Multivalent Fluorinated Nanorings for On-Cell ¹⁹F NMR

Area of Science:

• Molecular Imaging
• Bioconjugation Chemistry
• Nuclear Magnetic Resonance

Background:

• ¹⁹F Magnetic Resonance Imaging (MRI) faces sensitivity challenges.
• Chemically self-assembled nanorings (CSANs) offer a strategy to increase fluorine content via multivalent display.
• Previous monomeric constructs showed limited cell-based ¹⁹F NMR signals.

Purpose of the Study:

• To design and evaluate novel fluorinated imaging agents for improved ¹⁹F MRI.
• To enhance fluorine content and cellular signal amplification using multivalent CSANs.
• To assess the affinity and specificity of new constructs for EGFR-overexpressing cells.

Main Methods:

• Design and synthesis of new E₁-DD proteins bioconjugated to fluorinated peptides.
• Flow cytometry for assessing cellular binding characteristics.
• ¹⁹F NMR spectroscopy for evaluating spectral performance in cell-based assays.

Main Results:

• Structure-optimized protein RTC-3 demonstrated high affinity and specificity for EGFR-overexpressing cells.
• Engineered monomeric RTC-3 into multivalent CSAN, η-RTC-3, increasing fluorine content eightfold.
• η-RTC-3 achieved significant signal amplification in the first cell-based ¹⁹F NMR spectra.

Conclusions:

• Multivalent fluorinated CSANs represent a promising strategy for advancing ¹⁹F MRI molecular imaging.
• The η-RTC-3 construct shows potential for sensitive and specific detection of EGFR-expressing cells.
• This design overcomes limitations of monomeric constructs, enabling robust cell-based ¹⁹F NMR detection.