Binding Affinity of DNA Plasmids Using Surface Plasmon Resonance

11 Mar 2013

Laura Ruvuna is guest web writer for Analytical Methods. She is currently a PhD student at Northwestern University, Evanston, Illinois, USA.

Different plasmind isoforms on agarose gel

Nucleic acids have emerged as a vital tool for targeted gene therapy treatments. In particular, plasmid DNA (pDNA), has become important in pharmaceutical research. Typically, pDNA exists in supercoiled, linear, and open-circular isoforms, and affinity chromatography can separate the supercoiled from these other impurities. Although the capture ligand used in affinity chromatography demonstrates high specificity, it cannot determine the binding strength of the plasmid to the ligand.

Researchers at University of Beira Interior in Portugal measured the binding kinetics of pDNA using surface plasmon resonance spectroscopy (SPR). They successfully calculated dissociation constants for all three types of plasmid isoforms, with supercoiled showing the tightest binding to an affinity chromatography mimic support.