Surface potential microscopy of surfactant-controlled single gold nanoparticle.

Area of Science:

• Nanotechnology
• Surface Science
• Biomedical Engineering

Background:

• Nanoparticle surface potential is critical for drug delivery and cellular interactions.
• Accurate surface potential measurement is vital for designing effective nanoparticle-based biomedical platforms.

Purpose of the Study:

• To directly measure the nanoscale surface potential of individual gold nanorods (GNRs) using Kelvin probe force microscopy (KPFM).
• To investigate the effect of cetyltrimethylammonium bromide (CTAB) surfactant removal on GNR surface potential.
• To establish KPFM as a high-resolution technique for characterizing nanoparticle surface properties.

Main Methods:

• Utilized Kelvin probe force microscopy (KPFM) for nanoscale surface potential mapping of individual gold nanorods (GNRs).
• Employed centrifugation to remove the cetyltrimethylammonium bromide (CTAB) surfactant from GNRs.
• Performed comparative analysis on gold nanospheres (GNS) capped with citrates.

Main Results:

• KPFM revealed that the mean surface potential of GNRs becomes significantly more negative upon CTAB removal.
• Observed a similar trend in gold nanospheres (GNS) when citrate capping was removed.
• Demonstrated that CTAB molecules electrostatically shield the negative charge of the gold nanoparticles.

Conclusions:

• KPFM provides high-resolution characterization of individual nanoparticle surface potential and surfactant effects.
• CTAB removal is essential for accurate surface potential assessment in GNRs for biomedical use due to its cytotoxicity.
• This technique aids in the rational design of engineered nanoparticles for biomedical applications by understanding surface properties.