Analysis of lipid adsorption on nanoparticles by nanoflow liquid chromatography-tandem mass spectrometry

Abstract

Nanoparticles (NPs) tend to adsorb matrix molecules like proteins and lipids incubated with biological fluids, forming a biological corona. While the formation and functions of protein corona have been studied extensively, little attention has been paid to lipid adsorption on NPs. However, lipids are also abundantly present in biological fluids and play important roles in processes like cell signaling and angiogenesis. Therefore, in this study, we established the analytical procedure for study of lipid adsorption on three different types of NPs in two matrices: human serum and heavy cream, using nanoflow liquid chromatography-mass spectrometry (nanoflowLC-MS). Serum was chosen to represent the common environment the NPs would be present once entering human body, and heavy cream was the representative food matrix NPs may be added to improve the color or taste. Steps of liquid-liquid extraction were established and optimized to achieve maximum recovery of the adsorbed, standard lipids from the NPs. Then, the LC-MS/MS method was developed to attain base-line separation of the standard lipids that represent the major lipid classes. At last, the lipid adsorption profiles of the three NPs were compared. We found that the lipid adsorption profile on the same type of NP was significantly different between the two matrices. The established method will help us investigate lipid adsorption on additional NPs and reveal how it could be affected by the physiochemical properties of NPs and the presence of proteins and other components in the biological matrix.

The Nanomaterial Metabolite Corona Determined Using a Quantitative Metabolomics Approach: A Pilot Study

“…[ 22–24 ] Serum, a key transport media in the body, has also been assessed for its lipid corona forming ability. [ 25 ] These studies revealed that lipids adsorb to the surface of NMs and that they can impact upon the biological response to NMs. Furthermore, a limited number of studies have investigated a broader range of metabolites and demonstrated that a wide array of metabolites can interact with NMs to form a metabolite corona.…”

The rise of the nanomaterial metabolite corona, and emergence of the complete corona

“…[89][90][91] The most likely to work are successive washes in solvents ranging from the polar, such as water, to the less polar solvents such as methanol and hexane. 35 The chosen solvents would also be very much dependent upon the type of metabolite being isolated, for example the lipid corona will be more suited to an isopropanol or chloroform elution 92 whereas the more polar fractions would be better suited to water and/or methanol. 35 In cases where both the polar and non-polar Environmental Science: Nano Critical review portions of the corona need to be characterized then a biphasic extraction, such as the Bligh-Dyer, 93 Folch 94 and Matyash 95 methods or their derivatives, where phase separation occurs between water and chloroform/MTBE with polar metabolites in the aqueous phase and lipids in the organic phase is preferred.…”

“…[106][107][108] LC-MS has already found use in NM metabolite corona analysis. 92,96 In a typical separation using reversed phase chemistry, polar compounds elute first, typically with poor resolution, while more hydrophobic compounds elute later with better chromatographic resolution as the concentration of organic solvent increases over the run. This reversed phase separation is particularly suited for lipids and other nonpolar metabolites such as steroids and bile acids.…”

“…32,[118][119][120] Indeed, this technique has already had some success with determination of the lipid corona around nanofibrils, TiO 2 and PS NMs. 92 4.2.2 Gas chromatography-mass spectrometry (GC-MS). GC-MS is a reasonably common technique in the metabolomics fields and has been extensively described in previous reviews.…”

“…A subsequent lipid corona investigation examined the adsorption of lipids to cellulose nanofibrils, titania and polystyrene NMs from serum and heavy cream to represent exposures to humans directly via blood and food products, respectively. 92 A modified Folch method was applied to isolate the lipid corona with good recoveries being found across all NMs (>50%) when validated using a mixture of lipid standards. 92 The lipid coronas isolated from the two matrices varied significantly with the serum coronas for all 3 NMs being comprised of 75% triacylglycerides (TAGs), 15-17% phospholipids and 7.5-11% diacylglycerides (DAGs) whereas for the heavy cream coronas for polystyrene and cellulose nanofibrils TAGs and DAGs made up 59% and 13-14% of the lipid corona with phospholipids accounting for a further 25% and lysophospholipids the remaining 2-3%.…”