Taylor dispersion of nanoparticles

Abstract

The ability to detect and accurately characterize particles is required by many fields of nanotechnology, including materials science, nanotoxicology, and nanomedicine. Among the most relevant physicochemical properties of nanoparticles, size and the related surface-to-volume ratio are fundamental ones. Taylor dispersion combines three independent phenomena to determine particle size: optical extinction, translational diffusion, and sheer-enhanced dispersion of nanoparticles subjected to a steady laminar flow. The interplay of these defines the apparent size. Considering that particles in fact are never truly uniform nor monodisperse, we rigorously address particle polydispersity and calculate the apparent particle size measured by Taylor dispersion analysis. We conducted case studies addressing aqueous suspensions of model particles and large-scaleproduced Bindustrial^particles of both academic and commercial interest of various core materials and sizes, ranging from 15 to 100 nm. A comparison with particle sizes determined by transmission electron microscopy confirms that our approach is model-independent, nonparametric, and of general validity that provides an accurate account of size polydispersity-independently on the shape of the size distribution and without any assumption required a priori.

Taylor Dispersion of Inorganic Nanoparticles and Comparison to Dynamic Light Scattering and Transmission Electron Microscopy

“…Concerning the averages gathered by DLS, these are intensityweighted values. For TDA, this depends on whether the particle dominantly absorbs or scatters light at the given wavelength [32]. Table 1 shows that the data obtained by the various methods are overall comparable.…”

“…Colloid and Interface Science Communications 22 (2018) [29][30][31][32][33] mean that the obtained results from TEM, TDA and DLS cannot be compared, on the contrary, yet the reader should keep in mind that the values are obtained by different techniques based on different models and assumptions. With this in mind, we show both results obtained via cumulant and CONTIN analysis for DLS measurements [29].…”

“…Several effects, such as the polydispersity of the sample itself, wall interactions, or instrumental errors, may cause slight differences in the signal symmetry, however seem not to have a significant influence in the data analysis in our case. Additional literature on the analysis of nanoparticles with TDA can be found from Cipeletti et al [16,17], Belongia and Baygents [18], and Balog et al [32] Results for the sizes obtained by the three instruments are shown in Table 1. The numbers from the TEM correspond to the mean size of the counted particles followed by the standard deviation.…”

“…Colloid and Interface Science Communications 22 (2018) [29][30][31][32][33] are the mean values gathered from the instruments, with the corresponding standard deviations representing the instrumental reproducibility. Concerning the averages gathered by DLS, these are intensityweighted values.…”

“…Thus, when considering that the scope of this study was to have a minimal sample preparation, we conclude that TDA measurements are easier performed and analyzed than DLS. The next steps, to improve TDA as sizing instrumentation, are to move towards more polydisperse and anisotropic NPs [32] and to more complex NP dispersions, like biological fluids containing salts, small molecules or proteins.…”