Quantitative analysis of phospholipids using nanostructured laser desorption ionization targets
Simona Colantonio1, John T Simpson, Robert J Fisher
1Protein Chemistry Laboratory, Advanced Technology Program, SAIC-Frederick/NCI-Frederick, Frederick, MD 21702, USA. colantos@mail.nih.gov
Lipids
|February 18, 2011
Summary
Nano-structured laser desorption ionization (NALDI) enables quantitative analysis of small molecules in liposomes. This new method accurately quantifies phospholipids like DPPC and DC(8,9)PC, even after UV-induced cross-linking.
Area of Science:
- Analytical Chemistry
- Mass Spectrometry
- Lipidomics
Background:
- Matrix-assisted laser desorption ionization (MALDI) struggles with quantitative small molecule analysis due to matrix interference and surface inhomogeneity.
- Nano-structured laser desorption ionization (NALDI) offers a matrix-free alternative, improving quantitative capabilities for small molecules.
- Liposomes are crucial drug delivery systems, and understanding their phospholipid composition is vital.
Purpose of the Study:
- To develop and validate a NALDI-based assay for the quantitative analysis of specific phospholipid components in liposomes.
- To assess the stability and quantify changes in DPPC and DC(8,9)PC within liposomes after UV treatment.
Main Methods:
- Development of a NALDI assay for quantifying 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-bis(tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine) (DC(8,9)PC) in liposomes.
- Creation of calibration curves using 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) as an internal standard, achieving an R² of 0.992 for both lipids.
- Exposure of DPPC:DC(8,9)PC liposomes to UV radiation (254 nm) to induce cross-linking of DC(8,9)PC.
Main Results:
- The NALDI assay demonstrated high linearity and accuracy, with calibration curves showing an R² of 0.992.
- UV treatment resulted in a significant decrease of approximately 90% in the DC(8,9)PC signal, indicating successful cross-linking.
- DPPC signal remained unaffected by UV treatment, confirming its stability under the experimental conditions.
Conclusions:
- NALDI is a robust and quantitative technique for analyzing small molecules like phospholipids in liposomes.
- The developed assay effectively quantifies lipid components and their changes, such as UV-induced polymerization of DC(8,9)PC.
- This method provides a valuable tool for studying liposome composition and stability in various applications.
