROM AUTHOR]

Altered skin integrity increases the chance of infection, and bacterial infections often lead to a persistent inflammatory response that prolongs healing time. Functional artificial hydrogels are receiving increasing attention as suitable wound dressing barrier. However, the antimicrobial effect of the new dressing still needs to be explored in depth. In this work, the antimicrobial peptide MSI-1 was covalently attached to chitosan-modified poly (vinyl alcohol) hydrogels mixed with Prussian blue nanoparticles (PBNPs) via a primary amine group coupled to a carboxyl group. The synthesized hydrogel has a long-lasting antimicrobial surface and is able to maintain its bactericidal effect on Staphylococcus aureus and Escherichia coli for 24 h. Due to the presence of PBNPs, the hydrogel was able to rise to 48.3 °C within 10 min under near infrared (NIR) light irradiation at a wavelength of 808 nm and maintain this mild temperature to avoid bacterial biofilms. The hydrogel showed >90 % survival in co-culture with cells for 3 d and did not damage major organs in animal experiments. Thus, the photothermal dual-mode antimicrobial hydrogel synthesized in this study increases the selectivity as a safe and efficient wound dressing for the treatment of infected skin defects. [ABSTRACT FROM AUTHOR]

The development of polysaccharide-based wound dressings that are easy to prepare, adhere to tissue, adapt to diverse shapes and exhibit tunable mechanical properties holds significant clinical interest. This study introduced a simple spontaneous liquid-liquid phase separation technique employing low-molecular-weight and high polyion concentration of chitosan (CS) and hyaluronic acid (HA) to fabricate CS/HA coacervates. Upon increasing the molecular weight of chitosan from 7 kDa to 250 kDa, a transition in the CS/HA coacervates from liquid-like state to an elastic liquid and eventually to a solid-like state was observed. The resulting CS/HA coacervates demonstrated robust water resistance and adhesion to skin tissue. Notably, the molecular weight of chitosan significantly influenced the mechanical properties and hydration levels of the CS/HA coacervates. Moreover, in vivo studies using a full-thickness cutaneous defect model revealed that the CS/HA coacervates, prepared using 100 kDa chitosan, markedly accelerate wound healing. The coacervates' ease of preparation, wet adhesion, heterogeneous structure, suitability for irregularly shaped wounds, and exceptional wound healing promotion of the coacervates qualify them as an optimal wound dressing. [Display omitted] [ABSTRACT FROM AUTHOR]

We focus on optimizing acid-base interactions and hydrogen bonding networks to achieve enhanced proton conductivity under low relative humidity (RH) and high temperature. By functionalizing UiO-66-(COOH) 2 with glutamic acid (Glu) and lysine (Lys), we generate Glu-UiO-66-(COOH) 2 and Lys-UiO-66-(COOH) 2. These modified materials are subsequently incorporated into chitosan (CS) to produce the composites Glu-UiO-66-(COOH) 2 @CS and Lys-UiO-66-(COOH) 2 @CS. The successful incorporation of amino acids and cross-linking between -COOH and -NH 2 groups in the composites, confirmed by FTIR and PXRD analyses, significantly enhances the structural integrity and durability by strengthening the network, and reducing polymer chain mobility. Proton conductivity assessments reveal that Lys-UiO-66-(COOH) 2 @CS-7 exhibits a remarkable conductivity of 0.022 S/cm at 100 % RH and 363 K, outperforming Glu-UiO-66-(COOH) 2 @CS-7. The lower activation energy (E a) of 0.28 eV for Lys-UiO-66-(COOH) 2 @CS-7, compared to 0.336 eV for Glu-UiO-66-(COOH) 2 @CS-7, highlights the significant improvement in intramolecular acid-base interactions and hydrogen bonding. Furthermore, Lys-UiO-66-(COOH) 2 @CS-7 maintains notable proton conductivity at 43 % RH, with an E a of 0.216 eV, demonstrating its efficacy in low-humidity conditions. These findings underscore the profound impact of amino acid modifications and cross-linking on proton conductivity by reinforcing acid-base interactions, hydrogen bonding networks, and proton transfer efficiency. Amino acid-functionalized Glu-UiO-66-(COOH) 2 and Lys-UiO-66-(COOH) 2 boost proton conductivity in CS composites through effective cross-linking and strong acid-base interactions, achieving excellent performance even at low humidity. [Display omitted] [ABSTRACT FROM AUTHOR]

This study investigates the preliminary efficacy of drug encapsulation in chitosan hydrogels by cathodic electrodeposition for the encapsulation of the aromatic dye methyl orange to enhance drug delivery in biological systems. Chitosan, a biocompatible and transparent polymer, is known for its ability to effectively encapsulate and transport therapeutic agents, which is critical for sustained and targeted drug release. Methyl orange was selected as a model drug to study the effects of deposition and immersion times on encapsulation efficiency. The effects of deposition and immersion times on encapsulation efficiency were analyzed by synthesizing multilayer hydrogels via electrochemical oxidation. Characterization techniques, including UV–visible spectroscopy, FTIR, and NMR, were employed; FTIR indicated an effective absorption of 4.34 % for T d 50T i 60, while UV–Vis showed 46.41 % at T d 60T i 50. NMR analysis revealed effective concentrations of 0.47 mM for T d 70T i 60 and 0.38 mM for T d 60T i 50, indicating that longer immersion times enhance absorption. These findings provide a foundation for further studies aimed at optimizing drug delivery strategies and improving the therapeutic efficacy of encapsulated agents in biological applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Extensive traumatic injuries and difficult-to-heal wounds, induced by many circumstances, impose a significant social and economic burden on an annual basis. Thus, innovative wound dressings that encourage wound healing are greatly needed. In this work, we prepared a novel insect chitosan (MCS) using waste pupal shells from housefly (Musca domestica L.) culture. After conducting comparative investigations with commercially available chitosan, it was shown that MCS exhibited comparable qualities and may be used as a substitute source of commercial chitosan. A quaternized chitosan/pullulan/citric acid three-dimensional nanofiber sponge (3D-NS) of natural origin was prepared by electrostatic spinning and gas foaming techniques after MCS was quaternized. In vitro , tests showed that the 3D-NS had a higher liquid absorption capacity than the two-dimensional nanofibrous membrane (2D-NM). Additionally, the 3D-NS showed improved hemostatic, pro-cell proliferation, antibacterial, and anti-inflammatory qualities. In vitro , tests demonstrated that 3D-NS could inhibit the release of inflammatory factors, promote angiogenesis, accelerate collagen deposition, and promote wound contraction. These effects considerably facilitated the healing process of wounds in rats with full-thickness skin damage. In conclusion, the great bioactivity and physicochemical properties of 3D-NS render it an optimal candidate for developing novel wound dressings. [Display omitted] [ABSTRACT FROM AUTHOR]

Treating chronic wounds poses significant challenges in clinical medicine due to bacterial infection, reactive oxygen species (ROS) accumulation, and excessive inflammation. This study aimed to address these issues by developing a wound dressing with antibacterial, antioxidant, and anti-inflammatory properties. Chitosan was functionally modified with acrolein to covalently bind to epigallocatechin gallate (EGCG), enabling a high EGCG load. Subsequently, polyvinyl alcohol (PVA) and EGCG-modified chitosan were crosslinked to prepare a new double-network hydrogel with added cysteine (CSAEC/P50). CSAEC/P50 demonstrated optimal mechanical properties (low swelling rate, high water retention, and optimal flexibility), low hemolysis, high coagulation properties, and antibacterial and antioxidant activities. Cell scratch tests indicated that CSAEC/P50 can promote NIH3T3 cell migration. Immunofluorescence results showed that CSAEC/P50 promoted the transformation of proinflammatory M 1 macrophages to anti-inflammatory M 2 macrophages. These findings suggest that CSAEC/P50 has significant potential for use in wound dressing applications. [ABSTRACT FROM AUTHOR]

Chitosans are promising multi-functional biomolecules for various applications whose performance is dependent on three key structural parameters, including the pattern of acetylation (PA). To date, chitin deacetylases (CDAs) are the only tool to control the PA of chitosan polymers via their specific mode of action during de- or N -acetylation. For a start, this review summarizes the current state of research on the classification of carbohydrate esterase 4 enzymes, the features in sequence and structure of CDAs, and the different PAs produced by different CDAs during de- or N -acetylation. In the main part, we introduce three effects that guide the mode of action of these enzymes: the already established subsite capping effect, the subsite occupation effect, and the subsite preference effect. We show how their interplay controls the PA of CDA products and describe their molecular basis. For one thing, this review aims to equip the reader with the knowledge to understand and analyze CDAs – including a guide for in silico and in vitro analyses. But more importantly, we intend to reform and extend the model explaining their mode of action on chitosans to facilitate a deeper understanding of these important enzymes for biology and biotechnology. [Display omitted] [ABSTRACT FROM AUTHOR]

To improve the limited mechanical and water barrier properties of chitosan film while granting extra functionalities simultaneously, present study pioneered the incorporation of chitosan film with newly developed essential oil (EO)-based hydrophobic deep eutectic solvents (HDES, EO:octanoic acid (OA), EO:menthol (ME) and OA:ME:EO). The highest tensile strength (66.22 MPa) and elongation at break (45.99 %) were obtained in OA:ME:EO-40 and OA:ME:EO-80 films, respectively. The OA:EO-based films showed excellent and stable hydrophobicity. HDESs also endowed film with additional functionalities including thermal stability, bio-compatibility, controlled release, antioxidant, and antibacterial capacity. The extension of the storage period of strawberry treated with OA:EO-containing films confirmed their preservation ability. Compared with ME:EO and OA:ME:EO, OA:EO had better compatibility with chitosan matrix and could serve as a promising plasticizer for strengthening functionalities of chitosan film. These results also promote application of HDESs as emerging plasticizers in manufacture of other polymer-based packaging film. [Display omitted] [ABSTRACT FROM AUTHOR]

The single structure, poor mechanical properties, and low biological activity of wound dressings usually lead to unsatisfactory treatment effects. Gelatin and chitosan possess excellent biofunction, but they lack sufficient mechanical support. Magnetic biomaterials and magnetic fields have shown surprising tissue repair potential. Herein, inspired by the skin structure and considering the bioactive composition, a superparamagnetic asymmetric membrane was constructed by incorporating gelatin, chitosan, and magnetic Fe 3 O 4 nanoparticles. The proposed membrane exhibited a high degree of asymmetry, achieving functional diversification. The surface of the top layer was highly hydrophobic as an isolation barrier. The top layer consisted of dense fibrous chitosan with high mechanical strength and excellent antibacterial properties. The bottom layer was composed of gelatin sponge with distributed magnetic nanoparticles, possessing high porosity and swelling ratio to effectively absorb tissue exudates and support cell growth. Furthermore, the membrane demonstrated significant promotion of human dermal fibroblast proliferation under a static magnetic field. In a full-thickness mouse skin wound model, the membrane effectively accelerated wound healing with reduced wound area, abundant collagen disposition, and enhanced vascularization. Therefore, the superparamagnetic gelatin/chitosan asymmetric membrane with a biomimetic structure and function exhibits remarkable superiority and provides a promising approach to effective wound healing. [ABSTRACT FROM AUTHOR]