Nanoparticle number concentration measurements by multi-angle dynamic light scattering

Abstract

We present the use of Multi-angle Dynamic Light Scattering (MADLS®) for the measurement of nanoparticle concentration. We describe the theory of the method and its application to nanoparticles made of gold, silica and polystyrene, with diameters ranging from 30 to 400 nm, and demonstrate some of the limitations with particles of sizes 500 nm and above. We evaluate the method accuracy, linearity and reproducibility, as well as the operational nanoparticle concentration and size range. We show that the concentration working range depends on the material’s optical properties, size and concentration. Here it is shown that the level of accuracy that can be expected for the concentration of particles is typically within 50% of the nominal value across a range of materials and sizes and, for some samples, within 20%. The repeatability of the measurements, in terms of relative standard deviation, is typically below 30%. A linearity of within 40% across a concentration range of 3·108 to 2·1011 mL−1 for concentration measurements was also demonstrated by using gold nanoparticles and gravimetric dilutions for method validation. Overall, we show that MADLS® is a rapid and straightforward method for the reproducible measurement of particle concentration, as well as size, requiring minimal sample preparation, without the need to calibrate using a pre-determined concentration series, and applicable to a broad range of materials. These features make it an ideal tool to support both development and quality control of particle materials for a broad range of applications.

Effect of Two Unique Nanoparticle Formulations on the Efficacy of a Broadly Protective Vaccine Against Pseudomonas Aeruginosa

“…To investigate the change of particle size with the addition of L-PaF to ME further, we performed MADLS measurements (Figure 1) (Naiim et al, 2015;Austin et al, 2020). These results confirmed that L-PaF is heterogeneous with four distinct particle size populations based on intensity-based measurements, however particle numbers indicated that the smallest species (∼8 nm) was dominant.…”

Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles

“…Thanks to a number of international efforts in recent years, this situation is improving. [2][3][4][5][6][7][8][9][10][11][12] Documentary standards have been developed within the International Organization for Standardisation (ISO) for a number of techniques capable of performing number concentration measurements including population-averaging methods such as: small angle X-ray scattering (SAXS), 13 dynamic light scattering 14,15 and centrifugal liquid sedimentation (CLS), 16,17 as well as particle-counting methods such as, single particle inductively coupled plasma mass spectrometry (spICP-MS), 18 particle tracking analysis (PTA), 19 differential mobility analysis with integrated condensation particle counter 20 and resistive pulse sensing (RPS). 21 Many of these standards, however, describe aspects of particle size analysis rather than measurement of number concentration.…”

Characterization of Recombinant Adeno-Associated Viruses (rAAVs) for Gene Therapy Using Orthogonal Techniques

“…Multiangle dynamic light scattering (MADLS) allows for a higher-resolution size determination of multimodal samples, by using three different detection angles (back, side, and forward) and combining the information obtained into one angle-independent particle size distribution. An extension of MADLS is particle concentration measurements giving the total particle concentration and the particle concentration for each mode present in a sample [ 30 , 31 , 32 , 33 ].…”