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Issue 3, 2009
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Selective protein and DNA adsorption on PLL-PEG films modulated by ionic strength

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Abstract

We describe a soft thin film which selectively adsorbs DNA but averts the non-specific binding of proteins. Indium tin oxide (ITO) substrates were surface-modified with a poly(L-lysine)-g-poly(ethylene glycol) (PLL-PEG) film which carries an outer protein-repelling PEG layer and an underlying positively charged PLL layer that attracts DNA. Binding of DNA could be tuned by a factor of over 90 by varying the salt concentration. The dependence of DNA binding on ionic strength was described with a physicochemical model which led to the conclusion of an unexpectedly high enrichment of salt inside the PEG layer. In addition, the model led to an expanded definition of the Debye–Hückel type effective screening length parameter z. Our new findings on a film with dual passivation/attraction properties can find applications in biopolymer-specific coatings useful in bioseparation and biosensing. In addition, the physicochemical characterisation provides new insight into the interactions between biopolymers and polymer-coated interfaces.

Graphical abstract: Selective protein and DNA adsorption on PLL-PEG films modulated by ionic strength

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Publication details

The article was received on 29 Aug 2008, accepted on 15 Oct 2008 and first published on 25 Nov 2008


Article type: Paper
DOI: 10.1039/B815065F
Citation: Soft Matter, 2009,5, 613-621
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    Selective protein and DNA adsorption on PLL-PEG films modulated by ionic strength

    R. Schlapak, D. Armitage, N. Saucedo-Zeni, W. Chrzanowski, M. Hohage, D. Caruana and S. Howorka, Soft Matter, 2009, 5, 613
    DOI: 10.1039/B815065F

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