title: Integrated electrokinetic sample focusing and surface plasmon resonance imaging system for measuring biomolecular interactions.
abstract: Label-free biomolecular binding measurement methods, such as surface plasmon resonance (SPR), are becoming increasingly more important for the estimation of real-time binding kinetics. Recent advances in surface plasmon resonance imaging (iSPR) are emerging for label-free microarray-based assay applications, where multiple biomolecular interactions can be measured simultaneously. However, conventional iSPR microarray systems rely on protein printing techniques for ligand immobilization to the gold imaging surface and external pumps for analyte transport. In this article, we present an integrated microfluidics and iSPR platform that uses only electrokinetic transport and guiding of ligands and analytes and, therefore, requires only electrical inputs for sample transport. An important advantage of this new approach, compared to conventional systems, is the ability to direct a single analyte to a specific ligand location in the microarray, which can facilitate analysis parallelization. Additionally, this simple approach does not require complicated microfluidic channel arrangements, external pumps, or valves. As a demonstration, kinetics and affinity have been extracted from measured binding responses of human IgG and goat antihuman IgG using a simple 1:1 model and compared to responses measured with conventional pressure driven analyte transport. The measured results indicate similar binding kinetics and affinity between the electrokinetic and pressure-driven sample manipulation methods and no cross contamination to adjacent measurement locations has been observed.
authors.affiliation: BIOS Lab-On-A-Chip Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands. g.krishnamoorthy@tnw.utwente.nl
authors.forename: Ganeshram
authors.initials: G
authors.lastname: Krishnamoorthy
authors.forename: Edwin T
authors.initials: ET
authors.lastname: Carlen
authors.forename: Dietrich
authors.initials: D
authors.lastname: Kohlheyer
authors.forename: Richard B M
authors.initials: RB
authors.lastname: Schasfoort
authors.forename: Albert
authors.initials: A
authors.lastname: van den Berg
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D004563:Electrochemistry / Q000379:methods*; D007700:Kinetics; D008024:Ligands; D011485:Protein Binding; D025941:Protein Interaction Mapping / Q000379:methods; D020349:Surface Plasmon Resonance / Q000379:methods*; D013499:Surface Properties
chemical_list: D008024:Ligands