Comprehensive Characterization of Nano- and Microparticles by In-Situ Visualization of Particle Movement Using Advanced Sedimentation Techniques

Abstract

The state of a suspension is crucial with regard to processing pathways, functionality and performance of the end product. In the past decade, substantial progress has been made in designing highly specialized and functionalized particles. In current particle technology, besides classic particle properties such as particle size distribution, shape and density, surface properties play an essential role for processing, product specification and use. For example, in medical therapy, analytical diagnostic applications, as well as in separation processing and harvesting of high-valued materials, magnetic micro-and nanoparticles play an increasing role. In addition to traditional parameters such as size, the particle magnetization has to be quantified here. Sedimentation techniques have been used for hundreds of years to determine the geometrical characteristics of dispersed particles. Numerous national and international standards regarding these techniques have been published. Mainly due to the fast growing market share of laser scattering techniques over the past two decades, most customers these days are not aware of some advantageous features of particle characterization via a firstprinciple fractionating approach such as sedimentation. This is unfortunate as sedimentation techniques have made huge technological leaps forward regarding electronics, sensors and computing abilities. This paper aims to give a short review about different cumulative and incremental sedimentation approaches to measure the particle size distribution. It focuses mainly on the in-situ visualization (STEP-Technology ® ) of particle migration in gravitational and centrifugal fields. It describes the basics of the new multi-sample measuring approaches to quantify the separation kinetics by spatial and time-resolved particle concentration over the entire sample height. Based on these data, the sedimentation velocity and particle size distribution are elucidated and estimates of accuracy, precision and experimental uncertainties are discussed. Multi-wavelength approaches, correction of higher concentration, and the influence of rheological behavior of continuous phase will also be discussed. Applications beyond the traditional scope of sedimentation analysis are presented. This concerns the in-situ determination of hydrodynamic particle density and of magnetophoretic velocity distributions for magnetic particulate objects.

Validation of a Homogeneous Incremental Centrifugal Liquid Sedimentation Method for Size Analysis of Silica (Nano)particles

“…The characteristic parameters were estimated from lognormal functions fitted to linearly spaced PSDs. Detailed information about data acquisition and data processing procedures used by the SEPView TM 6.0 software are explained elsewhere [ 39 ].…”

Understanding Nanomedicine Size and Biological Response Dependency: What Is the Relevance of Previous Relationships Established on Only Batch-Mode DLS-Measured Sizes?

“…Size of dispersions P, F2, F3 and F4 were also evaluated at 25°C using an analytical photocentrifuge LUMiSizer® 6514 (12 measurement channels) (LUM GmbH, Berlin, Germany) and STEP-TechnologyTM [38]. Samples were diluted in Milli-Q® water to achieve a concentration in nanoparticles ranging from 2 to 10 mg/mL.…”

“…Several methods can be used to evaluate size characteristics of nanomedicines [19,[23][24][25][26][29][30][31][32][33][34][35][36][37][38][39]. However, Dynamic Light Scattering applied in the batch mode (batch-mode DLS) remains the most used method [19,25,27,40,41].…”

NMR as a Tool to Characterize the Aggregation Structure of Silica Nanoparticles in a Liquid

“…For the nanoparticles, of course, centrifugal force is required to reduce the time (Allain et al, 1995). Lerche et al (2007Lerche et al ( , 2014Lerche et al ( and 2019 proposed an analytical centrifuge (AC) system for determination of the characteristic material properties related to the sedimentation and consolidation behavior of the dispersions. The STEP TM -Technology (Space and Time resolved Extinction Profiles) allows one to simultaneously measure the intensity of the transmitted light as a function of time and position over the entire sample length.…”