Optimisation of a silicon/silicon dioxide substrate for a fluorescence DNA microarray

Area of Science:

• Biotechnology
• Materials Science
• Optics

Background:

• DNA microarrays are crucial for genetic analysis.
• Standard glass slides can limit fluorescence detection sensitivity.
• Optical interference effects can modulate light signals.

Purpose of the Study:

• To investigate the modulation of fluorescence intensity on silicon/silicon dioxide substrates for DNA microarrays.
• To develop a theoretical model predicting fluorescence signal variations based on oxide thickness.
• To experimentally validate the model and assess the potential of Si/SiO2 substrates for enhanced detection.

Main Methods:

• Fabrication of Si/SiO2 substrates with varying oxide thicknesses using thermal oxidation and buffered oxide etch (BOE).
• Functionalization of SiO2 surfaces with silane monolayers for in situ oligonucleotide probe synthesis.
• Hybridization of probes with complementary targets and measurement of fluorescence intensity.
• Comparison of fluorescence signals with standard glass substrates.

Main Results:

• A theoretical model predicted a 90-fold variation in fluorescence signal intensity based on oxide thickness.
• Maximal signal enhancement (7.5-fold) for Cy3 dye was observed at 90 nm oxide thickness.
• Experimental results showed excellent agreement with the theoretical model.
• A 10-fold enhancement in detection sensitivity was achieved compared to glass substrates.

Conclusions:

• Si/SiO2 substrates effectively modulate fluorescence intensity through optical interference.
• The developed model accurately predicts signal variations, guiding substrate optimization.
• Si/SiO2 substrates offer a significant improvement in detection sensitivity for fluorescence DNA microarrays.
• These substrates are a promising alternative to glass slides for sensitive genetic analysis.