Scratching the Surface (Modification): Developing
a Quantitative Liquid Chromatography–Tandem Mass Spectrometry
Method for the Investigation of PEGylated and Non-PEGylated Lipid
Mixtures on Lipid-Coated Lanthanide Nanoparticles
posted on 2021-12-08, 23:04authored byLoryn
P. Arnett, Matthew W. Forbes, Rachel Keunen, Mitchell A. Winnik
We are interested in developing lanthanide
nanoparticles (LnNPs)
of the general formula NaLnF4 as high-sensitivity reagents
for mass cytometry. These LnNPs must be coated to provide colloidal
stability in aqueous buffer and functionality for detecting cellular
biomarkers. Lipid bilayer coatings are a promising approach, but one
requires an analytical technique to enable characterization of the
NP coating composition as opposed to the composition of the lipid
formulation used in the coating process. However, quantification of
the lipid composition of lipid coatings on polymer and inorganic NPs
is not common practice in the field. Here we describe a method based
on high-performance liquid chromatography (LC) for separations and
triple quadrupole tandem mass spectrometry (MS/MS) instrumentation
for detection and show that it can quantify complex lipid mixtures
using small (<1 μg) amounts of sample. Our lipid formulation
consisted of a mixture of egg sphingomyelin, 1,2-dioleoyl-sn-glycero-3-phosphocholine, 1,2-dioleoyl-3-trimethylammonium-propane,
cholesterol-PEG600, and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[biotinyl(polyethylene glycol)-2000]. We were able to
extract the coating from lipid-coated 35 nm diameter LnNPs, quantify
the lipid/NP ratio, and show that the coating composition differed
from the composition of the lipid formulation for several of the species.
Knowledge of the actual composition of the lipid coating for lipid-coated
NPs is critical for designing and optimizing application of these
materials. Our results establish the value of LC-MS/MS characterization
of lipid-coated NPs, thus providing an important new addition to the
toolbox available for characterizing these types of nanomaterials.