4 August 2009 Selective functionalization of gold arms of a surface plasmon polariton Mach-Zehnder interferometer for biosensing
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Proceedings Volume 7386, Photonics North 2009; 73862U (2009) https://doi.org/10.1117/12.838461
Event: Photonics North 2009, 2009, Quebec, Canada
Abstract
In long range surface plasmon polariton (LRSPP) sensing, in a Mach-Zehnder interferometer (MZI) configuration, gold arms have to respond differently to the analyte as to form layers with different refractive indices. This can be achieved if the arms are coated with different thiol-based self-assembled monolayers (SAMs), one of which should block adsorption and the other should specifically adsorb the analyte of interest. Since the MZI arms' width and the distance between them are in the micron range, such a chemical differentiation is a challenging task which nevertheless could be achieved with two techniques (1) Microspotting trough droplet confinement and manipulation using a solvophilic guide and (2) Toposelective electrochemical desorption of SAMs where the arms are subjected to different potentials. We found the latter approach the most promising because of its scalability to the wafer level. During the electrochemical desorption the potentials of both arms have to be independently controlled with a multi-channel potentiostat. Subsequent deposition of another SAM on the freed MZI arm is accomplished with minimal thiol exchange. The resulting MZI was analyzed and imaged by time-of-flight secondary ion mass spectrometry (ToF- SIMS) and with phase shift atomic force microscopy which confirms the desired MZI structure in which only one arm has specific affinity to one protein while the other would block any interaction.
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Michal Tencer, Pierre Berini, "Selective functionalization of gold arms of a surface plasmon polariton Mach-Zehnder interferometer for biosensing", Proc. SPIE 7386, Photonics North 2009, 73862U (4 August 2009); doi: 10.1117/12.838461; https://doi.org/10.1117/12.838461
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