AVS 54th International Symposium
    Plasmonics Topical Conference Tuesday Sessions
       Session PL-TuP

Paper PL-TuP1
A Hydrogel Chip for Biosensing Studied by Imaging Surface Plasmon Resonance

Tuesday, October 16, 2007, 6:00 pm, Room 4C

Session: Plasmonics Poster Session
Presenter: O. Andersson, Linköping University, Sweden
Authors: O. Andersson, Linköping University, Sweden
A. Larsson, Linköping University, Sweden
B. Liedberg, Linköping University, Sweden
Correspondent: Click to Email

In protein microarray biosensors the use of surface enhancing matrices, or hydrogels, is of great interest. Properly constructed biosensor hydrogels exhibit low non-specific binding while allowing for covalent immobilization of ligands with maintained bio-functionality. In earlier work we have developed such a matrix, based on graft copolymerization of poly(ethylene glycol) and 2-hydroxyethyl methacrylate monomers.1 The matrix was graft polymerized using UV light and was subsequently modified by chemical introduction of carboxyl groups. In this contribution, we demonstrate the construction of a microarray consisting of proteins covalently immobilized to well defined spots of different thicknesses of our PEG-matrix. By using a photo mask and a movable shutter we are able to vary the UV light exposure time of different spots on our surface. This enables construction of surfaces consisting of arrays of spots with physical thicknesses ranging from a few to tens of nanometers. These surfaces were pre-activated with EDC/NHS and proteins were delivered through piezo-dispensation. Biomolecular interactions involving the immobilized proteins were monitored using imaging surface plasmon resonance (iSPR). More specifically, the proteins Human Serum Albumin and Fibrinogen were piezo-dispensed and the response upon flow delivery of their respective antibodies was monitored with iSPR. The dynamic range of iSPR in the Kretschmann configuration is typically limited by the width of the resonance dip. In this work, however, we have employed iSPR at multiple wavelengths to extend the dynamic range and enable measurements in surface spots of different thicknesses.2 Our results indicate that our sensor surfaces exhibit excellent properties for use as a template in protein micro-array fabrication. This type of thickness gradient surfaces are also useful when optimizing the properties of the hydrogel, for instance with respect to ligand binding, activity and non-specific binding.3 In addition, the hydrogel thickness gradient array is interesting as a scaffold in the immobilization of nano-particles and as a platform for the construction of more complex heterogeneously composed biosensor matrices.

1Larsson A, Ekblad T, Andersson O, Liedberg B. Biomacromolecules 2007, 8, 287-295.
2Johansen K, Arwin H, Lundstrom I, Liedberg B. Rev. Sci. Inst. 2000, 71, 3530-3538.
3Larsson A, Liedberg B. To appear in Langmuir.