Water-pluronic-ionic liquid based microemulsions: Preparation, characterization and application as micro-reactor for enhanced catalytic activity of Cytochrome-c

Microemulsions (& mu;Es), comprising water as polar component, pluronic (normal, L35 and reverse, 10R5) as surfactant and a hydrophobic ionic liquid (HIL) as non-polar component have been prepared and characterized. Owing to higher surface activity, pluronics have promoted the formation of & mu;Es without the use of co-surfactant. Thus prepared & mu;Es have been utilized as nano-reactors for the oxidation of guaiacol in the presence of Cytochrome-c (Cyt-c) at 15, 20, and 25 degrees C. A 3.2- and 1.3-fold increase in the rate of formation of product of enzymatic catalysis in direct & mu;E (HIL-in-water) with reverse pluronic (10R5) is observed at 15 and 20 degrees C as compared to that in buffer. However, negligible enzymatic activity is observed in the direct & mu;E formed by normal pluronic (L35). The catalytic activity of Cyt-c decreases in reverse & mu;Es (water-in-HIL) as compared to direct & mu;Es irrespective of the nature of pluronic used. The contrasting nature of nano-interfaces formed by pluronics in & mu;Es and the extent of hydration of these nano-interfaces controlled by temperature exerts varying influence on the catalytic activity of Cyt-c. It is expected that the present work would result in providing a versatile platform for the creation of new IL and pluronic-based & mu;Es for bio-catalytic applications, which have never been reported.