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BioMed Research International
Volume 2015 (2015), Article ID 284354, 12 pages
Research Article

Synthesis, 68Ga-Radiolabeling, and Preliminary In Vivo Assessment of a Depsipeptide-Derived Compound as a Potential PET/CT Infection Imaging Agent

1Department of Nuclear Medicine, University of Pretoria & Steve Biko Academic Hospital, Corner Malherbe and Steve Biko Road, Pretoria 0001, South Africa
2School of Chemistry and Physics, Westville Campus, University Road, Westville, Durban 3630, South Africa
3School of Health Sciences, Catalysis and Peptide Research Unit, E-Block 6th Floor, Westville Campus, University Road, Westville, Durban 3630, South Africa
4Department of Virology, University of KwaZulu-Natal, National Health Laboratory Service, P.O. Box 1900, Westville, Durban 3630, South Africa
5Division of PET Imaging & Radiochemistry, Molecular Imaging Research Centre, INMAS, Brig S. K. Mazumdar Marg, Timarpur, Delhi 110054, India
6Radiochemistry Section Necsa, Building P1600, Pelindaba, Brits, North West Province, South Africa
7Department of Science and Technology, Preclinical Drug Development Platform, North West University, 11 Hoffman Street, Potchefstroom 2520, South Africa

Received 7 June 2014; Revised 28 July 2014; Accepted 5 August 2014

Academic Editor: Alberto Signore

Copyright © 2015 Botshelo B. Mokaleng et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Noninvasive imaging is a powerful tool for early diagnosis and monitoring of various disease processes, such as infections. An alarming shortage of infection-selective radiopharmaceuticals exists for overcoming the diagnostic limitations with unspecific tracers such as 67/68Ga-citrate or 18F-FDG. We report here TBIA101, an antimicrobial peptide derivative that was conjugated to DOTA and radiolabeled with 68Ga for a subsequent in vitro assessment and in vivo infection imaging using Escherichia coli-bearing mice by targeting bacterial lipopolysaccharides with PET/CT. Following DOTA-conjugation, the compound was verified for its cytotoxic and bacterial binding behaviour and compound stability, followed by 68Gallium-radiolabeling. µPET/CT using 68Ga-DOTA-TBIA101 was employed to detect muscular E. coli-infection in BALB/c mice, as warranted by the in vitro results. 68Ga-DOTA-TBIA101-PET detected E. coli-infected muscle tissue (SUV = 1.3–2.4) > noninfected thighs > forearm muscles > background in the same animal. Normalization of the infected thigh muscle to reference tissue showed a ratio of 3.0 ± 0.8 and a ratio of 2.3 ± 0.6 compared to the identical healthy tissue. The majority of the activity was cleared by renal excretion. The latter findings warrant further preclinical imaging studies of greater depth, as the DOTA-conjugation did not compromise the TBIA101’s capacity as targeting vector.