Internal-Modified Dithiol DNA-Directed Au Nanoassemblies: Geometrically Controlled Self-Assembly and Quantitative...

Area of Science:

• Nanotechnology
• Materials Science
• Biotechnology

Background:

• DNA-directed self-assembly offers precise control over nanomaterial fabrication.
• Gold nanoparticles (Au NPs) are versatile building blocks for advanced nanostructures.
• Surface-Enhanced Raman Scattering (SERS) is a sensitive technique for molecular detection.

Purpose of the Study:

• To develop a hierarchical DNA-directed self-assembly strategy for structure-controlled gold nanoassemblies (Au NAs).
• To investigate the role of DNA modification and quantity in controlling Au NA geometry.
• To explore the SERS properties of geometrically controlled Au NAs for quantitative analysis.

Main Methods:

• Conjugating Au NPs with internal-modified dithiol single-strand DNA (ssDNA).
• Utilizing different DNA-ssDNA conjugates (Au-B-A and A-B-Au-B-A) to direct self-assembly.
• Employing Surface-Enhanced Raman Scattering (SERS) measurements and 3D finite-difference time domain (3D-FDTD) calculations.

Main Results:

• Achieved structure-controlled Au NAs with geometries ranging from 1D to quasi-2D and 2D by matching Au-DNA self-assembly units.
• Demonstrated that dithiol-ssDNA modification and ssDNA quantity critically influence Au NA assembly.
• Observed regular and linearly "hot spots"-number-dependent SERS properties in the fabricated Au NAs.
• Quantitatively evaluated the number of "hot spots" and SERS enhancement factor based on the number of Au NPs.

Conclusions:

• A hierarchical DNA-directed self-assembly strategy enables precise control over Au NA geometry.
• The geometry of Au NAs directly influences their SERS properties, offering tunable enhancement.
• This work establishes a new pathway for quantitative analysis using SERS based on controllable Au nanoassemblies.