An Advanced, Silicon-Based Substrate for Sensitive Nucleic Acids Detection

Area of Science:

• Biomedical Engineering
• Materials Science
• Nanotechnology

Background:

• Biosensor fabrication relies heavily on surface substrate properties and chemical functionalization for sensitivity.
• Microarray technology demands substrates that can amplify optical signals for enhanced detection.
• Existing substrates may have limitations in signal enhancement and probe immobilization efficiency.

Purpose of the Study:

• To describe an advanced silicon-based substrate (A-MA) designed for enhanced optical signal amplification in microarray applications.
• To demonstrate the substrate's capability for efficient immobilization of single-strand DNA (ssDNA).
• To evaluate the performance of the A-MA substrate in detecting Hepatitis B Virus (HBV).

Main Methods:

• Fabrication of a multilayer Si/Al/SiO₂ substrate (A-MA).
• Optimization of SiO₂ layer thickness (~830 nm) for maximum interference with Cy5 fluorescent labels.
• Immobilization of ssDNA probes onto the SiO₂ surface using standard silane chemistry.
• Detection of Hepatitis B Virus (HBV) using the fabricated microarray.

Main Results:

• The A-MA substrate achieves optical signal enhancement through a combination of an aluminum (Al) film's mirror effect and optimized SiO₂ thickness.
• High probe densities of approximately 2000 fluorescent units/µm² were reached.
• The microarray demonstrated a dynamic linear range of 0.05–0.5 nM for HBV detection.
• A high sensitivity of about 18000 arbitrary units/nM and a Limit of Detection (LOD) between 0.031–0.043 nM were achieved.

Conclusions:

• The developed A-MA substrate significantly enhances optical signals for biosensor applications.
• The substrate facilitates high-density ssDNA immobilization, crucial for sensitive assays.
• The A-MA microarray shows excellent performance in detecting Hepatitis B Virus, indicating its potential for diagnostic applications.