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

Schlapak, R; Armitage, D; Saucedo-Zeni, N; Chrzanowski, W; Hohage, M; Caruana, D; Howorka, S; (2009) Selective protein and DNA adsorption on PLL-PEG films modulated by ionic strength. SOFT MATTER , 5 (3) 613 - 621. 10.1039/b815065f.

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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-Huckel 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.

Type:Article
Title:Selective protein and DNA adsorption on PLL-PEG films modulated by ionic strength
DOI:10.1039/b815065f
Keywords:SELF-ASSEMBLED MONOLAYERS, DENSITY POLY(ETHYLENE GLYCOL), POLY(L-LYSINE)-G-POLY(ETHYLENE GLYCOL), OXIDE SURFACES, 3-DIMENSIONAL STRUCTURE, ELECTROCHEMICAL CONTROL, FORCE MICROSCOPY, GLASS SURFACES, THIN-FILMS, MICROARRAYS
UCL classification:UCL > School of Life and Medical Sciences > Faculty of Medical Sciences > Eastman Dental Institute > Restorative Dental Sciences
UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Chemistry

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