Highly sensitive biosensors based on amorphous silicon-carbon alloys

Larbi Touahir 1Anne Chantal Gouget-Laemmel 1Philippe Allongue 1Rabah Boukherroub 2,3Jean-Nöel Chazalviel 1Elisabeth Galopin 2,3Catherine Henry de Villeneuve 1Anne Moraillon 1Joanna Niedziolka-Jönsson 2,3Ionel Solomon 1Sabine Szunerits 2,3François Ozanam 1

1. Physique de la Matière Condensée (CNRS), Palaiseau 91128, France
2. Institut de Recherche interdisciplinaire (IRI), 50 avenue de Halley, BP 70478, Villeneuve d'Ascq 59652, France
3. Institut d'Electronique, de Microélectronique et de Nanotechnologie (IEMN), Cité Scientifique Avenue Poincaré, Villeneuve d'Ascq 59652, France


Biosensors based on fluorescence and/or surface plasmon resonance (SPR) detection schemes are widely used owing to their ease of processing and good sensitivity. Their performance is frequently limited by the control of the surface chemistry. In this framework, the use of silicon substrates offers a promising alternative route for the grafting of functionalized organic monolayers through Si-C covalent bonding, providing robust immobilization chemistry. First, a carboxyl-terminated monolayer is grafted on hydrogenated surfaces via hydrosilylation. Then, the carboxyl groups are activated using NHS/EDC, followed by amidation with biological probes bearing a primary amine linker. By combining Atomic Force Microscopy (AFM) imaging and infrared quantitative spectroscopy, we have optimized these multi-step modifications.

To combine the advantages of well-controlled surface chemistry and sensitive detection, we have designed fluorescent and SPR biosensors based on a thin layer of hydrogenated amorphous silicon-carbon alloy (a-SixC1-x:H) deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) on a metal layer. Chemical protocols developed on crystalline silicon surfaces were successfully transferred onto a-SixC1-x:H. The sensitivity is maximized by optimization of the amorphous layer thickness and its carbon content. In this way, a fluorescence-based microarray on aluminium exhibits an efficient amplification of the fluorescent signal by over one order of magnitude as compared to commercial slides. Novel Au- or Ag-based sensitive plasmonic interfaces were also developed.

In either case, the obtained sensitivity allows for monitoring the hybridization of DNA probes with their complementary DNA in situ and in real time. Many successive hybridization/dehybridization cycles have been recorded without measurable changes in performance.


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Presentation: Keynote lecture at SMCBS'2009 International Workshop, by Larbi Touahir
See On-line Journal of SMCBS'2009 International Workshop

Submitted: 2009-07-08 09:07
Revised:   2009-08-13 17:07