Measuring the Accessible Surface Area within the Nanoparticle Corona Using Molecular Probe Adsorption

Area of Science:

• Nanotechnology
• Materials Science
• Physical Chemistry

Background:

• The nanoparticle corona phase influences dispersion and surface accessibility.
• Existing methods struggle to directly probe corona phase structure (hard vs. soft).
• Understanding corona structure is crucial for nanoparticle applications in catalysis and sensing.

Purpose of the Study:

• To introduce and validate a novel method for measuring accessible nanoparticle surface area.
• To characterize the structure-property relationships of nanoparticle corona phases.
• To enable quantitative analysis of corona phases across diverse nanoparticle systems.

Main Methods:

• Development of a molecular probe adsorption (MPA) method.
• Utilizing titration of a quenchable fluorescent molecule (e.g., riboflavin).
• Analysis of surface coverage parameters including q/K_D and K_D.

Main Results:

• MPA successfully measured accessible surface area for gold nanoparticles, carbon nanotubes, and graphene sheets.
• The Gibbs free energy of probe binding was found to scale inversely with the cube root of surface area (q).
• MPA demonstrated its capability to discern critical structure-property relationships in corona phases.

Conclusions:

• MPA is a rapid, quantitative technique for elucidating nanoparticle corona structure.
• The method provides insights into the dynamic exchange within soft corona phases.
• MPA is broadly applicable for characterizing nanoparticle surface phases in various systems.