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  • cholinesterase  (1)
  • copper phthalocyanine  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 11 (1998), S. 241-250 
    ISSN: 1573-4846
    Keywords: copper phthalocyanine ; dimer ; monomer ; optical absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Dimer formation in sol-gel matrices was studied using optical absorption spectroscopy of copper phthalocyanine tetrasulfonate dopants in silicate and aluminosilicate sol-gel matrices. Changes in the optical absorption spectra of dimers and monomers were correlated with various stages of the sol-gel process. Dimerization is strongly influenced by the chemistry of the pore liquid. The primary factors that control dimerization are the quantity of solvent remaining in the pores, pore solvent alcohol/water ratio, and presence of protons which can be either from the catalyst or from silanol groups on the silicate pore surfaces. Synthesis conditions which cause dye protonation invariably lead to dimerization during the latter stages of drying when the pore liquid becomes water-rich and there is a high dye concentration. These studies also identify chemical conditions which are able to avoid dye protonation and subsequently reduce dimer formation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 8 (1997), S. 1067-1070 
    ISSN: 1573-4846
    Keywords: cholinesterase ; sol-gel ; pesticide ; THA ; enzyme activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Biological activity of cholinesterases can be determined by optically monitoring the enzymatic reaction with indophenyl acetate, (N-4′-acetoxyphenyl)-4-quinone imine. At pH 8.0 cholinesterases hydrolyze this yellow dye to yield a blue reaction product. Cholinesterase inhibitors reduce the rate of this hydrolysis. Thus, by monitoring absorbance of the hydrolysis product at its maximum (630 nm) as a function of time, reaction rates of both cholinesterase activity and cholinesterase inhibition may be quantified spectroscopically. Using this technique, we measured the enzymatic activity of butyrylcholinesterase (BuChE) molecules encapsulated in tetramethyl orthosilicate (TMOS) silicate gel-glass prepared by hydrolysis and condensation. This activity is reduced, in a concentration-dependent manner, by the reversible cholinesterase inhibitors 1,5-bis(4-allyldimethyl-ammoniumphenyl) pentan- 3-one dibromide (BADAPP) and 9-amino-1,2,3,4-tetrahydroacridine (THA; tacrine, Cognex). The gel-glasses are rigid and compact, transparent, and porous enough to allow reagents to diffuse in and out.
    Type of Medium: Electronic Resource
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