ADVANCES IN LABEL-FREE OPTICAL BIOSENSING: DIRECT COMPARISON OF WHISPERING GALLERY MODE SENSORS WITH SURFACE PLASMON RESONANCE

摘要

Whispering gallery modes (WGM) in fluorescent dielectric microcavities have recently become an attractive alternative to state-of-the-art label-free optical biosensors due to their high sensitivity to molecular adsorption and their ease of operation under a variety of environmental conditions. In particular the true microscopic dimension of the sensor as well as its purely radiative control without any need for external coupling opens new opportunities for label-free biosensing on microscopic scale. While these are obvious advantages, a direct comparison of the performance of WGM biosensors with well-established techniques of known high sensitivity, such as surface plasmon resonance sensors, has not been undertaken to date, thus obscuring the opportunities of the newly rising approach. We have therefore studied the performance of both WGM biosensors and a commercial SPR sensor using a selection of specifically and non-specifically binding biomolecules in-situ and under same conditions. The WGM biosensors consist of 10 μm dye-doped polystyrene beads immobilized in a flow cell. The performance of the two techniques is compared in view of the efficiency and sensitivity towards detection of both model interaction pairs (e.g. biotin/Streptavidin) and specific interaction pairs such as antigen-antibody with a lower degree of interaction affinities.