@article{yao_xue_he_bao_xie_ge_2017, title={Climate projections of spatial variations in coastal storm surges along the Gulf of Mexico and U.S. east coast}, volume={16}, ISSN={1672-5182 1993-5021}, url={http://dx.doi.org/10.1007/S11802-017-3012-6}, DOI={10.1007/s11802-017-3012-6}, number={1}, journal={Journal of Ocean University of China}, publisher={Springer Nature}, author={Yao, Zhigang and Xue, Zuo and He, Ruoying and Bao, Xianwen and Xie, Jun and Ge, Qian}, year={2017}, month={Jan}, pages={1–7} }
 @article{nazari_ekelof_khodjaniyazova_elsen_williams_muddiman_2017, title={Direct screening of enzyme activity using infrared matrix-assisted laser desorption electrospray ionization}, volume={31}, ISSN={["1097-0231"]}, DOI={10.1002/rcm.7971}, abstractNote={RationaleHigh‐throughput screening (HTS) is a critical step in the drug discovery process. However, most mass spectrometry (MS)‐based HTS methods require sample cleanup steps prior to analysis. In this work we present the utility of infrared matrix‐assisted laser desorption electrospray ionization (IR‐MALDESI) for monitoring an enzymatic reaction directly from a biological buffer system with no sample cleanup and at high throughput.MethodsIR‐MALDESI was used to directly analyze reaction mixtures from a well plate at different time points after reaction initiation. The percent conversion of precursors to products was used to screen the enzyme activity. The reaction was performed with two different concentrations of precursors and enzyme in order to assess the dynamic range of the assay. Eventually, a pseudo‐HTS study was designed to investigate the utility of IR‐MALDESI screening enzyme activity in a high‐throughput manner.ResultsIR‐MALDESI was able to readily monitor the activity of IDH1 over time at two different concentrations of precursors and enzyme. The calculated Z‐factors of 0.65 and 0.41 confirmed the suitability of the developed method for screening enzyme activity in HTS manner. Finally, in a single‐blind pseudo‐HTS analysis IR‐MALDESI was able to correctly predict the identity of all samples, where 8/10 samples were identified with high confidence and the other two samples with lower confidence.ConclusionsThe enzymatic activity of IDH1 was screened by directly analyzing the reaction content from the buffer in well plates with no sample cleanup steps. This proof‐of‐concept study demonstrates the robustness of IR‐MALDESI for direct analysis of enzymatic reactions from biological buffers with no sample cleanup and its immense potential for HTS applications.}, number={22}, journal={RAPID COMMUNICATIONS IN MASS SPECTROMETRY}, author={Nazari, Milad and Ekelof, Mans and Khodjaniyazova, Sitora and Elsen, Nathaniel L. and Williams, Jon D. and Muddiman, David C.}, year={2017}, month={Nov}, pages={1868–1874} }
 @article{bokhart_manni_garrard_ekelöf_nazari_muddiman_2017, title={IR-MALDESI Mass Spectrometry Imaging at 50 Micron Spatial Resolution}, volume={28}, ISSN={1044-0305 1879-1123}, url={http://dx.doi.org/10.1007/S13361-017-1740-X}, DOI={10.1007/s13361-017-1740-x}, abstractNote={High spatial resolution in mass spectrometry imaging (MSI) is crucial to understanding the biology dictated by molecular distributions in complex tissue systems. Here, we present MSI using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) at 50 μm resolution. An adjustable iris, beam expander, and an aspherical focusing lens were used to reduce tissue ablation diameters for MSI at high resolution. The laser beam caustic was modeled using laser ablation paper to calculate relevant laser beam characteristics. The minimum laser spot diameter on the tissue was determined using tissue staining and microscopy. Finally, the newly constructed optical system was used to image hen ovarian tissue with and without oversampling, detailing tissue features at 50 μm resolution. Graphical Abstract ᅟ.}, number={10}, journal={Journal of The American Society for Mass Spectrometry}, publisher={Springer Nature}, author={Bokhart, Mark T. and Manni, Jeffrey and Garrard, Kenneth P. and Ekelöf, Måns and Nazari, Milad and Muddiman, David C.}, year={2017}, month={Jul}, pages={2099–2107} }
 @article{nazari_muddiman_2016, title={Enhanced Lipidome Coverage in Shotgun Analyses by using Gas-Phase Fractionation}, volume={27}, ISSN={["1879-1123"]}, DOI={10.1007/s13361-016-1446-5}, abstractNote={A high resolving power shotgun lipidomics strategy using gas-phase fractionation and data-dependent acquisition (DDA) was applied toward comprehensive characterization of lipids in a hen ovarian tissue in an untargeted fashion. Using this approach, a total of 822 unique lipids across a diverse range of lipid categories and classes were identified based on their MS/MS fragmentation patterns. Classes of glycerophospholipids and glycerolipids, such as glycerophosphocholines (PC), glycerophosphoethanolamines (PE), and triglycerides (TG), are often the most abundant peaks observed in shotgun lipidomics analyses. These ions suppress the signal from low abundance ions and hinder the chances of characterizing low abundant lipids when DDA is used. These issues were circumvented by utilizing gas-phase fractionation, where DDA was performed on narrow m/z ranges instead of a broad m/z range. Employing gas-phase fractionation resulted in an increase in sensitivity by more than an order of magnitude in both positive- and negative-ion modes. Furthermore, the enhanced sensitivity increased the number of lipids identified by a factor of ≈4, and facilitated identification of low abundant lipids from classes such as cardiolipins that are often difficult to observe in untargeted shotgun analyses and require sample-specific preparation steps prior to analysis. This method serves as a resource for comprehensive profiling of lipids from many different categories and classes in an untargeted manner, as well as for targeted and quantitative analyses of individual lipids. Furthermore, this comprehensive analysis of the lipidome can serve as a species- and tissue-specific database for confident identification of other MS-based datasets, such as mass spectrometry imaging.}, number={11}, journal={JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY}, author={Nazari, Milad and Muddiman, David C.}, year={2016}, month={Nov}, pages={1735–1744} }
 @article{nazari_bokhart_muddiman_2016, title={Whole-body mass spectrometry imaging by infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI)}, number={109}, journal={Jove-Journal of Visualized Experiments}, author={Nazari, M. and Bokhart, M. T. and Muddiman, D. C.}, year={2016} }
 @article{rosen_bokhart_nazari_muddiman_2015, title={Influence of C-Trap Ion Accumulation Time on the Detectability of Analytes in IR-MALDESI MSI}, volume={87}, ISSN={["1520-6882"]}, DOI={10.1021/acs.analchem.5b02641}, abstractNote={Laser desorption followed by post electrospray ionization requires synchronized timing of the key events (sample desorption/ionization, mass spectrometry analysis, and sample translation) necessary to conduct mass spectrometry imaging (MSI) with adequate analyte sensitivity. In infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) MSI analyses, two laser pulses are used for analysis at each volumetric element, or voxel, of a biological sample and ion accumulation in the C-trap exceeding 100 ms is necessary to capture all sample-associated ions using an infrared laser with a 20 Hz repetition rate. When coupled to an Orbitrap-based mass spectrometer like the Q Exactive Plus, this time window for ion accumulation exceeds dynamically controlled trapping of samples with comparable ion flux by Automatic Gain Control (AGC), which cannot be used during MSI analysis. In this work, a next-generation IR-MALDESI source has been designed and constructed that incorporates a mid-infrared OPO laser capable of operating at 100 Hz and allows requisite C-trap inject time during MSI to be reduced to 30 ms. Analyte detectability of the next-generation IR-MALDESI integrated source has been evaluated as a function of laser repetition rate (100-20 Hz) with corresponding C-trap ion accumulation times (30-110 ms) in both untargeted and targeted analysis of biological samples. Reducing the C-trap ion accumulation time resulted in increased ion abundance by up to 3 orders of magnitude for analytes ranging from xenobiotics to endogenous lipids, and facilitated the reduction of voxel-to-voxel variability by more than 3-fold.}, number={20}, journal={ANALYTICAL CHEMISTRY}, author={Rosen, Elias P. and Bokhart, Mark T. and Nazari, Milad and Muddiman, David C.}, year={2015}, month={Oct}, pages={10483–10490} }
 @article{nazari_muddiman_2015, title={Cellular-level mass spectrometry imaging using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) by oversampling}, volume={407}, ISSN={["1618-2650"]}, DOI={10.1007/s00216-014-8376-5}, abstractNote={Mass spectrometry imaging (MSI) allows for the direct and simultaneous analysis of the spatial distribution of molecular species from sample surfaces such as tissue sections. One of the goals of MSI is monitoring the distribution of compounds at the cellular resolution in order to gain insights about the biology that occurs at this spatial level. Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) imaging of cervical tissue sections was performed using a spot-to-spot distance of 10 μm by utilizing the method of oversampling, where the target plate is moved by a distance that is less than the desorption radius of the laser. In addition to high spatial resolution, high mass accuracy (±1 ppm) and high mass resolving power (140,000 at m/z = 200) were achieved by coupling the IR-MALDESI imaging source to a hybrid quadrupole Orbitrap mass spectrometer. Ion maps of cholesterol in tissues were generated from voxels containing <1 cell, on average. Additionally, the challenges of imaging at the cellular level in terms of loss of sensitivity and longer analysis time are discussed.}, number={8}, journal={ANALYTICAL AND BIOANALYTICAL CHEMISTRY}, author={Nazari, Milad and Muddiman, David C.}, year={2015}, month={Mar}, pages={2265–2271} }