Light Scattering as an Easy Tool to Measure Vesicles Weight Concentration

Abstract

Over the last few decades, liposomes have emerged as promising drug delivery systems and effective membrane models for studying biophysical and biological processes. For all applications, knowing their concentration after preparation is crucial. Thus, the development of methods for easily controlling vesicles concentration would be of great utility. A new assay is presented here, based on a suitable analysis of light scattering intensity from liposome dispersions. The method, tested for extrusion preparations, is precise, easy, fast, non-destructive and uses a tiny amount of sample. Furthermore, the scattering intensity can be measured indifferently at different angles, or even by using the elastic band obtained from a standard spectrofluorimeter. To validate the method, the measured concentrations of vesicles of different matrix compositions and sizes, measured by light scattering with different angles and instruments, were compared to the data obtained by the standard Stewart assay. Consistent results were obtained. The light scattering assay is based on the assessment of the mass fraction lost in the preparation, and can be applied for methods such as extrusion, homogenization, French press and other microfluidic procedures.

Nanoalgosomes: Introducing extracellular vesicles produced by microalgae

“…At MPIP, multi-angle DLS was performed with an ALV spectrometer (ALV-GmbH, Germany), including a goniometer and an ALV/ LSE-5004 multiple-tau full-digital correlator with 320 channels and equipped with a He-Ne laser with λ = 632.8 nm. Scattered intensity and intensity autocorrelation function g  (t) were measured simultaneously at different scattering angle ϑ to measure the z-averaged hydrodynamic diameters D h , the average diameter D g , which is twice the radius of gyration, and eventually the full size distribution (Mailer et al, 2015;Noto et al, 2012;Prima et al, 2020;Schmitz, 1990). Full details about the analysis are reported in the Supporting Materials and Method's Section and Supporting Figure S.…”

Using light scattering to assess how phospholipid–protein interactions affect complex I functionality in liposomes

“…48 In N ves measurements, the time-averaged photon count-rate scattered by the sample is recorded and then transformed into a vesicle distribution (see Supporting Information Section 3.2). The total lipid concentration (c Lipid ) in vesicles was derived from both DLS measurements and the Stewart assay (see Methods) 39 and, in combination with N ves , allowed calculation of the average number of phospholipids and CLs per vesicle. The NADH:APAD + assay 14 characterises the total R-CI flavin-site activity.…”

“…two approaches below, based on Di Prima et al 39 The total phospholipid content was 7.3-8.6 mg mL À1 for all lipid compositions.…”

Small Angle X-ray Scattering Sensing Membrane Composition: The Role of Sphingolipids in Membrane-Amyloid β-Peptide Interaction

“…Samples were prepared considering a lipid mass at a final concentration of 15 mg/mL. To assess whether mass loss had occurred during the extrusion step, the final concentration of the LUV was checked using static light scattering (SLS), as described elsewhere [ 21 ]. Liposomes samples, if necessary, were concentrated through Centricon 100 KDa centrifuge filters before the addition of the Aβ peptides.…”