Cryogenic electron tomography to determine thermodynamic quantities for nanoparticle dispersions

Abstract

Nanoparticle dispersions were studied by cryogenic electron tomography, which was found to allow extraction of key thermodynamic quantities.

Experimental Method to Distinguish between a Solution and a Suspension

“…The latter case was chosen because similar systems tend to aggregate in such conditions. [ 30 ] We studied the particles in the two cases with cryo‐electron tomography (cryo‐ET) [ 31 ] and SAXS. As shown in Figure S7 (Supporting Information), the particles did not show significant difference when studied with these two techniques.…”

Monovalent ion-mediated charge–charge interactions drive aggregation of surface-functionalized gold nanoparticles

“…, for NPs constituted by 100% charged ligands, this results in entirely soluble NPs’ solutions that do not form aggregates. 49 …”

“…To clarify this controversy, and to gain atomistic-level insights into the mechanism of NP aggregation, here we investigate NP aggregation with two high-resolution methodologies: by explicitly computing the Potential of Mean Force (PMF) of this process using fully atomistic MD simulations, a computational method with kcal accuracy, 43–48 and by directly collecting cryogenic electron tomography images of NPs in solution. 49 Both approaches suggest that already at physiological ion concentrations, NP dimers are stabilized by complexes formed by negatively charged ligands of the two NPs and positively charged monovalent ions. Taken together, our results suggest that not only van der Waals forces, but also electrostatic interactions mediated by monovalent ions at physiological concentrations, contribute to attraction between nano-sized charged particles at very short length scales.…”