Key Technique Investigation Of Imaging MALDI-TOF/TOF Mass Spectrometry And Its Applications

Some key technique of Imaging Mass Spectrometry were Investigated. The procedure of fresh tissue storage and slicing transfer were investigated; MALDI matrix coating protocol were selected; influential factor on the resolution of IMS image were introduced. A new type of target plate was designed for improving slicing transfer. A specifically spray system was developed to solve the problem of co-crystallization size and uniformity control. Software was developed for MS average spectrum and Component Distribution (Hits) statistic. Hits value reflected the component distribution in tissues. Hits bigger, the distribution of component was larger.The evaluation method for the reproducibility and the stability of IMS were investigated. The reproducibility methodology should included three parts: tissue section preparation, matrix coating and MALDI-TOF MS analysis. The stability should included two parts: shelf life for fresh biological tissue and for tissue sections after coating matrixes. The results show that reproducibility between several of species groups was good. The shelf life for fresh biological tissue stored at -80℃was 18 months and for tissue sections after coating matrixes stored at -20℃was 2 days.The difference of SD-rat brain hippocampus between microwave radiation and normal was analysis used IMS. 5902 spectra and 320 MS images per slice for normal group were acquired, 5993 spectra and 346 MS images per slice for microwave radiation group were acquired. Software was developed to calculate the Hits values, which reflected the component distribution and abundance. By statistic analysis of normal species and radiation group, total 199 differentiate molecules were found, 194 molecules were up regulated. These molecules might be important for investigating the injury mechanism of hippocampus microwave radiation.In order to directly analysis the peptides from formalin-fixed tissue. New method that Biological Tissue Section tryptic digestions in situ coupled with imaging mass spectrometry was established. The optimal conditions as follows: the digestion solution with 0.1ug/ul of trypsin was deposited in section, sonic oscillation for 10 minutes at 60℃; using the sinapic acid as the MALDI matrix.