Chitosan composite

With regard to biosensor applications, a wide variety of electrochemically active species (ferrocene, ruthenium complexes, or carbon and metal (Pt, Pd, Au...) [185,186] were also introduced into the sol-gel matrices or adsorbed to improve the electron transfer from the biomolecules to the conductive support [187,188]. For instance, glucose oxidase has been trapped in organically modified sol-gel chitosan composite with adsorbed ferrocene to construct a low-cost biosensor exhibiting high sensitivity and good stability [189]. 

Zeolite-chitosan composites promising materials for catalysis and separation... 

The zeolites-chitosan composites were prepared by adding a known amount of zeolite (X, Y, or mordenite) into a 3 % chitosan solution in 1 % aqueous acetic acid. The zeolite powder was dispersed in the chitosan solution and stirred at room temperature during 1-2 hours. The gelling procedures were later carried out like as in the absence of zeolites. 

Figure 2. Scanning electron microscopy of (a) zeolite X-chitosan, (b) zeolite Y-chitosan and (c) mordenite-chitosan composites prepared by encapsulation of zeolites during the gelling of chitosan.

Figure 3. (lefthand) X-ray powder diffraction pattern and (righthand) scanning electron micrograph of zeolite A-chitosan composite resulting from in-situ synthesis of the zeolite... 

Figure 4. (a) Adsorption-desorption isotherms of N2 at -196°C of 80°C-outgassed (empty squares) chitosan, (filled trangles) zeolite X-chitosan composite from in-situ zeolite synthesis and (empty triangles) zeolite Y-chitosan composite from encapsulation of the zeolite in the gelling chitosan. (b) Scanning electron micrographs of a calcined zeolite-chitosan bead prepared by zeolitisation of a silica-chitosan composite. 

Hsieh CY, Tsai SP, Wang DM et al (2005) Preparation of y-PGA/chitosan composite tissue engineering matrices. Biomaterials 26 5617-5623... 

In view of the conductive and electrocatalytic features of carbon nanotubes (CNTs), AChE and choline oxidases (COx) have been covalently coimmobilized on multiwall carbon nanotubes (MWNTs) for the preparation of an organophosphorus pesticide (OP) biosensor [40, 41], Another OP biosensor has also been constructed by adsorption of AChE on MWNTs modified thick film [8], More recently AChE has been covalently linked with MWNTs doped glutaraldehyde cross-linked chitosan composite film [11], in which biopolymer chitosan provides biocompatible nature to the enzyme and MWNTs improve the conductive nature of chitosan. Even though these enzyme immobilization techniques have been reported in the last three decades, no method can be commonly used for all the enzymes by retaining their complete activity. 

V.B. Kandimalla and H.X. Ju, Binding of acetylcholinesterase to multiwall carbon nanotube-cross-linked chitosan composite for flow-injection amperometric detection of an organophosphorous insecticide. Chem. Eur. J. 12, 1074—1080 (2006). 

Monoglyceride (MG) is one of the most important emulsifiers in food and pharmaceutical industries [280], MG is industrially produced by trans-esterification of fats and oils at high temperature with alkaline catalyst. The synthesis of MG by hydrolysis or glycerolysis of triglyceride (TG) with immobilized lipase attracted attention recently, because it has mild reaction conditions and avoids formation of side products. Silica and celite are often used as immobilization carriers [281], But the immobilized lipase particles are difficult to reuse due to adsorption of glycerol on this carriers [282], PVA/chitosan composite membrane reactor can be used for enzymatic processing of fats and oils. The immobilized activity of lipase was 2.64 IU/cm2 with a recovery of 24%. The membrane reactor was used in a two-phase system reaction to synthesize monoglyceride (MG) by hydrolysis of palm oil, which was reused for at least nine batches with yield of 32-50%. 

When chitosan is added to the culture medium the BC/chitosan composites formed include the properties of both components, mainly an extraordinary bactericidal and barrier effect against microorganisms. Therefore, this modified BC is well suited for wound dressings [42]. 

Feng, K. J., Yang, Y. H Wang, Z. J., Jiang, J. H., Shen, G. L. and Yu, R. Q. (2006), A nano-porous Ce02/Chitosan composite film as the immobilization matrix for colorectal cancer DNA sequence-selective electrochemical biosensor. Talanta, 70(3) 561-565. 

Figure 2. The mechanism for preparation of Nano ZnO-CHIT electrode and immobilization of ChOx onto NanoZnO-CHIT Nanocomposite, Reprinted from Analytica Chimica Acta, 616, R. Khan, A. Kaushik, P. R. Solanki, A.A. Ansari, M.K. Pandy, B.D. Malhotra, Zinc oxide nanoparticles -chitosan composite film for cholesterol biosensor, 209,Copyright( 2008) with permission fom Elsevier.

Sheng-Fu Wang, Tan Yu-Mei (2007) A novel amperometric immunosensor based on Fe O magnetic nanoparticles/chitosan composite film for determination of ferritin. Anal Bioanal Chem 387 703-708... 

Cyclic voltammograms of luminol at different electrodes in 0.1 mol/L phosphate buffer (PBS, pH=7.5) were obtained (Fig. 3A). Similarly, an enhancement of redox current from the analyte was observed at the PDDA-chitosan modified GCE, compared with the response at the bare GCE. This is due to the good permselectivity and highly positive charge density of the PDDA-chitosan composite layer. The negatively charged luminol could be easily absorbed on the surface of modified GCE through electrostatic interaction, which was supported by the linear increase of oxidation current vs. scan rates. 

Tanabe, T., Okitsu, N., Tachibana, A., and Yamauchi, K. 2002. Preparation and characterization of keratin-chitosan composite film. Biomaterials 23 817-825. 

The particle size of silica-chitosan composite nanoparticles increased slightly from about 10 to 14 nm with a reaction time of 15 to 360 min. The silica-chitosan nanoparticles prepared after different hours of reaction are designated as silica-chitosan 1H-6H (nanoparticles) in the rest of the discussion. The hydrodynamic particle sizes of silica from silicate were 188.3 11.5 nm and of silica from TEOS were 236.3 6.85 nm. The hydrodynamic particle size of silica-chitosan composite nanoparticles increased slightly from about 153 to 177 nm with a reaction time of 15 to 360 min. 

Y. Zhang, M. Zhang Calcium phosphate/chitosan composite scaffolds for controlled in vitro antibiotic drug release. J. Biomed. Mater. Res. 62, 378 (2002). 

Calcium phosphate-chitosan composite scaffold prepared by adding HA and calcium phosphate glass powder to chitosan and keeping it at — 20°C for 4 days and then freeze-drying the frozen sample... 

Collagen/chitosan composite hydrogels as comeal implants stabilized by EDC and NHS or a hybrid of poly (ethylene glycol) dibuty-raldehyde (PEG-DBA)/ EDC/NHS... 

Venkatesan J, Kim SK (2010) Chitosan composites for bone tissue engineering - an overview. Mar Drugs 8 2252-2266... 

Jiang T, Nair LS, Laurencen CT (2006) Chitosan composites for tissue engineering bone tissue engineering scaffolds. Asian Chitin J 2 1-10... 

Zhang Y, Ni M, Zhang M et al (2003) Calcium phosphate-chitosan composite scaffolds for bone tissue engineering. Tissue Eng 9 337-345... 

Fig. 14 Scanning electron photomicrographs of electrodeposited coatings onto titanium (a) brushite (b) bmshite after conversion to hydroxyapatite (c) brushite-chitosan composite (d) brushite-chitosan composite coating after conversion to HA-chitosan. Reprinted with kind permission from Redepenning et al. [115], John Wiley Sons, Inc., 2003...

Lu X, Leng Y, Zhang Q (2008) Electrochemical deposition of octacalcium phosphate micro-fiber/chitosan composite coatings on titanium substrates. Surf Coat Technol 202(13) 3142... 

Pang X, Casagrande T, Zhitomirsky I (2009) Electrophoretic deposition of hydroxyapatite-CaSi03-chitosan composite coatings. J Colloid Interface Sci 330(2) 323... 

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