个人简介

B.Sc.; Ph.D. (PolyU) 1999

研究领域

Analytical chemistry

Fundamental and Analytical Mass Spectrometry: Surface-assisted laser desorption/ionization mechanism, development and application of Imaging Mass Spectrometry technology and other new ionization method(s) for direct sample analysis, such as TCM raw herb analysis. Research programmes: 1. Fundamentals of Surface-Assisted Laser Desorption/Ionization (SALDI) The advancement of SALDI is driven by the development of material sciences and understanding towards the laser/material interaction. Novel materials, specifically nanomaterials, have been prepared as the laser-absorbing substrates for SALDI, for enhancing the detection sensitivity and specificity of SALDI-MS. We have been working on the development of new nanomaterials as SALDI substrates, and understanding their interaction with laser, in order to elucidate important substrate parameter(s) for enhancing the ion desorption processes and shedding light on the SALDI desorption mechanism(s). Our studies include the preparation of new SALDI substrates, to characterize various physiochemical properties of the substrates, and to investigate the desorption process(es) with different approaches, such as probing the internal energy transfer, microscopic examination of the substrates, and performing theoretical calculation and simulation. Figure 1: Schematic of SALDI process 2. Imaging Mass Spectrometry (IMS) IMS is a molecular-specific, label-free imaging tool for the parallel detection of a vast variety of analytes from a given sample in solid state. It has been widely adopted for biological tissue imaging analysis, for revealing the distribution of both endogenous and exogenous metabolites, such as drugs, peptides, lipids within biological tissues. The spatial distribution of these metabolites could be correlated to the physiological/biological status of the tissues, and provide information for the understanding of underlying biochemical process(es). Our team has developed solvent-free IMS platform for analysis of animal tissues, raw herb slices and forensic samples (e.g. latent fingerprints and documents). We are going to further develop our SALDI-IMS platform to analyze biological tissues for drug, food and Traditional Chinese Medicine research. Figure 2: Schematic of Fingerprint Analysis by IMS Figure 3: Histological Analysis by IMS 3. Development of New Ionization Methods for Direct Sample Analysis Direct Sample Analysis by MS allows fast and specific detection of analytes with minimal sample treatment. However, MS usually requires sample in form of solution extract, and requires chromatographic separation to facilitate analyte ionization and/or minimize ion suppression by sample matrix. Hence, we have been working on the development of new ionization method(s) which allows the seamless application of MS for direct sample analysis. We have developed the tissue-spray ionization method, which allows the direct detection of phytochemicals and other plant metabolites from raw American ginseng tissues. We believe direct analysis of raw herbal materials can be an efficient analysis method to facilitate the quality control of raw herbs. In addition, we are going to develop other new ionization methods which allow a wider variety of daily samples to be directly analyzed by MS. Figure 4: Direct Analysis of Raw Herb

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Wong M.Y.M.; Tang H.W.; Man S.H.; Lam C.W.; Che C.M.* and Ng K.M.*, "Electrospray Ionization on Porous Spraying Tips for Direct Sample Analysis by Mass Spectrometry: Enhanced Detection Sensitivity and Selectivity Using Hydrophobic/ Hydrophilic Materials as Spraying Tips", Rapid Communications in Mass Spectrometry, 27(6), 713-721 2013. Tang H.W.; Wong M.Y.M.; Lam W.; Cheng Y.C.; Che C.M.* and Ng K.M.*, "Molecular Histology Analysis by MALDI Imaging Mass Spectrometry Using Gold Nanoparticles as Matrix", Rapid Communications in Mass Spectrometry, 25, 3690-3696, 2011. Chan S.L.F.; Wong M.Y.M.; Tang H.W.; Che C.M.* and Ng K.M.*, "Tissue-Spray Ionization Mass Spectrometry for Raw Herb Analysis", Rapid Communications in Mass Spectrometry, 25, 2837-2843, 2011. Tang H.W.; Wong M.Y.M.; Chan S.L.F.; Che C.M.* and Ng K.M.*, "Molecular Imaging of Banknote and Questioned Document Using Solvent-Free Gold Nanoparticle-Assisted Laser Desorption/ Ionization Imaging Mass Spectrometry", Analytical Chemistry, 83, 453-458, 2011. Tang H.W.; Lu W.; Che C.M.* and Ng K.M.*, "Gold Nanoparticles and Imaging Mass Spectrometry: Double Imaging of Latent Fingerprints", Analytical Chemistry, 82, 1589-1593, 2010. Tang H.W.; Ng K.M.*; Lu W. and Che C.M*. "Ion Desorption Efficiency and Internal Energy Transfer in Carbon-Based Surface-Assisted Laser Desorption/Ionization Mass Spectrometry: Desorption Mechanism(s) and the Design of SALDI Substrates", Analytical Chemistry, 81, 4720-4729, 2009. Tang H.W.; Ng K.M.*; Chui S.S.Y.; Che C.M.*; Lam C.W.; Yuen K.Y.; Siu T.S.; Lan L.C.L. and Che X. "Analysis of Melamine Cyanurate in Urine Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry" Analytical Chemistry, 81, 3676-3682, 2009. Ng K.M.*; Liang Z.T.; Lu W.; Tang H.W.; Zhao Z.Z.; Che C.M. and Cheng Y.C. "In Vivo Analysis and Spatial Profiling of Phytochemicals in Herbal Tissues by Matrix-Assisted Laser Desorption / Ionization Mass Spectrometry" Analytical Chemistry, 79, 2745 - 2755, 2007. Ng K.M.*; Che C.M.*; Wo S.K.; Tam P.K.H. and Lau A.S.Y. "Analytical Application of Acetate Anion in Negative Electrospray Ionization Mass Spectrometry for the Analysis of Triterpenoid Saponins - Ginsenosides" Rapid Communications in Mass Spectrometry, 20, 1545 - 1550, 2006. Ng K.M.; Li W.K*.; Wo S.K.; Tsang C.W.* and Ma N.L.* "Silver (I) Affinities of Amides: a Combined Ab Initio and Experimental Study". Physical Chemistry Chemical Physics, 6, 144 - 153, 2004.