Discrete lanthanide and transition metal complexes possess attractive properties for bioimaging and treatment, including emission within the optical window, wavelength-selective photoactivation, resistance to photobleaching processes complemented by high synthetic flexibility and modularity with respect to polarity, redox activity and targeting. However, the translation of these compounds beyond cell-based imaging is often hampered by the lack of tissue permeability of short wave light, which is required for the excitation of a majority of biologically interesting photoreactive coordination complexes. To overcome this limitation, our lab has established Cherenkov radiation energy transfer (CRET) from beta-particle emitting radioisotopes as an in situ excitation source for such coordination complexes. Following our initial proof of concept studies on discrete Tb and Eu luminescent complexes that show a limit of detection (LOD) of &gt;10 nmol in presence of 10 µCi <sup>18</sup>F, we will discuss recent and ongoing work in further reducing the LOD of lanthanide complexes, enhancing the sensitivity of lanthanide-based sensor probes and viability to expand the CRET concept to transition-metal complexes with biomedical relevance.

In situ excitation of metal complexes with Cherenkov radiation emitted by diagnostic PET isotopes - merging in vivo imaging, biosensing and therapy with innovative probe design

ACS Spring 2022

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