Alumina sol-gel matrices

Some experiments report on the realization of amperometric biosensors based on alumina sol-gel matrices (Liu, 1999, 2000a, 2000b). Alumina is formed via the hydrolysis of aluminium aUcoxides Al(OPr )3 and heated around 90°C to give a boehmite sol (y-AlOOH). This sol can be mixed with an aqueous suspension of enzyme and deposited onto an electrode (Liu, 1999). The pore size can be easily controlled by changing the AI/H2O ratio allowing the encapsulation of molecules of different sizes. Amperometric tyrosinase biosensors for instance were made in which the enzyme (polyphenol oxidase) is trapped in a matrix with large pores whereas smaller pores are formed to trap the [Fe(CN)6] ] mediator (Liu, 2000a). 

Although most studies on catalysts entrapment were carried out with silica as the main model material, it should be emphasized that practically all other sol-gel oxides can serve for that purpose. An example is the entrapment of Ru3(CO)i2, Rh2Co2(CO)i2, and Os3(CO)i2 within alumina sol-gel matrices [7], which were used as recyclable catalysts for hydrogen transfer, for isomerization of allylbenzene, or for the disproportionation of dihydroarenes. In feet, this study is an example for a situation where moving to another sol-gel matrk can solve problems of inactivity Whereas Rh2Co2(CO)i2 silica neither promotes the isomerization nor the disproportionation, Rh2Co2(CO)i2 alumina is an efficient catalyst for these reactions. 

Eliahu, N., Avnir, D., and Blum, J. (2005) Conversion of metal carbonyl clusters into active catalysts by their entrapment within alumina sol-gel matrices. J. Sol-Gel Sci, Technol., 35 (2), 159-167. 

Thermal stability of enzymes entrapped in alumina sol-gel matrices. Chem. 

Vinogradov, V.V. and Avnir, D. (2014) Exceptional thermal stability of therapeutical enzymes entrapped in alumina sol-gel matrices. J. Mater. Chem,... 

Liu Z., Liu B., Kong J., Deng J. Probing trace phenols based on mediator-free alumina sol-gel derived tyrosinase biosensor. Anal. Chem. 2000 72 4707-4712 Livage J., Roux C., Da Costa J.M., Desportes I., Quinson J.Y. Immunoassays in sol-gel matrices. J. Sol-Gel Sci. Technol. 1996 7 45-51... 

Guney, V., Jones, F.R., James, PR, and Bailey, J.E., Alumina ceramic matrices for fibre composites prepared by modified sol-gel processing. Institute of Physics Publishing, London, 1990. 

Recently, many inorganic porons materials such as clay [62], montmoriUonite [63-64], porous alumina [65], sol-gel matrix [66], etc. have been shown to be promising as immobilization matrices. They have many significant advantages of high mechanical, thermal, and chemical stability and good adsorption and penetrability due to their regular structures and appreciable surface areas. 

Wu J, Chen M, Jones FR, James PF, Characterisation of sol-gel derived alumina-silica matrices for continuous fibre reinforced composites, J Eur Ceram Soc, 16(6), 619-626, 1996. 

Galiy PV, Lesiv TI, Monastyrskii LS, Nenchuk TM, Olenych IB (1998) Surface investigations of nanostructured porous silicon. Thin Solid Films 318 113-116 Gaponenko N (2001) Sol-gel derived Aims in meso-porous matrices porous silicon, anodic alumina and artificial opals. Synth Met 124 125-130... 

Schubert U., Egger C., Rose K., Alt C. Metal-complexes in inorganic matrices. 3. catalytic activity of Rh(CO)Cl(Pr3)2 heterogenised by the sol-gel method. J. Mol. Catal. 1989b 55 330-339 Seker E., Gulari E. Improved N2 selectivity for platinum on alumina prepared by sol-gel technique... 

High-performance ceramic-ceramic composites such as SiC-reinforced alumina are candidate materials for turbine blades as well as highly efficient ceramic diesel engines. To date these materials have been prepared principally by slurry-coating ceramic fibers or textiles followed by composite assembly and hot-pressing. Not only is this process cost-intensive, but fiber strengths are degraded due to abrasion. Ceramic matrices prepared by sol-gel... 

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