Figure 1

Schematic illustration of some techniques allowing the determination of NP size. Such techniques can be classified into two categories, those giving access to the size of the metallic core and those providing NP hydrodynamic diameters. Central part: Scheme of a functionalized NP with the water molecules of its solvation layer. Upper part: TEM and UV–vis spectroscopy allows the determination of the core size. TEM necessitates the measurement of a sufficiently high number of objects to obtain a meaningful distribution as the one presented. Correlation between PR position and NP diameters can be extracted from literature and so UV–vis spectroscopy can give an estimation of NP size in a routine control procedure. Some data were extracted from supplier websites (Sigma-Aldrich and Nanopartz). Lower part: TEM, with an extrinsic coloration, allows the visualization of the biomolecular corona and the measurement of its thickness. DLS and NTA utilize the properties of Brownian motion to provide hydrodynamic diameters. However, the average and distribution given by DLS is weighted by particule size whereas NTA is a particle by particle analysis.