Prof. (apl.) Dr. Reiner Dahint – Biosensors and Biomaterials Research Group
Optically Responsive Nanoparticle Layers for the Label-Free Readout of Binding Events in High-Density Peptide Arrays
Array concepts have become very popular and powerful tools to facilitate highly parallel, rapid identification of binding events. Interaction analysis is usually facilitated by labelling the potential binding partners with additional markers. To overcome the associated obstacles, strong efforts have been made to establish label-free detection schemes. However, marker-free and sensitive readout of high-density arrays is still a technological challenge. In recent years, optical detection methods based on surface plasmon resonance (SPR) in plain metal films and localized surface plasmon resonance (LSPR) in both metal clusters and metal-coated nanospheres have gained increasing attraction. However, to date there exist only few examples for the expansion of this technique to the interaction analysis in array format.
The goal of our studies is the development of an integrated bioanalytical system which facilitates the marker-free and parallel detection of biospecific binding events in high-density peptide chips for applications in basic research, diagnostics or drug discovery. For this purpose, a monolayer of metal-coated dielectric nanoparticles is prepared on a metallized substrate. Upon reflection of white light, surface plasmons are excited, and the layer exhibits a pronounced extinction spectrum. When molecules bind to the surface, the spectrum shifts to higher wavelengths, thus, providing a label-free detection mechanism. Our marker-free approach avoids costly and time-consuming labelling procedures, provides valuable information on binding kinetics and affinity, and even facilitates the detection of low-affinity binding events.
It has already been proven that high sensitivity and spatial resolution can be obtained with comparatively simple and cheap instrumentation. To utilize the full capability of the biosensor we will combine it with a complex library of peptides to use it for high throughput screening for binding events. The latter studies are performed in close cooperation with the Chip-Based Peptide Libraries Research Group at the Cancer Research Center Heidelberg (DKFZ) and the Institute of Microstructure Technology (IMT) at the Karlsruhe Institute of Technology (KIT), where novel methods for combinatorial peptide array synthesis based on printing technologies are being developed.