• Mass Spectrometry Letters
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• 제5권1호
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• pp.1-11
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• 2014

Lipids play important roles in biological systems; they store energy, play a structural role in the cell membrane, and are involved in cell growth, signal transduction, and apoptosis. Phospholipids (PLs) in particular have received attention in the medical and lipidomics research fields because of their involvement in human diseases such as diabetes, obesity, atherosclerosis, and many cancers associated with lipid metabolic disorders. Here I review experimental strategies for PL analysis based on nanoflow liquid chromatography-electrospray ionization-tandem mass spectrometry (nLC-ESI-MSn). In particular, discussed are lipid extraction methods, nanoflow LC separation of PLs, effect of ionization modifiers on the ESI of PLs, influence of chain lengths and unsaturation degree of acyl chains of PLs on MS intensity, structural determination of the molecular structure of PLs and their oxidized products, and quantitative profiling of PLs from biological samples such as tissue, urine, and plasma in relation to cancer and coronary artery disease.

• 멤브레인
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• 제26권4호
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• pp.291-300
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• 2016

분리막(Separation membrane)을 이용하여 기체 또는 액체상태로 존재하는 분자들을 선택적으로 분리하는 기술은 화학, 생물, 제약, 석유화학 등의 산업에서 매우 다양하게 응용되고 있으며 산업적으로 매우 큰 비중을 차지하고 있다. Anodic aluminum oxide (AAO) 막은 nanochannel의 직경, nanochannel 간의 거리 및 원통형 nanochannel의 길이 등을 정밀하게 조절할 수 있어 AAO 막을 이용하여 혼합분자를 효과적으로 분리하려는 다양한 연구가 진행되고 있다. 본 연구에서는 양 말단이 열려있어 through-hole 구조로 다양한 직경의 nanochannel을 가지는 AAO 막을 제작하였으며, 이것을 이용하여 용매에 녹아있는 고분자 사슬의 수력학적 부피에 따른 선택적 투과를 관찰하였다. Nanochannel을 투과한 고분자 사슬의 회전반지름과 nanochannel의 직경 사이에 정량적인 관계가 있음을 확인하였다. 또한 AAO 막의 nanochannel을 흐르는 고분자 용액의 유동률(flow rate)이 Hagen-Poiseuille 관계식으로 정확하게 설명될 수 있음을 확인하여 AAO 내에 존재하는 원통형태의 nanochannel 내에서 흐르는 용액의 나노흐름(nanoflow)에 대한 이론적 해석이 가능함을 증명하였다.

• Mass Spectrometry Letters
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• 제2권3호
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• pp.65-68
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• 2011

The effects of column length and particle size on the efficiency of separation and characterization of phospholipids (PLs) are investigated using nanoflow liquid chromatography-electrospray ionization-tandem mass spectrometry (nLC-ESI-MS-MS). Since PLs are associated with cell proliferation, apoptosis, and signal transduction, it is of increasing interests in lipidomics to establish reliable analytical methods for the qualitative and quantitative profiling of PLs related to biomarker development in adult diseases. Due to the complexity of PLs, the preliminary separation of PLs is necessary prior to MS analysis. In this study, length of capillary column and the particle size of reversed phase ($C_{18}$) packing materials are varied to find a reliable condition for the high speed and high resolution separation using 8 PL standard mixtures. From experiments, it was found that a capillary column of nLC-ESI-MS-MS analysis for PL mixtures can be minimized to a 5 cm long pulled tip column packed with 3 ${\mu}m$ $C_{18}$ particles without losing resolution.

• Mass Spectrometry Letters
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• 제1권1호
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• pp.21-24
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• 2010

The development of clinical biomarkers involves discovery, verification, and validation. Recently, multiple reaction monitoring (MRM) coupled with stable isotope dilution mass spectrometry (IDMS) has shown considerable promise for the direct quantification of proteins in clinical samples. In particular, multiple biomarkers have been tracked in a single experiment using MRM-based MS approaches combined with liquid chromatography. We report here a highly reproducible, quantitative, and dynamic MRM system for validating multi-biomarker proteins using Nanoflow HPLC-Microfluidics Chip/Triple-Quadrupole MS. In this system, transitions were acquired only during the retention window of each eluting peptide. Transitions with the highest MRM-MS intensities for the five target peptides from colon cancer biomarker candidates were automatically selected using Optimizer software. Relative to the corresponding non-dynamic system, the dynamic MRM provided significantly improved coefficients of variation in experiments with large numbers of transitions. Linear responses were obtained with concentrations ranging from fmol to pmol for five target peptides.

• 반도체디스플레이기술학회지
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• 제1권1호
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• pp.29-33
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• 2002

In the flip-chip process, the problem like electric defect or fatigue crack caused by the difference of CTE, between chip and substrate board had occurred. Underfill of flip chip to overcome this defects is noticed as important work developing in whole reliability of chip by protecting the chip against the external shock. In this paper, we introduce the underfill methods using mold and plunge and improvement of process and reliability, and the advantage which can be taken from embodiment of device.

• Molecular & Cellular Toxicology
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• 제1권2호
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• pp.87-91
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• 2005

Although 2D-PAGE has been widely used as the primary method for protein separation, difficulties in displaying proteins with an extreme values of isoelectric paint (pI), molecular size and hydrophobicity limit the technique. In addition, time consuming steps involving protein transfer and extraction from the gel-pieces can result in sample loss. Here, we describe a novel protein separation technique with capillary size-exclusion chromatography (CSEC) for rapid protein identification from human plasma. The method includes protein fractionation along with molecular size followed by in-solution tryptic digestion and peptide analysis through reversed phase liquid chromatography (RPLC) coupled to nanoflow electrospray-tandem mass spectrometry (ESI-MS/MS). Tryptic peptides are applied an a $100\;{\mu}m\;i.d.{\times}10mm$ length pre-column and then separated on a $75\;{\mu}m{\times}200mm$ analytical column at -100 nL/min flaw rate. Proteins were identified over the wide ranges of pI (3.7-12.3) when this technique was applied to the analysis of $1-2\;{\mu}L$ of human plasma. This gel-free system provides fast fractionation and may be considered a complementary technique to SDS-PAGE in proteomics.

• Bulletin of the Korean Chemical Society
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• 제35권4호
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• pp.1133-1138
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• 2014

Ultrahigh performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI- MS/MS) provides a high-speed method to screen a large number of samples for small molecules with specific properties. In this study, UPLC-ESI-MS/MS with multiple reaction monitoring (MRM) was employed to screen urinary phospholipid (PL) content for biomarkers of prostate cancer. From lists of urinary PLs structurally identified using nanoflow LC-ESI-MS/MS, 52 PL species were selected for quantitative analysis in urine samples between 22 cancer-free urologic patients as controls and 45 prostate cancer patients. Statistical treatment of data by receiver operating characteristic (ROC) analysis yielded 14 PL species that differed significantly in relative concentrations (area under curve (AUC) > 0.8) between the two groups. Among PLs present at higher levels in prostate cancer urine, phosphatidylcholines (PCs) and phosphatidylinositols (PIs) constituted the major head group PLs (3 PCs and 7 PIs). For technical reasons, PL species of low abundance may be underrepresented in data from UPLC-ESI-MS/MS performed in MRM mode. However, the proposed method enables the rapid screening of large numbers of plasma or urine samples in the search for biomarkers of human disease.

• Restorative Dentistry and Endodontics
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• 제49권2호
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• pp.20.1-20.13
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• 2024

Objectives: This study investigated the nanoleakage of root canal obturations using calcium silicate-based sealer according to different drying methods. Materials and Methods: Fifty-two extracted mandibular premolars with a single root canal and straight root were selected for this study. After canal preparation with a nickel-titanium rotary file system, the specimens were randomly divided into 4 groups according to canal drying methods (1: complete drying, 2: blot drying/distilled water, 3: blot drying/NaOCl, 4: aspiration only). The root canals were obturated using a single-cone filling technique with a calcium silicate-based sealer. Nanoleakage was evaluated using a nanoflow device after 24 hours, 1 week, and 1 month. Data were collected twice per second at the nanoscale and measured in nanoliters per second. Data were statistically analyzed using the Kruskal-Wallis and Mann-Whitney U-tests (p < 0.05). Results: The mean flow rate measured after 24 hours showed the highest value among the time periods in all groups. However, the difference in the flow rate between 1 week and 1 month was not significant. The mean flow rate of the complete drying group was the highest at all time points. After 1 month, the mean flow rate in the blot drying group and the aspiration group was not significantly different. Conclusions: Within the limitations of this study, the canal drying method had a significant effect on leakage and sealing ability in root canal obturations using a calcium silicate-based sealer. Thus, a proper drying procedure is critical in endodontic treatment.

• IMMUNE NETWORK
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• 제23권4호
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• pp.28.1-28.20
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• 2023

Lipid accumulation in macrophages is a prominent phenomenon observed in atherosclerosis. Previously, intimal foamy macrophages (FM) showed decreased inflammatory gene expression compared to intimal non-foamy macrophages (NFM). Since reprogramming of lipid metabolism in macrophages affects immunological functions, lipid profiling of intimal macrophages appears to be important for understanding the phenotypic changes of macrophages in atherosclerotic lesions. While lipidomic analysis has been performed in atherosclerotic aortic tissues and cultured macrophages, direct lipid profiling has not been performed in primary aortic macrophages from atherosclerotic aortas. We utilized nanoflow ultrahigh-performance liquid chromatography-tandem mass spectrometry to provide comprehensive lipid profiles of intimal non-foamy and foamy macrophages and adventitial macrophages from Ldlr^-/- mouse aortas. We also analyzed the gene expression of each macrophage type related to lipid metabolism. FM showed increased levels of fatty acids, cholesterol esters, phosphatidylcholine, lysophosphatidylcholine, phosphatidylinositol, and sphingomyelin. However, phosphatidylethanolamine, phosphatidic acid, and ceramide levels were decreased in FM compared to those in NFM. Interestingly, FM showed decreased triacylglycerol (TG) levels. Expressions of lipolysis-related genes including Pnpla2 and Lpl were markedly increased but expressions of Lpin2 and Dgat1 related to TG synthesis were decreased in FM. Analysis of transcriptome and lipidome data revealed differences in the regulation of each lipid metabolic pathway in aortic macrophages. These comprehensive lipidomic data could clarify the phenotypes of macrophages in the atherosclerotic aorta.