Accessing Self-Illuminated, Luminescent Lanthanide Probes by Enzymatic Radiophosphorylation

Area of Science:

• Inorganic Chemistry
• Bioconjugation Chemistry
• Radiochemistry

Background:

• Lanthanide complexes offer unique luminescent properties for imaging.
• Developing highly sensitive probes for biological applications remains a challenge.
• Enzymatic radiophosphorylation provides a pathway for novel probe synthesis.

Purpose of the Study:

• To design and synthesize Tb3+ and Eu3+ complexes for dual-mode imaging.
• To develop a metallacyclized peptide structure with a dual turn-on luminescence effect.
• To achieve high sensitivity and selectivity in optical imaging.

Main Methods:

• Synthesis of Tb3+ and Eu3+ complexes appended to kinase-substrate peptides.
• Optimization of macrocycle coordination for phosphate binding.
• Enzymatic phosphorylation using 32P and PKCα kinase.
• Characterization using NMR spectroscopy and Molecular Dynamics (MD) simulations.
• Optical imaging experiments to assess probe sensitivity.

Main Results:

• Developed an 8-coordinate tricazamacrocycle ideal for selective phosphate binding.
• Achieved a 15% selective turn-on luminescence response upon phosphate binding.
• Demonstrated successful enzymatic incorporation of 32P with 95% radiochemical yield.
• Attained the highest probe sensitivity reported to date for lanthanide probes in optical imaging.
• Showcased 0.2 nmol Tb3+ complex detection with 10 μCi 32P.

Conclusions:

• Enzymatic radiophosphorylation is a viable strategy for synthesizing self-illuminated lanthanide complexes.
• The developed probes exhibit exceptional sensitivity for optical imaging.
• This approach enables the creation of advanced metallacyclized peptide structures for bioimaging.