| Summary: | 碩士 === 國立臺灣大學 === 化學研究所 === 105 === Ambient ionization mass spectrometry (AIMS) techniques have been widely introduced to the field of biomedical analysis due to their simplicity in sample pretreatment and low cost of operation. The advantages of paper-based ambient ionization contains fast extraction of analytes from the raw sample, featuring in its high sampling efficiency and convenience of preserving sample.
Blood test for endogenous small metabolites to determine physiological and biochemical states is routine for laboratory analysis. In this thesis we demonstrate that by combining a commercial direct analysis in real time (DART) ion source with an ion trap mass spectrometer in positive mode, native cholesterol in its dehydration form ([M-H2O+H+], m/z 369) is readily detected from few hundred nanoliters of human serum loaded onto a chromatography paper. Deuterium-labeled cholesterol was used as the internal standard to obtain the absolute quantity of the endogenous cholesterol. The amount of the cholesterol measured by this paper-loaded DART mass spectrometry (pDART-MS) is statistically comparable with that obtained by using commercially available fluorometric-enzymatic assay and LC/MS. Furthermore, serums from twenty-one participants at three different time points in an ultra-marathon were collected to obtain their cholesterol levels. The test requires only minimal sample preparations, and the concentrations of cholesterol in each sample were acquired within a minute.
Furthermore, we also explored the possibility of utilizing paper-based AIMS to cancer diagnosis. In the case of breast cancer, breast tissue is extracted with a hypodermic needle, and wiped onto filter papers for the following pathology diagnosis in hospital. We used this routine paper-based tissue sample incorporating with AIMS for a rapid metabolite profiling to discriminate cancerous/noncancerous tissues. To reduce the chemical noise in the complex matrix without additional sample pretreatment, we interfaced field asymmetric waveform ion mobility spectrometry with paper spray ionization mass spectrometry (FAIMS-PSI-MS). Statistical analysis of MS spectral profiles in the mass range of m/z 600-900, in which the phospholipid species were dominant, was performed. Relative signal intensity of 28 species showed significant difference in cancerous and noncancerous breast tissue with p value <0.05 in t-test. These markers were used to discriminate the 43 tissue samples from patients, potentially assist to locate the tumor during clinical treatment.
AIMS is characteristic for its speed and ease of use together that allows a rapid, direct, and quantitative analysis of complex biological samples. The two approaches of paper-based analysis of biological samples demonstrate that AIMS has the ability to perform clinical applications.
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