RESUMO
Burkholderia cepacia lipase was immobilized on various types of phenyl-functionalized mesoporous silicates (MPS). MPS, anchored with a phenyl group on the silica wall and with three dimensional (3D) mesoporosity, showed highest lipase adsorption capacity and best activities both in aqueous and organic reagents.
Assuntos
Burkholderia cepacia/enzimologia , Proteínas Imobilizadas/metabolismo , Lipase/metabolismo , Silicatos/química , Adsorção , Estabilidade Enzimática , Proteínas Imobilizadas/química , Lipase/química , Água/químicaRESUMO
Aryl alcohol oxidase was immobilized on two mesoporous materials, MS-A and MS-B. The immobilization rate for the larger pore material MS-A (11.5 nm) was higher than for the smaller pore material MS-B (4.2 nm). Furthermore, the sol-gel silica encapsulation of MS-immobilized enzymes improved thermal stability.
Assuntos
Oxirredutases do Álcool/metabolismo , Enzimas Imobilizadas/metabolismo , Adsorção , Oxirredutases do Álcool/química , Enzimas Imobilizadas/química , Concentração de Íons de Hidrogênio , Cinética , Tamanho da Partícula , Transição de Fase , Silicatos , Propriedades de SuperfícieRESUMO
An ESR study has been made on the adsorption of three types of aminoxyl radicals with different substituent groups in the nanochannel of MCM-41 in benzene. In the suspensions of MCM-41, all the aminoxyl radicals, usually called as spin probes, show the ESR spectra composed of two signals: the main broader one from the spin probes trapped in the nanochannel, and a sharp minor signal from those in the bulk. The spin probes adsorbed in the nanochannel retain considerable mobility especially at higher temperatures over 300 K. When fumed silica, having a surface structure similar to that of MCM-41, is employed, on the other hand, the relatively hydrophobic spin probe mainly remains in the bulk, but the hydrophilic one is mostly adsorbed and immobilized rigidly. From these results, the adsorption by the MCM-41 nanochannel in benzene is characterized by medium selectivity and considerable motional allowance to the adsorbate molecule. The mobility of the spin probe in the MCM-41 nanochannel increases and the adsorption efficiency decreases by either of the following changes made to the system: (a) increasing the channel diameter, (b) increasing the hydrophobicity of the spin probe, (c) adding a small amount of 2-propanol in the solution, (d) methylation of the surface OH groups of the nanochannel, and (e) elevating the system temperature. A model of this special type of adsorption has been proposed on the basis of the thermodynamic parameters and the ESR spectra for the modified systems including those with different solvents.
Assuntos
Benzeno/química , Espectroscopia de Ressonância de Spin Eletrônica , Compostos Orgânicos/química , Dióxido de Silício/química , Marcadores de Spin , Adsorção , Interações Hidrofóbicas e Hidrofílicas , Modelos Químicos , Nanopartículas , Porosidade , Soluções/química , TemperaturaRESUMO
Catalytic antibodies (38C2 and 84G3) were encapsulated in hybrid organic-inorganic sol-gel powder prepared from tetraethoxysilane (TEOS) and organoalkoxysilanes, then used to catalyze enantioselective aldol reactions. Sol-gel immobilization enhanced antibody stability with respect to the effect of temperature and organic solvent concentration.
