Talaignair N. Venkatraman1, Artek Tovmasyan2, Ines Batinic-Haberle2, Ivan Spasojevic2, Christopher D. Lascola1
1Radiology, Duke University Medical Center, Durham, NC, United States; 2Radiation Oncology, Duke University Medical Center, Durham, NC, United States
This study investigates the potential impact of common biological moieties on the relaxation properties of our two lead candidate MnPs (MnTE-2-PyP5+ and MnTnHex-2-PyP5+). These include the most abundant intracellular redox mediator, ascorbate; (2) the most metabolically relevant counter-anion, citrate; (3) and the most abundant serum protein, albumin. With respect to likely biological redox modifiers, both MnP isoforms showed a systematic reduction in relaxivity in the presence of ascorbate, consistent with the hypothesis that metal center oxidation state will have a significant impact on relaxation properties of MnPs in vivo. Intriguingly, citrate anion does not negatively impact relaxation, and in the case of MnTE2PyP5+, may actually enhance contrast enhancement. These two isoforms of MnP demonstrate impressive relaxation properties that enable MR detection in vivo.