A New Perspective On The Use Of Ambient Ionization Mass Spectrometry For Biomolecule Testing

Mass spectrometry(MS) is a central analytical technique for the study of biomolecules in general. It can provide rich molecular structure with fast response, high sensitivity. In recent years, driven by the need to identify, characterize,and quantify biomolecules at ever increasing sensitivity and in ever more complex samples, a wide range of ambient mass spectrometry-based analytical platforms and experimental strategies have emerged. Here we use mass spectrometry instrumentation to establishe a rapid and high-throughput methods for qualitative or quantitative analysis in bimolecules science.The main contents of this thesis are as follows:1、The value of bimolecules detection are introduced. Reviews the mechanism, advantages and disadvantages of the methods that used for detect bimolecules. Describe the mechanism and application value of electrospray ionization mass spectrometry(ESI-MS) and extractive electrospray ionization mass spectrometry(EESI-MS)in biomolecules analysis.2、 ESI can transfer biomolecules into the gas-phase without significant changes to their native structure. However, the low charge states of native biomolecular ions make them poorly visible by mass spectrometry. Herein we introduced an alternative supercharging(SC) approach in which biomolecules are ionized from the native aqueous buffer with low-vapor reagent molecules(e.g., m-nitro benzyl alcohol, m-NBA; sulfolane) added at a low concentration(< 1%) into the spraying solution. In this work, we explored ESI-MS charging and SC behavior of several biopolymers including proteins and DNA oligonucleotides. Analytes were ionized from 100 m M ammonium acetate(NH4Ac) aqueous buffer in both positive(ESI+) and negative(ESI-) ion modes. SC was induced either with m-NBA or by the elevated temperature of ESI capillary. For all the analytes studied we found striking differences in the ESI MS response to these two modes of activation. Activation with m-NBA resulted in stronger and softer supercharging. When analyte solution with m-NBA was analyzed at elevated temperatures, the SC effect from m-NBA was neutralized. Instead, the net SC effect was equal to the SC effect achieved by thermal activation only. Overall, the data support the hypothesis that the SC phenomenon involves a direct interaction between a biopolymer and SC reagent occurring in evaporating ESI droplets.3、 A novel method, based on EESI tandem mass spectrometry, was developed for the direct detection of amino acids in biological fluids(urine, plasma) with minimal sample pretreatment. We constructed interface between EESI and LTQ-MS, optimized EESI-MS conditions using representative amino acid standards. We analyzed plasma samples from patients of lung cancers, measured the change of amino acids concentration in the samples. We analyzed data using multivariate statistical analysis methods. The result showed that the average time for a single sample analysis was less than 1 min. Based on the application of principal component analysis(PCA), lung cancer group were successfully differentiated from the normal group. This study showed that EESI-MS is a powerful tool for the rapid, sensitive, and quantitative detection of amino acids in complex biological samples.4、Sum up the analytical methods and its applications, proposed some improving suggestions, and provide a new perspective on the use of ambient ionization mass spectrometry for biomolecule testing...