Robust nano-enzyme conjugates for the sustainable synthesis of a rare sugar D-tagatose.

Aim of present study was to develop biological catalysts of L-arabinose isomerase (L-AI) by immobilizing on four different supports such as multiwalled carbon nanotube (MWCNT), graphene oxide (GOx), Santa Barbara Amorphous (SBA-15) and mobile composite matter (MCM-41). Also, comparative analysis of the developed catalysts was performed to evolve the best in terms of transformation efficiency for D-tagatose production. The developed nano-enzyme conjugates (NECs) were characterized using the high resolution transmission electron microscopy (HR-TEM) and elemental analysis was performed by energy dispersive X-ray spectroscopy (EDS). The functional groups were investigated by Fourier transform infra red spectroscopy. Also, the thermo gravimetric analysis (TGA) was employed to plot a thermal degradation weight loss profile of NECs. The conjugated L-AI with MWCNT and GOx were found to be more promising immobilized catalysts due to their ability to provide more surface area. Conversion of D-Galactose to D-Tagatose at moderate temperature and pH was observed to attain the equilibrium level of transformation (~50 %). On the contrary, NECs prepared using SBA-15 and MCM-41 as support matrix were unable to reach the equilibrium level of conversion. Additionally, the developed NECs were suitable for reuse in multiple batch cycles. Thus, promising nanotechnology coupled with biocatalysis made the transformation of D-Galactose into D-tagatose more economically sustainable.