(568e) Biomimetic Carrier-Mediated Membrane for Transport of Hydrophilic Molecules

The ability of biological membranes to facilitate the selective transport of ions or hydrophilic molecules using carrier proteins inspired the design of carrier-mediated transport membranes for selective separations in aqueous solute systems. Thin film mesoporous silica, which have tunable pore morphology, chemical, thermal stability and ease of organic functionalization, serve as a support for lipid bilayers. Solute carriers are incorporated in lipid bilayers, which acting as barriers. Solute carriers of particular interest are boronic acid derivatives, which can reversibly interact with the 1, 2-diols or 1, 3-diols of molecules (carbohydrates, glycoproteins, nucleosides and dopamine etc.) to form cyclic esters with five or six member rings. Furthermore, the association strength is largely dependent on the structure of solute, which makes this reversible reaction with specific complexation very attractive for selective separation. The combination of high surface area silica materials and selectively permeable lipid bilayers suggests potential applications for efficient, selective dilute aqueous solute separations.

In this work, the transport properties of boronic acid carrier immobilized lipid bilayer which is supported by orthogonally oriented hexagonally close packed (HCP) silica thin films on macroporous support will be examined. The effect of lipid bilayer preparation methods (in the form of pore enveloping, pore filling, tethering) on the barrier properties are first explored, as a good barrier is essential for detecting selective separation with the incorporation of biomimetic carriers in the bilayer. Next, the ability of immobilized boronic acid to facilitate the transport of active molecules through the membrane is demonstrated. The effect of factors like pH gradient, temperature (related to the lipid bilayer diffusivity) and the moleculeâ??s affinity for boronic acid are explored to improve the selectivity and permeability of this boronic acid-mediated membrane. In addition to boronic acid, other carriers immobilized in lipid bilayers are explored for the construction of selective biomimetic carrier-facilitated membranes.