Lipidomic profiling has been linked to the detection of cancers as dysregulation of lipid metabolism is closely associated with many disease states. Current work on chip‐based profiling has been limited and is largely hindered by issues associated with the chip's sophisticated fabrication processes. We report here the design and fabrication of a highly efficient microfluidic mixer/extractor by using three‐dimensional (3D) printing technology for on‐chip cell lysis/enrichment for lipidomic profiling with matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS). The platform consists of a micropillar mixer for flow‐through lysis and an on‐chip reservoir to separate phases where the lipid‐enriched layer was collected for subsequent MS analysis. The mass transfer between the two phases was simulated by a computational fluid dynamics study, and the efficiency in cell lysis in different extraction solvent systems was characterized by fluorescence microscopy. Results showed increased performance in extraction with the micropillar mixer as compared with the standard Bligh‐Dyer method. For lipid profiling of
Dissolve‐Spin: Desalting Oligonucleotides for MALDI MS Analysis
Desalting oligonucleotides (ONs) for matrix assisted laser desorption ionization mass spectrometry (MALDI MS) analysis was achieved using a simple dissolve-spin approach. The ON is dissolved in an organic solvent. Insoluble salts are removed by centrifugation. ONs are highly polar molecules, and are generally believed insoluble in organic solvents with moderate polarity such as acetonitrile (ACN), 1,4-dioxane, ethyl acetate and THF. However, we found that in the presence of a suitable proton source such as pyridinium chloride, a quantity of ON that is sufficient for MALDI MS analysis could be dissolved. Because inorganic salts are insoluble in such relatively non-polar solvents, the finding can be utilized for desalting ONs for MALDI MS analysis. Comparisons of MS spectra of intentionally salted ONs that underwent the new desalting procedure with those that did not undergo the procedure provided unambiguous evidence that the desalting method is highly effective.
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- Award ID(s):
- 1954041
- NSF-PAR ID:
- 10381360
- Date Published:
- Journal Name:
- Journal of Mass Spectrometry
- ISSN:
- 1076-5174
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract C. reinhardtii cells by MALDI‐MS, over 65 lipid species from the monogalactosyldiacylglycerol, digalactosyldiacylglycerol, diacylglyceryltrimethylhomo‐Ser, and triacylglycerol lipid families have been identified. The effect of organic solvents on extraction and lipid profiles was also investigated, and the results indicated that the extractant formula has a diverse impact on the collection of certain types of lipid species, presenting useful guidance for the system to be applied to targeted enrichment of lipids with specific cells. The microfluidic chips by the 3D printing technique reported here offer new platforms potentially for clinical lipidomics and can provide a novel avenue in disease diagnosis. -
null (Ed.)Our previous work demonstrated formation of highly insoluble and strongly light-absorbing organic particles in reactions between catechol or guaiacol with Fe( iii ) under pH = 3 conditions characteristic of aerosol liquid water. This work extends these measurements to reactions of Fe( iii ) with 2,4-dinitrophenol, 4-nitrocatechol, 4-methylcatechol, 1,2,4-benzenetriol, 1,2,3-benzenetriol (pyrogallol) and coniferaldehyde to better understand the mechanism of particle formation catalyzed by Fe( iii ). Particles were observed after 2 h of reactions of catechol (43 ± 1% mass yield), 1,2,4-benzenetriol (32 ± 3%), pyrogallol (27 ± 2%) and coniferaldehyde (35 ± 4%), while reactions of 2,4-dinitrophenol and 4-nitrocatechol did not produce any insoluble products. No particles were observed in reaction of 4-methylcatechol after 2 h, however, insoluble products appeared after a 24 h reaction time. Irradiation of a catechol + Fe( iii ) mixture by 405 nm light was found to reduce (but not fully suppress) the particle yield due to a competition between photodegradation and Fe( iii )-catalyzed oligomerization. Particles produced from precursors + Fe( iii ) solutions were dissolved in organic solvents and analyzed with ultra performance liquid chromatography coupled to a photodiode array spectrophotometer and a high resolution mass spectrometer. Major separated chromophores were identified as dimeric, trimeric, and tetrameric products of precursor molecules. Purpurogallin was identified as a major reaction product of pyrogallol reaction with Fe( iii ). To test whether this chemistry can occur in more realistic atmospheric aerosols, reactions of biomass burning organic aerosol (BBOA) extracts with Fe( iii ) were also examined. Two BBOA samples collected under flaming conditions produced no particles, whereas a BBOA sample produced under smoldering conditions resulted in particle formation under both dark and 405 nm irradiation conditions. The results suggest that Fe( iii )-catalyzed chemistry can take place in aging BBOA plumes resulting from smoldering fires and make aerosol particles more light-absorbing.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1002/jms.4893
