Electrostatic switching of biopolymer layers. Insights from combined electrokinetics and reflectometric interference

Document Type

Article

Publication Date

8-15-2006

Abstract

Structural integrity and functional characteristics of biomacromolecules are largely defined by electrostatic forces between ionized moieties, which are often altered at interfaces. Unraveling these changes requires access to charge state and structure of surface-confined biopolymers in aqueous environments. We therefore combined electrokinetic measurements of interfacial electrical potentials with the simultaneous determination of the optical layer thickness by reflectometric interference spectroscopy. Two examples are summarized to demonstrate the resulting options: The pH-switching of grafted poly(L-glutamic acid) layers caused by dissociation-dependent helix-coil transitions was studied; potential distribution and ion mobility within the grafted polyelectrolyte were unraveled using an new theoretical model for the charging of polyelectrolyte layers. The charge-driven modulation of biopolymers at interfaces was furthermore analyzed in the adsorption of fibronectin onto polymer substrates with varied charge density; the results permit us to reach a conclusion about the relevance of electrostatic matching for orientation and anchorage of the protein. Altogether, the introduced methodology was found suitable to follow the electrosurface characteristics of biomacromolecules in situ. © 2006 American Chemical Society.

Identifier

33747626337 (Scopus)

Publication Title

Analytical Chemistry

External Full Text Location

https://doi.org/10.1021/ac060471p

ISSN

00032700

PubMed ID

16906732

First Page

5851

Last Page

5857

Issue

16

Volume

78

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