Layer-by-layer modification of high surface curvature nanoparticles with weak polyelectrolytes using a multiphase...

Area of Science:

• Materials Science
• Nanotechnology
• Surface Chemistry

Background:

• Handling and modifying extremely small materials like gold nanoparticles presents significant practical challenges.
• Existing surface modification techniques often struggle with efficiency and reproducibility for nanoscale materials.

Purpose of the Study:

• To develop an effective and generalizable multi-step method for layer-by-layer modification of gold nanoparticles.
• To overcome practical issues in handling and surface modification of ≈5 nm mercaptocarboxylic acid stabilized gold nanoparticles.
• To enhance the colloidal stability of modified nanoparticles across a broad pH range and ionic strength.

Main Methods:

• Utilized a multi-step process with controlled solution pH during polyelectrolyte adsorption and centrifugation.
• Incorporated a solvent precipitation step for sample concentration and pH exchange before ultracentrifugation.
• Assessed pH-dependent assembly by monitoring plasmon peak absorbance, surface charge, and nanoparticle recovery after each deposition cycle.

Main Results:

• Optimized solution pH during adsorption significantly enhanced particle recovery and maximized surface charge with weak polyelectrolytes.
• Achieved high yield deposition of one bilayer onto gold nanoparticles.
• Demonstrated enhanced colloidal stability of modified nanoparticles across a broad pH range and increased ionic strength.

Conclusions:

• The proposed multi-step processing approach is effective for improving the stability of high surface curvature particles.
• This method offers a generalizable strategy for overcoming challenges in nanoparticle surface modification.
• Controlled pH is a critical parameter for successful layer-by-layer assembly on nanoparticles.