ABSTRACT
The subject of microenvironment in catalytic reactions drew its inspiration from the water activity paradox encountered in biocatalysis in 1980s. The enzyme activity in biomedia with low water content was found to differ with that observed in dilute aqueous solutions [1]. The thermodynamic state of water was found to be an important factor influencing enzyme activity in aqueous media. Barzana et al. [2] demonstrated that an immobilized dehydrated enzyme oxidizes methanol and ethanol vapors at elevated temperature in the absence of water. Similar conclusions were drawn in another study on alcohol and aldehyde production in a solid-gas bio-reactor [3]. These investigations had shown that the presence or absence of aqueous environment around enzyme catalysts plays a key part in influencing their activity. The developments at the beginning of twenty-first century have firmly established the need to study the effect of microenvironment in solid-gas bioreactors by employing powerful analytical tools coupled with science driven industrial R&D [4]. Furthermore, artificial microenvironments in synthetic biology have shown great promise for tuning the properties of the industrially important enzymes to achieve the desired stability and activity even in chemical environments. Very recently Alamillo et al., [23] successfully tailored microenvironment for catalytic biomass conversion in inorganic-organic nanoreactors. Intercalation of polyvinyl pyrrolidone, a polar aprotic polymer, into the pores of SBA-15 silica catalyst significantly enhanced the selectivity to 5-hydroxy methyl furfural formation during the dehydration of fructose.
