Application of Flow Cytometry As Novel Technology in Studying the Effect of Droplet Size on Lipid Oxidation in Oil-in-Water Emulsions

Abstract

Despite several published studies, the impact of emulsion droplet size on lipid oxidation rates is unclear. This could be because oil-in-water emulsions are typically polydisperse and the oxidation rate of individual droplets is difficult to discern. Flow cytometry is a technique for studying individual cells and their subpopulations using fluorescence technologies, which is possible to be used in studying individual emulsion droplets. Typical emulsion droplets are too small to be visualized by flow cytometer so emulsions were prepared to have droplets >2 μm that were stabilized by weighting agent and xanthan gum to minimize creaming during storage. A radical-sensitive fluorescence probe (BODIPY665/676) was added to the lipid used to prepare the emulsion so that the susceptibility of individual emulsion droplets could be determined. The results showed that in a polydisperse emulsion system, small droplets were oxidized faster than large droplets. A conventional method was also carried out by blending two emulsions with different droplet sizes and oil densities, and results were in agreement with the observation obtained from flow cytometry. As a new approach, flow cytometry could be utilized in emulsion studies to reveal insights of lipid oxidation mechanisms in individual droplets.

A review on methods for diagnosis of breast cancer cells and tissues

“…Surely, FCM also has sorting function for tumour cells and can rapidly detect cells or biological particles through the one‐by‐one flow state, multi‐parameters or rapidly qualitative and quantitative analysis 117‐120 . Figure 8 shows how marked sites on cell surface are detected by FCM 121 . In the FCM, the cells or biological particles need to firstly be treated and labelled, so that they can be detected by laser.…”

“…Isolation of individual droplets by flow cytomtry 121 . (Reproduced with permission from Copyright 2020, American Chemical Society)…”

“…[117][118][119][120] Figure 8 shows how marked sites on cell surface are detected by FCM. 121 In the FCM, the cells or biological particles need to firstly be treated and labelled, so that they can be detected by laser.…”

Stabilization of infant formulas against lipid oxidation: What are the key structural levers?

“…There are many contradictory results in the literature about the effect of droplet size. Some studies demonstrate that decreasing droplet sizes resulted in increased oxidation, [ 26 ] whereas others show that there was no effect of droplet size on lipid oxidation initiation or propagation, [ 14 ] or the opposite, an increased stability with a decreasing of the droplets size. [ 25 ] This dissensus supports our hypothesis that other factors, such as the interface composition, are more important than the total surface area itself.…”

Unravelling the effect of droplet size on lipid oxidation in O/W emulsions by using microfluidics

“…A logical hypothesis would be that smaller droplets would oxidise faster because they have a larger specific interfacial area (m 2 interface/m 3 oil), allowing for more initiation reactions. Some results in literature accordingly confirmed that small droplets oxidise faster than large ones 6 , 10 – 19 , whereas others indicated that larger droplets oxidise faster 17 – 25 , or that the droplet size does not influence lipid oxidation 6 , 15 , 16 , 18 , 24 , 26 – 29 . Whether small droplets or large droplets oxidise faster has been argued to be dependent on the components present, such as antioxidants, emulsifiers, and oil 6 , 17 , 19 .…”