Non-equivalence of different evaluation algorithms to derive mean particle size from dynamic light scattering data

Abstract

Different manufacturers of dynamic light scattering (DLS) instruments implement various evaluation algorithms. Users often implicitly assume that the various algorithms yield the same mean value and deliver results of the same precision. This assumption was tested using results obtained by cumulants analysis, CONTIN and Non-Negative Least Squares fitting (NNLS) of distributions, and frequency analysis on near-spherical silica and polystyrene latex particles obtained in one laboratory and results on near-spherical silica obtained in other laboratories. Particles have been measured in the size range of 10 to 200 nm. The results show that the average particle diameters from different algorithms differ significantly and that these differences increase with an increasing polydispersity of the material. Also, precision, both within-laboratory (repeatability) as well as between-laboratory standard deviations (reproducibility), differs between the algorithms investigated, especially for the more polydisperse silica materials. The results obtained from the cumulants method usually show the best repeatability and the lowest between-laboratory standard deviation. The results also show that the conversion of intensity-weighted results to volume-weighted results increase the betweenlaboratory standard deviation, confirming the theoretical expectations that conversion increases the variation significantly.

Influence of Ce3+ Substitution on Antimicrobial and Antibiofilm Properties of ZnCexFe2−xO4 Nanoparticles (X = 0.0, 0.02, 0.04, 0.06, and 0.08) Conjugated with Ebselen and Its Role Subsidised with γ-Radiation in Mitigating Human TNBC and Colorectal Adenocarcinoma Proliferation In Vitro

“…The polydispersity index (PDI) can be obtained from instruments that use DLS or are determined from electron micrographs. International standards organisations (ISOs) have established that PDI values < 0.05 are more common to monodisperse samples, while values > 0.7 are common to a broad size (e.g., polydisperse) distribution of particles [ 43 ]. Herein, for the obtained PDI values ( Figure 6 ), we found that the PDI value increases as Ce 3+ ions content increases in the prepared sample and was found to be 0.304, 0.395, 0.399, and 0.539 in ZnCe x Fe 2−x O 4 NPs when X = 0.0, 0.02, 0.04, 0.06, 0.08, respectively.…”

Formulation of Liver-Specific PLGA-DY-635 Nanoparticles Loaded with the Protein Kinase C Inhibitor Bisindolylmaleimide I

“…Furthermore, considering the fact that differently sized particles scatter light with different intensities, where larger particles typically dominate the results [ 47 , 48 ], and taking into account the relatively high PDI of PLGA-DY-635 (BIM-I) NPs, the results from the volume- and number-weighted size distributions are also reported, which are more relevant in this case ( Table 1 ). Compared to the intensity-weighted distributions, for all NPs, the volume- and number-weighted distributions showed a shift to considerably smaller sizes, which can be considered typical for disperse particle populations [ 49 ]. Nevertheless, all DLS distributions of ultrafiltrated NPs showed that the drug-loaded NPs were apparently smaller on average than the unloaded NPs by a factor of approximately two.…”

Novel fabrication of SiO2/Ag nanocomposite by gamma irradiated Fusarium oxysporum to combat Ralstonia solanacearum

“…Based on the obtained PDI values, the prepared particles in the nanocomposite showed moderate mono-size dispersion. The international standards organizations (ISOs) have established that PDI values < 0.05 are more common to monodisperse samples, while values > 0.7 are common to a broad size (e.g., poly-disperse) distribution of particles (Franks et al 2019 ). SEM–EDX elemental mapping also confirmed the preparation of nanocomposite as reported in recent studies (Kim et al 2005 ; Alimunnisa et al 2017 ).…”