Effect of DNA Density on Nucleic Acid Detection Using Cross-Linking Aggregation of DNA-Modified Gold Nanoparticles

Area of Science:

• Nanotechnology
• Biotechnology
• Molecular Diagnostics

Background:

• Gold nanoparticles (AuNPs) function as colorimetric biosensors, detecting molecular aggregation via color changes.
• Single-stranded DNA (ssDNA)-functionalized AuNPs (ssDNA-AuNPs) are established tools for genetic analysis.

Purpose of the Study:

• To investigate how the density of immobilized ssDNA on AuNPs impacts the sensitivity of target ssDNA detection.
• To compare the efficacy of two distinct ssDNA-AuNP cross-linking aggregation models: unidirectional (UD) and bidirectional (BD).

Main Methods:

• Utilized two cross-linking aggregation models (UD and BD) with ssDNA-AuNPs.
• Systematically varied the density of immobilized ssDNA probes on AuNPs.
• Assessed target ssDNA detection sensitivity across different ssDNA densities and model types.

Main Results:

• Lower immobilized ssDNA density significantly enhanced target ssDNA detection sensitivity in both UD and BD models.
• The UD aggregation model exhibited higher sensitivity than the BD model, potentially due to cross-linking efficiency.
• Sensitivity was also influenced by the number of bases between AuNPs at higher DNA densities.

Conclusions:

• Controlling the density of immobilized probe ssDNA is crucial for improving detection sensitivity in ssDNA-AuNP-based biosensors.
• Optimized ssDNA density enhances the duplex formation ratio, leading to more reliable genetic detection.
• Findings provide a foundation for developing more sensitive and accurate AuNP-based diagnostic tools.