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1.
Performance of synthesized cast and electrospun PVA/chitosan/ZnO-NH2 nano-adsorbents in single and simultaneous adsorption of cadmium and nickel ions from wastewater.
Bozorgi, M, Abbasizadeh, S, Samani, F, Mousavi, SE
Environmental science and pollution research international. 2018;(18):17457-17472
Abstract
The performance of synthesized cast and electrospun polyvinyl alcohol/chitosan/zinc oxide/aminopropyltriethoxylsilane (PVA/chitosan/ZnO-APTES) nano-adsorbents were compared in removal of Cd(II) and Ni(II) ions from wastewater. The adsorbents were characterized by SEM, BET, FTIR and TGA analyses. Furthermore, the swelling investigations were carried out to study the adsorbent stability in aqueous solution. The effect of several parameters such as contents of ZnO-NH2, contact time, initial Cd(II) and Ni(II) concentration and temperature on the adsorption capacity was investigated in a batch mode. In comparison with cast adsorbent, nanofiber adsorbent indicated the better adsorption performance. The experimental data well fitted the double-exponential kinetic model. In single metal ion system, the maximum adsorption capacity of nanofiber for Cd(II) and Ni(II) ions is estimated to be 1.239 and 0.851 mmol/g, respectively, much higher than qm of cast adsorbent for Cd(II) (0.625 mmol/g) and Ni(II) (0.474 mmol/g) ions. Thermodynamic parameters were investigated to identify the nature of adsorption process. In binary system of Cd(II)-Ni(II) ions, the inhibitory effect of competitive Cd(II) ion on the Ni(II) adsorption was greater than the inhibitory effect of competitive on the Cd(II) adsorption. The selectivity adsorption of both nanofiber and cast adsorbents was in order of Cd(II) > Ni(II).
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2.
Alpha tocopherol loaded chitosan oleate nanoemulsions for wound healing. Evaluation on cell lines and ex vivo human biopsies, and stabilization in spray dried Trojan microparticles.
Bonferoni, MC, Riva, F, Invernizzi, A, Dellera, E, Sandri, G, Rossi, S, Marrubini, G, Bruni, G, Vigani, B, Caramella, C, et al
European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V. 2018;:31-41
Abstract
An amphiphilic chitosan salt, chitosan oleate (CS-OA), was previously proposed for the physical stabilization of lemongrass antimicrobial nanoemulsions (NE) through a mild spontaneous emulsification process. As both chitosan and oleic acid are described in the literature for their positive effects in wound healing, in the present study CS-OA has been proposed to encapsulate alpha tocopherol (αTph) in NEs aimed to skin wounds. A NE formulation was developed showing about 220 nm dimensions, 36% drug loading, and αTph concentration up to 1 mg/ml. Both CS-OA and αTph NE stimulated cell proliferation on keratinocytes and fibroblast cell cultures, and in ex vivo skin biopsies, suggesting the suitability of CS-OA and of the antioxidant agent for topical application in wound healing. αTph stability was further improved with respect of encapsulation, by spray drying the NE into a powder (up to about 90% αTph residual after 3 months). The spray drying process was optimized, to improve powder yield and αTph recovery, by a design of experiments approach. The powder obtained was easily re-suspended to deliver the NE and resulted able to completely release αTph.
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3.
Successive grafting of poly(hydroxyethyl methacrylate) brushes and melamine onto chitosan microspheres for effective Cu(II) uptake.
Yuan, S, Zhang, P, Yang, Z, Lv, L, Tang, S, Liang, B
International journal of biological macromolecules. 2018;:287-302
Abstract
Cross-linked chitosan (CCS) microspheres tethered with melamine-conjugated poly(hydroxyethyl methacrylate) (PHEMA) brushes were synthesized by combination of surface-initiated atom transfer radical polymerization (ATRP) of HEMA and subsequent covalent immobilization of melamine onto the chain ends of PHEMA brushes. The as-synthesized CCS microsphere was used as a novel adsorbent for effective uptake of Cu(II) ions from aqueous solution. Success in each functionalization step was ascertained by SEM, ATR-FTIR and XPS characterization. Batch adsorption experimental results demonstrated that the adsorption equilibrium of Cu(II) ions on the melamine-grafted CCS microsphere was rapidly established within 20 min, and the adsorption process was found to be governed by intra-particle diffusion and chemisorption processes. The Langmuir-fitted maximum adsorption capacity of Cu(II) ions on the as-synthesized CCS microspheres was as high as circa 4.67 mmol L-1 (299 mg g-1). The calculated thermodynamic parameters revealed an endothermic and spontaneous adsorption process of Cu(II) ions on the melamine-grafted CCS microspheres. XPS spectra revealed that the adsorption mechanism was attributed to coordination (or chelation) interactions between amino (or hydroxyl) groups with cationic Cu(II) ions.
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4.
Chitosan oligosaccharides affect xanthone and VOC biosynthesis in Hypericum perforatum root cultures and enhance the antifungal activity of root extracts.
Badiali, C, De Angelis, G, Simonetti, G, Brasili, E, Tobaruela, EC, Purgatto, E, Yin, H, Valletta, A, Pasqua, G
Plant cell reports. 2018;(11):1471-1484
Abstract
Water-soluble chitosan oligosaccharides (COS) affect xanthone and volatile organic compound content, as well as antifungal activity against human pathogenic fungi of extracts obtained from Hypericum perforatum root cultures. Several studies have demonstrated the elicitor power of chitosan on xanthone biosynthesis in root cultures of H. perforatum. One of the major limitations to the use of chitosan, both for basic and applied research, is the need to use acidified water for solubilization. To overcome this problem, the elicitor effect of water-soluble COS on the biosynthesis of both xanthones and volatile organic compounds (VOCs) was evaluated in the present study. The analysis of xanthones and VOCs was performed by HPLC and GC-MS headspace analysis. The obtained results showed that COS are very effective in enhancing xanthone biosynthesis. With 400 mg L-1 COS, a xanthone content of about 30 mg g-1 DW was obtained. The antifungal activity of extracts obtained with 400 mg L-1 COS was the highest, with MIC50 of 32 µg mL-1 against Candida albicans and 32-64 µg mL-1 against dermatophytes, depending on the microorganism. Histochemical investigations suggested the accumulation of isoprenoids in the secretory ducts of H. perforatum roots. The presence of monoterpenes and sesquiterpenes was confirmed by the headspace analysis. Other volatile hydrocarbons have been identified. The biosynthesis of most VOCs showed significant changes in response to COS, suggesting their involvement in plant-fungus interactions.
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5.
The Multifunctional Role of Chitosan in Horticultural Crops; A Review.
Sharif, R, Mujtaba, M, Ur Rahman, M, Shalmani, A, Ahmad, H, Anwar, T, Tianchan, D, Wang, X
Molecules (Basel, Switzerland). 2018;(4)
Abstract
Chitosan is a naturally occurring compound and is commercially produced from seafood shells. It has been utilized in the induction of the defense system in both pre and post-harvest fruits and vegetables against fungi, bacteria, viruses, and other abiotic stresses. In addition to that, chitosan effectively improves the physiological properties of plants and also enhances the shelf life of post-harvest produces. Moreover, chitosan treatment regulates several genes in plants, particularly the activation of plant defense signaling pathways. That includes the elicitation of phytoalexins and pathogenesis-related (PR) protein. Besides that, chitosan has been employed in soil as a plant nutrient and has shown great efficacy in combination with other industrial fertilizers without affecting the soil's beneficial microbes. Furthermore, it is helpful in reducing the fertilizer losses due to its coating ability, which is important in keeping the environmental pollution under check. Based on exhibiting such excellent properties, there is a striking interest in using chitosan biopolymers in agriculture systems. Therefore, our current review has been centered upon the multiple roles of chitosan in horticultural crops that could be useful in future crop improvement programs.
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6.
Tripolyphosphate-crosslinked chitosan/poly (ethylene oxide) electrospun nanofibrous mats as a floating gastro-retentive delivery system for ranitidine hydrochloride.
Darbasizadeh, B, Motasadizadeh, H, Foroughi-Nia, B, Farhadnejad, H
Journal of pharmaceutical and biomedical analysis. 2018;:63-75
Abstract
The present study describes the fabrication of Tripolyphosphate (TPP)-crosslinked nanofibrous mats based on chitosan for use as a floating gastro-retentive delivery system. TPP-crosslinked chitosan (CH)/poly (ethylene oxide) (PEO)- ranitidine hydrochloride (RH) electrospun nanofibers (75.27 ± 2.10 nm) were prepared by electrospinning 70% v/v acetic acid solutions, and followed by crosslinking by TPP anions. The mechanical, structural and morphological properties of the prepared nanofibers were evaluated via tensile testing, XRD, FT-IR, TGA, NMR, AFM and SEM experimental techniques. The prepared nanofibrous mats showed a pH sensitive swelling profile with maximum water absorbing at pH 1.2. Results obtained from above experimental techniques indicated that crosslinking process did not significantly altered morphological property of nanofibers but rather decreased their diameter and swelling degree, and increased their mechanical properties, thermal stability and bioadhesive strength. Viscosity measurements showed that the addition of PEO and RH to the chitosan solution, depending to its concentration lead to decrease in the viscosity of its solution. Also, floating test showed that the prepared nanofibrous mats remain floated onto surface of the dissolution medium for more than 48 h. Based on in- vitro drug release data analysis, TPP-crosslinked CH/PEO nanofibrous mats decreased initial burst release and it was exhibited a sustained release profile for the RH from the TPP-crosslinked CH/PEO-RH electrospun nanofibrous mats.
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7.
Rheological behavior of pH responsive composite hydrogels of chitosan and alginate: Characterization and its use in encapsulation of citral.
Afzal, S, Maswal, M, Dar, AA
Colloids and surfaces. B, Biointerfaces. 2018;:99-106
Abstract
The pure and composite hydrogels of chitosan with sodium alginate were synthesized at various pH values and characterized by rheology and IR-spectroscopy. Chitosan shows gelation at neutral and basic pH while sodium alginate remains in solution form at all pH values. By careful adjustment of mixing weight fraction ratio and pH, an array of hydrogels with modulated structural dynamics and viscoelasticity, mechanical strength and encapsulation capacity were obtained. At acidic pH, a higher weight fraction of alginate increased the elasticity of the hydrogels while at basic pH more percentage of chitosan stabilized the hydrogel. Strongest composite hydrogels were obtained at acidic pH and gel strength decreased on increasing pH of the synthetic medium. The synthesized hydrogels were studied for their encapsulation capability towards Citral. The pure chitosan hydrogels showed maximum encapsulation capacity followed by the composite hydrogels prepared at neutral pH. This study highlights that a range of composite hydrogels with modified properties can be obtained by simple changes in experimental conditions exploiting physical interactions and can help in better understanding of niche of its applicability in research and industry.
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8.
Assessment of the Quorum Sensing Inhibition Activity of a Non-Toxic Chitosan in an N-Acyl Homoserine Lactone (AHL)-Based Escherichia coli Biosensor.
Qin, X, Emich, J, Goycoolea, FM
Biomolecules. 2018;(3)
Abstract
New approaches to deal with drug-resistant pathogenic bacteria are urgent. We studied the antibacterial effect of chitosans against an Escherichia coli quorum sensing biosensor reporter strain and selected a non-toxic chitosan to evaluate its quorum sensing (QS) inhibition activity and its effect on bacterial aggregation. To this end, chitosans of varying degree of acetylation (DA) (12 to 69%) and molecular weight (Mw) (29 to 288 kDa) were studied. Only chitosans of low DA (~12%) inhibited bacterial growth, regardless of their Mw. A chitosan with medium degree of polymerization (named MDP) DA30, with experimental DA 42% and Mw 115 kDa was selected for further QS inhibition and scanning electron microscopy (SEM) imaging studies. MDP DA30 chitosan exhibited QS inhibition activity in an inverse dose-dependent manner (≤12.5 µg/mL). SEM images revealed that this chitosan, when added at low concentration (≤30.6 µg/mL), induced substantial bacterial aggregation, whereas at high concentration (234.3 µg/mL), it did not. Aggregation explains the QS inhibition activity as the consequence of retardation of the diffusion of N-acylated homoserine lactones (AHLs).
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9.
Interaction between chitosan and its related enzymes: A review.
Shinya, S, Fukamizo, T
International journal of biological macromolecules. 2017;(Pt B):1422-1435
Abstract
Chitosan-related enzymes including chitosanases, exo-β-glucosaminidases, and enzymes having chitosan-binding modules recognize ligands through electrostatic interactions between the acidic amino acids in proteins and amino groups of chitosan polysaccharides. However, in GH8 chitosanases, several aromatic residues are also involved in substrate recognition through stacking interactions, and these enzymes consequently hydrolyze β-1,4-glucan as well as chitosan. The binding grooves of these chitosanases are extended and opened at both ends of the grooves, so that the enzymes can clamp a long chitosan polysaccharide. The association/dissociation of positively charged glucosamine residues to/from the binding pocket of a GH2 exo-β-glucosaminidase controls the p Ka of the catalytic acid, thereby maintaining the high catalytic potency of the enzyme. In contrast to chitosanases, chitosan-binding modules only accommodate a couple of glucosamine residues, predominantly recognizing the non-reducing end glucosamine residue of chitosan by electrostatic interactions and a hydrogen-bonding network. These structural findings on chitosan-related enzymes may contribute to future applications for the efficient conversion of the chitin/chitosan biomass.
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10.
An accurate coarse-grained model for chitosan polysaccharides in aqueous solution.
Tsereteli, L, Grafmüller, A
PloS one. 2017;(7):e0180938
Abstract
Computational models can provide detailed information about molecular conformations and interactions in solution, which is currently inaccessible by other means in many cases. Here we describe an efficient and precise coarse-grained model for long polysaccharides in aqueous solution at different physico-chemical conditions such as pH and ionic strength. The Model is carefully constructed based on all-atom simulations of small saccharides and metadynamics sampling of the dihedral angles in the glycosidic links, which represent the most flexible degrees of freedom of the polysaccharides. The model is validated against experimental data for Chitosan molecules in solution with various degree of deacetylation, and is shown to closely reproduce the available experimental data. For long polymers, subtle differences of the free energy maps of the glycosidic links are found to significantly affect the measurable polymer properties. Therefore, for titratable monomers the free energy maps of the corresponding links are updated according to the current charge of the monomers. We then characterize the microscopic and mesoscopic structural properties of large chitosan polysaccharides in solution for a wide range of solvent pH and ionic strength, and investigate the effect of polymer length and degree and pattern of deacetylation on the polymer properties.