290383 Responsive Membranes for Tunable Flux and Biomolecule Immobilization

Monday, October 29, 2012
Hall B (Convention Center )
Thao Ngo1, Andrew Tomaino2, Thomas D. Dziubla3 and D.B. Bhattacharyya2, (1)Chemical Engineering, Arizona State University, Tempe, AZ, (2)Chemical and Materials Engineering, University of Kentucky, Lexington, KY, (3)Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY

Separations in traditional membranes rely on size exclusions or solute diffusion; the creation of pH-responsive surfaces in membrane pores allows flux modulation and reactions/separations in one platform. In this project, multilayered functionalization was carried out in the membrane’s pore domain instead of surface under convective flow conditions using a pH-responsive polymer, polyacrylic acid. The pore domain of membrane was utilized because 1) it offers higher internal surface area, potentially increase the loading capacity of the membrane, and 2) convective flow conditions allow uniform assembly of the polyelectrolyte layers. Three layers of polyelectrolytes (polyacrylic acid, polyallylamine hydrochloride, and poly(sodium 4-styrenesulfonate)) were deposited into the pores of hydrophilized PVDF membrane, followed by immobilization of avidin. Water permeability tests indicated permeability decreased as number of layers increased, with the exception of permeability after the deposition of PSS, which was attributed to loss of polymer on surface of membrane.  Avidin was electrostatically immobilized on the membrane and active site accessibility was tested by permeation of biotin 4-amidobenzoic acid. It was shown that 152.5% of BABA was absorbed by the membrane. In other words, BABA interacted with both avidin and the negatively charged PSS. At pH 12, 84.1% of immobilized avidin was dislodged from the membrane. Moreover, FTIR showed that avidin was the only species that detached the membrane, confirming the stability of the multilayered polyelectrolyte membranes. The results were obtained as a part of a research supported by the NSF/REU program and NIEHS-SRP program at the University of Kentucky.

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