# Separation and Detection of Charged Unilamellar Vesicles in Vacuum by a Frequency-Controlled Quadrupole Mass Sensor

## TL;DR

Researchers developed a new method to separate and detect charged lipid vesicles in vacuum using a frequency-controlled quadrupole mass sensor, which could improve biomarker analysis.

## Contribution

A novel approach for separating lipid vesicles using frequency-controlled quadrupole mass sensors for mass spectrometry analysis is demonstrated.

## Key findings

- Lipid vesicles with diameters of 88–190 nm were successfully separated using m/z settings with a rate of 20–100 counts per minute.
- The method enabled separation of bioparticles with masses between 10⁸ and 10¹⁰ Da from human blood serum.
- The nondestructive single-pass charge detector allowed measurement of m/z, charges, and masses of individual vesicles.

## Abstract

Extracellular vesicles
(EVs) are membranous particles released
by cells and are considered to be promising sources of biomarkers
for various diseases. Mass spectrometry (MS) analysis of EVs requires
a sample of purified and detergent-lysed EVs. Purification of EVs
is laborious, based on size, density, or surface nature, and requires
large amounts of the source material (e.g., blood, spinal fluid).
We have employed synthetically produced large unilamellar lipid vesicles
(LUVs) as analogs of EVs to demonstrate an alternative approach to
vesicle separation for subsequent mass spectrometry analysis of their
composition. Mass-to-charge ratio m/z separation by frequency-controlled quadrupole was employed to filter
narrow-size distributions of LUVs from a water sample. Lipid vesicles
were positively charged with nanoelectrospray and transferred into
a vacuum using two wide m/z-range
frequency-controlled quadrupoles. The m/z, charges, and masses of individual vesicles were obtained by the
nondestructive single-pass charge detector. The resolving mode of
the second quadrupole with m/z RSD
< 10% allowed to separate size selected distributions of vesicles
with modal diameters of 88, 112, 130, 162, and 190 nm at corresponding
quadrupole m/z settings of 2.5 ×
105, 5 × 105, 8 × 105,
1.5 × 106, and 2.5 × 106, respectively
with a rate of 20–100 counts per minute. The distributions
of bioparticles with masses between 108 and 1010 Da were separated from human blood serum in the pilot experiment.
The presented approach for lipid vesicle separation encourages the
development of new techniques for the direct mass-spectrometric analysis
of biomarkers in MS-separated EVs in a vacuum.