Thermally Stable Ionic Liquid-Based Microemulsions for High-Temperature Stabilization of Lysozyme at Nanointerfaces

Abstract

The development of new strategies for thermal stability and storage of enzymes is very important, considering the nonretention of catalytic activity by enzymes under harsh conditions of temperature. Following this, herein, a new approach based on the interfacial adsorption of lysozyme (LYZ) at nanointerfaces of ionic liquid (IL)-based microemulsions, for enhanced thermal stability of LYZ, is reported. Microemulsions (MEs) composed of dialkyl imidazoliumbased surface active ILs (SAILs) as surfactants, ILs as the nonpolar phase, and ethylene glycol (EG) as the polar phase, without any cosurfactants, have been prepared and characterized in detail. Various regions corresponding to polar-in-IL, bicontinuous, and IL-in-polar phases have been characterized using conductivity measurements. Dynamic light scattering (DLS) measurements have provided insights into the size distribution of microdroplets, whereas temperature-dependent DLS measurements established the thermal stability of the MEs. Nanointerfaces formed by SAILs with EG in thermally stable reverse MEs act as fluid scaffolds to adsorb and provide thermal stability, up to 120 °C, to LYZ. Thermally treated LYZ upon extraction into a buffer shows enzyme activity owing to negligible change in the active site of LYZ, as marked by retention of microenvironment of Trp residues present in the active site of LYZ. The present work is expected to establish a new platform for the development of novel nanointerfaces utilizing biobased components for other biomedical applications.

Potential cooling of an accretion-heated neutron star crust in the low-mass X-ray binary 1RXS J180408.9−342058

“…However, due to the limiting quality of the data the contribution from the power-law component was unconstraining. The source also showed a sub-luminous outburst in 2012 during which its peak luminosity likely did not exceed a few times 10 34 erg s −1 (Chenevez et al 2012;Kaur & Heinke 2012). This low peak luminosity makes it unclear if this was a real outburst or that it was due to a period of an increased low-level accretion rate.…”

“…They calculated an upper limit on its distance as determined from the brightness of the thermonuclear burst, of D 5.8 kpc (assuming an Eddington luminosity limit for helium-rich material L Edd = 3.8×10 38 erg s −1 ; Kuulkers et al 2003). It subsequently returned to quiescence as reported by Kaur & Heinke (2012). It went into outburst again on 2015 January 22 as determined using the BAT instrument on board Swift (Barthelmy et al 2015a,b;Krimm et al 2015a).…”

Recent Advances in Ionic Liquids in Biomedicine

“…[ 140 ] Investigations into the interactions involved in these systems [ 141 , 142 , 143 ] became more relevant in order to determine the best ways to design ILs for stabilization of native proteins. [ 144 ] Recently, ionic liquids have shown to interact with proteins, [ 145 , 146 , 147 ] including enzymes, [ 148 , 149 , 150 , 151 ] with ammonium‐based ionic liquids in particular offering low toxicity and thermal and conformational stability. [ 152 , 153 , 154 ] Although the interactions between proteins and other biological materials and ionic liquids are not yet perfectly understood, great progress has been made in this arena by uniting experimental and theoretical approaches.…”

Biocompatible Solvents and Ionic Liquid-Based Surfactants as Sustainable Components to Formulate Environmentally Friendly Organized Systems

“…As an alternative to traditional non-polar solvents to formulate microemulsion and/or RMs, ILs (hydrophobic) have been used as the external component [ 121 , 122 , 123 , 124 , 125 , 126 , 127 , 128 , 129 , 130 , 131 , 132 , 133 , 134 , 135 , 136 , 137 , 138 , 139 , 140 , 141 , 142 , 143 , 144 , 145 , 146 ]. Particularly, the most used hydrophobic IL is 1-butyl-3-methylimidazolium hexafluorophosphate (bmim-PF 6 ) [ 125 , 126 , 127 , 128 , 129 , 130 , 131 , 132 , 134 , 135 , 136 , 137 , 138 , 141 , 142 , 143 , 146 ].…”