Search results

1

Quaternary ammonium salt of chitosan: preparation and antimicrobial property for paper

100%

Liu P., Meng W., Wang S., Sun Y., Aqeel Ashraf M.

Open Medicine

|

2014

|

vol. 10

|

issue 1

EN

A series of 2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC) was prepared by the reaction of chitosan with glycidyl trimethyl ammonium chloride. Structure of HACC was characterized by FT IR and 1H NMR spectroscopies, and it was proved that substitution reaction mainly occurs on the N element. Antimicrobial activities of HACC was examined against S. aureus, E. coli, and A. niger. Results indicatd that the inhibitory effects of HACC solutions were varied with HACC concentration, quaternization degrees, pH values, metal ions, and heat treatment. The antimicrobial properties of handsheets prepared from HACC were studied by the inhibition zone method, and the sheets had good antimicrobial properties against S. aureus and E. coli, and low inhibition rate against A. niger.

2

Synthesis and characterization of thermoresponsive hydrogels cross-linked with chitosan

100%

Yu Y., Chang X., Ning H., Zhang S.

Open Chemistry

|

2008

|

vol. 6

|

issue 1

107-113

EN

Hydrogels composed of N-isopropylacrylamide (NIPAAm) and acrylic acid (AAc) were prepared by redox polymerization with degradable chitosan cross-linkers. Chitosan degradable cross-linkers were synthesized by the acrylation of the amine groups of glucosamine units within chitosan and characterized with 1H NMR. With the chitosan cross-linkers, loosely cross-linked poly(N-isopropylacryamideco-acrylic acid) [P(NIPAAm-co-AAc)] hydrogels were prepared, and their phase transition behavior, lower critical solution temperature (LCST), water content and degradation properties were investigated. The chitosan cross-linked P(NIPAAm-co-AAc) hydrogels were pliable and transparent at room temperature. The LCST could be adjusted at 32∼39°C by alternating the feed ratio. Swelling was influenced by NIPAAm/AAc monomer ratio, cross-linking density, swelling media, and temperature. All hydrogels with different feeding ratios contained more than 95% water at 25°C in the ultra pure water and phosphate-buffered saline (PBS, pH = 7.4 ± 0.1), and had a prospective swelling in the simulated gastric fluids (SGF, pH = 1.2) > 72.54%. In degradation studies, breakdown of the chitosan cross-linked P(NIPAAm-co-AAc) hydrogels was dependent on the cross-linking density. The chitosan cross-linked P(NIPAAm-co-AAc) hydrogels which can be tailored to create environmentally-responsive artificial extracellular materials have great potential for future use. [...]

3

COMBINED MICROWAVE-ASSISTED SUBCRITICAL LIQUID EXTRACTION OF CHITOSAN FROM CRAB SHELL WASTE

100%

Segaran R., Omar R., Kusumastuti Y., Harun R., Kamal S. M. M.

Progress on Chemistry and Application of Chitin and its Derivatives

|

2022

|

vol. 27

204-216

EN

Current chitosan extraction methods require a highly concentrated alkaline solvent that is costly and environmentally unfriendly. This study aimed to assess the potential of using subcritical liquid deproteination to produce amorphous chitin to reduce the alkaline concentration during the deacetylation step to obtain high-quality chitosan. A combination of microwave-assisted demineralisation, subcritical liquid (SL) deproteination, and conventional deacetylation was employed for chitosan production. Distilled water and 2% and 4% sodium hydroxide (NaOH) were used at subcritical liquid treatment temperatures of 100 to 250°C. Meanwhile, deacetylation using 20%-50% NaOH was attempted on the deproteinised chitin. 1.8 M hydrochloric acid at a 1:10 solid-to-liquid solvent ratio produced chitin with acceptable quality during microwave-assisted demineralisation. Demineralised chitin subjected to SL treatment at 150°C and 4% NaOH had the best protein removal (84.6%). Chitosan with a high degree of deacetylation (80.68%) was obtained at a lower alkalinity of 30% NaOH, derived from SL-deproteinised chitin (4% NaOH at 100°C). The crystallinity of chitin after SL treatment was reduced significantly from 72.4% to 59.4%, which allows easier access for the solvent to hydrolyse the acetamide bond. This study confirms that good quality chitosan can be produced by utilising SL treatment of demineralised chitin at a significantly short time and lower deacetylation solvent concentration.

4

Multifunctional PEG-grafted chitosan copolymer possessing amino and carboxyl (or formyl) groups

100%

Liu C., Wu Y., Wang X., Hu Z., Luo S.

Open Chemistry

|

2010

|

vol. 8

|

issue 3

576-581

EN

New multifunctional PEG-grafted chitosan copolymers possessing both amino and carboxyl (4) or formyl (5) groups were synthesized by the grafting reaction method between chitosan and heterobifunctional PEG from anionic polymerization of ethylene oxide. Completion of the reactions and characterization of the resulting polymers were demonstrated by 1H NMR, FT-IR and GPC studies. The multifunctional polymers may have potential utility in gene/drug co-delivery or heterogeneous catalysis.

5

CYTOTOXICITY OF CHITOSAN BASED THERMO-SENSITIVE HYDROGELS INTENDED FOR NERVOUS TISSUE ENGINEERING

100%

Nawrotek K., Modrzejewska Z., Paluch D., Zarzycki R., Rusak A.

Progress on Chemistry and Application of Chitin and its Derivatives

|

2015

|

vol. 20

222-235

EN

The damage to the central nervous system is one of the most difficult cases of trauma to treat. Over the last few years, increasing attention has been focused on the development of strategies based on biomaterials for regeneration and repair of the spinal cord injury. In particular, materials in the form of hydrogels based on chitosan are being actively investigated due to their intrinsic properties that are favorable in spinal cord tissue regeneration. The purpose of this study was to develop a thermo-gelling chitosan solution that will be prepared with the use of acids that naturally occur in the human nervous tissue. For this purpose, two types of chitosan gels were prepared based on chitosan glutamate and chitosan lactate. In order to reduce toxic action of the system obtained gels were conditioned in distilled water with pH 5.00. The changes in the structures of systems obtained were determined with the use of FTIR method. Biocompatibility was primarily evaluated through cytotoxicity testing by MTT assay with respect to mouse fibroblast cells.

6

INFLUENCE OF INITIAL STATE OF CHITOSAN MEMBRANES ON THEIR SEPARATION PROPERTIES IN PERVAPORATIVE DEHYDRATION

88%

Gnus M.

Progress on Chemistry and Application of Chitin and its Derivatives

|

2022

|

vol. 27

92-105

EN

In this study, membranes from chitosan with different molecular weights (175-230 kDa) and degree of deacetylation (92%-98%) were prepared and dehydration of a ethanol-water azeotropic mixture by pervaporation on membranes in the swollen and dry initial state was investigated. The influence of chitosan characteristics and the effect of the initial membrane state on separation properties are discussed. The structure of the obtained membranes changed during the drying process and affected the membrane transport parameters and time to membrane stabilisation. The impact of chitosan characteristics on the transport parameters depended on the initial membrane state. The chitosan molecular weight influenced ethanol transport, whereas the chitosan degree of deacetylation affected water transport. In addition, chitosan with the lowest molecular weight improved the separation properties of the membranes.

7

Physico-chemical properties of Chitosan films

75%

Balau L., Lisa G., Popa M., Tura V., Melnig V.

Open Chemistry

|

2004

|

vol. 2

|

issue 4

638-647

EN

Chitosan films obtained by dry phase inversion were prepared from an aqueous solution of chitosan in acetic acid. The films, of thickness less than 20 μm, were transparent, very flexible and had smooth surfaces. Increasing the film thickness induced an increase of the internal tensions and the consequent formation of a rough surface. Structural investigations by X-ray diffraction and Fourier transform IR analysis, showed that the chitosan films, as prepared, are amorphous. Further annealing to evaporate acetic acid and water traces, changed the amorphous phase into a more ordered phase, characterized by diffraction peaks at 2θ values of 9, 17, 20 and 23 degrees. Thermal investigations by TG, DTG, and DTA revealed that the decomposition of the chitosan films as prepared proceeds in two stages, starting from 180°C and 540°C.

8

FUNCTIONAL THREE-COMPONENT POLYMERIC BIOCOMPOSITES FOR THE TREATMENT OF BEDSORES

75%

Wiśniewska-Wrona M., El Fray M.

Progress on Chemistry and Application of Chitin and its Derivatives

|

2018

|

vol. 23

185 - 206

EN

Presented here are the results of investigations into the preparation of three-component dressing materials from various biopolymers in the form of a single-layer film which is suitable as a carrier for pain-relieving (lidocaine) and bacteriostatic (sulphanilamid) therapeutic agents. Physical-chemical, biological and usable properties of the prepared materials were tested and assessed. The amount of added active substance was adopted based on the dose recommended by the Polish Pharmacopeia for external medicinal preparations. Antibacterial activity against gram (-) Escherichia coli and gram (+) Staphylococcus aureus was assessed in some of the biocomposites by quantitative methods. The cytotoxic action in direct contact with the mouse fibroblast NCTC clone 929 was also estimated. Thermal analysis (DSC), infrared spectrophotometry (FTIR) and nuclear magnetic resonance spectroscopy were employed to investigate the impact of the variable contents of chitosan, alginate, carboxymethyl cellulose (CMC), and the active substance upon the chemical- and phase-structure of the prepared three-component polymeric biocomposites. It was found that the quantitative composition of the biocomposites and the additive of active substances lidocaine and sulphanilamide exert a vital impact upon their physical-mechanical and usable properties (imbibition, absorption). Investigations into the release of the medicinal substance from the investigated biocomposites to an acceptor fluid led to the conclusion that the kinetics of the process may be described by a complex first order rate equation with two exponential functions.

Refine search results

Quaternary ammonium salt of chitosan: preparation and antimicrobial property for paper

Synthesis and characterization of thermoresponsive hydrogels cross-linked with chitosan

COMBINED MICROWAVE-ASSISTED SUBCRITICAL LIQUID EXTRACTION OF CHITOSAN FROM CRAB SHELL WASTE

Multifunctional PEG-grafted chitosan copolymer possessing amino and carboxyl (or formyl) groups

CYTOTOXICITY OF CHITOSAN BASED THERMO-SENSITIVE HYDROGELS INTENDED FOR NERVOUS TISSUE ENGINEERING

INFLUENCE OF INITIAL STATE OF CHITOSAN MEMBRANES ON THEIR SEPARATION PROPERTIES IN PERVAPORATIVE DEHYDRATION

Physico-chemical properties of Chitosan films

FUNCTIONAL THREE-COMPONENT POLYMERIC BIOCOMPOSITES FOR THE TREATMENT OF BEDSORES