Using atomic force microscopy to assess surface modification of gold nanoparticles

This paper proposed an approach for analyzing surface modification of nanoparticles based on atomic force microscopy (AFM). The work was carried out on unmodified gold nanoparticles and gold nanoparticles coated with a protein shell (a conjugate of goldnanoparticles and immunoglobulin G). The proposed analysis of surface modification of gold nanoparticles consists of the registration of force curves, which reflect the dependences of the deflection of the beam of the AFM probe when interacting with the surface from moving the cantilever in the vertical direction. The elastic modulus and the force of the interaction between the probe and the modified or unmodified surface of the nanoparticles are proposed as the parameters characterizing the modification. Significant differences were obtained between the unmodified and modified gold nanoparticles using the AFM method in the spectroscopy mode.