This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Introduction: Imaging contrast agents (or contrast media) are a category of diagnostic pharmaceuticals for enhancing the image contrast of organs/tissues and for displaying the organ function in medical imaging. Macromolecular contrast agents have found their important role in the characterization of microvascular permeability of tumor vessels, due to their blood-pool characteristics. New dendritic contrast agents with well-defined structure, high degree of size homogeneity, varying molecular weights and polyethyleneglycol (PEG) cores, will be synthesized. Their average molecular weights (MW) and MW distribution will be obtained from mass spectrometry, which info will be highly helpful for the chemical synthesis and for the study of their structure-property relationship. In addition, some new small molecular intermediates, which are attributed to the image contrast, need the structure characterization by mass spectrometry, too. Methods: For different macromolecular derivatives (MW 3,000 - 150,000), MALDI-MS could be used for the measurements of their MW and distributions in MW. For small molecular compounds (MW 500 - 2000), ESI-MS or other approaches may be applicable. Results & Discussion: Mass spectra data will be correlated with the data from physical and imaging measurements, the relationship between chemical structure and physical (or imaging) properties will be sought for this new class of macromolecular contrast agents. During the synthesis, the mass spectra data will be highly helpful in the guidance and optimization of synthetic procedures.
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