AOT/isooctane reverse micelles

AOT-isooctane-H20 reversed micelles Ti02 particles prepared by mixing anhydrous isooctane solutions of titanium tetraisopropoxide with AOT-isooctane reversed micelles [H20] to [AOT] ratio determined Ti02 formation 616... 

Solubilization of amino acids in AOT/isooctane reversed micelle... 

Fluorescent naphthol-based polymers were prepared by HRP-catalyzed polymerization of 2-naphthol in AOT/isooctane reverse micelles to give the polymer microspheres.31 The precipitated polymer was soluble in a range of polar and nonpolar organic solvents and possessed quinonoid structure. The reverse micellar system induced the peroxidase-catalyzed copolymerization of p-hydroxythiophenol and />ethylphenol, yielding the thiol-containing polyphenol particles.32 The attachment of CdS to the particles gave the CdS—polymer nanocomposite showing fluorescence characteristics. 

CaseUi M, Mangone A, Paolillo P, Traini A. Determination of the acid dissociation constant of bromocresol green and cresol red in waler/AOT/isooctane reverse micelles by multiple linear regression and extended principal component analysis. Ann Chim 2002 May-Jun 92(5-6) 501-512. 

Sato etal. [238] studied the mechanism of formation of silver halide particles grown from reverse microemulsions. In a typical process, aqueous solutions of either (a) silver nitrate or (b) a sodium salt, i.e. sodium chloride, bromide or iodide was injected into AOT/isooctane reverse micelles. When equal volumes of the two kinds of microemulsion were rapidly mixed at 25°C, particles started forming. The particle diameter was a function of the type of the anion, the w value as also reaction time. For AgBr, the maximum diameter was - 2.7 nm for Agl, it went up to 5.5 nm. Bagwe and Khilar [444] synthesized AgCl nanoparticles from AOT/ alkane (cyclohexane, heptane, decane) systems. The aqueous phases were solutions of silver nitrate or alkali/alkaline earth halides. The number average particle size was in the range of 4-10 nm. 

Hebrant et al, [151] investigated the transport of amino acids (p-iodopheny la la-nine and tryptophan) through AOT/isooctane reverse micelles, and the rates of transport were compared and analyzed in relation to partition coefficients between water and the AOT palisade layer. The rate of uptake of amino acids by the reverse micelles and the influence of the ionization states of the acids on the extent of transport were also presented. Enantioselective transport using chiral AOT was also attempted, but the rigidity of the interfacial film according to them is not sufficient for chiral recognition for enantiomeric enrichment. 

The measured activities showed that the optimum enzyme activity occurred at near pH = 7 (IT = 11), different from the conclusion reached in the earlier study by Gupte and coworkers. They had observed a pH optimum of 5 (1T= 10) for AOT/isooctane reverse micelles. This observation can be rationalized on the basis that a more basic aqueous buffer was needed to offset the substantially more acidic environment encountered within the PFPE/SCCO2 water pool. 

In 1999, the same group reported the synthesis of the precursor dipeptides, as mentioned above, catalyzed by free and immobilized a-chymotrypsin in AOT/ isooctane reverse micelles at product yields exceeding 80% [60]. The dipeptide products were successfully separated from the reaction medium by using a silica gel column. 

The microenviromnent of AOT/isooctane reverse micelles was considered as a biomimetic system for the solubilization of flavodoxin, aldehyde oxidoreductase, and a membrane-associated hydrogenase, all isolated from the sulfate reducing bacteria Desulfovibrio gigas [153,154], The main perspective of this research group was the encapsulation of aU the three microbial enzymes mentioned above in reverse micelles and the observation of the electron-transfer chain under the water restricted conditions. 

Liithi and Luisi [44] have used a hoUow fiber membrane reactor for peptide synthesis catalyzed by a-chymotrypsin in microemulsion. Chang et al. [110] described the immobilization of lipase on liposomes, which, in turn, were solubilized in AOT/isooctane reversed micelles and used for the continuous glycerolysis of olive oil in an ultrafiltration cell. The half-Ufe of the Chromo. viscosum lipase was 7 weeks. The development of an ultrafiltration ceramic membrane bioreactor for the simultaneous lipolysis of olive oil and product separation in AOT/isooctane reversed micellar media has been also reported [106,107], Cutinase performance was also evaluated in a ceramic membrane reactor [9]. An attempt to minimize the surfactant contamination problem was based on the use of an electro-ultrafiltration method which can decrease the gel formation in the membrane surface, improving the filtration flux, achieving the separation of the AOT reverse micelles [187],... 

Ishikawa, H., Noda, K., Oka, T. 1990. Kinetic properties of enzymes in AOT-isooctane reversed micelles. J. Ferment. Bioeng. 70, 381—385. 

Marangoni, A.G. 1993 Effects of the interaction of porcine pancreatic lipase with AOT/isooctane reversed micelles on enzyme structure and function follow predictable patterns. Enzyme Microb. Technol. 15, 944-949. 

Tsai, S.W., Lee, K.P., Chiang, C.L. 1995. Surfactant effects on lipase catalyzed hydrolysis of olive oil in AOT/isooctane reverse micelles. Biocatal. Biotrans. 13, 89-98. 

Han, D., Rhee, J.S. 1986. Characteristics of lipase-catalyzed hydrolysis of olive oil in AOT-isooctane reversed micelles. Biotechnol. Bioeng. 28, 1250-1255. 

Bru, R., Sanchez-Ferrer, A., Garcia-Carmona. 1989. Characteristics of tyrosinase in AOT-isooctane reverse micelles. Biotechnol. Bioeng. 34, 304-308. 

Andrade, S., Moura, J.J.G. 2002. Hydrogen evolution and consumption in AOT-isooctane reverse micelles by Desulfovibrio gigas hydrogenase. Enzyme Microb. Technol. 31, 398-402. 

The solubilization of hydrosoluble polymers, like poly ethyleneglycol (PEG), in the water pools of reverse micelles is known to produce a decrease of the interdroplet attractive interactions, at least when the polymer chains are smaller than the water droplets. Addition of PEG (molecular weight 2000 or 10,000 at maximum) to water/AOT/n-decane systems shifts the threshold of conductivity percolation to higher water volume fractions, as expected, because of the polymer/surfactant stabilizing interactions. Similar observations were reported for water/AOT/isooctane reverse micelles in the presence of triblock copolymers or of PEG of varied molecular weights. ... 

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