Name: natural product discovery with lc-ms/ms diagnostic fragmentation filtering: application for microcystin analysis
Uploaded: 2019-05-31T14:00:00
Description: Watch this Scientific Journal Video about Natural Product Discovery with LC-MS/MS Diagnostic Fragmentation Filtering: Application for Microcystin Analysis at JoVE.com

提交人感谢 He进roscon (加拿大水文文化中心、滑铁卢大学) 提供了所研究的蓝藻养殖, 并感谢 Sahsan Abusharkh (Carleton 大学) 的技术援助。

1. 非目标液相色谱 (LC)-ms变数据集的制备
注: DFF 可以使用针对目标类分析物优化的任何高分辨率质谱仪和分析方法执行。在轨道说唱质谱仪上的 mc 优化 LC-MSMS 条件列在材料表中。
<ol><li>
下载 MZmine 2(http://mzmine.github.io/) 注: 示例数据 cpcc300. 原始数据可在 https://drive.google.com/open?id=1HHbLdvxCMycSasyNXPRqIe5pkaSqQoS0 找到。<ol>
<li>在 "原始数据方法</strong...

<ol>
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J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+six+new+Alternaria+sulfoconjugated+metabolites+by+high-resolution+neutral+loss+filtering.">Identification of six new Alternaria sulfoconjugated metabolites by high-resolution neutral loss filtering.</a> Rapid Communications in Mass Spectrometry. 29 (19), 1805-1810 (2015).</li><li>Renaud, J. B., Kelman, M. J., Qi, T. F., Seifert, K. A., Sumarah, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Product+ion+filtering+with+rapid+polarity+switching+for+the+detection+of+all+fumonisins+and+AAL-toxins.">Product ion filtering with rapid polarity switching for the detection of all fumonisins and AAL-toxins.</a> Rapid Communications in Mass Spectrometry. 29 (22), 2131-2139 (2015).</li><li>Renaud, J. B., Kelman, M. J., McMullin, D. R., Yeung, K. K. -. C., Sumarah, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+C8+liquid+chromatography-tandem+mass+spectrometry+for+the+analysis+of+enniatins+and+bassianolides.">Application of C8 liquid chromatography-tandem mass spectrometry for the analysis of enniatins and bassianolides.</a> Journal of Chromatography A. 1508, 65-72 (2017).</li><li>Walsh, J. 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R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blooming+algae:+a+Canadian+perspective+on+the+rise+of+toxic+cyanobacteria.">Blooming algae: a Canadian perspective on the rise of toxic cyanobacteria.</a> Canadian Journal of Fisheries and Aquatic Sciences. 73 (7), 1149-1158 (2016).</li><li>Carmichael, W. W., Boyer, G. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Health+impacts+from+cyanobacteria+harmful+algae+blooms:+Implications+for+the+North+American+Great+Lakes.">Health impacts from cyanobacteria harmful algae blooms: Implications for the North American Great Lakes.</a> Harmful algae. 54, 194-212 (2016).</li><li>Mayumi, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+characterization+of+microcystins+by+LC/MS/MS+under+ion+trap+conditions.">Structural characterization of microcystins by LC/MS/MS under ion trap conditions.</a> The Journal of antibiotics. 59 (11), 710 (2006).</li><li>Frias, H. V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+electrospray+tandem+mass+spectrometry+for+identification+of+microcystins+during+a+cyanobacterial+bloom+event.">Use of electrospray tandem mass spectrometry for identification of microcystins during a cyanobacterial bloom event.</a> Biochemical and biophysical research communications. 344 (3), 741-746 (2006).</li><li>Kessner, D., Chambers, M., Burke, R., Agus, D., Mallick, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ProteoWizard:+open+source+software+for+rapid+proteomics+tools+development.">ProteoWizard: open source software for rapid proteomics tools development.</a> Bioinformatics. 24 (21), 2534-2536 (2008).</li><li>Watanabe, M. F., Oishi, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+environmental+factors+on+toxicity+of+a+cyanobacterium+(Microcystis+aeruginosa)+under+culture+conditions.">Effects of environmental factors on toxicity of a cyanobacterium (Microcystis aeruginosa) under culture conditions.</a> Applied and Environmental microbiology. 49 (5), 1342-1344 (1985).</li><li>Hollingdale, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Feasibility+study+on+production+of+a+matrix+reference+material+for+cyanobacterial+toxins.">Feasibility study on production of a matrix reference material for cyanobacterial toxins.</a> Analytical and bioanalytical chemistry. 407 (18), 5353-5363 (2015).</li><li>Yuan, M., Namikoshi, M., Otsuki, A., Sivonen, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+amino+acid+side-chain+on+fragmentation+of+cyclic+peptide+ions:+differences+of+electrospray+ionization/collision-induced+decomposition+mass+spectra+of+toxic+heptapeptide+microcystins+containing+ADMAdda+instead+of+Adda.">Effect of amino acid side-chain on fragmentation of cyclic peptide ions: differences of electrospray ionization/collision-induced decomposition mass spectra of toxic heptapeptide microcystins containing ADMAdda instead of Adda.</a> European Mass Spectrometry. 4 (4), 287-298 (1998).</li><li>Schymanski, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identifying+small+molecules+via+high+resolution+mass+spectrometry:+communicating+confidence.">Identifying small molecules via high resolution mass spectrometry: communicating confidence.</a> Environmental science &#38; technology. 48 (4), 2097 (2014).</li></ol>

DFF 是一种直接和快速的检测整类化合物的策略, 尤其适用于天然产品化合物的发现。DFF 最重要的方面是为目标类化合物定义特定的 msms 碎片化标准。在这个具有代表性的例子中, DFF 被用来检测铜绿假单胞菌提取物中存在的所有含有 mcs 的 Ada 残留物。虽然绝大多数的 Mc 含有阿达残留物, 但这一位置的其他残留物已经知道, 特别是脱甲基和乙酰二甲基-阿达变种 19.不会使用规?...

串联质谱 (mssms) 是一种广泛使用的质谱方法, 它涉及通过应用活化能 (如碰撞诱导离解 (cid)1) 来分离前体离子并诱导碎裂。离子碎片与其分子结构密切相关的方式。天然产物通常作为结构相似化合物的混合物进行生物合成, 而不是作为一种独特的化学物质2。因此, 属于同一生物合成类别的结构相关化合物通常具有关键的 mmsms 碎裂特性, 包括共享产品离子和/或中性损失。能够筛选复杂的样品中含有类特定产品离子和中性损耗的化合物, 这是检测整个类别化合物的有力策略, 有可能导致发现新的天然产品3,4 个,5,6. 几十年来, 在低分辨率仪器上进行中性损耗扫描和前体离子扫描等质谱方法使具有相同中性损耗的离子或产物离子被检测出来。但是, 在执行实验之前, 需要定义特定的离子或跃迁。由于高分辨率质谱仪在研究实验室中越来越流行, 复杂样品现在通常使用非目标采集 (DDA) 方法进行筛选。与传统的中性损耗和前驱离子扫描相比, 通过采集后分析7可以识别结构上相关的化合物。在这项工作中, 我们展示了一种我们开发的策略, 称为诊断碎片过滤 (dff)5,6, 一种直接和用户友好的方法来检测复杂矩阵中的整个类别的化合物。此 DFF 模块已实现到开源 MZmine 2 平台中, 并可通过下载 MZmine 2.38 或较新版本获得。DFF 允许用户有效地筛选 DDA 数据集的 msms 光谱, 其中包含产品离子和/或中性损耗, 可诊断为整个类别的化合物。DFF 的限制是典型的产物离子, 一类化合物的中性损耗必须由分析师定义。
例如, 在确定的60多个不同的富莫尼辛霉菌毒素中 ,每个都有一个三甲菌侧链, 产生一个m/z157.0142 (c6h5o5-) 产品离子[M-H]-离子4的碎裂。因此, 通过筛选包含突出的 msz157.0142 产品离子的 DDA 数据集中的所有 M/Z 光谱, 可以使用 DFF 检测样品中的所有假定富莫尼辛。同样, 通过筛选含有 79 9.9574 da (SO3) 3 的诊断中性损耗的 msms 光谱的 dda 数据集, 可以检测到硫化化合物。该方法也已成功地应用于检测新的循环肽5和含有色氨酸或苯基丙氨酸残留物6的天然产物。
为了证明 DFF 的有效性及其在 MZmine 平台10中的易用性, 我们将此方法应用于微囊藻毒素 (mc) 的分析;由淡水蓝藻 11、12、13产生的超过240种与结构有关的毒素。
最常见的报告氰基毒素是 Mc, 其中最常研究的是 MC-LR (亮氨酸 [L]/精氨酸 [R]) 同源物 (图 1)。Mc 是单环细胞非核糖体七肽, 由多个蓝藻属 (包括微囊藻、阿纳巴纳、诺斯托克和普兰克托特里克斯12,13) 进行生物合成。Mc 由5个常见残基和两个由 l-氨基酸占据的可变位置组成.几乎所有的 Mc 都有一个典型的β-氨基酸 3-氨基-9-甲氧基-2, 6, 8-三甲基-10-4, 6-二烯酸 (Ada) 残留在位置5 11。 Mcs 的 msms 碎裂途径得到了充分的描述14,15;ada 残渣负责突出的 m/z 产品离子, m/z 135.0803+ (c9h 11o +) 以及其他产品离子, 包括m/z 163.1114 + (c11h15) O+) (图 2)。使用这些诊断离子可以对存在的所有微囊藻进行非靶向 dda 数据集, 证明微囊藻毒素存在添加残留。

<table>
	<tbody>
		<tr>
			<td>Cyanobacteria</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Microcystis aeruginosaCPCC300</td>
			<td>CANADIAN PHYCOLOGICAL CULTURE CENTRE</td>
			<td>CPCC300</td>
			<td>https://uwaterloo.ca/canadian-phycological-culture-centre/</td>
		</tr>
		<tr>
			<td>Software</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Proteowizard (software)</td>
			<td></td>
			<td>software</td>
			<td>http://proteowizard.sourceforge.net/</td>
		</tr>
		<tr>
			<td>Mzmine 2</td>
			<td></td>
			<td>software</td>
			<td>http://mzmine.github.io/</td>
		</tr>
		<tr>
			<td>LC-MS</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Q-Exactive Orbitrap</td>
			<td>Thermo</td>
			<td>-</td>
			<td>Equipped with HESI ionization source</td>
		</tr>
		<tr>
			<td>1290 UHPLC</td>
			<td>Agilent</td>
			<td></td>
			<td>Equipped with binary pump, autosampler, column compartment</td>
		</tr>
		<tr>
			<td>C18 column</td>
			<td>Agilent</td>
			<td>959757-902</td>
			<td>Eclipse Plus C18 RRHD column (2.1 &#215; 100 mm, 1.8 &#956;m)</td>
		</tr>
		<tr>
			<td>Solvents</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Optima LC-MS grade Methanol</td>
			<td>Fisher</td>
			<td>A456-4</td>
			<td></td>
		</tr>
		<tr>
			<td>OptimaLC-MS grade Acetonitrile</td>
			<td>Fisher</td>
			<td>A955-4</td>
			<td></td>
		</tr>
		<tr>
			<td>OptimaLC-MS grade Water</td>
			<td>Fisher</td>
			<td>W6-4</td>
			<td></td>
		</tr>
		<tr>
			<td>LC-MS grade Formic Acid</td>
			<td>Fisher</td>
			<td>A11710X1-AMP</td>
			<td></td>
		</tr>
		<tr>
			<td>Vortex-Genie 2</td>
			<td>Scientific Industries</td>
			<td>SI-0236</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge Sorvall Micro 21</td>
			<td>Thermo Scientific</td>
			<td>75-772-436</td>
			<td></td>
		</tr>
		<tr>
			<td>Other</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Amber HPLC vials 2 mL/caps</td>
			<td>Agilent</td>
			<td>5182-0716/5182-0717</td>
			<td></td>
		</tr>
		<tr>
			<td>0.2-&#956;m PTFE syringe filters</td>
			<td>Pall Corp.</td>
			<td>4521</td>
			<td></td>
		</tr>
		<tr>
			<td>Whatman 47mm GF/A glass microfiber filters</td>
			<td>Sigma-Aldrich</td>
			<td>WHA1820047</td>
			<td></td>
		</tr>
		<tr>
			<td>Media</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>MA media (pH 8.6) ( quantity / L)</td>
			<td></td>
			<td></td>
			<td>Watanabe, M. F. &#38; Oishi, S. Effects of environmental factors on toxicity of a cyanobacterium (Microcystis aeruginosa) under culture conditions. Applied and Environmental microbiology. 49 (5), 1342-1344 (1985).</td>
		</tr>
		<tr>
			<td>Ca(NO3)&#183;4H2O, 50 mg</td>
			<td>Sigma-Aldrich</td>
			<td>C2786</td>
			<td></td>
		</tr>
		<tr>
			<td>KNO3, 100 mg</td>
			<td>Sigma-Aldrich</td>
			<td>P8291</td>
			<td></td>
		</tr>
		<tr>
			<td>NaNO3, 50 mg</td>
			<td>Sigma-Aldrich</td>
			<td>S5022</td>
			<td></td>
		</tr>
		<tr>
			<td>Na2SO4, 40 mg</td>
			<td>Sigma-Aldrich</td>
			<td>S5640</td>
			<td></td>
		</tr>
		<tr>
			<td>MgCl2&#183;6H20, 50 mg</td>
			<td>Sigma-Aldrich</td>
			<td>M2393</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium glycerophosphate, 100 mg</td>
			<td>Sigma-Aldrich</td>
			<td>G9422</td>
			<td></td>
		</tr>
		<tr>
			<td>H3BO3, 20 mg</td>
			<td>Sigma-Aldrich</td>
			<td>B6768</td>
			<td></td>
		</tr>
		<tr>
			<td>Bicine, 500 mg</td>
			<td>Sigma-Aldrich</td>
			<td>RES1151B-B7</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>P(IV) metal solution, 5 mL</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bring the following to 1 L with ddH2O</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>NaEDTA&#183;2HO</td>
			<td>Sigma-Aldrich</td>
			<td>E6635</td>
			<td></td>
		</tr>
		<tr>
			<td>FeCl3 &#183;6H2O</td>
			<td>Sigma-Aldrich</td>
			<td>236489</td>
			<td></td>
		</tr>
		<tr>
			<td>MnCl2&#183;4H2O</td>
			<td>Baker</td>
			<td>2540</td>
			<td></td>
		</tr>
		<tr>
			<td>ZnCl2</td>
			<td>Sigma-Aldrich</td>
			<td>Z0152</td>
			<td></td>
		</tr>
		<tr>
			<td>CoCl2&#183;6H2O</td>
			<td>Sigma-Aldrich</td>
			<td>C8661</td>
			<td></td>
		</tr>
		<tr>
			<td>Na2MoO4&#183;2H2O</td>
			<td>Baker</td>
			<td>3764</td>
			<td></td>
		</tr>
		<tr>
			<td>Cyanobacteria BG-11 50X Freshwater Solution</td>
			<td>Sigma-Aldrich</td>
			<td>C3061-500mL</td>
			<td></td>
		</tr>
	</tbody>
</table>

natural product discovery with lc-ms/ms diagnostic fragmentation filtering: application for microcystin analysis

天然产物通常作为结构相似化合物的混合物而生物合成, 而不是单一的化合物。由于其共同的结构特点, 同一类别中的许多化合物经历了类似的 mmsms 碎裂, 并具有几个相同的产品离子和/或中性损失。诊断碎片过滤 (DFF) 的目的是通过筛选包含类特定产品离子和中性损耗的 mmsms 光谱的非目标 LC-MMS-MS 数据集, 有效地检测复杂提取物中给定类的所有化合物。该方法基于在开源 MZmine 平台内实现的 DFF 模块, 该模块要求在高分辨率质谱仪 (如四极 Orbitrap 或四极飞行时间质量) 上通过依赖数据的采集来分析样本提取物分析仪。这种方法的主要局限性是, 分析师必须首先定义哪些产品离子和/或中性损失是特定于目标类别的天然产品。DFF 允许随后在复杂的样品中发现所有相关的天然产品, 包括新的化合物。在这项工作中, 我们证明了 DFF 的有效性, 通过筛选提取物的铜绿小细胞石, 一个突出的有害藻类绽放导致蓝藻, 产生微囊藻。

图 4显示了在分析铜绿假单胞菌 ccc300 后生成的 dff 图。该图的x轴是满足定义的 dff 标准的前体离子的m/z,而y轴显示 mcs m/z 光谱中所有产物离子的m/z 。对于此分析, MC 检测的标准包括440-1200 范围内的前体离子, 保留时间在2.00–6.00 分钟之间。最重要的是, 这些 M/Z 光谱包含超过规定的15% 基峰强度阈值的 m/z135...

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Natural Product Discovery with LC-MS/MS Diagnostic Fragmentation Filtering: Application for Microcystin Analysis

诊断碎片过滤, 实现到 MZmine, 是一种优雅的, 采集后的方法, 筛选 LC-MMSMS 数据集的整个类别的已知和未知的天然产品。此工具搜索 msms 光谱, 以查找分析师定义为诊断整个类别化合物的产品离子和中性损耗。

LC-MCYMS 诊断碎裂过滤的天然产物发现: 微囊藻毒素分析的应用

Natural products are often biosynthesized as mixtures of structurally similar compounds, rather than a single compound. Due to their common structural ...

天然产品通常作为一类化合物进行生物合成，而不是作为单个产品。诊断碎片过滤是检测复杂混合物中所有结构相关化合物的简单方法。在 MZmine 软件中实现的诊断碎片过滤使分析师能够探索新的天然产品的质谱数据集，否则可能会遗漏这些数据集。这包括新的生物产品，以及新的毒素。诊断碎片过滤，应用于污染食物和水的毒素类，可以通知暴露评估。当应用于微生物和植物提取物时，它可能导致发现新的化合物。使用诊断碎片滤波需要了解定义化学类的关键串联质谱特征。这意味着结构上相似的化合物将产生特征离子。我叫肖恩·胡格斯特拉我是我们中心的研究技术人员和软件开发人员，我将演示该过程。为了准备微囊素分析的样本，在无菌条件下，在250毫升的Erlenmeyer烧瓶中，接种30毫升无菌蓝藻生长介质，以大约5倍至10至5至50倍的细胞，在无菌条件下，用血细胞计监测细胞密度。经过26天的光自动培养，使用12小时光暗的光亮光在27摄氏度下照明，每天旋转一次，使用直径47毫升的GF/C玻璃微纤维过滤纸，通过真空过滤将细胞从培养基中分离。在14毫升试管中，将三毫升80%甲醇加入收获的细胞中，然后涡流，然后对每个管进行声波化30秒。声波化后，连续用三个一小时、零下20摄氏度的冷冻和15分钟的室温解冻循环对样品进行筛选，并通过单独的0.22微米聚四氟乙烯注射器过滤器过滤每个产生的蓝藻细胞提取物。使用温和的氮气流，用蒸发器在30摄氏度下干燥提取物，并在零下20摄氏度时将提取物储存干燥。对于液相色谱串联质谱分析，用500微升90%甲醇重新组合干燥残留物，对样品进行30秒的涡流。转移到琥珀色高压液相色谱小瓶。然后根据标准协议，在高分辨率质谱仪上使用数据依赖采集法分析蓝藻提取物。大多数微囊素含有 ATA 残留物，在串联质谱中产生两个诊断产品离子，M 到 Z 135.0803 和 163.1114。对于非靶向液相色谱串联质谱数据集的制备，打开 MZmine 2，并选择原始数据导入"原始数据方法下"下拉菜单。然后从微囊素分析中选择数据文件，然后选择峰值拾取过滤器以应用供应商提供的质心算法。对于导入的数据相关采集文件的诊断碎片筛选或 DFF，请使用光标突出显示数据文件，然后打开可视化"下拉菜单以选择 DFF 选项。在显示的 DFF 对话框中，输入目标分析物类将上升的保留时间范围和分钟数，并查找目标类分析物的量-电荷比范围，包括酌情使用多种电荷化合物的可能性。输入质谱仪可实现的串联质谱质量精度，并输入质量-电荷比的类特异性产品离子。输入类特定的中性损耗，并定义诊断产品离子和/或中性损耗的最低强度，以视为串联质谱光谱基峰的百分比。然后选择一个路径和文件名来输出结果，然后单击"确定"以启动 DFF。成功完成设置后，将显示 DFF 绘图。分析人员必须解释化合物类中已知化合物的串联质谱，以确定对全类化合物进行诊断的产品离子和/或中性损耗。此 DFF 图是在 M.aeruginosa CPCC 300 分析后生成的。x 轴表示满足定义 DFF 标准的前体离子的这种质量-电荷比，而 y 轴表示微囊串联质谱光谱中所有产品离子的质量-电荷比。对于这项分析，微细胞素检测的标准包括质量-电荷比为400至1，200的前体离子，以及2至6分钟的保留时间。最重要的是，这些串联质谱光谱包含两个质量-电荷比高于定义的15%基峰强度阈值。在分析过程中获得的4，116个串联质谱光谱中，26个符合DFF标准，并在M.aeruginosa CPCC 300提取物中检测到。检测到的主要微囊素可自信地被指定为微囊素精氨酸和脱乙基酸微囊素精氨酸。由于使用诊断碎片过滤发现新化合物，生物可以大规模生长，通过 NMR 对化合物进行分离和表征。当应用于微囊素时，诊断碎片过滤使我们能够确定传统的靶向筛选方法是否检测样品中存在的主要毒素。

Research

JoVE Journal

Chemistry

NMR Spectroscopy as a Robust Tool for the Rapid Evaluation of the Lipid Profile of Fish Oil Supplements

核磁共振作为鱼油补充剂的血脂的快速评价一个强大的工具

The western diet is poor in n-3 fatty acids, therefore the consumption of fish oil supplements is recommended to increase the intake of these essential ...

科研

化学

Integration of Miniaturized Solid Phase Extraction and LC-MS/MS Detection of 3-Nitrotyrosine in Human Urine for Clinical Applications

微型固相萃取和LC-MS / MS检测人尿中3-硝基酪氨酸的临床应用

Free 3-nitrotyrosine (3-NT) has been extensively used as a possible biomarker for oxidative stress. Increased levels of 3-NT have been reported in a wide ...

Minimum Burning Pressures of Water-based Emulsion Explosives

水性乳化炸药的最小燃烧压力

This manuscript describes a protocol to measure the minimum pressure required for sustained burning of water-based emulsion explosives. Pumping ...

Breath Collection from Children for Disease Biomarker Discovery

儿童疾病生物标志物发现的呼吸收集

Breath collection and analysis can be used to discover volatile biomarkers in a number of infectious and non-infectious diseases, such as malaria, ...

A Two-Step Pyrolysis-Gas Chromatography Method with Mass Spectrometric Detection for Identification of Tattoo Ink Ingredients and Counterfeit Products

一种用于检测纹身油墨成分和假冒产品的两步热解-气相色谱法

Tattoo inks are complex mixtures of ingredients. Each of them possesses different chemical properties which have to be addressed upon chemical analysis. ...

Application of Voltage in Dynamic Light Scattering Particle Size Analysis

电压在动态光散射粒子尺寸分析中的应用

Dynamic light scattering (DLS) is a common method for characterizing the size distribution of polymers, proteins, and other nano- and microparticles. ...

Synthesis of Aptamer-PEI-g-PEG Modified Gold Nanoparticles Loaded with Doxorubicin for Targeted Drug Delivery

合成阿普塔默-PEI-g-PEG改性金纳米粒子装载多索鲁比辛用于靶向药物输送

Due to drug resistance and toxicity in healthy cells, use of doxorubicin (DOX) has been limited in clinical cancer therapy. This protocol describes the ...

Atomic Force Microscopy Combined with Infrared Spectroscopy as a Tool to Probe Single Bacterium Chemistry

原子力显微镜与红外光谱相结合，作为探测单一细菌化学的工具

Atomic Force Microscopy-Infrared Spectroscopy (AFM-IR) is a novel combinatory technique, enabling simultaneous characterization of physical properties and ...

Nanoparticle Tracking Analysis of Gold Nanoparticles in Aqueous Media through an Inter-Laboratory Comparison

通过实验室间比较，对液态介质中的金纳米粒子进行纳米粒子跟踪分析

In the field of nanotechnology, analytical characterization plays a vital role in understanding the behavior and toxicity of nanomaterials (NMs). ...

Preparation of Nanoparticles for ToF-SIMS and XPS Analysis

用于ToF-SIMS和XPS分析的纳米颗粒的制备

Nanoparticles have gained increasing attention in recent years due to their potential and application in different fields including medicine, cosmetics, ...