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Polyelectrolyte complexes (PEC) of chitosan and ulvan were fabricated to study alkaline phosphatase (ALP) mediated formation of apatitic minerals. Scaffolds of the PEC were subjected to ALP and successful mineral formation was studied using SEM, Raman and XRD techniques. Investigation of the morphology via SEM shows globular structures of the deposited minerals, which promoted cell attachment, proliferation and extracellular matrix formation. The PEC and their successful calcium phosphate based mineralization offers a greener route of scaffold fabrication towards developing resorbable materials for tissue engineering., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Porous biodegradable scaffolds represent promising candidates for tissue-engineering applications because of their capability to be preseeded with cells. We report an uncrosslinked chitosan scaffold designed with the aim of inducing and supporting enzyme-mediated formation of apatite minerals in the absence of osteogenic growth factors. To realize this, natural enzyme alkaline phosphatase (ALP) was incorporated into uncrosslinked chitosan scaffolds. The uncrosslinked chitosan makes available amine and alcohol functionalities to enhance the biomineralization process. The physicochemical findings revealed homogeneous mineralization, with the phase structure of the formed minerals resembling that of apatite at low mineral concentrations, and similar to dicalcium phosphate dihydrate (DCPD) with increasing ALP content. The MC3T3 cell activity clearly showed that the mineralization of the chitosan scaffolds was effective in improving cellular adhesion, proliferation and colonization. Copyright © 2015 John Wiley & Sons, Ltd., (Copyright © 2015 John Wiley & Sons, Ltd.)

Chitosan is a non-toxic, biocompatible, biodegradable natural cationic polymer known for its low imunogenicity, antimicrobial, antioxidant effects and wound-healing activity. To improve its therapeutic potential, new chitosan-sulfonamide derivatives have been designed to develop new wound dressing biomaterials. The structural, morphological and physico-chemical properties of synthesized chitosan derivatives were analyzed by FT-IR, (1)H NMR spectroscopy, scanning electron microscopy, swelling ability and porosity. Antimicrobial, in vivo testing and biodegradation behavior have been also performed. The chitosan derivative membranes showed improved swelling and biodegradation rate, which are important characteristics required for the wound healing process. The antimicrobial assay evidenced that chitosan-based sulfadiazine, sulfadimethoxine and sulfamethoxazole derivatives were the most active. The MTT assay showed that some of chitosan derivatives are nontoxic. Furthermore, the in vivo study on burn wound model induced in Wistar rats demonstrated an improved healing effect and enhanced epithelialization of chitosan-sulfonamide derivatives compared to neat chitosan. The obtained results strongly recommend the use of some of the newly developed chitosan derivatives as antimicrobial wound dressing biomaterials., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The objective of this study was to develop new films based on chitosan functionalized with sulfonamide drugs (sulfametoxydiazine, sulfadiazine, sulfadimetho-xine, sulfamethoxazol, sulfamerazine, sulfizoxazol) in order to enhance the biological effects of chitosan. The morphology and physical properties of functionalized chitosan films as well the antioxidant effects of sulfonamide-chitosan derivatives were investigated. The chitosan-derivative films showed a rough surface and hydrophilic properties, which are very important features for their use as a wound dressing. The film based on chitosan-sulfisoxazol (CS-S6) showed the highest swelling ratio (197%) and the highest biodegradation rate (63.04%) in comparison to chitosan film for which the swelling ratio was 190% and biodegradation rate was only 10%. Referring to the antioxidant effects the most active was chitosan-sulfamerazine (CS-S5) which was 8.3 times more active than chitosan related to DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging ability. This compound showed also a good ferric reducing power and improved total antioxidant capacity.

Injectable hydrogels for bone regeneration consisting of chitosan, sodium beta-glycerophosphate (Na-β-GP) and alkaline phosphatase (ALP) were enriched with the polyphenols phloroglucinol (PG) and gallic acid (GA) and characterized physicochemically and biologically with respect to properties relevant for applications in bone regeneration, namely gelation kinetics, mineralizability, antioxidant properties, antibacterial activity, cytocompatibility and ability to support adhesion and growth of human osteoblast-like MG63 cells. Enrichment with PG and GA had no negative effect on gelation kinetics and mineralizability. PG and GA both enhanced antioxidant activity of unmineralized hydrogels. Mineralization reduced antioxidant activity of hydrogels containing GA. Hydrogels containing GA, PG and without polyphenols reduced colony forming ability of Escherichia coli after 1h, 3h and 6h incubation and slowed E. coli growth in liquid culture for 150min. Hydrogels containing GA were cytotoxic and supported cell growth more poorly than polyphenol-free hydrogels. PG had no negative effect on cell adhesion and growth., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

New xanthine derivatives as antidiabetic agents were synthesized and new chitosan formulations have been developed in order to improve their biological and pharmacokinetic profile. Their physicochemical properties in terms of particle size, morphology, swelling degree, crystalline state, the loading efficiency as well as in vitro release and biodegradation rate were evaluated. According to the results the optimized formulations have a high drug loading efficiency (more than 70%), small particle size, a good release profile in the simulated biological fluids (the percentage of cumulative release being more than 55%) and improved biodegradation rate in reference with chitosan microparticles. The presence of xanthine derivatives (6, 7) in chitosan microparticles was demonstrated by means of FTIR analysis. The X-ray diffraction (XRD) proved that xanthine derivatives present a crystalline state. The biological evaluation assays confirmed the antioxidant and antidiabetic effects of the xanthine derivatives (6, 7) and their chitosan formulations (CS-6, CS-7). Xanthine derivative 6 showed a high antiradical scavenging effect (DPPH remaining=41.78%). It also reduced the glucose blood level with 59.30% and recorded level of glycosylated hemoglobin was 4.53%. The effect of its chitosan formulation (CS-6) on the level of blood glucose (114.5mg/dl) was even more intense than the one recorded by pioglitazone (148.5mg/dl) when used as standard antidiabetic drug. These results demonstrated the potential application of xanthine derivative 6 and its chitosan formulation (CS-6) in the treatment of the diabetes mellitus syndrome., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Keywords: polyphenol; chitosan; antioxidant; oxidative stress; human health EN polyphenol chitosan antioxidant oxidative stress human health 1768 23 11/17/22 20221101 NES 221101 1. Addition of NHS forms a stable active intermediate, unlike the previous one, which then reacts with chitosan's amino or hydroxyl group to form chitosan-polyphenol conjugate (Figure 4B). The flow diagram of the limitations and advantages of chitosan, polyphenols, and chitosan-polyphenol conjugates is given in Figure 3. Chitosan-Polyphenol Conjugates Chitosan-polyphenol conjugates impart properties of both components with high efficiency; however, both chitosan and polyphenol possess some disadvantages, such as poor solubility, dietary metabolism, and poor availability of H-atom donor etc., when used alone [[85]]. The therapeutic efficacy of chitosan-polyphenols is attributed to the presence of an active amine group in chitosan and phenolic hydroxyl groups of polyphenols. [Extracted from the article]

The objective of this study was to develop new films based on chitosan functionalized with sulfonamide drugs (sulfametoxydiazine, sulfadiazine, sulfadimetho-xine, sulfamethoxazol, sulfamerazine, sulfizoxazol) in order to enhance the biological effects of chitosan. The morphology and physical properties of functionalized chitosan films as well the antioxidant effects of sulfonamide-chitosan derivatives were investigated. The chitosan-derivative films showed a rough surface and hydrophilic properties, which are very important features for their use as a wound dressing. The film based on chitosan-sulfisoxazol (CS-S6) showed the highest swelling ratio (197%) and the highest biodegradation rate (63.04%) in comparison to chitosan film for which the swelling ratio was 190% and biodegradation rate was only 10%. Referring to the antioxidant effects the most active was chitosan-sulfamerazine (CS-S5) which was 8.3 times more active than chitosan related to DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging ability. This compound showed also a good ferric reducing power and improved total antioxidant capacity. [ABSTRACT FROM AUTHOR]

Angiogenesis is a physiological process involving the growth of new blood vessels, which provides oxygen and required nutrients for the development of various pathological conditions. In a tumor microenvironment, this process upregulates the growth and proliferation of tumor cells, thus any stage of angiogenesis can be a potential target for cancer therapies. In the present study, chitosan and his derivatives have been used to design novel polymer-based nanoparticles. The therapeutic potential of these newly designed nanoparticles has been evaluated. The antioxidant and MTT assays were performed to know the antioxidant properties and their biocompatibility. The in vivo antiangiogenic properties of the nanoparticles were evaluated by using a chick Chorioallantoic Membrane (CAM) model. The obtained results demonstrate that chitosan derivatives-based nanostructures strongly enhance the therapeutic effect compared to chitosan alone, which also correlates with antitumor activity, demonstrated by the in vitro MTT assay on human epithelial cervical Hep-2 tumor cells. This study opens up new direction for the use of the chitosan derivatives-based nanoparticles for designing of antiangiogenic nanostructured materials, for future cancer therapy. [ABSTRACT FROM AUTHOR]

Hydrogels mineralized with calcium phosphate (CaP) are increasingly popular bone regeneration biomaterials. Mineralization can be achieved by phosphatase enzyme incorporation and incubation in calcium glycerophosphate (CaGP). Gellan gum (GG) hydrogels containing the enzyme phytase and chitosan oligomer were mineralized in CaGP solution and characterized with human osteoblast-like MG63 cells and adipose tissue-derived stem cells (ADSC). Phytase induced CaP formation. Chitosan concentration determined mineralization extent and hydrogel mechanical reinforcement. Phytase-induced mineralization promoted MG63 adhesion and proliferation, especially in the presence of chitosan, and was non-toxic to MG63 cells (with and without chitosan). ADSC adhesion and proliferation were poor without mineralization. Chitosan did not affect ADSC osteogenic differentiation. [ABSTRACT FROM AUTHOR]