Crosslinking chitosan

Gupta et al. prepared crosslinked chitosan microspheres by dropping a polysaccharide solution into a methanolic solution of NaOH and then adding a solution of glutaraldehyde for crosslinking. They demonstrated that the obtained microspheres were non-toxic and biodegradable, and therefore may be considered suitable candidates for oral drug delivery [130]. 

Radical-induced Ce, KjSjOj, Fenton s reagent (Fe + + H O ), tributyl borane Acrylonitrile, N-isopropyl acrylamide, methyl methacrylate, vinyl monomers 

Radiation-induced y-rays, Co Styrene, 2-hydroxyethyl methacrylate Polyacryl-amide 

Microwave irradiation Grafting onto method Various catalysts are used [4,4 -Azobis (4-cyanovaleric acid)] Telechelic polymers, polyethylene glycol, poly-dimethyl siloxane 

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Chitosan crosslinked with dimethyl 3-3, dithio bis (propionimidate) (CS-DTBP) or glutaraldehyde (CS-GA) Cytotoxicity test Human dermal fibroblast cells in the presence of leachate from different chitosan scaffolds (chitosan, CS-GA and CS-DTBP) The number of cells that grew in the leachate from the CS-DTBP sample was significantly higher than the number of cells in the leachate from the CS-GA sample DTBP-crosslinked chitosan is less toxic than CS-GA scaffolds Adekogbe and Ghanem [80]... 

On the other hand, we already described the study of C-13 NMR and X-ray photoelectron spectral analysis for chitosan to clarify the electronic structure in the formation of properties of biological molecule from the DFT calculations [3] and to understand the changes in adsorption behavior of chemically modified biopolymer chitosan (crosslinked biopolymer) [4],... 

Wang, W., Lin, S., Xiao, Y. et al. 2008. Acceleration of diabetic wound healing with chitosan-crosslinked collagen sponge containing recombinant human acidic fibroblast growth factor in healing-impaired STZ... 

Nasal delivered antigenic mncoadhesive nanoparticles, made up of N-trimethyl chitosan crosslinked (TMC) with tripolyphosphate (TPP) has been confirmed to overcome certain obstacles faced during nasal delivery such as poor absorption and... 

Without using an anionic polymer, chitosan crosslinks ionically with polyphosphoric acid and forms a gel. The release behavior from a methotrexate-containing gelatin capsule, which is coated with this gel, has been investigated in a model stomach or intestinal fluids [40]. 

Mahkam et al. modified chitosan crosslinked starch polymers for oral insulin delivery. Increasing the chitosan content in the copol5mier enhanced the hydrolysis in the SIF and thus led to slower release in intestinal pH [29]. 

Cross-linking agents have been proposed for the improvement of chitin fibres in the wet state. Epichlorohydrin is a convenient base-catalysed crosslinker to be used in 0.067 M NaOH (pH 10) at 40 °C. The wet strength of the fibres was considerably improved, whereas cross-hnking had neghgible effect on the dry fibre properties. Of course, the more extended the chemical modification, the more unpredictable the biochemical characteristics and effects in vivo. Every modified chitin or modified chitosan fibre should be studied in terms of biocompatibiUty, biodegradabiUty and overall effects on the wounded tissues. 

The selective dense layer of hydrophilic membranes is made from different polymers with a high affinity for water. These polymers contain ions, oxygen functions like hydroxyl, ester, ether or carboxylic moieties, or nitrogen as imino or imi-do groups. Preferred hydropilic polymers are polyvinylalcohol (PVA) [32], poly-imides, cellulose acetate (CA) or natural polymers like chitosan [33] or alginates. Organophilic membranes usually consist of crosslinked silicones, mostly polydimethyl siloxane (PDMS) or polymethyl octyl siloxane (POMS). 

The process does not stabilize the removed heavy metals, additional treatment is required for recycling or disposal of the removed ions. The crosslinking process renders the chitosan beads insoluble in dilute acid but reduces compression strength and adsorption capacity relative to the uncrosslinked chitosan adsorbent bead. Adsorption capacity of chitosan is reduced as pH decreases. 

Subramanian, A. and Lin, H. Y. (2005). Crosslinked chitosan Its physical properties and the effects of matrix stiffness on chondrocyte cell morphology and proliferation. ]. Biomed. Mater. Res. 75A, 742-753. 

In addition to ABS, membranes using a polymer blend of chitosan and ABS with glutaraldehyde as a crosslinking agent have been used as coating materials for PES ultrafiltration membranes (90). 

Berger J, Reist M, Mayer JM, Felt O, Peppas NA, Gurny R. Structure and interactions in covalently and ionically crosslinked chitosan hydrogels for biomedical applications. European Journal of Pharmaceutics and Biopharmaceutics 2004, 57, 19-34. 

Cetinus SA, Oztop HN (2003) Immobilization of catalase into chemically crosslinked chitosan heads. Enzyme Microb Technol 32 889-894... 

Remunan-Lopez C, Bodmeier R (1997) Mechanical, water uptake and permeability properties of crosslinked chitosan glutamate and alginate films. J Control Rel 44 215-225... 

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