Isostructural Re and ^99mTc Complexes of Biotin Derivatives for Fluorescence and Radioimaging Studies

Abstract

The reaction of biotinamine with two equivalents of 2-quinoline aldehyde in the presence of Na(OAc)3BH in dichloroethane provides N,N-bis(methylquinoline)biotinamine (L1), a molecule displaying a tridentate donor terminus which has proven effective in coordinating to the {M(CO)3}+ core (M = Tc, Re). Reaction of L1 with (NEt4)2[Re(CO)3Br3] yields [Re(CO)3(L1)]Br, a compound with an absorbance at 350 nm and luminescence emission maxima at 425 and 580 nm. The luminescence lifetime of 11.4 mus, which is associated with the 580 nm emission, is sufficiently prolonged to enable time-gating techniques to be used during in vitro imaging studies and to overcome interference from endogenous fluorescence. Exposure of avidin beads to {Re(CO)3(L1)]Br resulted in binding, which was qualitatively imaged using fluorescence microscopy. The 99mTc analogue [99mTc(CO)3(L1)]+1 was prepared by reacting L1 with [99mTc(CO)3(H2O)3]+1 and purified by HPLC. The 99mTc complex is chemically robust and resistant to cysteine and histidine challenges. This study demonstrates that complementary fluorescent and radioactive biotin-derived probes may be readily prepared to allow direct correlation of in vitro and in vivo molecular imaging studies.

Synthesis, characterisation and bioimaging of a fluorescent rhenium-containing PNA bioconjugate

“…The lifetime in the presence of dioxygen is considerably shorter ( = 3.97  0.57 s) compared to degassed solutions ( = 10.65  0.14 s), which is a common phenomenon and characteristic for 3 MLCT emissions. 18,38 Also in accordance with our tentative assignment of a charge-transfer transition is the observation of a strong solvent-dependence of the quantum yields for this band (Table 1). Table S1 in the ESI).…”

“…5 Herein, we present the preparation and in-depth characterization, including X-ray crystallography, of Tc congeners, were already used for the (radio-)labeling of biomolecules by Zubieta, Valliant, Babich and our groups for both in vitro and in vivo imaging purposes. [18][19][20][21][22][23][24][25][26][27][28][29][30] We then report on 31 with triphenyl phosphine, diisopropyl azodicarboxylate and diphenylphosphoryl azide in THF following a similar procedure described by our groups (Scheme 1). 32 The presence of L-N 3 Figure S2 in the SI).…”

Re(I) carbonyl complexes: Multimodal platforms for inorganic chemical biology

“…Other biomolecules could also be labelled and imaged, e.g. biotin [100,101], folic acid [97] or thymidine derivatives [22,51,102].…”

Pyrazolyl–Diamine Ligands That Bear Anthracenyl Moieties and Their Rhenium(I) Tricarbonyl Complexes: Synthesis, Characterisation and DNA‐Binding Properties

“…By profiting from the similarities between the chemistry of Re and Tc, fluorescent probes that are based on organometallic Re I complexes emerged recently as an attractive alternative to bridge this gap between in vitro fluorescence-imaging studies and in vivo radioimaging. [25] As stated in the introductory part of the paper, we intended to prove that the intrinsic fluorescence of anthracenyl chromophores, which were introduced at different positions of the framework of pyrazolyl-diamine chelators should enable us to image the intracellular localisation of their Re I -tricarbonyl complexes. To confirm this possibility, we studied the cell uptake of the two Re complexes, fac-[Re(CO) 3 {3,5-Me 2 pzNN-Ant}]Br (7) and fac-[Re(CO) 3 {Ant-3,5-Me 2 pzNN}]Br (9), for which the DNAbinding properties have been evaluated.…”