Shaking-Induced Aggregation and Flotation in Immunoglobulin Dispersions: Differences between Water and Water-Ethanol Mixtures

Nikolai F Bunkin; Alexey V Shkirin; Barry W Ninham; Sergey N Chirikov; Leonid L Chaikov; Nikita V Penkov; Valeriy A Kozlov; Sergey V Gudkov

doi:10.1021/acsomega.0c01444

Shaking-Induced Aggregation and Flotation in Immunoglobulin Dispersions: Differences between Water and Water-Ethanol Mixtures

ACS Omega. 2020 Jun 12;5(24):14689-14701. doi: 10.1021/acsomega.0c01444. eCollection 2020 Jun 23.

Authors

Nikolai F Bunkin^{1

2}, Alexey V Shkirin^{2

3}, Barry W Ninham⁴, Sergey N Chirikov³, Leonid L Chaikov⁵, Nikita V Penkov⁶, Valeriy A Kozlov^{1

2}, Sergey V Gudkov²

Affiliations

¹ Bauman Moscow State Technical University, 2-nd Baumanskaya str. 5, Moscow 105005, Russia.
² Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilova str. 38, Moscow 119991, Russia.
³ National Research Nuclear University MEPhI, Kashirskoe sh. 31, Moscow 115409, Russia.
⁴ The Australian National University, Acton, Canberra ACT 2600, Australia.
⁵ Lebedev Physics Institute of the Russian Academy of Sciences, Leninskiy pr. 53, Moscow 119991, Russia.
⁶ Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institute of Cell Biophysics of the Russian Academy of Sciences, Institutskaya str. 3, Pushchino 142290, Moscow region, Russia.

Abstract

Structural characterization by three complementary methods of laser diagnostics (dynamic light scattering, laser phase microscopy, and laser polarimetric scatterometry) has established that shaking of immunoglobulin G (IgG) dispersions in water and ethanol-water mixtures (36.7 vol %) results in two effects. First, it intensifies the aggregation of IgG macromolecules. Second, it generates bubbles with a size range that is different in each solvent. The aggregation is enhanced in ethanol-water mixtures because of IgG denaturation. IgG aggregates have a size of ∼300 nm in water and ∼900 nm in ethanol-water mixtures. The flotation of IgG is much more efficient in water. This can be explained by a better adsorption of IgG particles (molecules and aggregates) on bubbles in water as compared to ethanol-water mixtures. Bulk nanobubbles and their association with IgG aggregates were visualized by laser phase microscopy in water but were not detected in ethanol-water mixtures. Therefore, the nanobubble flotation mechanism for IgG aggregates acting in water is not feasible for ethanol-water mixtures.