68Ga‐labeled Ciprofloxacin Conjugates as Radiotracers for Targeting Bacterial Infection |
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| Authors: | Drishty Satpati Chanda Arjun Repaka Krishnamohan Grace Samuel Sharmila Banerjee |
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| Affiliation: | 1. Radiopharmaceuticals Chemistry Section, Radiochemistry and Isotope Group, Bhabha Atomic Research Center, Mumbai, India;2. Board of Radiation and Isotope Technology, Navi Mumbai, India |
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| Abstract: | With an aim of developing a bacteria‐specific molecular imaging agent, ciprofloxacin has been modified with a propylamine spacer and linked to two common bifunctional chelators, p‐SCN‐Bz‐DOTA and p‐SCN‐Bz‐NOTA. The two ciprofloxacin conjugates, CP‐PA‐SCN‐Bz‐DOTA ( 1 ) and CP‐PA‐SCN‐Bz‐NOTA ( 2 ), were radiolabeled with 68Ga in >90% radiochemical yield and were moderately stable in vitro for 4 h. The efficacy of 68Ga‐ 1 and 68Ga‐ 2 has been investigated in vitro in Staphylococcus aureus cells where bacterial binding of the radiotracers (0.9–1.0% for 68Ga‐ 1 and 1.6–2.3% for 68Ga‐ 2 ) could not be blocked in the presence of excess amount of unlabeled ciprofloxacin. However, uptake of radiotracers in live bacterial cells was significantly higher (p < 0.01) than that in non‐viable bacterial cells. Bacterial infection targeting efficacy of 68Ga‐ 1 and 68Ga‐ 2 was tested in vivo in rats where the infected muscle‐to‐inflamed muscle (68Ga‐ 1 : 2 ± 0.2, 68Ga‐ 2 : 3 ± 0.5) and infected muscle‐to‐normal muscle ratios (68Ga‐ 1 : 3 ± 0.4, 68Ga‐ 2 : 6.6 ± 0.8) were found to improve at 120 min p.i. Fast blood clearance and renal excretion was observed for both the radiotracers. The two 68Ga‐labeled infection targeting radiotracers could discriminate between bacterial infection and inflammation in vivo and are worthy of further detailed investigation as infection imaging agents at the clinical level. |
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| Keywords: | 68Ga bacterial infection ciprofloxacin
DOTA
NOTA
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