@article{brown_liu_he_2015, title={Matrix-enhanced surface-assisted laser desorption/ionization mass spectrometry (ME-SALDI-MS) for mass spectrometry imaging of small molecules}, volume={1203}, journal={Mass spectrometry imaging of small molecules}, author={Brown, V. L. and Liu, Q. and He, L.}, year={2015}, pages={175–184} } @article{zou_liu_deiters_2011, title={Synthesis of the Pyridine Core of Cyclothiazomycin}, volume={13}, ISSN={["1523-7052"]}, DOI={10.1021/ol201682k}, abstractNote={A highly convergent synthesis of the pyridine core of the thiopeptide antibiotic cyclothiazomycin has been developed based on a [2+2+2] cyclotrimerization key step. The regioselective assembly of the heterocyclic center of this important class of antibiotics takes advantage of a temporary silicon tether and the ruthenium-catalyzed cyclotrimerization reaction of a diyne and an electron-poor thiazole nitrile.}, number={16}, journal={ORGANIC LETTERS}, author={Zou, Yan and Liu, Qingyang and Deiters, Alexander}, year={2011}, month={Aug}, pages={4352–4355} } @article{liu_xiao_pagan-miranda_chiu_he_2009, title={Metabolite Imaging Using Matrix-Enhanced Surface-Assisted Laser Desorption/Ionization Mass Spectrometry (ME-SALDI-MS)}, volume={20}, ISSN={["1879-1123"]}, DOI={10.1016/j.jasms.2008.09.011}, abstractNote={We describe here the use of a hybrid ionization approach, matrix-enhanced surface-assisted laser desorption/ionization mass spectrometry (ME-SALDI-MS) in bioimaging. ME-SALDI combines the strengths of traditional matrix-assisted laser desorption/ionization (MALDI) and SALDI and enables successful MS imaging of low-mass species with improved detection sensitivity. Using 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) as the MS standard, MS performances of MALDI, SALDI, and ME-SALDI are systematically compared. The analyte desorption and ionization mechanism in ME-SALDI is qualitatively speculated based on the observation of significantly reduced matrix background and improved survival yields of molecular ions. Improvements in detection sensitivity of low-mass species using ME-SALDI over MALDI in imaging are demonstrated with mouse heart and brain tissues.}, number={1}, journal={JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY}, author={Liu, Qiang and Xiao, Yongsheng and Pagan-Miranda, Coral and Chiu, Yu Matthew and He, Lin}, year={2009}, month={Jan}, pages={80–88} } @article{liu_guo_he_2007, title={Mass spectrometry imaging of small molecules using desorption/ionization on silicon}, volume={79}, ISSN={["1520-6882"]}, DOI={10.1021/ac0611465}, abstractNote={Development of novel tools to image spatial distribution of small molecules in biological samples is essential in disease diagnosis and biomarker discovery. To simplify sample preparation and reduce background noise in the low-mass region, we describe here the use of a matrix-free mass spectrometric imaging method, i.e., desorption/ionization on silicon (DIOS), for biological surface analysis. The imaging parameters, such as the laser beam diameter and the translation stage movement, were studied and optimized to improve imaging performance. The use of DIOS imaging to map small molecules on mouse liver tissues was demonstrated. In addition, phosphatidylcholine (PC) and propidium iodide (PI) were used as the cell membrane and nucleus markers, respectively, to "visualize" the presence of HEK 293 cells. The reconstructed ion maps of PC and PI were compared with the optical images collected from the same sample using bright-field and fluorescence microscopy. A good correlation of the spatial distribution of cells confirmed the validity of this DIOS imaging approach.}, number={10}, journal={ANALYTICAL CHEMISTRY}, author={Liu, Qiang and Guo, Zhong and He, Lin}, year={2007}, month={May}, pages={3535–3541} } @article{liu_he_2008, title={Quantitative study of solvent and surface effects on analyte ionization in desorption ionization on silicon (DIOS) mass spectrometry}, volume={19}, ISSN={["1044-0305"]}, DOI={10.1016/j.jasms.2007.10.002}, abstractNote={Deuterated solvents and DIOS surfaces derivatized with different functional groups are used to investigate impacts of local chemical environment on analyte ionization. Both solvent molecules and surface functional groups are found to directly participate in analyte protonation in the condensed phase. The corresponding protonation effectiveness is quantitatively estimated based on the relative MS peak intensities of [M+2]+/[M+1]+. A direct correlation between ionization of triethylamine and the relative acidities of the surface and the solvent is evident. In addition, the proton donating effectiveness of a solvent is found to be related to its vapor pressure. Improved MS detection of small molecules via proper surface treatment and solvent selection is demonstrated.}, number={1}, journal={JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY}, author={Liu, Qiang and He, Lin}, year={2008}, month={Jan}, pages={8–13} } @misc{guo_ganawi_liu_he_2006, title={Nanomaterials in mass spectrometry ionization and prospects for biological application}, volume={384}, ISSN={["1618-2650"]}, DOI={10.1007/s00216-005-0125-3}, abstractNote={The rapid development of nanotechnology has revolutionized scientific developments in recent decades. Mass spectrometry (MS) measurements are no exception and have benefited greatly from integration of nanomaterials in every step of analysis. This brief review summarizes recent developments in the field with the focus on the use of nanomaterials as alternative media to facilitate analyte ionization in laser-desorption ionization-mass spectrometry (LDI-MS) and secondary ion mass spectrometry (SIMS). The biological applications of both techniques are also detailed. The use of nanomaterials in other aspects of MS analysis, for example in sample clean-up and indirect analyte quantification, is briefly discussed.}, number={3}, journal={ANALYTICAL AND BIOANALYTICAL CHEMISTRY}, author={Guo, Z and Ganawi, AAA and Liu, Q and He, L}, year={2006}, month={Feb}, pages={584–592} }