Core-Shell Modeling of Light Scattering by Vesicles: Effect of Size, Contents, and Lamellarity

Abstract

Having a fast, reliable method for characterizing vesicles is vital for their use as model cell membranes in biophysics, synthetic biology, and origins of life studies. Instead of the traditionally used Rayleigh-Gans-Debye approximation, we use an exact extended Lorenz-Mie solution for how core-shell particles scatter light to model vesicle turbidity. This approach enables accurate interpretations of simple turbidimetric measurements and is able to accurately model highly scattering vesicles, such as larger vesicles, those with multiple layers, and those with encapsulated material. We uncover several surprising features, including that vesicle lamellarity has a larger effect on sample turbidity than vesicle size and that the technique can be used to measure the membrane thickness of vesicles. We also examine potential misinterpretations of turbidimetry and discuss when measurements are limited by forward and multiple scattering and by the geometry of the instrument.

Prebiotic amino acids bind to and stabilize prebiotic fatty acid membranes

“…3 D and E suggest that the serine-induced increase in turbidity is due to an increase in vesicle lamellarity. This interpretation is consistent with a recent theoretical analysis predicting a strong effect of lamellarity on turbidity (38). We rule out that the increased turbidity is due to oil drops forming (SI Appendix, Fig.…”

Development of Novel High-Resolution Size-Guided Turbidimetry-Enabled Particle Purification Liquid Chromatography (PPLC): Extracellular Vesicles and Membraneless Condensates in Focus

“…Monitoring EV separation in the turbidity range (400–600 nm) could be a better approach for EV detection. Indeed, the hydrophobic interlayer of the EV membrane scatters light in the visible spectrum range of light, making the lipid vesicle-containing solution turbid [ 40 ]. On the other hand, the UV spectrum range (190–350 nm) is essential, as it contains critical information regarding the nature, the concentration, and the purity of organic molecules.…”

“…Fortunately, the UV-Vis measurements in our system are coupled with a high-resolution size-guided separation that yielded the populations of the monodisperse particles per fraction. This monodispersity implies that the particle size can be directly inferred from the turbidity spectra, whether by applying the exact Lorenz-Mie solution [ 40 ] or the Rayleigh-Gans-Debye approximation [ 46 ], without the need to invoke a distribution function, such as the log-normal Gaussian distribution [ 47 ]. Indeed, turbidity represents the attenuation of incident light due to light scattering and determination of the particle size spectrophotometrically.…”

Programmed Recognition between Complementary Dinucleolipids To Control the Self‐Assembly of Lipidic Amphiphiles

“…Under these conditions, an initial assessment of self‐assembly was obtained by UV/Vis turbidity measurements, monitoring the absorbance at 400 nm ( A 400 ) with dinucleolipid concentration. As none of the studied compounds present any absorption band at such a wavelength (Figure S1), this kind of measurement accounted for the scattering caused by the obtained assemblies . In particular, Figure A was assembled from three different series of concentration‐dependent UV/Vis spectra (i.e., for 1 A , 1 T and 1 A⋅1 T ; see Figure S2 as an example).…”

“…All samples were prepared by injecting small volumes of stock solutions in dimethyl sulfoxide (DMSO) (normally 1.5 or 10 mm,d epending on the final target concentration) into freshly prepared HEPES buffer,e nsuring that the final proportion of DMSO was < 5%.U nder these conditions, an initial assessment of self-assembly was obtained by UV/Vis turbidity measurements, monitoringt he absorbance at 400 nm (A 400 ) with dinucleolipid concentration.A sn one of the studied compounds present any absorption band at such aw avelength ( Figure S1), this kind of measurement accounted for the scattering caused by the obtained assemblies. [36,37] In particular, Figure2Aw as assembled from three different series of concentration-dependentU V/Vis spectra (i.e.,f or 1A, 1T and 1A·1 T;s ee Figure S2 as an example). The scattering increased gradually with dinucleolipid concentration,s howing that both 1A and 1T self-assembled in the aqueousm edium,b ut the extento fs elf-assembly wasm uch more prominent for the 1A·1 T mixture.…”