Development of an IR/UV Laser Desorption Electrospray Ionization Source for Mass

描述(申请人提供)：该研究项目的长期目标是开发一种激光解吸电喷雾电离(LDESI)质谱源。解吸激光器是一种基于光学参量振荡器(OPO)技术的可调谐中红外激光系统。光源将根据应用提供正面和背面激光照明模式，并可选择用于基质辅助样品的紫外光。据我们所知，目前还没有同时使用激光解吸和电喷雾电离的商用来源。我们设想在室温和大气压下对各种样品进行质量分析。因此，样品将保留在其自然环境中，并且无需样品前处理即可获得样品成分的实时质量鉴定。使用这种技术的质谱仪将提供一种有用的工具来获得对蛋白质组学、医疗诊断、消费品、制药研究和法医学等领域重要的各种化合物的质量鉴定。在LDESI分析中，样品用激光解吸，生成的以中性粒子为主的羽流被电喷射源捕获并被指向样品表面上方几毫米处的质谱仪入口处的电喷雾源电离。这里的关键原理是解吸和电离是分开的。用这种方法分析样品比一步解吸和电离的技术有很多优点。一个优点是提高了灵敏度，因为大部分激光解吸的中性粒子被电喷雾电离。此外，由于中红外软脱附和ESI的多次充电效应，超过100 kDa的高质量分子可以在常压下分析。我们设想在一个光源中有两种类型的激光解吸几何结构：用于直接分析高质量蛋白质、凝胶分离蛋白质和药片和食品等大宗材料的正面照明，以及用于高空间分辨率组织成像和激光捕获显微切割的背面照明。在两种采样模式之间的切换将简单地涉及改变光纤输送位置。当不使用激光解吸时，电喷雾保持在ESI MS的适当位置，无需将LDESI源切换为原始电喷雾源。该光源将由OPOTEK公司建造，基于我们过去对中红外OPO可调谐激光器和MALDI MS光源的研究。MS性能测试将在加州大学洛杉矶分校化学和生物化学系的商用质谱仪上进行，方法是与蛋白质结构表征生物分析方法领域的专家Joseph Loo博士合作。与公共健康相关：这项拨款申请中提出的分析设备将为研究人员提供一个简单的工具，以分析所有活着的有机体发挥功能所必需的最重要的一组分子：蛋白质。了解蛋白质的特性将使我们的科学家获得知识，以开发更好的医疗和法医工具、药物、食品和其他与公众健康和福祉相关的重要领域。拟议中的设备将为现有的被称为质谱学的分析方法增加能力，在这种方法中可以获得关于蛋白质结构的信息。

DESCRIPTION (provided by applicant): The long-term objective of this research project is the development of a laser desorption electrospray ionization (LDESI) mass spectrometer source. The desorption laser is a tunable mid-IR laser system based on optical parametric oscillator (OPO) technology. The source will be available in front and back-side laser illumination modes depending on the application and have the option of UV laser light for matrix-assisted samples. To our knowledge, no commercially available source is available using both laser desorption and electrospray ionization. We envision a mass analysis of a variety of samples at room temperature and atmospheric pressure. Therefore, the sample would remain in its native environment and real time mass identification of sample constituents would be obtained with little to no sample pretreatment. Mass spectrometers using this technique will offer a useful tool to obtain mass identification for a variety of compounds important to fields such as proteomics, medical diagnostics, consumer products, pharmaceutical research and forensics. In an LDESI analysis, the sample is desorbed with the laser and the resultant plume of predominately neutral particles are captured and ionized by an electrospray source directed towards the mass spectrometer inlet millimeters above the sample surface. The key principle here is that desorption is separated from ionization. Analyzing samples in this way has many advantages over techniques that desorb and ionize in one step. One advantage is an increase in sensitivity since a larger portion of laser desorbed neutral particles are ionized by the electrospray. Also, high mass molecules in excess of 100 kDa can be analyzed at atmospheric pressure because of the "soft" mid-IR desorption and the multiple charging effect of ESI. We envision two types of laser desorption geometries in one source: front-side illumination for direct analysis of high mass proteins, gel separated proteins and bulk materials such as drug tablets and food products and back-side illumination for high spatial resolution tissue imaging and laser capture microdissection. Switching between the two sampling modes will simply involve changing fiber delivery position. When not using laser desorption, the electrospray remains in place for ESI MS. No switching of the LDESI source for the original electrospray source is necessary. The source will be constructed by OPOTEK, based on our past research with mid-IR OPO tunable lasers and MALDI MS sources. MS performance tests will be carried out on commercial mass spectrometers at the UCLA Department of Chemistry and Biochemistry through collaboration with Dr. Joseph Loo, an expert in the field of bioanalytical methods for the structural characterization of proteins. PUBLIC HEALTH RELEVANCE: The analytical device proposed in this grant application will provide a simple tool for researchers to analyze one of the most important groups of molecules necessary for the functioning of all living organisms: proteins. Learning about the characteristics of proteins will give our scientists the knowledge to develop better medical and forensic tools, medicines, food products, and other important fields relevant to the health and well-being of the general public. The proposed device will add capabilities to an existing analytical methodology called mass spectrometry where information about the structure of proteins can be obtained.