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Updated: Jan 22, 2026

Multi-timescale Microscopy Methods for the Characterization of Fluorescently-labeled Microbubbles for Ultrasound-Triggered Drug Release
Published on: June 12, 2021
Development of 68Ga-labelled ultrasound microbubbles for whole-body PET imaging
Javier Hernández-Gil1, Marta Braga2, Bethany I Harriss1
1Department of Chemistry , Imperial College London , UK . Email: j.hernandez-gil@imperial.ac.uk ;
Abstract:
Microbubble (MB) contrast agents have revolutionalised the way ultrasound (US) imaging can be used clinically and pre-clinically. Contrast-enhanced US offers improvements in soft-tissue contrast, as well as the ability to visualise disease processes at the molecular level. However, its inability to provide in vivo whole-body imaging can hamper the development of new MB formulations. Herein, we describe a fast and efficient method for achieving 68Ga-labelling of MBs after a direct comparison of two different strategies. The optimised approach produces 68Ga-labelled MBs in good yields through the bioorthogonal inverse-electron-demand Diel-Alder reaction between a trans-cyclooctene-modified phospholipid and a new tetrazine-bearing HBED-CC chelator. The ability to noninvasively study the whole-body distribution of 68Ga-labelled MBs was demonstrated in vivo using positron emission tomography (PET). This method could be broadly applicable to other phospholipid-based formulations, providing accessible solutions for in vivo tracking of MBs.
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