Simultaneous Multiple-Point Adsorption of Aluminum Ions and Charged Molecules by a Polyampholyte Thermosensitive Gel:  Controlling Frustrations in a Heteropolymer Gel

Abstract

We report the data on concurrent multiple point adsorption of two oppositely charged species of “target molecules” (aluminum ions and 1,3,6,8-pyrenetetrasulfonic sodium salt (Py-4)) by a polyampholyte gel of N-isopropylacrylamide (NIPA, 6 M) with methacrylic acid (MAA, 80 mM) and methacrylamidopropyl trimethylammonium chloride (MAPTAC, 80 mM). The goal of this study is to test the mutual frustrations created by adsorption of one species on the adsorption of the other. Understanding these frustrations is an important step toward elucidating the memory of conformations in heteropolymer systems. We found that in the absence of aluminum, the adsorption of Py-4 was suppressed by gel collapse, presumably because of an increase in MAA/MAPTAC ionic pairs that prevents the formation of potential adsorbing centers. Adding a moderate amount of aluminum significantly enhances adsorption of Py-4 by the collapsed gel, indicating that aluminum ions compete for bonds with MAA and help release vacant MAPTAC centers. Finally, with further increase of aluminum, the Py-4 multiple point adsorption is again suppressed, pointing out the frustrations created by aluminum-mediated effective cross-links. We analyze also the cooperativity of the adsorption process.

A Thermosensitive Monolithic Column as an Artificial Antibody for the On‐line Selective Separation of the Protein

“…[29] The grafted thermosensitive protein MIP existed in their collapsed form at 40 8C, and there was little resistance to the flow through the mobile phase. However, the grafted thermosensitive protein MIP expanded and plugged the macropores at 20 8C, thus affecting the permeability of the column.…”

“…[26][27][28] This kind of stimuli-sensitive recognition is very similar to the recognition of proteins in natural systems. [29][30][31] So far, to the best of our knowledge, the preparation of a thermosensitive polymer to imprint a protein has been limited to static formats, such as our previous study on the bulk polymerization of a macroporous thermosensitive imprinted hydrogel for the recognition of proteins, [32] and has not been applied to monolithic columns for proteins. [33][34][35][36] This study focuses on the combined merits of the monolithic column and the thermosensitive protein MIP to selectively separate a template protein in an on-line method.…”

“…nal temperature, thus exhibiting a shrinking-to-swelling conformational transition at different temperatures and effecting the architecture of the pores. [29] Therefore, the back pressure of the thermosensitive MIP3 monolith was also sensitive to a change in temperature. Figure 4 exhibits the swing of the back pressure of the MIP3 monolith when the column temperature changed repeatedly between 20 and 40 8C.…”

Dependence of Molecular Recognition for a Specific Cation on the Change of the Oxidation State of the Metal Catalyst Component in the Hydrogel Network

“…21 In addition, a wide range of cross-linked imprinted hydrogels has been proven to be useful as drug delivery platforms. 22 Recently, Tanaka et al [23][24][25] have described a stimuli-sensitive recognizing hydrogel using the intelligent character of stimuli-sensitive hydrogel, which is very similar to the recognition in proteins by combining the two functions of sensitivity and molecular recognition in a gel. Their design includes a stimuli-sensitive monomer, such as a temperaturesensitive monomer, for the polymerization of molecular recognition hydrogel in the presence of the target molecule.…”

“…The obtained result for the temperature effect on the adsorption in the oscillating hydrogel composed of NIPAAm/ Pb(MAA) 2 /Ru(bpy) 3 2+ is similar with the result obtained by Tanaka et al using a non-oscillating hydrogel composed of NIPAAm/Pb(MAA) 2 . 23,24 Decreasing the environmental temperature could increase the distance between the nearest MAA by swelling of the hydrogels, and decrease the probability for pair formation. Therefore, the sites for the formation of Ca 2+ assemblies are decreased by the swelling of the gel.…”