Spectral properties of pro-multimodal imaging agents derived from a NIR dye and a metal chelator.
Monomolecular multimodal imaging agents (MOMIAs) are able to provide complementary diagnostic information of a target diseased tissue. We developed a convenient solid-phase approach to construct two pro-MOMIAs (before incorporating radiometal) derived from 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and cypate, a near-infrared (NIR) fluorescent dye analogous to indocyanine green (ICG). The possible interaction between d orbitals of transition metal DOTA complexes or free metals and the p orbitals of cypate chromophore could quench the fluorescence of pro-MOMIAs. However, we did not observe significant changes in the spectral properties of cypate upon conjugation with DOTA and subsequent chelation with metals. The fluorescence intensity of the chelated and nonmetal-chelated PRO-MOMIAs remained fairly the same in dilute 20% aqueous dimethylsulfoxide (DMSO) solution (1 x 10(-6) M). Significant reduction in the fluorescence intensity of pro-MOMIAs occurred in the presence of a large excess of metal ions (>1 molar ratio for indium and 20-fold for a copper relative to pro-MOMIA). This study suggests the feasibility of using MOMIAs for combined optical and radioisotope imaging.
Zhang
Zongren
Z
Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
Achilefu
Samuel
S
D002614:Chelating Agents / Q000737:chemistry*; D003287:Contrast Media / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D007204:Indium / Q000737:chemistry*; D015394:Molecular Structure; D019265:Spectroscopy, Near-Infrared
D002614:Chelating Agents; D003287:Contrast Media; D005456:Fluorescent Dyes; D007204:Indium; D003300:Copper