DNA immobilization using biocompatible diblock phosphorylcholine copolymers

In this work, we examined the immobilization of bioactive Luciferase plasmid DNA (Luc) and antisense oligodeoxynucleotide (ODN) onto a biocompatible diblock copolymer preadsorbed at the hydrophilic silicon oxide/water interface using spectroscopic ellipsometry. We found that the amount of DNA immobilized was determined by the charge ratio between the cationic copolymer and the anionic DNA and that there was little measurable difference arising from the different DNA types and their molecular sizes. For comparison, we also examined the adsorption of premixed polymer/DNA complexes onto the silicon oxide/solution interface. We found that in this case the amount of DNA immobilized onto the surface was dictated by the electrostatic interaction between the substrate surface and the copolymer/DNA complex. When the copolymer was in excess, the amount of DNA immobilized was determined by the competitive process of interfacial adsorption between the free copolymer and the complex. Our results thus demonstrated that DNA molecules could be immobilized differently onto the support surface via electrostatic interactions. Copyright © 2006 John Wiley & Sons, Ltd.