Assembly Dynamics of Plasmonic DNA-Capped Gold Nanoparticle Monolayers

Area of Science:

• Materials Science
• Nanotechnology
• Physical Chemistry

Background:

• Nanoparticle self-assembly in aqueous solutions is crucial for applications but challenging due to complex parameters.
• Electrostatic interactions in water offer unique control over nanoparticle assembly, distinct from organic solvents.

Purpose of the Study:

• To investigate the influence of electrostatic interactions on the adsorption of DNA-capped gold nanoparticles onto a charged surface in aqueous solutions.
• To explore how ionic strength and DNA ligand length control nanoparticle assembly kinetics and monolayer structure.

Main Methods:

• Utilized quartz crystal microbalance with dissipation (QCM-D) to study nanoparticle adsorption kinetics.
• Employed grazing incidence small-angle X-ray scattering (GISAXS) and scanning electron microscopy (SEM) to characterize adsorbed monolayer structures.

Main Results:

• Adsorption kinetics and monolayer structure were found to be controllable by DNA ligand length, ionic strength, and salt species.
• Increasing ionic strength and decreasing DNA ligand length enhanced surface coverage and reduced nanoparticle spacing.
• Kinetics were accurately modeled by a modified Langmuir model, converging to the simple Langmuir model at high MgCl2 concentrations.

Conclusions:

• The DNA-capped gold nanoparticle system provides a tunable platform for controlled self-assembly in aqueous solutions.
• Precise control over nanoparticle array structure enables the design of materials with tunable plasmonic responses.
• Findings facilitate the development of advanced plasmonic and optoelectronic devices.