Browsing by Subject "Silver Nanoparticles"
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Item Development of Advanced Optics and High Resolution Instrumentation for Mass Spectrometry Based Proteomics(2010-01-14) Sherrod, Stacy D.Imaging mass spectrometry (MS) analysis allows scientists the ability to obtain spatial and chemical information of analytes on a wide variety of surfaces. The ability to image biological analytes is an important tool in many areas of life science research, including: the ability to map pharmaceutical drugs in targeted tissue, to spatially determine the expression profile of specific proteins in healthy vs. diseased tissue states, and to rapidly interrogate biomolecular microarrays. However, there are several avenues for improving the imaging MS experiment for biological samples. Three significant directions this work addresses include: (1) reducing chemical noise and increasing analyte identification by developing sample preparation methodologies, (2) improving the analytical figures of merit (i.e., spatial resolution, analysis time) by implementing a spatially dynamic optical system, and (3) increasing both mass spectral resolution and ion detection sensitivity by modifying a commercial time-of-flight (TOF) MS. Firstly, sample methodology schemes presented in these studies consist of obtaining both ?top-down? and ?bottom-up? information. In that, both intact mass and peptide mass fingerprinting data can be obtained to increase protein identification. This sample methodology was optimized on protein microarrays in preparation for bio tissue analysis. Other work consists of optimizing novel sample preparation strategies for hydrated solid-supported lipid bilayer studies. Sample methods incorporating nanomaterials for laser desorption/ionization illustrate the ability to perform selective ionization of specific analytes. Specifically, our results suggest that silver nanoparticles facilitate the selective ionization of olefin containing species (e.g., steroids, vitamins). Secondly, an advanced optical design incorporating a spatially dynamic optical scheme allows for laser beam expansion, homogenization, collimation, shaping, and imaging. This spatially dynamic optical system allows user defined beam shapes, decreases analysis times associated with mechanical movement of the sample stage, and is capable of increasing the MS limits of detection by simultaneously irradiating multiple spots. Lastly, new data acquisition strategies (multiple anode detection schemes) were incorporated into a commercial time-of-flight mass spectrometer to increase both sensitivity and resolution in a matrix assisted laser desorption/ionization mass spectrometer. The utility of this technique can be applied to many different samples, where high mass spectral resolution allows for increased mass measurement accuracy.Item Development of and Application of Plasmonic Nanomaterials for Mass Spectrometry Based Biosensing(2014-05-05) Gamez, RobertoThe use of nanomaterials for sensing and biological applications has recently gained interest owing to the unique physical, chemical and optical properties that arise when materials are reduced to the nanoscale. The unique optical properties exhibited by gold (Au) and silver (Ag) nanomaterials have made for versatile platforms in a wide range of applications including surface plasmon biosensing techniques and laser desorption/ionization mass spectrometry (LDI-MS). A primary driver for this work is the relative ease performing surface modifications to nanoparticles (NPs), which can be used to enhance the selectivity of ionization and/or facilitate analyte capture. The research presented here focuses on the development of AuNP and AgNP based biosensors for selective capture and ionization of low abundance compounds from complex mixtures and subsequent detection by LDI-MS and Matrix Assisted Laser Desorption Ionization- Mass Spectrometry (MALDI-MS). First, a ?strategy? for selective capture and ionization of specific compound classes based on chemical derivatization of gold nanorods (AuNRs) and infrared laser desorption ionization (IR-LDI) is described. LDI is performed at near infrared wavelengths (1064 nm) that overlap with the longitudinal surface plasmon resonance (LSPR) mode of AuNRs which allows absorbed energy from the laser to facilitate the desorption and ionization of the analyte. Capture of hydrophobic species using surfactant coated AuNRs and subsequent detection by IR-LDI-MS was also demonstrated in these experiments. Second, the fabrication of a label-free MS and optical detection based biosensor platform consisting of a phospholipid layer partially tethered to the surface of a gold nanorod for the detection of low abundance lipophilic analytes from complex mixtures is described. In these experiments, stable phospholipid capped AuNRs are produced by tethering some of the phospholipids to the surface of the AuNRs though a covalent, gold-thiol linkage. The effectiveness of the biosensor is demonstrated for the label-free detection of a membrane active lipophilic drug from aqueous solution and of a lipopeptide from fetal bovine serum. Lastly, porous AgNP embedded thin films were fabricated by the sol-gel method and utilized as matrix-free LDI-MS biosensors applicable to several chemical classes. In these experiments, UV laser irradiation (337 nm) of the AgNP facilitates desorption and ionization of a number of peptides, triglycerides, and phospholipids. Preferential ionization of sterols from vesicles composed of olefinic phosphosphatidylcholines is also demonstrated.