Spray-drying and rehydration on β-carotene encapsulated Pickering emulsion with chitosan and seaweed polyphenol

The spray-drying process to generate microcapsules from Pickering emulsions needs high temperatures, leading to instability of emulsions and degradation of encapsulated thermosensitive compounds (β-carotene). However, these effects may be attenuated by the introduction of seaweed polyphenols into the emulsion interfacial layers, although the effects underlying this protective mechanism have not been explored. This study evaluates the effects of spray-drying/rehydration on the morphology, encapsulation efficiency, redispersibility, and stability of β-carotene loaded Pickering emulsions stabilized by chitosan (PESC) and Pickering emulsions stabilized by chitosan/seaweed polyphenols (PESCSP). The encapsulation efficiency of β-carotene in PESCSP microcapsules (61.13 %) was higher than PESC (53.91 %). Rehydrated PESCSP exhibited more regular droplet size distribution, higher stability, stronger 3D network morphology, and lower redispersibility index (1.5) compared to rehydrated PESC. Analyses of interfacial layers of emulsions revealed that chitosan covalently bound fatty acids at their hydrophobic side. Polyphenols were linked to chitosan at the hydrophilic side of emulsions through hydrogen bonds, providing 3D network between droplets and antioxidant activities to inhibit the degradation of β-carotene. This study emphasized the role of polyphenols in the interfacial layers of Pickering emulsions for the development of efficient delivery systems and protection of β-carotene and other thermosensitive bioactive compounds during spray-drying and rehydration.

Therapeutic effects of electrospun chitosan nanofibers on animal skin wounds: A systematic review and meta-analysis

Electrospun chitosan nanofibers (QSNFs) enhance the healing process by mimicking skin structure and function. The aim of this study was to analyze the therapeutic effects of QSNFs application on animal skin wounds to identify a potential direction for translational research in dermatology. The PRISMA methodology and the PICO scheme were used. A random effects model and mean difference analysis were applied for the meta-analysis. A meta-regression model was constructed, risk of bias was determined, and methodological quality assessment was performed. Of the 2370 articles collected, 54 studies were selected based on the inclusion and exclusion criteria. The wound healing area was used for building models on the 3rd, 7th, and 14th days of follow-up; the results were - 10.4% (95% CI, -18.2% to -2.6%, p = 0.001), -21.0% (95% CI, -27.3% to -14.7%, p = 0.001), and - 14.0% (95% CI, -19.1 to -8.8%, p = 0.001), respectively. Antioxidants and synthetic polymers combined with QSNFs further reduced skin wound areas (p < 0.05). The results show a more efficient reduction in wound area percentages in experimental groups than in control groups, so QSNFs could potentially be applied in translational human medicine research.

Polysaccharides in contact lenses: From additives to bulk materials

As the number of applications has increased, so has the demand for contact lenses comfort. Adding polysaccharides to lenses is a popular way to enhance comfort for wearers. However, this may also compromise some lens properties. It is still unclear how to balance the variation of individual lens parameters in the design of contact lenses containing polysaccharides. This review provides a comprehensive overview of how polysaccharide addition impacts lens wear parameters, such as water content, oxygen permeability, surface wettability, protein deposition, and light transmittance. It also examines how various factors, such as polysaccharide type, molecular weight, amount, and mode of incorporation into lenses modulate these effects. Polysaccharide addition can improve some wear parameters while reducing others depending on the specific conditions. The optimal method, type, and amount of added polysaccharides depend on the trade-off between various lens parameters and wear requirements. Simultaneously, polysaccharide-based contact lenses may be a promising option for biodegradable contact lenses as concerns regarding environmental risks associated with contact lens degradation continue to increase. It is hoped that this review will shed light on the rational use of polysaccharides in contact lenses to make personalized lenses more accessible.

Hydrophilic chitosan/graphene oxide composite sponge for rapid hemostasis and non-rebleeding removal

Hydrophilic hemostatic sponge plays an important role in trauma bleeding control because of its robust coagulant functions. However, its strong tissue adhesion can easily result in wound tear and rebleeding during removing the sponge. Herein, the design of a hydrophilic anti-adhesive chitosan/graphene oxide composite sponge (CSAG) that possesses stable mechanical strength, rapid liquid absorption and strong intrinsic/extrinsic coagulation stimulations, is reported. For one thing, CSAG exhibits outstanding hemostatic performance, which significantly outperforms two commercial hemostats in two in vivo serious bleeding models. For another, CSAG shows low tissue adhesion; its peeling force is approximately 79.3 % lower than the commercial gauze. Moreover, in the peeling process, CSAG triggers partial detachment of the blood scab, because of the exist of bubbles or cavities at the interface, allowing the CSAG to be easily and safely peeled off from the wound without rebleeding. This study opens new avenues in constructing anti-adhesive trauma hemostatic materials.

Drug-free and non-crosslinked chitosan/hyaluronic acid hybrid hydrogel for synergistic healing of infected diabetic wounds

The management of infected diabetic wounds remains a major challenge in clinical practice. Recently, multifunctional hydrogels have attracted much attention in the area of wound healing. Herein, we developed the drug-free and non-crosslinked chitosan (CS)/hyaluronic acid (HA) hybrid hydrogel, so as to combine the multiple functions of CS and HA for synergistic healing of the methicillin-resistant Staphylococcus aureus (MRSA)-infected diabetic wound. As a result, CS/HA hydrogel showed the broad-spectrum antibacterial activity, the great capacity for promoting fibroblasts proliferation and migration, the excellent reactive oxygen species (ROS) scavenging ability, and the great cell-protection effects under oxidative stress. In the MRSA-infected diabetic mouse wounds, CS/HA hydrogel significantly promoted the wound healing via eliminating MRSA infection and enhancing epidermal regeneration, collagen deposition and angiogenesis. Considering the drug-free feature, the ready availability, the great biocompatibility and the excellent wound healing efficacy, CS/HA hydrogel may have great potentials in clinical use for the management of chronic diabetic wounds.

Chitosan-based Pickering emulsion: A comprehensive review on their stabilizers, bioavailability, applications and regulations

BACKGROUND

Chitosan-based particles are one of the most promising Pickering emulsions stabilizers due to its cationic properties, cost-effective, biocompatibility, biodegradability. However, there are currently no comprehensive reviews analyzing the role of chitosan to develop Pickering emulsions, and the bioavailability and multiple uses of these emulsions.

SCOPE AND APPROACH

This review firstly summarizes the types, preparation and functional properties of chitosan-based Pickering emulsion stabilizers, followed by in vivo and in vitro bioavailability, main regulations, and future application and trends.

KEY FINDINGS AND CONCLUSIONS

Stabilizers used in chitosan-based Pickering emulsions include 6 categories: chitosan self-aggregating particles and 5 types of composites (chitosan-protein, chitosan-polysaccharide, chitosan-fatty acid, chitosan-polyphenol, and chitosan-inorganic). Chitosan-based Pickering emulsions improved the bioavailability of different compounds compared to traditional emulsions. Current applications include hydrogels, microcapsules, food ingredients, bio-based films, cosmeceuticals, porous scaffolds, environmental protection agents, and interfacial catalysis systems. However, due to current limitations, more research and development are needed to be extensively explored to meet consumer demand, industrial manufacturing, and regulatory requirements. Thus, optimization of stabilizers, bioavailability studies, 3D4D printing, fat substitutes, and double emulsions are the main potential development trends or research gaps in the field which would contribute to increase adoption of these promising emulsions at industrial level.

Chitosan and polyhexamethylene guanidine dual-functionalized cotton gauze as a versatile bandage for the management of chronic wounds

Development of versatile medical dressing with good immediate and long-lasting antibacterial, hygroscopic and moisturizing abilities is of great significance for management of chronic wounds. Cotton gauze (CG) can protect wounds and promote scabbing, but can cause wound dehydration and loss of biologically active substances, thereby greatly delays wound healing. Herein, a bi-functional CG dressing (CPCG) was developed by chemically grafting polyhexamethylene guanidine (PHMG) and physically adsorbing chitosan (CS) onto the CG surface. Due to the powerful microbicidal activity of PHMG, CPCG exhibited excellent immediate and long-lasting antibacterial activity against gram-positive and gram-negative bacteria. Moreover, the abundant hydroxyl and amino groups in CS endowed CPCG with good biocompatibility, moisture absorption, moisturizing and cell scratch healing performances. Importantly, CPCG can be easily fabricated into a bandage to conveniently manage infected full-skin wounds. Together, this study suggests that CPCG is a versatile wound dressing, having enormous application potential for management chronic wounds.

Protein-polysaccharide interactions for the fabrication of bioactive-loaded nanocarriers: Chemical conjugates and physical complexes

As unique biopolymeric architectures, covalently and electrostatically protein-polysaccharide (PRO-POL) systems can be utilized for bioactive delivery by virtue of their featured structures and unique physicochemical attributes. PRO-POL systems (i. e, microscopic /nano-dimensional multipolymer particles, molecularly conjugated vehicles, hydrogels/nanogels/oleogels/emulgels, biofunctional films, multilayer emulsion-based delivery systems, particles for Pickering emulsions, and multilayer coated liposomal nanocarriers) possess a number of outstanding attributes, like biocompatibility, biodegradability, and bioavailability with low toxicity that qualify them as powerful agents for the delivery of different bioactive ingredients. To take benefits from these systems, an in-depth understanding of the chemical conjugates and physical complexes of the PRO-POL systems is crucial. In this review, we offer a comprehensive study concerning the unique properties of covalently/electrostatically PRO-POL systems and introduce emerging platforms to fabricate relevant nanocarriers for encapsulation of bioactive components along with a subsequent sustained/controlled release.

Progress in research on natural cellulosic fibre modifications by polyelectrolytes

In order to improve the mechanical properties and functionalities of natural cellulosic fibres, this paper first analyzed the characteristics of natural cellulosic fibres and the conventional modification methods of natural cellulosic fibres, and then focused on the polyelectrolytes modified natural cellulosic fibres. The main methods and process parameters of this modification were described in detail; the modification effects of polyelectrolytes on different types of fibres were systematically summarized; the influencing factors on modification of fibres were also discussed in depth; the characterization methods of polyelectrolytes modified fibres were analyzed in detail. Finally, the main application fields of polyelectrolytes modified fibres were systematically summarized.

The influence of bioactive glyoxylate bearing Schiff base on antifungal and antioxidant activities to chitosan quaternary ammonium salts

In this study, to investigate the influence of glyoxylate bearing Schiff base on bioactivity to chitosan quaternary ammonium salts, different chitosan derivatives were synthesized by ion exchange of glyoxylate bearing Schiff base with chitosan quaternary ammonium salts (TMCI and HACC). For this purpose, glyoxylate was prepared by Schiff base reaction of glyoxylic acid and amino heterocycles and it was further ionization to substitute iodide ions and chloride ions. After structural characterization by FTIR and ¹H NMR, the antifungal and antioxidant activities were measured. Results indicated that glyoxylate bearing Schiff base could improve the bioactivity of TMCI and HACC obviously. Specifically, anionic TMCI with Schiff base of amino pyridines possessed best antioxidant activity >92.40% at 1.6 mg/mL against DPPH radicals. Meanwhile, they showed antifungal activity >84.88% at 1.0 mg/mL against G. cingulate. Furthermore, the cytotoxicity was evaluated, and all samples showed good cell viability >80.14% at 1000 μg/mL.

Applications of chitin and chitosan based biomaterials for the adsorptive removal of textile dyes from water - A comprehensive review

The presence of pollutants in the water bodies deteriorate the water quality and make it unfit for use. From an environmental perspective, it is essential to develop new technologies for the wastewater treatment and recycling of dye contaminated water. The surface modified chitin and chitosan biopolymeric composites based adsorbents, have an important role in the toxic organic dyes from removal wastewater. The surface modification of biopolymers with various organics and inorganics produces more active sites at the surface of the adsorbent, which enhances dye and adsorbent interaction more reliable. Herein, the work brought in the thought of the application of various chitin and chitosan composites in wastewater remediation and suggested the versatility in composites for the development of rapid, selective and effective removal processes for the detoxification of a variety of organic dyes. It further emphasizes the existing obstruction and impending prediction for the deprivation of dyes via adsorption techniques.

New synthetic adriamycin-incorporated chitosan nanoparticles with enhanced antioxidant, antitumor activities and pH-sensitive drug release

In this paper, adriamycin-incorporated chitosan nanoparticles were synthesized by ionic gelation using negatively charged carboxymethyl chitosan and positively charged 2-hydroxypropyltrimethyl ammonium chloride chitosan. The method was efficient to obtain nanoparticles with low polydispersity index and small hydrodynamic diameter. And high zeta potential value indicated that nanoparticles had good stability. The adriamycin release of nanoparticles represented a significant response to pH, with the fastest release in phosphate buffer solution at pH 6.8. Meanwhile, the antioxidant efficiency of nanoparticles was assayed, and nanoparticles represented significant enhancement in radicals scavenging activity. The assay of cell viability by CCK-8 test exhibited that nanoparticles led to statistically significant decrease in cell viability for four kinds of cancer cells (HEPG-2, A549, MCF-7, and BGC-823). It was indicated that the nanoparticles with enhanced biological activity, reduced cytotoxicity, and pH-sensitive release could be served as potential drug carrier in drug delivery system.

Chitosan as a matrix of nanocomposites: A review on nanostructures, processes, properties, and applications

Chitosan is a biopolymer that is natural, biodegradable, and relatively low price. Chitosan has been attracting interest as a matrix of nanocomposites due to new properties for various applications. This study presents a comprehensive overview of common and recent advances using chitosan as a nanocomposite matrix. The focus is to present alternative processes to produce embedded or coated nanoparticles, and the shaping techniques that have been employed (3D printing, electrospinning), as well as the nanocomposites emerging applications in medicine, tissue engineering, wastewater treatment, corrosion inhibition, among others. There are several reviews about single chitosan material and derivatives for diverse applications. However, there is not a study that focuses on chitosan as a nanocomposite matrix, explaining the possibility of nanomaterial additions, the interaction of the attached species, and the applications possibility following the techniques to combine chitosan with nanostructures. Finally, future directions are presented for expanding the applications of chitosan nanocomposites.

Thermomechanically processed chitosan:gelatin films being transparent, mechanically robust and less hygroscopic

Chitosan and gelatin are attractive polymeric feedstocks for developing environmentally benign, bio-safe, and functional materials. However, cost-effective methods to achieve advantageous materials properties and tailor their functionality are still lacking, but interesting. Herein, we found that physically mixing chitosan and gelatin at 1:1 (w/w) ratio resulted in materials with properties (higher Young's modulus (603.8 MPa) and tensile strength (33.6 MPa), and reduced water uptake (45%) after 6 h of water soaking) better than those of the materials based on mainly chitosan or gelatin. We attribute this synergy to the ionic and hydrogen-bonding interactions between the two biopolymers enabled by high-viscosity thermomechanical processing. Despite the lowest hygroscopicity, the 1:1 chitosan:gelatin films displayed the highest surface hydrophilicity. Besides, addition of gelatin to chitosan led to films being brighter, more transparent and amorphous. Thus, this work has generated new understanding to enhance the application of biopolymers for e.g. packaging, coating, and biomedical applications.

Chitosan-poloxamer-based thermosensitive hydrogels containing zinc gluconate/recombinant human epidermal growth factor benefit for antibacterial and wound healing

Chitosan/poloxamer-based thermosensitive hydrogels containing zinc gluconate/recombinant human epidermal growth factor (ZnG/rhEGF@Chit/Polo) were developed as a convenient, safe and effective dressing for skin wound treatment. Their fabrication procedure and characterization were reported, and their morphology was examined by a scanning electron microscope. Antibacterial and biofilms activities were evaluated by in vitro tests to reveal the inhibitory effects and scavenging activity on the biofilms of Staphylococcus aureus and Pseudomonas aeruginosa. ZnG/rhEGF@Chit/Polo was also investigated as a potential therapeutic agent for wound healing therapy. In vivo wound healing studies on rats for 21 days proves that ZnG/rhEGF@Chit/Polo supplements the requisite Zn²⁺ and rhEGF for wound healing to promote the vascular remodeling and collagen deposition, facilitate fibrogenesis, and reduce the level of interleukin 6 for wound basement repair, and thus is a good wound therapy.

Recent advances in polymeric core-shell nanocarriers for targeted delivery of chemotherapeutic drugs

The treatment effect of chemotherapeutics is often impeded by nonspecific biodistribution and limited biocompatibility. Polymeric core-shell nanocarriers (PCS NCs) composed of a polymer core and at least one shell have been widely applied for cancer therapy and have shown great potential in selectively delivering chemotherapeutic drugs to tumor sites. These PCS NCs can effectively ameliorate the delivery efficiency and therapeutic index of anticarcinogens by prolonging drug residence in the bloodstream, enhancing tumor tissue drug penetration, facilitating cellular drug uptake, controlling the spatiotemporal release of payloads, or codelivering two or more bioactive agents. This review summarizes recently published literature on using PCS NCs to transport chemotherapeutic drugs with poor aqueous solubility and discusses their design principles, structural features, functional properties, and potential limitations.

Inhibitory effect of polysaccharides on acrylamide formation in chemical and food model systems

The inhibitory effect of three polysaccharides (alginate, pectin and chitosan) on acrylamide formation was investigated in chemical and fried potato food model systems, under two heating regimes (heating block and microwave). In the chemical system, acrylamide formation followed a second order reaction kinetic behaviour. Activation energies (Ea) were 17.85 and 110.78 kJ/mol for conventional and microwave heating respectively. Acrylamide content was highest at 180 °C after 60 min conventional heating (27.88 ng/ml) and 3.5 fold higher after microwave heating for 60 s (800 W, 98.02 ng/ml). Alginate (0.3% w/v) and pectin (0.2% w/v) solutions efficiently inhibited acrylamide formation by 65% and 56% respectively under conventional heating, and 36% and 30% respectively under microwave heating. Coating potatoes with alginate, pectin and chitosan (1% w/v) prior to frying dramatically inhibited acrylamide formation by 54%, 51% and 41% respectively. However only alginate and pectin slightly reduced acrylamide by 5% in the microwave.

The kinetics and release behaviour of curcumin loaded pH-responsive PLGA/chitosan fibers with antitumor activity against HT-29 cells

The bioavailability and clinical effect of curcumin (Cur) are greatly restricted due to its physicochemical instability and high hydrophobicity. To overcome the disadvantages, the nanofibers of poly(lactide-glycolide)/chitosan loaded with Cur (PLGA/CS/Cur) was developed here by electrospinning technique for controlled Cur delivery. The incorporated Cur was well-dispersed and maintained crystalline form in PLGA/CS fiber matrix by hydrogen bonding. The incorporation of Cur had no obvious influence on the fiber size and morphology but exerted impacts on thermal stability. At pH 7.4, the release followed Fickian diffusion mechanism; while at pH 2.0, the release followed the coexistence of diffusion and erosion mechanisms. In addition, the amount of Cur released at pH 2.0 was much higher than that at pH 7.4. As a result, the nanofibers demonstrated higher anticancer activity at acidic environment. Therefore, the PLGA/CS/Cur nanofibers may be served as a potential pH responsive vehicle for the controlled drug delivery.

Current trends and challenges in the synthesis and applications of chitosan-based nanocomposites for plants: A review

Chitosan, a low-cost and multipurpose polymer with numerous desired physicochemical and biological properties has been tested for various applications in agriculture, pharmacy, and biomedicine industries. The availability of functional groups along the backbone makes chitosan readily available for other polymers and metal ions to form bio-nanocomposites. Different types of chitosan-based nanocomposites have been designed and tested for the enhancement of chitosan efficiency and ultimately widening the application areas of chitosan in plants. These nanocomposites serve different purposes such as eliciting plant's defence systems against different threats (pathogen attack), antimicrobial agent against bacteria, fungi and viruses, enhancement of nutrient uptake by plants, control release of micro/macronutrients, fungicides and herbicides. In this review, an extensive outlook has been provided (mainly in the last five years) to recent trends and advances in the fabrication and application of chitosan-based composites. Finally, current challenges and future development opportunities of chitosan-based nanocomposites for plants are discussed.

Development and properties of bacterial cellulose, curcumin, and chitosan composite biodegradable films for active packaging materials

To deal with serious environmental damage resulting from plastic packaging materials, biodegradable films using natural products have gained considerable attention. Here, we provide a simple, fast, and environmentally-friendly route to construct a biodegradable film using chitosan (CS), bacterial cellulose (BC), and curcumin (Cur). Composite films (CSn-BC-Cur) using CS with different molecular weights were investigated, and their water moisture content (MC), water solubility (WS), contact angle (CA), mechanical properties, barrier properties, and antioxidant properties were compared. The obtained films were characterized by SEM, XRD, and TGA. The results showed that chitosan with a higher molecular weight presented higher contact angles and mechanical properties, along with a lower moisture content, water vapor transmission rate, and oxygen transmission rate. Furthermore, when the composite film was placed in 95 % ethanol, it released active substances. The results suggest that these composite films can be used as promising materials for food packaging.

Properties and kinetics of the in vitro release of anthocyanin-rich microcapsules produced through spray and freeze-drying complex coacervated double emulsions

This study aimed to prepare anthocyanin-rich microcapsules by spray and freeze-drying complex coacervated double emulsion using gelatin-acacia gum (GE-AG) and chitosan-carboxymethylcellulose (CS-CMC) and to investigate their properties and in vitro release kinetics. Microencapsulation efficiency (MEE) of the microcapsules varied from 84.9% to 94.7%. CS-CMS microcapsules showed significantly higher MEEs than those of GE-AG microcapsules. A significant higher MEE and lower moisture content and hygroscopicity was observed in spray-dried double emulsion (SDE) microcapsules. Freeze-dried double emulsion (FDE) microcapsules possessed higher total anthocyanin and total phenolic contents. The best fit for release kinetics was achieved using first-order and Higuchi models for SDE and FDE microcapsules, respectively. Diffusion-controlled release in the simulated gastric fluid was found for SDE microcapsules, while erosion-controlled release in simulated gastric and intestinal fluids predominated for FDE microcapsules. These findings suggest that the microcapsules can be applied for loading anthocyanins as a nutraceutical with controllable release requirement.

New synthetic chitosan derivatives bearing benzenoid/heterocyclic moieties with enhanced antioxidant and antifungal activities

In this paper, several novel chitosan derivatives bearing benzenoid / heterocyclic moieties were synthesized via introducing aminobenzene and heterocyclic compounds onto carboxymethyl chitosan. The specific structures of chitosan derivatives were confirmed by FTIR, ¹H NMR, and elemental analysis. Meanwhile, the antioxidant efficiencies of chitosan derivatives were assayed in vitro. In particular, all chitosan derivatives showed significant improvement in superoxide-radical scavenging activity and DPPH radical scavenging activity. Their antifungal activities against two plant pathogenic fungi (Colletotrichum lagenarium and Phomopsis asparagi) were estimated in vitro by hyphal measurement, and all products exhibited excellent antifungal activity. Besides, the cytotoxicity of them was also measured by CCK-8 in vitro on L929 cells, and all samples showed low cytotoxicity. The good biocompatibility and enhanced biological activity of new synthetic chitosan derivatives might be obvious advantages, while applied in wide range of applications as antifungal agents or antioxidants in food, medicine, cosmetics, and other fields.

Chitosan-modified lipid nanodrug delivery system for the targeted and responsive treatment of ulcerative colitis

Targeted and sensitive drug release at the colitis site is critical for the effective therapy of ulcerative colitis and reduction of side effects from the drug. Herein, we used 3,3'-dithiodipropionic acid (DTPA) to covalently link quercetin (Qu) and glyceryl caprylate-caprate (Gcc) via ester bonds to prepare Qu-SS-Gcc lipid nanoparticles (Qu-SS-Gcc LNPs). Dexamethasone (Dex) was used as a model drug, and chitosan (CSO) was modified on the surface of Qu-SS-Gcc LNPs to obtain CSO-modified Dex-loaded Qu-SS-Gcc LNPs (CSO/Dex/LNPs). The encapsulation efficiency and drug loading of CSO/Dex/LNPs were 93.1 % and 8.1 %, respectively. The in vitro release results showed that CSO/Dex/LNPs had esterase-responsive characteristics and could release the drug rapidly in esterase-containing artificial intestinal fluid. A human colorectal adenocarcinoma cell (Caco-2) monolayer was used as the intestinal cell barrier model. Transmembrane resistance measurements and permeation experiments showed that CSO/Dex/LNPs had a protective effect on the lipopolysaccharide (LPS)-stimulated Caco-2 cell monolayer and increased the expression of E-cadherin in LPS-stimulated Caco-2 cells. Moreover, CSO/Dex/LNPs could significantly reduce the expression of the inflammatory factors TNF-α, IL-6 and NO in LPS-stimulated RAW 264.7 cells. The ulcerative colitis mouse model was constructed by using C57BL/6 mice. The in vivo distribution results showed that CSO/Dex/LNPs had colon-targeting effects and strong retention ability in the colons of mice with colitis. The results also showed that CSO/Dex/LNPs had better anti-inflammatory effects than free Dex, which could reduce colonic atrophy, reduce histomorphological changes and increase the expression of E-cadherin in the colon. Furthermore, the expression levels of TNF-α, IL-6 and NO in the CSO/Dex/LNP-treated group were 37.4 %, 35.5 % and 33.2 % of those in mice with colitis, respectively.

Synthesis, characterization and antifungal efficacy of chitosan derivatives with triple quaternary ammonium groups

A novel type of water soluble chitosan derivatives (TQCSPX) were synthesized including 3-aminopyridine (TQCSP1) and 3-Amino-4-methylpyridine (TQCSP2). The theoretical structures of TQCSPX were calculated by Gaussian 09 and confirmed by FT-IR, ¹H NMR, ¹³C NMR, elemental analysis and XRD. The antifungal properties of TQCSPX against Phytophthora capsici (P. capsici), Rhizoctonia solani (R. solani), Fusarium oxysporum (F. oxysporum) and Fusarium solani (F. solani) were evaluated at concentrations ranging from 0.2mg/mL to 0.8mg/mL. Antifungal results indicated that the derivatives have significantly enhanced antifungal activity after quaternized compared with the original chitosan (CS). Moreover, TQCSP1 inhibited the growth of P. capsici with inhibitory indices of 91.94% at 0.8mg/mL. The experimental results demonstrated that the increasing number of the positive charge would improve the antifungal efficiency of chitosan, which may provide a novel direction for the development of fungicides.

In-vitro and in-vivo cytotoxicity and efficacy evaluation of novel glycyl-glycine and alanyl-alanine conjugates of chitosan and trimethyl chitosan nano-particles as carriers for oral insulin delivery

PURPOSE

The aim of this research work was to explore the possibility of providing multifunctional oral insulin delivery system by conjugating several types of dipeptides on chitosan and trimethyl chitosan to be used as drug carriers.

METHOD

Conjugates of Glycyl-glycine and alanyl-alanine of chitosan and trimethyl chitosan (on primary alcohol group of polymer located on carbon 6) were synthesized and nanoparticles containing insulin were prepared for oral delivery. Preparation conditions of nanoparticles were optimized and their performance to enhance the permeability of insulin as well as cytotoxicity of nanoparticles in Caco-2 cell line was evaluated. To evaluate the efficacy of orally administered nanoparticles, nanoparticles with the most permeability enhancing ability were studied in male Wistar rats as animal model by measuring insulin and glucose Serum levels.

RESULT

Structural study of all the conjugates by infrared spectroscopy and nuclear magnetic resonance confirmed the successful formation of the conjugates with the desirable substitution degree. By optimizing preparation conditions, nanoparticles with expected size (157.3-197.7 nm), Zeta potential (24.35-34.37 mV), polydispersity index (0.365-0.512), entrapment efficiency (70.60-86.52%) and loading capacity (30.92-56.81%), proper morphology and desirable release pattern were obtained. Glycyl-glycine and alanyl-alanine conjugate nanoparticles of trimethyl chitosan showed 2.5-3.3 folds more effective insulin permeability in Caco-2 cell line than their chitosan counterparts. In animal model, oral administration of glycyl-glycine and alanyl-alanine conjugate nanoparticles of trimethyl chitosan demonstrated reasonable increase in Serum insulin level with relative bioavailability of 17.19% and 15.46% for glycyl-glycine and alanyl-alanine conjugate nanoparticles, respectively, and reduction in Serum glucose level compared with trimethyl chitosan nanoparticles (p < 0.05).

CONCLUSION

It seems that glycyl-glycine and alanyl-alanine conjugate nanoparticles of trimethyl chitosan have met the aim of this research work and have been able to orally deliver insulin with more than one mechanism in animal model. Hence, they are promising candidates for further research studies.

Influence of different classes of crosslinkers on alginate polyelectrolyte nanoparticle formation, thermodynamics and characteristics

Complexation of linear alginate polyanions with different classes of crosslinkers (divalent cations, polycations, positively charged surfactants) was investigated, to unravel their effects on nanoparticle formation. The goal was to define the crosslinker-to-alginate molar ratios at which nanoparticles are formed, and to reveal the underlying thermodynamics and molecular interactions using dynamic and electrophoretic light scattering, isothermal titration calorimetry, and infrared spectroscopy. Alginate nanoparticles were formed across a limited range of molar ratios that was specific for each crosslinker, and had different size and stability. Thermodynamic parameters of alginate complexation with crosslinkers showed that nanoparticle formation was in all cases entropy driven, together with a minor enthalpic contribution. The crosslinking mechanism was based on ionic interactions, with accompanying weaker interactions specific for each crosslinker, and involved characteristic macroscopic association constants (K_a1) for complexation of alginate (range, 10⁴-10⁹M^-1). Additionally, the ionic strengths of the media influenced the characteristics and stabilities of the polyelectrolyte nanoparticles.

Bilayered buccal films as child-appropriate dosage form for systemic administration of propranolol

Buccal mucosa has emerged as an attractive site for systemic administration of drug in paediatric patients. This route is simple and non-invasive, even if the saliva wash-out effect and the relative permeability of the mucosa can reduce drug absorption. Mucoadhesive polymers represent a common employed strategy to increase the contact time of the formulation at the application site and to improve drug absorption. Among the different mucoadhesive dosage forms, buccal films are particularly addressed for paediatric population since they are thin, adaptable to the mucosal surface and able to offer an exact and flexible dose. The objective of the present study was to develop bilayered buccal films for the release of propranolol hydrochloride. A primary polymeric layer was prepared by casting and drying of solutions of film-forming polymers, such as polyvinylpyrrolidone (PVP) or polyvinylalcohol (PVA), added with different weight ratios of gelatin (GEL) or chitosan (CH). In order to achieve unidirectional drug delivery towards buccal mucosa, a secondary ethylcellulose layer was applied onto the primary layer. Bilayered films were characterized for their physico-chemical (morphology, thickness, drug content and solid state) and functional (water uptake, mucoadhesion, drug release and permeation) properties. The inclusion of CH into PVP and PVA primary layer provided the best mucoadhesion ability. Films containing CH provided a lower drug release with respect to films containing GEL and increased the amount of permeated drug through buccal mucosa, thanks to its ability of interfering with the lipid organization. The secondary ethylcellulose layer did not interfere with drug permeation, but it could limit drug release in the buccal cavity.

Synergistic effect of quercetin and pH-responsive DEAE-chitosan carriers as drug delivery system for breast cancer treatment

Amphiphilic chitosans, which may self-assemble in aqueous solution to form nanoaggregates with different conformations depending to the environmental pH, can be used as drug transport and delivery agents, when the target pH differs from the delivery medium pH. In this study, quercetin, a bioactive flavonoid, was encapsulated in a pH-responsive system based on amphiphilic chitosan. The hydrophilic reagent 2-chloro-N,N-diethylethylamine hydrochloride (DEAE), also known to inhibit the proliferation of cancer cells, was used as a grafting agent. Drug loading experiments (DL ∼5%) showed a quercetin entrapment efficiency of 73 and 78% for the aggregates. The sizes of blank aggregates measured by dynamic light scattering (DLS) varied from 169 to 263nm and increased to ∼410nm when loaded with quercetin. The critical aggregation concentration, zeta potential and morphology of the aggregates were determined. pH had a dominant role in the release process and Fickian diffusion was the controlling factor in drug release according to the Korsmeyer-Peppas mathematical model. In vitro studies indicated that the DEAE-modified chitosan nanoaggregates showed a synergistic effect with quercetin on the control of the viability of MCF-7 cells. Therefore, DEAE-modified chitosan nanoaggregates with pH-sensibility can be used as optimized nanocarriers in cancer therapy.

C-coordinated O-carboxymethyl chitosan metal complexes: Synthesis, characterization and antifungal efficacy

A novel type of O-carboxymethyl chitosan Schiff bases (O-CSPX) was synthesized via a condensation reaction. After the coordination reaction of cupric ions, zinc ions and nickel ions, metal complexes (O-CSPX-M) were achieved. The theoretical structure of O-CSPX-M calculated by Gaussian 09 reveals that the copper ions and nickel ions underwent dsp² hybridization, the zinc ions underwent sp³ hybridization, and they all coordinated by the carbon atom in the p-π conjugate group. Then, the structures were confirmed by FT-IR, ¹H NMR, CP-MAS ¹³C NMR, elemental analysis, DSC and XRD. The antifungal properties of O-CSPX-M against Phytophthora capsici (P. capsici), Gibberella zeae (G. zeae), Fusarium oxysporum (F. oxysporum) and Botrytis cinerea (B. cinerea) were evaluated at concentrations ranging from 0.05mg/mL to 0.40mg/mL. The experiments indicated that the derivatives have significantly enhanced antifungal activity after metal ions complexation compared with the original chitosan. Moreover, it was shown that 0.20mg/mL of O-CSPX-Cu can 100% inhibit the growth of P. capsici and 0.20mg/mL of O-CSPX-Ni can 87.5% inhibit the growth of B. cinerea. In addition, the phytotoxicity assay and cell viability assay were also evaluated. The experimental results may provide a novel direction for the development of metal fungicides.

Peptides derived from tryptic hydrolysate of Bacillus subtilis culture suppress fungal spoilage of table grapes

This study confirmed the anti-fungal effect of trypsin-treated Bacillus subtilis culture (BC) (tryptic hydrolysate, TH) on mold growth on Kyoho grapes. We examined the anti-fungal activity of TH by identifying TH peptides and performing a computational docking analysis. TH was more potent than untreated BC in suppressing fungal growth on grapes. Specifically, TH maintained grape freshness by inhibiting respiration and rachis browning, maintaining firmness, and preventing weight loss. Thirty-six inhibitory peptides against β-1,3-glucan synthase (GS) were screened from 126 TH peptides identified through proteomic analysis. Among them, 13 peptides bound tightly to GS active pockets with lower binding energies than that of GppNHp. The most potent peptides, LFEIDEELNEK and FATSDLNDLYR, were synthesized, and further experiments showed that these peptides had a highly suppressive effect on GS activity and Aspergillus niger and Penicillium chrysogenum growth. Our results confirm that tryptic treatment is effective for improving the anti-fungal activity of BC.

Microencapsulation of sardine oil: Application of vanillic acid grafted chitosan as a bio-functional wall material

Vanillic acid grafted chitosan (Va-g-Ch) was evaluated as a new antioxidant wall material for microencapsulation of polyunsaturated fatty acid rich sardine oil. A high grafting ratio of 305mg vanillic acid equivalent/g of polymer was achieved using a free radical mediated grafting reaction. Oil in water emulsion was prepared with an optimised combination of Va-g-Ch and Tween 20 (3.2:1). Sardine oil loaded microparticles (SO-M) were produced (∼75% yield) by spray drying. The average diameter and polydispersity Index (PDI) of the particles were found to be 2.3μ and 0.345. XRD spectra of SO-M showed reduction in crystallinity due to microencapsulation. After four weeks of storage, a moderate (∼12%) decrease in the EPA and DHA content and a low PV of 5.5±0.51meq/kg oil in SO-M demonstrated good oxidative stability. Satisfactory encapsulation efficiency (84±0.84%) and loading efficiency (67±0.51%) values, also demonstrated the suitability of Va-g-Ch for microencapsulation of sardine oil.

Dehydroascorbate-derivatized chitosan particles for targeting antimalarial agents to infected erythrocytes

The mammalian glucose transporter GLUT-1 and Plasmodium falciparum hexose transporter PfHT1 are overexpressed on human RBC infected with the parasite (iRBC), presumably for enhanced glucose uptake. Dehydroascorbic acid (DHA) competes out glucose in GLUT-1 binding. We prepared particles containing chloroquine phosphate using novel derivatives of chitosan (CSN). CSN was either pre-derivatized with DHA (PRE) or particles made of CSN were derivatized by surface-grafting DHA (POST). The optimized formulations were analyzed for size (170-200nm) drug content (about 40%) entrapment efficiency (50-57%), in vitro drug release (80% in 72h, Higuchi's model), hemolysis on exposure to whole blood or RBC at 5% hematocrit, cytotoxicity towards cultured HEK 293T (kidney) and HepG2 (hepatic) cells, targeting iRBC and in vitro efficacy against P. falciparum. PRE particles were superior to POST CSN particles in terms of uptake and extent of preferential targeting to iRBCs than RBCs. Unlike starch particles reported earlier, dextrose did not competitively inhibit uptake of DHA-derivatized CSN particles. Both formulations significantly induced parasite inhibition at 1nM while free drug showed comparable activity at 100nM. Both PRE and POST particles were superior to free drug in efficacy. Targeting with high efficiency promises dose reduction and possibility of overcoming efflux-based drug resistance.

Synthesis, characterization and antifungal efficacy of C-coordinated O-carboxymethyl chitosan Cu(II) complexes

A novel type of O-carboxymethyl chitosan Schiff bases (O-CSPX) was synthesized via a condensation reaction. After the coordination reaction of cupric ions, Cu(II) complexes (O-CSPX-Cu) were achieved. The theoretical structure of O-CSPX-Cu calculated by Gaussian 09 reveals that the copper ions underwent dsp² hybridization, coordinated by the carbon atom in the p-π conjugate group and the oxygen atoms in the acetate ion. Then, the structures were confirmed by FT-IR, ¹H NMR, CP-MAS ¹³C NMR, elemental analysis, DSC and XRD. The antifungal properties of O-CSPX-Cu against Phytophthora capsici (P. capsici), Gibberella zeae (G. zeae) and Glomerella cingulata (G. cingulata) were evaluated at concentrations ranging from 0.05mg/mL to 0.20mg/mL. The experiments indicated that the derivatives have significantly enhanced antifungal activity after copper ion complexation compared with the original chitosan. Moreover, it was shown that 0.20mg/mL of O-CSP3-Cu and O-CSP4-Cu can 100% inhibit the growth of P. capsici. The experimental results reveal that the antifungal efficiency is related to the space steric hindrance on the benzene ring, which may provide a novel direction for the development of copper fungicides.

Targeted drug delivery of Sunitinib Malate to tumor blood vessels by cRGD-chiotosan-gold nanoparticles

The unique characteristics of tumor vasculature represent an attractive strategy for targeted delivery of antitumor and antiangiogenic agents to the tumor. The purpose of this study was to prepare c(RGDfK) labeled chitosan capped gold nanoparticles [cRGD(CS-Au) NPs] as a carrier for selective intracellular delivery of Sunitinib Malate (STB) to the tumor vasculature. cRGD(CS-Au) NPs was formed by electrostatic interaction between cationic CS and anionic AuNPs. cRGD modified CS-Au NPs had a spherical shape with a narrow size distribution. The entrapment efficiency of sunitinib molecule was found to be 45.2%±2.05. Confocal microscopy showed enhanced and selective uptake of cRGD(CS-Au) NPs into MCF-7 and HUVEC cells compared with non-targeted CS-Au NPs. Our results suggest that it may be possible to use cRGD(CS-Au) NPs as a carrier for delivery of anticancer drugs, genes and biomolecules for inhibiting tumor vasculature.

Probiotic-loaded microcapsule system for human in situ folate production: Encapsulation and system validation

This study focused on the use of a new system, an alginate|Ɛ-poly-l-lysine|alginate|chitosan microcapsule (APACM), able to immobilize a folate-producing probiotic, Lactococcus lactis ssp. cremoris (LLC), which provides a new approach to the utilization of capsules and probiotics for in situ production of vitamins. LLC is able to produce 95.25±26μg·L^-1 of folate, during 10h, and was encapsulated in the APACM. APACM proved its capacity to protect LLC against the harsh conditions of a simulated digestion maintaining a viable concentration of 6logCFU·mL^-1of LLC. A nutrients exchange capacity test, was performed using Lactobacillus plantarum UM7, a high lactic acid producer was used here to avoid false negative results. The production and release of 2g·L^-1 of lactic acid was achieved through encapsulation of L. plantarum, after 20h. The adhesion of APACM to epithelial cells was also quantified, yielding 38% and 33% of capsules adhered to HT-29 cells and Caco-2 cells, respectively.

Co-loading and intestine-specific delivery of multiple antioxidants in pH-responsive microspheres based on TEMPO-oxidized polysaccharides

In this study, pH-responsive microspheres loaded with multiple antioxidants were developed for intestine-specific delivery and exhibited synergistic activity. They consist of chitosan (CS)-coated microspheres made of TEMPO-oxidized Konjac glucomannan (OKGM) polymers, of which the carboxyl (COO^-) groups are cross-linked via ferric ions (Fe³⁺), allowing the hydrophobic (β-carotene) and hydrophilic (anthocyanins) antioxidants to be simultaneously incorporated. CLSM images showed successful co-encapsulation of β-carotene and anthocyanins. The in vitro release kinetics of co-loaded CS-OKGM microspheres in simulated GI fluids indicated that the microspheres retain the dual antioxidants in an acidic gastric environment and release them at intestinal pH. Free radical scavenging experiments demonstrated that multiple antioxidants loaded into OKGM system had synergistic activity with enhanced stability against heat. The multi-functional CS-OKGM microspheres showed great potential for multiple antioxidants and intestine-specific delivery with enhanced stability.

Functionalization of chitosan by a free radical reaction: Characterization, antioxidant and antibacterial potential

Chitosan was functionalized with epigallocatechin gallate (EGCG) by a free radical-induced grafting procedure, which was carried out by a redox pair (ascorbic acid/hydrogen peroxide) as the radical initiator. The successful preparation of EGCG grafted-chitosan was verified by spectroscopic (UV, FTIR and XPS) and thermal (DSC and TGA) analyses. The degree of grafting of phenolic compounds onto the chitosan was determined by the Folin-Ciocalteu procedure. Additionally, the biological activities (antioxidant and antibacterial) of pure EGCG, blank chitosan and EGCG grafted-chitosan were evaluated. The spectroscopic and thermal results indicate chitosan functionalization with EGCG; the EGCG content was 25.8mg/g of EGCG grafted-chitosan. The antibacterial activity of the EGCG grafted-chitosan was increased compared to pure EGCG or blank chitosan against S. aureus and Pseudomonas sp. (p<0.05). Additionally, EGCG grafted-chitosan showed higher antioxidant activity than blank chitosan. These results indicate that EGCG grafted-chitosan might be useful in active food packaging.

Effect of PEGylated chitosan as multifunctional stabilizer for deacetyl mycoepoxydience nanosuspension design and stability evaluation

Here a series of multifunctional stabilizers was designed and used in a nanosuspension stability enhancement study. Methoxypolyethylene glycol (M PEG)-grafted chitosan, accompanied by space steric hindrance, an electrostatic repulsion function, and a solvation effect, is a multifunctional stabilizer. Deacetyl mycoepoxydience (DM) nanosuspension was prepared using the anti-solvent precipitation approach. The effects of the DM and the multifunctional stabilizer concentration, solvent to anti-solvent ratio, crystallization and storage temperature, and ultrasonic time on drug particle formation during the anti-solvent processing were investigated and the nanosuspension stability was studied. The nanosuspension showed dendritic-like nanostructures and a crystalline state in a morphology and crystalline state study. The optimized drug and multifunctional stabilizer concentration range were selected through the response surface optimization method. The most appropriate and stable nanosuspension could be obtained through the optimal parameters. This study demonstrated that M PEG-grafted chitosan (M PEGC) could be used as a multifunctional stabilizer to control particle size and improve nanosuspension stability.

Development of chitosan/β-glycerophosphate/glycerol hydrogel as a thermosensitive coupling agent

This work develops a dual-function thermosensitive hydrogel to prevent overheating, a side effect of focused ultrasound therapy. The proposed hydrogel has the components of chitosan, β-glycerophosphate, and glycerol. Its thermosensitive sol-to-gel transition gives an instant signal of overheating without the need of any awkward sensing device. Impacts of varying component concentrations on the sol-to-gel temperature, rate, and degree of transparency are also investigated. Chemical structures and ultrasonic coefficients after heating are obtained with a Fourier transform infrared spectroscopy and ultrasonic measurement, respectively. Optimized formula of the proposed hydrogel is 0.5% chitosan, 5% β-glycerophosphate, and 25% glycerol. This hydrogel has a high acoustic impedance (Z=1.8 Mrayl) close to that of human skin, high ultrasonic transmission (T=99%, which is normalized to water) from 25 to 55°C, and low attenuation coefficient (α=4.0Np/m). These properties assure the success of dual functions of the hydrogel developed in this work.

Ethyl chitosan synthesis and quantification of the effects acquired after grafting it on a cotton fabric, using ANOVA statistical analysis

Three ethyl chitosans (ECSs) have been prepared using the ethyl chloride (AA) that was obtained in situ. Each ECS was applied on a 100% cotton fabric through a pad-dry-cure technology. Using the ANOVA as statistic method, the wrinkle-proofing effects have been determined varying the concentrations of AA (0.1-2.1mmol) and chitosan (CS) (0.1-2.1mmol). Alkylation and grafting mechanisms have been confirmed by the results of FTIR, (1)H NMR, XPS, SEM, DSC and termogravimetric analyses. The performances of each ECS as wrinkle-proofing agent have been revealed through quantitative methods (taking-up degree, wrinkle-recovering angle, tensile strength and effect's durability). The ECSs confer wrinkle-recovering angle and tensile strength higher than those of the witness sample. Durability of ECSs grafted on cotton have been demonstrated by a good capacity of dyeing with non-specific (acid/anionic and cationic) dyes under severe working conditions (100°C, 60min) and a good antimicrobial capacity.

Gastroretentive montmorillonite-tetracycline nanoclay for the treatment of Helicobacter pylori infection

The paper aims to explore the potential benefits provided by an organically modified montmorillonite (nanoclay) in the problematic management of the Helicobacter pylori gastric infection that is one of the most prevalent infectious diseases worldwide. Two nanoclay samples were produced by the intercalation of tetracycline (TC) into the interlayer of montmorillonite (MM) under two different pH reaction conditions (pH 3.0 and 8.7). MM/TC nanoclays were characterized by EDX, XRD, FTIR, DSC, drug adsorption extent, in vitro mucoadhesiveness and desorption in simulated gastric media. The reaction between MM and TC led to a complete MM cation (Na(+) and Ca(2+)) exchange process, an increase of MM characteristic interlayer spacing as well as an involvement of NHR3(+) group of TC, regardless of the reaction pH value. However, MM/TC nanoclay obtained under alkaline conditions provided a lower TC adsorption as well as a drug fraction weakly linked to MM in comparison with the nanoclay obtained in acidic conditions. Both the nanoclays exhibited good mucoadhesion properties to porcine mucin and TC desorption occurring mainly via a cation exchange process by H(+) ions. Based on the results obtained, TC intercalation into MM nanoplatelets could represent a potential advantageous approach allowing the antibiotic to distribute homogeneously on the gastric mucosa, diffuse through the gastric mucus layer and achieve the microorganism localization.

The supramolecular structure of LPS-chitosan complexes of varied composition in relation to their biological activity

The complexes of chitosan (Ch) with lipopolysaccharides (LPSs) from Escherichia coli O55:B5 (E-LPS) and Yersinia pseudotuberculosis 1B 598 (Y-LPS) of various weight compositions were investigated using quasi-elastic light scattering, ζ-potential distribution assay and atomic force microscopy. The alteration of ζ-potential of E-LPS-Ch complexes from negative to positive values depending on Ch content was detected. The Y-LPS-Ch complexes had similar positive ζ-potentials regardless of Ch content. The transformation of the supramolecular structure of E-LPS after binding with to Ch was revealed. Screening of E-LPS and Y-LPS particles by Ch in the complexes with high polycation was detected. The ability of LPS-Ch complex to induce biosynthesis of TNF-α and reactive oxygen species in stimulated human mononuclear cells was studied. A significant decrease in activity complexes compared to that of the initial LPS was observed only for E-LPS-Ch complexes.

Adsorption of uranium by amidoximated chitosan-grafted polyacrylonitrile, using response surface methodology

The amidoximated chitosan-grafted polyacrylonitrile (CTS-g-PAO) was prepared for the adsorption of uranium from water. The effects of pH, concentration of uranium and the solid-liquid ratio on the adsorption of uranium by CTS-g-PAO were optimized using Doehlert design of response surface methodology (RSM). The adsorption capacity and removal efficiency achieved 312.06 mg/g and 86.02%, respectively. The adsorption process attained equilibrium only in 120 min. More than 80% of the absorbed uranium could be desorbed by 0.1 mol/l HCl or EDTA-Na, and CTS-g-PAO could be reused at least 3 times. The CTS-g-PAO and U(VI) ions formed a chelate complex due to FTIR spectral analysis. The surface morphology of CTS-g-PAO was also investigated by SEM. The adsorption process was better described by Langmuir isotherm and pseudo second order kinetic model. Results obtained indicated that CTS-g-PAO was very promising in adsorption of uranium from water.

Glycerophosphate-based chitosan thermosensitive hydrogels and their biomedical applications

Chitosan is non-toxic, biocompatible and biodegradable polysaccharide composed of glucosamine and derived by deacetylation of chitin. Chitosan thermosensitive hydrogel has been developed to form a gel in situ, precluding the need for surgical implantation. In this review, the recent advances in chitosan thermosensitive hydrogels based on different glycerophosphate are summarized. The hydrogel is prepared with chitosan and β-glycerophosphate or αβ-glycerophosphate which is liquid at room temperature and transits into gel as temperature increases. The gelation mechanism may involve multiple interactions between chitosan, glycerophosphate, and water. The solution behavior, rheological and physicochemical properties, and gelation process of the hydrogel are affected not only by the molecule weight, deacetylation degree, and concentration of chitosan, but also by the kind and concentration of glycerophosphate. The properties and the three-dimensional networks of the hydrogel offer them wide applications in biomedical field including local drug delivery and tissue engineering.

Polysaccharide-based strategies for heart tissue engineering

Polysaccharides are abundant biomolecules in nature presenting important roles in a wide variety of living systems processes. Considering the structural and biological functions of polysaccharides, their properties have raised interest for tissue engineering. Herein, we described the latest advances in cardiac tissue engineering mediated by polysaccharides. We reviewed the data already obtained in vitro and in vivo in this field with several types of polysaccharides. Cardiac injection, intramyocardial in situ polymerization strategies, and scaffold-based approaches involving polysaccharides for heart tissue engineering are thus discussed.