Ionic Liquid Doped β Lactoglobulin as Template for Nanoclusters of Nickel Oxide

Abstract

In this work, Langmuir films of organized assemblies of β-lactoglobulin (βLG) with 1-ethyl-3-methyl imidazolium ethyl sulfate (IL-emes) have been characterized at air/water interface using surface pressure-specific area isotherms and dilational rheology. The protein in the IL-mediated assembly shows excellent packing at the interface and is stable as seen in circular dichroic spectroscopy. These spread films on nickel chloride were transferred as Langmuir–Schaffer films of βLG and βLG+IL-emes and used as template for designing nanoclusters of nickel oxide. The nanoclusters have been characterized using transmission electron microscopy (TEM) and powder XRD. While pure protein template gives needle-shaped structures, the IL-mediated template gives spherical shapes of hexagonal nickel oxide in the range 30 nm to 40 nm. Presence of ionic liquid seems to slow down the growth of the cluster and also prevents aggregation of the clusters.