Sensing with colors


Ungureanu, F. (2012) Sensing with colors. thesis.

open access
Abstract:In this thesis, we introduce a new optical method based on gold nanoparticles as
individual sensing platforms for the detection of low concentrations of analytes (DNA or
proteins). Here we provide the proof of principle of the methodology in the detection of
immunoreactions and determine its limit of detection. We show that with a simple colour
camera we are able to detect simultaneously immunobinding on thousands of individual
gold nanoparticles [92], by measuring the change in the colour of many individual
nanoparticles [93]. If an amplification step is used the LOD of such a system can be
boosted even more [94].
In order to get the best sensing strategies an understanding of the physical
background is needed. Chapter 2 presents a review of the physical aspects of LSPR and
continues with a theoretical discussion on the sensing strategies employing individual gold
nanoparticles as sensing platforms. The concept of parallel detection of multiple
individually addressable nanoparticles is introduced and a theoretical LOD is determined.
Chapter 3 introduces a new detection method of binding events using a colour
camera in a DF setup. The feasibility of this approach was tested in an adsorption assay
and an immunoassay and the LOD of the method for this sensing strategy was
experimentally measured. In addition, two different detection approaches are tested and
their performances compared.
In Chapter 4, we introduce a new sensing strategy using gold nanoparticle probes
in microfluidic cells in colorimetric darkfield microscopy enabling the simultaneous
sensing of hundreds of binding events of individual particles simultaneously. Here, single
binding events can be observed and the results were confirmed by independent methods
like Scanning Electron Microscopy.
After demonstrating the proof of principle of our detection method in an unamplified
protein assay and direct immunoassay, in Chapter 5 we test our setup in an
amplified protein assay and determine the performances of the setup by measuring
experimentally the LOD of the system.
In Chapter 6, we review the main achievements presented in this thesis, and we
present several future recommendations for this line of research.
Item Type:Thesis
Science and Technology (TNW)
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