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. and Howorka, S. (2009) Selective protein and DNA adsorption on PLL-PEG films modulated by ionic strength. Soft Matter, 5(3), pp. 613-621. (doi: 10.1039/b815065f)

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.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Chrzanowski, Dr Wojciech
• Authors: Schlapak, R., Armitage, D., Saucedo-Zeni, N., Chrzanowski, W., Hohage, M., Caruana, D., and Howorka, S.
• College/School: College of Science and Engineering > School of Engineering > Systems Power and Energy
• Journal Name: Soft Matter
• ISSN: 1744-683X