Optimisation of a silicon/silicon dioxide substrate for a fluorescence DNA microarray.
This paper presents a comprehensive theory and experimental characterisation of the modulation of the fluorescence intensity by the construction of optical interferences on oxidised silicon substrates used for DNA microarrays. The model predicts a 90-fold variation of the fluorescence signal depending on the oxide thickness. For a Cy3 dye, the signal is maximal for a 90 nm oxide thickness corresponding to a 7.5-fold enhancement with respect to a standard glass substrate. For experimental validation of the model, we have prepared Si/SiO2 substrates with different parallel steps of decreasing oxide thicknesses on the same sample using a buffered oxide etch (BOE) etching process after thermal oxidation. The SiO2 surface has been functionalized by a silane monolayer before in situ synthesis of L185 oligonucleotide probes. After hybridisation with complementary targets, the variations of the fluorescence intensity versus oxide thickness are in very good accordance with the theoretical model. The experimental comparison against a glass substrate shows a 10-fold enhancement of the detection sensitivity. Our results demonstrate that a Si/SiO2 substrate is an attractive alternative to standard glass slides for the realisation of fluorescence DNA microarrays whenever detection sensitivity is an important issue.
Bras
M
M
LEOM, Laboratoire d'Electronique, Optoélectronique et Microsystèmes, UMR 5512, Ecole Centrale de Lyon, 36, avenue Guy de Collongue, F69134 Ecully, France.
Dugas
V
V
Bessueille
F
F
Cloarec
J P
JP
Martin
J R
JR
Cabrera
M
M
Chauvet
J P
JP
Souteyrand
E
E
Garrigues
M
M
D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008956:Models, Chemical; D020411:Oligonucleotide Array Sequence Analysis / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012825:Silicon / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000295:instrumentation* / Q000379:methods
D020099:Coated Materials, Biocompatible; D012822:Silicon Dioxide; D012825:Silicon