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Sébastien Laurent

Detections of biological interactions by surface plasmon resonance imaging: Applications to pharmaceutical screening of chemical libraries & to detection of toxins

Published on 18 December 2007
Thesis presented December 18, 2007

Abstract:
The significant development of biosensors for medical applications result, in recent years, to consider other ways of constructing experimental designs. Thus, the work presented here try to respond to original problem of detecting events with low probability of occurring following two approaches "antagonists", on the one hand, pharmaceutical screening of chemical molecules and secondly, the detection of toxins for bioterrorist use. Alternatively, the probes and targets have unknown activity toward their partner. To answer this, we considered the combination of the imaging technique of surface plasmon resonance (SPRi) and the use of microarrays. Immobilization of chemical compounds from combinatorial chemistry is performed according to a prior design of molecules so that they are compatible to a standstill on a polymer end of polypyrrole. Applied to the search for new molecules that interact with bacterial RNA polymerase, an enzyme target for the development of molecules with antibiotic activity, this process has allowed the isolation of several molecules belonging to the family of hydantoins and quinazoline-2, 4-diones capable of reacting with the pharmacological target selected. Miniaturization of manufacturing processes opens the way to increased rates of this type of screening method. In the context of the detection of toxins, ricin B chain has been taken as a model study. To overcome the limitations of the technique SPRi a signal amplification protocol was developed. This has revealed down to 10 pM of analyte, that is to say, a similar sensitivity to other methods of transduction. With this multi-step analytical strategy, a dynamic range of 3 orders of magnitude has been established. An extension of this analytical approach may lead to short-term simultaneous determination of several toxins.

Keywords:
SPR imaging, combinatorial chemistry, small ligand biochips, toxin immunosensor, nanoparticles

On-line thesis.