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A-βcyclodextrin/siloxane hybrid polymer: synthesis, characterization and inclusion complexes
Abbehausen, Camilla;Formiga, André L. B.;Sabadini, Edvaldo;Yoshida, Inez V. P.;
Journal of the Brazilian Chemical Society , 2010, DOI: 10.1590/S0103-50532010001000011
Abstract: a hybrid polymer derived from siloxane and β-cyclodextrin (β-cd) was obtained by reaction of β-cd with g-isocyanatopropyltriethoxysilane (ipts), followed by hydrolysis/condensation reactions, generating a β-cd-modified polysilsesquioxane resin (pss-β-cd). pss-β-cd hybrid was characterized by infrared spectroscopy and 13c and 29si nuclear magnetic resonance. this hybrid was typically amorphous and thermally stable up to 180 oc. pss-β-cd was able to form films and its morphology was evaluated by scanning electron microscopy. the capability of β-cd grafted in the hybrid polymer to form inclusion complex was evaluated by the formation of a β-cd-phenolphthalein complex using uv-vis spectroscopy. even without changes in ph, the red form of phenolphthalein converts to the colorless one when pss-β-cd is immersed in the solution. theoretical calculations (am1 and dft methods) show that the complex is formed through the inclusion of the phenolate ring into β-cd cavity, favoring the colorless form of phenolphthalein by more than 15 kcal mol-1.
Preparation, characterization and antimicrobial studies of chitosan/silica hybrid polymer
Selvakumar Dhanasingh,Mallesha,Jagannath Jambur Hiriyannaiah
Biointerface Research in Applied Chemistry , 2011,
Abstract: Organic/inorganic hybrid polymer systems based on chitosan/silica have gained much importance due to their application in enzyme immobilization, sensors and as novel biomaterials. The present study involves the preparation, characterization and antimicrobial studies of chitosan/silica hybrid polymers incorporated with disodium salt of ethylene diamine tetraacetic acid (EDTA) as non-reactive cross-linker, propylene glycol as plasticizer to enhance film forming properties and glutaraldehyde as cross-linking agent. The free standing films were studied by infrared spectroscopy, thermal studies, scanning electron microscopy and X-ray diffraction. The studies indicate that hybrids with 30% silica are the most compatible with chitosan and their physical and thermal properties are dependent on the amount of silica, EDTA, propylene glycol and gluteraldehyde. The films and hybrid polymer coated cotton fabrics were found to have good antimicrobial performance against Bacillus cereus and Escherichia coli.
Antimicrobial chitosan–PVA hydrogel as a nanoreactor and immobilizing matrix for silver nanoparticles
Shekhar Agnihotri,Soumyo Mukherji,Suparna Mukherji
Applied Nanoscience , 2012, DOI: 10.1007/s13204-012-0080-1
Abstract: Hydrogels are water-insoluble crosslinked hydrophilic networks capable of retaining a large amount of water. The present work aimed to develop a novel chitosan–PVA-based hydrogel which could behave both as a nanoreactor and an immobilizing matrix for silver nanoparticles (AgNPs) with promising antibacterial applications. The hydrogel containing AgNPs were prepared by repeated freeze–thaw treatment using varying amounts of the crosslinker, followed by in situ reduction with sodium borohydride as a reducing agent. Characterization studies established that the hydrogel provides a controlled and uniform distribution of nanoparticles within the polymeric network without addition of any further stabilizer. The average particle size was found to be 13 nm with size distribution from 8 to 21 nm as per HR-TEM studies. Swelling studies confirmed that higher amount of crosslinker and silver incorporation inside the gel matrices significantly enhanced the porosity and chain entanglement of the polymeric species of the hydrogel, respectively. The AgNP-hydrogel exhibited good antibacterial activity and was found to cause significant reduction in microbial growth (Escherichia coli) in 12 h while such activity was not observed for the hydrogel without AgNPs.
Chitosan-Based Hyaluronic Acid Hybrid Polymer Fibers as a Scaffold Biomaterial for Cartilage Tissue Engineering  [PDF]
Norimasa Iwasaki,Yasuhiko Kasahara,Shintarou Yamane,Tatsuya Igarashi,Akio Minami,Shin-ichiro Nisimura
Polymers , 2011, DOI: 10.3390/polym3010100
Abstract: An ideal scaffold material is one that closely mimics the natural environment in the tissue-specific extracellular matrix (ECM). Therefore, we have applied hyaluronic acid (HA), which is a main component of the cartilage ECM, to chitosan as a fundamental material for cartilage regeneration. To mimic the structural environment of cartilage ECM, the fundamental structure of a scaffold should be a three-dimensional (3D) system with adequate mechanical strength. We structurally developed novel polymer chitosan-based HA hybrid fibers as a biomaterial to easily fabricate 3D scaffolds. This review presents the potential of a 3D fabricated scaffold based on these novel hybrid polymer fibers for cartilage tissue engineering.
Matrix Assisted Formation of Ferrihydrite Nanoparticles in a Siloxane/Poly(Oxyethylene) Nanohybrid  [PDF]
Nuno J. O. Silva,Vitor S. Amaral,Veronica de Zea Bermudez,Silvia C. Nunes,Denis Ostrovskii,Joao Rocha,Luis D. Carlos
Physics , 2004,
Abstract: Matrix-assisted formation of ferrihydrite, an iron oxide hydroxide analogue of the protein ferritin-core, in a sol-gel derived organic-inorganic hybrid is reported. The hybrid network (named di-ureasil) is composed of poly(oxyethylene) chains of different average polymer molecular weights grafted to siloxane domains by means of urea cross-linkages and accommodates ferrihydrite nanoparticles. Magnetic measurements, Fourier transform infrared and nuclear magnetic resonance spectroscopy reveal that the controlled modification of the polymer molecular weight allows the fine-tuning of the ability of the hybrid matrix to assist and promote iron coordination at the organic-inorganic interface and subsequent nucleation and growth of the ferrihydrite nanoparticles whose core size (2-4 nm) is tuned by the amount of iron incorporated. The polymer chain length, its arrangement and crystallinity, are key factors on the anchoring and formation of the ferrihydrite particles.
SENSING PROPERTIES OF HYBRID POLYMERIC FILMS OBTAINED BY SOL-GEL
Martínez,Y.; Retuert,J.; Yazdani-Pedram,M.;
Journal of the Chilean Chemical Society , 2004, DOI: 10.4067/S0717-97072004000200004
Abstract: hybrid nanocomposites based on siloxane sols, chitosan and poly(monomethyl itaconate) (pmmi) as organic polymer counterparts were prepared. tetraethyl ortosilicate was used as inorganic network forming reagent that was first transformed into soluble polymeric species by acid catalyzed hydrolysis and condensation reactions. the siloxane sol was then mixed with different amounts of pmmi and chitosan at room temperature to form the hybrid material. these hybrid materials could be easily cast as transparent and flexible films. atomic force microscopy study showed that the organic components are more or less homogeneously distributed at nanometer scale. the hybrid films were used as membranes for the construction of all-solid-state type potentiometric electrodes. the ion-sensing capacity of the nanocomposite was tested for different anions and the best results were obtained for no3-. it was concluded that the -nh3+hcoo- groups of chitosan act as anion exchanger creating a potential difference that vary with ion concentration in solution in the concentration range of 1.5 ·10-4 - 10-2 mol/dm3
SENSING PROPERTIES OF HYBRID POLYMERIC FILMS OBTAINED BY SOL-GEL  [cached]
Y. Martínez,J. Retuert,M. Yazdani-Pedram
Journal of the Chilean Chemical Society , 2004,
Abstract: Hybrid nanocomposites based on siloxane sols, chitosan and poly(monomethyl itaconate) (PMMI) as organic polymer counterparts were prepared. Tetraethyl ortosilicate was used as inorganic network forming reagent that was first transformed into soluble polymeric species by acid catalyzed hydrolysis and condensation reactions. The siloxane sol was then mixed with different amounts of PMMI and chitosan at room temperature to form the hybrid material. These hybrid materials could be easily cast as transparent and flexible films. Atomic force microscopy study showed that the organic components are more or less homogeneously distributed at nanometer scale. The hybrid films were used as membranes for the construction of all-solid-state type potentiometric electrodes. The ion-sensing capacity of the nanocomposite was tested for different anions and the best results were obtained for NO3-. It was concluded that the -NH3+HCOO- groups of chitosan act as anion exchanger creating a potential difference that vary with ion concentration in solution in the concentration range of 1.5 ·10-4 - 10-2 mol/dm3
An Attractive Biocompatible Polymer for pharmaceutical application in various dosage forms – Chitosan  [cached]
Shridhar pandya,D. Harinarayana,Devendra Jain,Shital J Bidkar
Pharmaceutical Reviews , 2007,
Abstract: Chitosan comes from chitin a natural biopolymer originating from crustacean shells. Chitin is similar to cellulose in morphology; a bountiful natural polysaccharide that contains amino sugars.Partial deacetylation of chitin gives rise to chitosan, a linear polysaccharide with interspersed D-glucosamine, and acetyl-D-glucosamine units. The preponderance and distribution of acetyl-D-glucosamine residues lead to differing physicochemical properties and biological responses. Chitosan is a weak cationic polysaccharide composed essentially of β(1→4) linked glucosamine units together with some N-acetylglucosamine units. It is obtained by extensive deacetylation of chitin, a polysaccharide common in nature. Chitosan is a biocompatible, biodegradable, and nontoxic natural polymer that exhibits excellent film-forming ability. As a result of its cationic character, chitosan is able to react with polyanions giving rise to polyelectrolyte complexes. Therefore, because of these interesting properties, it has become the subject of numerous scientific reports and patents on the preparation of microspheres and microcapsules. The techniques employed to microencapsulate with chitosan include, among others, ionotropic gelation, spray drying, emulsion phase separation, simple and complex coacervation, and polymerization of a vinyl monomer in the presence of chitosan. The aim of this work is to review is for a taste masking by various methods.
Characterization of a Gelatin/Chitosan/Hyaluronan scaffold-polymer
Enrione,Javier; Osorio,Fernando; López,Daniel; Weinstein-Oppenheimer,Caroline; Fuentes,Miguel A; Ceriani,Ricardo; Brown,Donald I; Albornoz,Fernando; Sánchez,Elizabeth; Villalobos,Patricio; Somoza,Rodrigo A; Young,Manuel E; Acevedo,Cristian A;
Electronic Journal of Biotechnology , 2010,
Abstract: gelatin, chitosan and hyaluronic acid are natural components used to prepare polymeric scaffold in tissue engineering. the physical properties of these materials confer an appropriate microenvironment for cells, which can be used as a regeneration system for skin and cartilage. in this work, we prepared and characterized a gelatin/chitosan/hyaluronan lyophilized-polymer. physical properties of lyophilized-polymer changed slightly with moisture, but when polymer was totally hydrated the elasticity changed significantly. thermophysical characterisation indicated that temperatures higher than 30oc could modify irreversibly the polymeric matrix probably due to protein denaturation. besides, we used the polymer as scaffold to prepare a biosynthetic-skin, reporting biological behaviour and its mechanical properties.
CHITOSAN: A BIOCOMPATIBLE POLYMER FOR PHARMACEUTICAL APPLICATIONS IN VARIOUS DOSAGE FORMS  [PDF]
Pesaramelli Karteek*
International Journal of Pharmacy and Technology , 2010,
Abstract: Chitosan is a weak cationic polysaccharide composed essentially of β(1→4) linked glucose amine units together with some acetyl glucose amine units. It is obtained by extensive deacetylation of chitin,a polysaccharide common in nature. Chitosan is biocompatible, biodegradable, and non toxic natural polymer that exhibits excellent film forming ability. As a result of its cationic character, chitosan is able to react with polyanions giving rise to polyelectrolyte complexes. Therefore, because of these interesting properties, it has become the subject of numerous scientific reports and patents on thepreparation of micro spheres and microcapsules. The techniques employed to microencapsulate with chitoson include, among others, ionotropic gelation, spray drying, emulsion phase separation, simpleand complex coacervation, and polymerization of vinyl monomer in the presence of chitosan. The aim of the work is to review some of the more common techniques used and to put forward the results obtained in preparing chitosan-based microcapsules: for taste masking and improving the stability of nutritional oil, the sustained release of drugs, as well as the preparation of chitosan super paramagneticmicrocapsules for immobilization of enzymes.
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