Studies On Biological Molecules Analysis Using Inductively Coupled Plasma Mass Spectrometry

Inductively coupled plasma mass spectrometry (ICP-MS) has been proven to be a powerful elemental detection technique. Although elemental analysis using ICP-MS is quite successful for the quantitation of metal containing proteins, it was accepted, for a long time, that if a biological molecule does not ligate or incorporate a metal atom, it should be analyzed by another means instead of elemental analysis methods. However, our systemic studies showed that non-metal containing biological molecules can also be determined by measurements of the atomic composition of a tag conjugated to a biological molecule with ICP-MS detection. This method shows great promise to be applied in clinical diagnosis, drug discovery, and proteome study. The main achievements obtained in this research are:1. Using thyroid-stimulating hormone (TSH) and thyroxin (T4) as the model compounds, we demonstrate the possibility of ICP-MS as a good endpoint detector for the determination of biological molecules by the measurement of a rare earth elemental tag Eu3+ that is specifically attached to an immuno-reagent.2. Due to the inherent analytical advantage of multielement capability of ICP-MS, it is reasonable to expect that multiple element-tagged antibodies can be used to probe one sample for simultaneous determination. The simultaneous determination of two large molecule proteins, alpha-fetoprotein (AFP) and freeβ-human chorionic gonadotropin (HCG) with ICP-MS detection was achieved by measuring of two rare earth elemental tags Eu3+ and Sm3+ after dissociating them from the labeled antibody into the nitric acid solution. The result showed the potential multi-analyte detection by ICP-MS using different elements conjugated to different antibodies.3. Inorganic elemental nanoparticles are especially attractive for quantitation because of their uniform size and significant number of atoms per conjugate. Thus, there is the possibility of increasing the signal response by conjugating the biological molecule to inorganic elemental nanoparticles. Colloidal gold was selected to serve as a biological molecule tag due to its regular size and easy preparation. Using rabbit anti human IgG as a model compound, a sandwich-type immunoreaction coupled to ICP-MS using colloidal gold nanoparticle-labeled antibody was establised.4. High performance liquid chromatography in combination with ICP-MS was used for the separation of the different arsenic species in two Chinese edible seaweed extracts. The structures of arsenic species, which were confirmed by electrospray mass spectrometry, were mainly arsenosugars. The metabolites of these arsenosugars in human urine after ingestion of seaweed were also studied. The results are helpful not only in the evaluation of seafood safety but also in understanding the metabolism and the possible adverse health effects of arsenosugars in humans.