Surfactants, enzyme activity retention

Sensor fabrication occurs in two steps. The first step is the immobilization of GOx on the surface of the nanotube. This is accomplished by adding GOx to a solution of surfactant stabilized nanotubes and dialyzing away the surfactant. Dialysis is an ideal method for assembling enzymes on a nanotube surface, because the method allows retention of enzyme activity while simultaneously maintaining nanotube colloidal stability. The resulting GOx-S WNT solution exhibits a shift in the nanotube fluorescence indicative of the enzyme layer being less tightly packed around the nanotube than the surfactant layer. The second step is addition of ferricyanide to the GOx-SWNT solution. Adsorption of ferricyanide to the nanotube surface... 

Effect of Surfactant and Other Additives on the Retention of Enzyme Activity A... 

Homogeneous biocatalysis in both fluorous biphasic and supercritical CO systems has been demonstrated [6]. By forming protein-surfactant complexes by hydrophobic ion pairing with a highly fluorinated anionic surfactant cytochrome c can be solubilized in perfluoromethylcyclohexane (PMFC) and in scCO. The secondary structure of the proteins within these ion-paired complexes has been shown to remain intact, and particle size analysis indicated that small aggregates of protein molecules surrounded by surfactant molecules are formed. The presence of the KDP (perfluoropolyether carboxylate surfactants) ion paired with a-chymotrypsin appears to enhance its catal)4ic activity as compared to that of the native enzyme in a fluorous biphasic system. The facile recycling of the a-chymotrypsin-KDP complex in a fluorous biphasic system has been demonstrated with retention of enzyme artivity over four reaction cycles. 

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