A Fluorescence Microscopy Assay for Assessing Beam Damage to Nanoparticle Capping Ligands During Liquid Cell Electron Microscopy

Abstract

Liquid cell electron microscopy is commonly used to characterize the dynamics of nanoparticles (NPs) in a liquid medium, often during nanoparticle self-assembly. Many studies have been done in this area to investigate the self-assembly of NPs functionalized with different capping ligands such as small molecules, polymers and DNA [1,2,3]. Critically, the specific chemistry of the organic capping ligands on NPs determines their interactions during self-assembly and the morphology of the final self-assembled structure. It is well known that organic materials in liquid undergo oxidative attack from oxidizing radicals and molecules created by the electron beam, including hydroxyl radicals and hydrogen peroxide [4]. However, the effect of electron beam irradiation on the surface functional groups on NPs has not been systematically investigated, which has prohibited discovery of acceptable dose limits for imaging NPs during self-assembly with minimal beam induced changes to their surface chemistry.