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Molecular & Cellular Analysis Technologies
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Characterization of an acute leukemia (AML) cell requires measurement of biomarkers such as proteins, genes and small molecules. An unambiguous biomarker signature cannot be obtained by determining only a few proteins. A quantitative, massively multiplexed bioassay (MMB) for a constellation of proteins, small molecules, and gene transcripts would be a significant medical breakthrough. 'Personalized health care', unambiguous disease identification, and patient- specific diagnosis/prognosis will be enabled by the simultaneous quantitative determination of many biomarkers in a patient's sample. We will develop a new, robust, multimetallic tagging system based on functionalized polymer microbeads (PMBs) analyzed by the proven, high-sensitivity, time-resolved, and element-specific detection technique of flow-cytometry inductively- coupled-plasma mass spectrometry (FC-ICP-MS). Our interdisciplinary group of recognized experts will address this significant challenge. Prof. S. Stevenson (Univ. of Southern Mississippi, USM) will optimize the synthesis of 7 different M3N@C80 endometallofullerenes (EMFs) with interference-free metals that are not endogenous in biomedical samples. Prof. S. H. Strauss and Dr. O. V. Boltalina (Colorado State Univ., CSU) will optimize the synthesis of chemical derivatives of the EMFs, determine the optimum type and number of functional groups to achieve uniformity. Preferred derivatives will be sent to Prof. J. P. Phillips (USM), who will attach polymerizable groups to EMF derivatives, optimize preparation of narrow-size-distribution PMBs containing many specific mixtures of the seven metals (all of which will be permanently sequestered in their carbon nanocages and therefore cannot leach out over time). The Univ. of Toronto (UofT) group, led by Prof. V. I. Baranov, will develop purpose-specific analytical methods that combine robotic sample introduction and FC-ICP-MS instrumentation to allow massively multiplexed detection and classification of thousands of multimetallic encoded beads with element-tagged reporter affinity molecules. They will estimate the tagging multiplexity and show the integrity and virtually infinite shelf-life of the tagged PMBs, and that massive multiplexing with thousands of differently tagged PMBs is possible when this technology is reduced to practice. Dr. O. I. Ornatsky (UofT) will perform analyte selection, testing and validation of the encoded beads, immunoassays, and oligonucleotide hybridization, and will covalently link a range of antibodies (Abs) to the surfaces of the tagged PMBs, which will be tested in sandwich assays with secondary Abs linked to a reporter tag. We will prove that our tagging system has the potential to be used for massively multiplexed bioassays in which thousands of antigens, gene transcripts, and small-molecule cell markers for many diseases and conditions are determined simultaneously in a single sample. We will test our massively multiplexed bioanalytical platform on acute myeloid leukemia (AML) cells. We will show the advantages of FC-ICP-MS analysis of multi-metal-tagged PMBs coated with capture Abs against cytokines, chemokines, growth factors, and soluble receptors present in human serum. PUBLIC HEALTH RELEVANCE: The goals of the proposed investigation are the development of an advanced metal encoding system for bead-based assays. This novel system uses combinations of trimetallic endometallofullerenes embedded in polymeric microbeads to encode hundreds of thousands of unique carriers which together with time-resolved multi- element detection by flow-cytometry inductively-coupled-plasma mass spectrometry (FC-ICP-MS) will enable quantitative gene expression analysis and massively multiplexed immunoassays. Unambiguous disease identification and patient-specific diagnosis and prognosis will all be enabled by the simultaneous, rapid, and quantitative determination of many biomarkers in a patient's sample.