Structural Engineering of Fluorescent Self-Threaded Peptide Probes for Targeted Cell Imaging

Area of Science:

• Biochemistry
• Molecular Biology
• Biotechnology

Background:

• Squaraine figure-eight (SF8) molecules represent a novel class of deep-red fluorescent probes.
• These probes exhibit high fluorescence brightness and excellent photostability, making them suitable for fluorescence microscopy.

Purpose of the Study:

• To synthesize and evaluate homologous SF8 probes with varying peptidyl loops for cancer cell uptake.
• To investigate the role of specific targeting motifs, such as the RGD peptide, in probe cellular internalization.

Main Methods:

• Synthesis of three homologous SF8 probes with minor peptide sequence modifications.
• Assessment of probe uptake in cancer cells using fluorescence microscopy.
• Investigation of cellular internalization mechanisms, including receptor-mediated endocytosis.

Main Results:

• One SF8 probe functionalized with the RGD motif demonstrated significant cellular uptake.
• This RGD-targeted probe permeated cancer cells via receptor-mediated endocytosis.
• Two homologous SF8 probes without the RGD motif showed negligible cellular uptake, indicating limited targeting capability.

Conclusions:

• Peptidyl modifications, particularly the inclusion of targeting motifs like RGD, are critical for SF8 probe cellular uptake in cancer cells.
• The synthetic strategy allows for facile modification of peptide sequences, enabling the development of targeted SF8 probes for specific cancer biomarkers.
• SF8 probes hold potential as advanced tools for cancer cell imaging and diagnostics.