Towards a label-free optical porous silicon DNA sensor

TitleTowards a label-free optical porous silicon DNA sensor
Publication TypeArticolo su Rivista peer-reviewed
Year of Publication2005
AuthorsDi Francia, G., La Ferrara V., Manzo Sonia, and Chiavarini Salvatore
JournalBiosensors and Bioelectronics
Keywordsarticle, Biosensing Techniques, bridged compound, chemical labeling, Chemiluminescent Measurements, complementary DNA, Composition, DNA, DNA determination, electrochemical analysis, Electrochemical etching, Equipment Design, Equipment Failure Analysis, hydrobromic acid, imide, In Situ Hybridization, interactions with DNA, Labeling steps, nucleic acid immobilization, Oligonucleotide Array Sequence Analysis, optical biosensor, Optics, Photoluminescence, physical chemistry, Pore distribution, Porosity, Porous silicon, Reproducibility of Results, Sampling, Sensitivity and Specificity, Sensors, silane derivative, silicon, Silicon wafers, Single strand DNA (ss-DNA), single stranded DNA, Staining and Labeling

We report on the fabrication of an optical silicon-based label-free DNA sensor. n-Type crystalline silicon wafers have been electrochemically etched to form porous silicon layers and characterized in terms of porosity, pore distribution, surface composition and photoluminescence. Samples (0.25 cm 2) have been cut and properly derivatized using trimethoxy-3- bromoacetamidopropylsilane in order to link single strand DNA (ss-DNA). Such a molecule is not commercially available and has been ad-hoc prepared by reacting hydrobromic acid and 3-aminopropyltrimethoxysilane in presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide as coupling agent. Trimethoxy-3-bromoacetamidopropylsilane acts as a bridge anchored to the porous silicon surface through the silane group while immobilizing ss-DNA by means of the bromoacetamido moiety. We have found that derivatized samples exhibit a photoluminescence that is stable in time and is not modified after exposure to non-complementary DNA strand. On the other hand, a sensible enhancement of the light emission has been observed when the derivatized samples react with the complementary strand, showing that the specific ss-DNA/complementary DNA (c-DNA) interaction can be optically sensed without using further labeling steps. This strongly strengthens the possible role of silicon as a material for biosensors. © 2004 Elsevier B.V. All rights reserved.


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