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Authors
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Müller, M. ; Keßler, B. ; Houbenov, N. ; Bohata, K. ; Pientka, Z. ; Brynda, E.
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Title
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pH Dependence and Protein Selectivity of Poly(ethyleneimine)/Poly(acrylic acid) Multilayers Studied by in Situ ATR-FTIR Spectroscopy
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Date
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12.04.2006
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Number
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14003
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Abstract
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The selective interaction between polyelectrolyte multilayers (PEM) consecutively adsorbed from poly(ethyleneimine) (PEI) and poly(acrylic acid) (PAC) and a binary mixture containing concanavalin A (COA) andlysozyme (LYZ) based on electrostatic interaction is reported. The composition and structure of the PEM and theuptake of proteins were analyzed by in situ attenuated total reflection (ATR) Fourier transform infrared (FTIR)spectroscopy, and the morphology and thickness were characterized by atomic force microscopy (AFM) andellipsometry. The PEM dissociation degree and charge state and the protein adsorption were shown to be highlydependent on the outermost layer type and the pH in solution. High protein uptake was obtained underelectrostatically attractive conditions. This was used to bind selectively one protein from a binary mixture ofLYZ/COA. In detail it could be demonstrated that six-layered PEM-6 at pH = 7.3 showed a preferential sorptionof positively charged LYZ, while at PEM-5 and pH = 7.3 negatively charged COA could be selectively bound.No protein sorption from the binary mixture was observed at pH = 4.0 for both PEM, when COA, LYZ, and theoutermost PEI layer of PEM-5 were positively charged or the outermost PAC layer of PEM-6 was neutral.Furthermore, from factor analysis of the spectral data the higher selectivity was found for PEM-5 compared toPEM-6. Increasing the ionic strength revealed a drastic decrease in the selectivity of both PEM. Evidence wasfound that the proteins were predominantly bound at the surface and to a minor extent in the bulk phase o<br />f PEM.These results suggest possible working regimes and application fields of PEI/PAC multilayer assemblies relatedto the preparative separation of binary and multicomponent protein mixtures (biofluids, food) as well as to thedesign of selective protein-resistant surfaces.
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Publisher
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Biomacromolecules
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Wikidata
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Citation
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Biomacromolecules 7 (2006) 1285-1294
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DOI
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https://doi.org/10.1021/bm050631r
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Tags
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self-assembled monolayers including charge regulation human serum-albumin polyelectrolyte multilayers secondary structure globular-proteins solid-surfaces adsorption films model
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