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Towards dual SPECT/optical bioimaging with a mitochondrial targeting, 99mTc(i) radiolabelled 1,8-naphthalimide conjugate

Day, Adam H.; Domarkas, Juozas; Nigam, Shubhanchi; Renard, Isaline; Cawthorne, Christopher; Burke, Benjamin P.; Bahra, Gurmit S.; Oyston, Petra C. F.; Fallis, Ian A.; Archibald, Stephen J.; Pope, Simon J. A.


Adam H. Day

Juozas Domarkas

Shubhanchi Nigam

Isaline Renard

Christopher Cawthorne

Benjamin P. Burke

Gurmit S. Bahra

Petra C. F. Oyston

Ian A. Fallis

Simon J. A. Pope


A series of six different 1,8-naphthalimide conjugated dipicolylamine ligands (L1-6) have been synthesised and characterised. The ligands possess a range of different linker units between the napthalimide fluorophore and dipcolylamine chelator which allow the overall lipophilicity to be tuned. A corresponding series of Re(i) complexes have been synthesised of the form fac-[Re(CO)3(L1-6)]BF4. The absorption and luminescence properties of the ligands and Re(i) complexes were dominated by the intramolecular charge transfer character of the substituted fluorophore (typically absorption ca. 425 nm and emission ca. 520 nm). Photophysical assessments show that some of the variants are moderately bright. Radiolabelling experiments using a water soluble ligand variant (L5) were successfully undertaken and optimised with fac-[99mTc(CO)3(H2O)3]+. Confocal fluorescence microscopy showed that fac-[Re(CO)3(L5)]+ localises in the mitochondria of MCF-7 cells. SPECT/CT imaging experiments on naïve mice showed that fac-[99mTc(CO)3(L5)]+ has a relatively high stability in vivo but did not show any cardiac uptake, demonstrating rapid clearance, predominantly via the biliary system along with a moderate amount cleared renally.


Day, A. H., Domarkas, J., Nigam, S., Renard, I., Cawthorne, C., Burke, B. P., …Pope, S. J. A. (in press). Towards dual SPECT/optical bioimaging with a mitochondrial targeting, 99mTc(i) radiolabelled 1,8-naphthalimide conjugate. Dalton Transactions : an international journal of inorganic chemistry, 49(2), 511-523.

Journal Article Type Article
Acceptance Date Dec 9, 2019
Online Publication Date Dec 17, 2020
Deposit Date Jan 20, 2020
Publicly Available Date Oct 27, 2022
Journal Dalton Transactions
Print ISSN 1477-9226
Electronic ISSN 1477-9234
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 49
Issue 2
Pages 511-523
Keywords Inorganic Chemistry
Public URL
Publisher URL!divAbstract


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