Bipyridinium and Imidazolium Ionic Liquids for Nanomaterials Synthesis: pH Effect, Phase Transfer Behavior, and Protein Extraction

Abstract

We demonstrate the potential use of 1,1′-bis(2-(cyclo­hexyloxy)-2-oxoethyl)-[4,4′-bipyridin]-1,1′-diium bromide (BP) and 1-ethyl-3-methyl­imidazolium chloride (EMI) ionic liquids (ILs) in in situ synthesis of gold nanoparticles (Au NPs) without using any external reducing or stabilizing agents. Both ILs produced nearly monodisperse NPs of 4–8 nm which were present in the form of self-assembled states. BP coated NPs formed self-assembled sheets and easily transferred to the organic phase by employing the water insoluble IL as a phase transfer agent. The efficiency of the phase transfer process was related to the extent of aggregation as well as functional groups. Both IL coated NPs were further used to extract the proteins from the complex biological mixtures. EMI coated NPs extracted proteins of large molar masses whereas BP coated NPs were good for the extraction of low molecular mass proteins. This disparity was controlled by the substituted functional groups of ILs. Bulky cyclohexyloxy functional groups of BP did not allow extraction of large molar mass proteins. Such a wide applicability of ILs in nanomaterials synthesis opens several new applications in the field of nanomedicine and nanobiotechnology where IL coated NPs can be used for diverse protein complexation.

Ionic Liquid-Assisted Laser Desorption/Ionization–Mass Spectrometry: Matrices, Microextraction, and Separation

“…The properties of the anion moieties influence the hydrogen bond basicity of ILs, while the properties of the cation moieties influence π–π interactions and in some cases the hydrogen bond acidity. Ionic liquids can be used for green processing industry [7], synthesis of nanomaterials [8], as solvents for clean synthesis [1], catalysis [9], supercapacitors [10], electronic and bioelectronic nose instruments [11].…”

Role of Gluten in Surface Chemistry: Nanometallic Bioconjugation of Hard, Medium, and Soft Wheat Protein

“…This phase transfer trend can be placed in the order of soft < medium < hard wheat protein. Phase transfer is driven by the strong electrostatic interactions operating between the organic layer solubilized 1-butyl-3-methylimidazolium cations and the negatively charged SDS solubilized protein coated NPs (Figure a) . NPs which are fully coated with protein are transferred to the organic phase.…”

“…Phase transfer is driven by the strong electrostatic interactions operating between the organic layer solubilized 1-butyl-3-methylimidazolium cations and the negatively charged SDS solubilized protein coated NPs (Figure 6a). 58 NPs which are fully coated with protein are transferred to the organic phase. Thus, all samples of hard wheat protein (i.e., 1, 2, and 3, Figure 5a) are fully coated, while this is not the case for sample 6 (Figure 5b) of medium wheat protein and for samples 8 and 9 (Figure 5c) of soft wheat protein.…”

Naringin–Chalcone Bioflavonoid-Protected Nanocolloids: Mode of Flavonoid Adsorption, a Determinant for Protein Extraction

“…Thus, Au NPs produced at pH 2.5 and 7 under in situ reaction conditions of naringin can be made colloidal suspensions in basic medium and/or in glycerol in neutral medium, whereas Au NPs produced at pH 11.5 (bottle “F”) can be easily extracted in the organic phase by using water-insoluble ionic liquids (ILs) such as 1-butyl-3-methylimidazolium hexafluorophosphate (see sequence “F → G → H”). 23…”

“…Pure zein provides bands of 21.3, 25.7, 45.7, and 66 kDa of four different fractions. 23 The first two bands indicate the presence of α-zein, 38,39 while the next two bands are due to dimerization or oligomerization. 40 Unfolding of zein is related to the amount of SDS used and low amounts of SDS, that is, in the low mM concentration range greater than its critical micelle concentration partially reduce zein.…”