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Accessing Structurally Diverse Near-Infrared Cyanine Dyes for Folate Receptor-Targeted Cancer Cell Staining
Sandra G König1, Roland Krämer1
1Institute of Inorganic Chemistry, Heidelberg University, Im Neuenheimer Feld 274, 69120, Heidelberg, Germany.
Abstract:
Folate receptor (FR) targeting is one of the most promising strategies for the development of small-molecule-based cancer imaging agents considering that the FR is highly overexpressed on the surface of many cancer cell types. FR-targeted conjugates of near-infrared (NIR) emissive cyanine dyes are in advanced clinical trials for fluorescence-guided surgery and are valuable research tools for optical molecular imaging in animal models. Only a small number of promising conjugates has been evaluated so far. Analysis of structure-performance relations to identify critical factors modulating the performance of targeted conjugates is essential for successful further optimization. This contribution addresses the need for convenient synthetic access to structurally diverse NIR-emissive cyanine dyes for conjugation with folic acid. Structural variations were introduced to readily available cyanine precursors in particular via C-C-coupling reactions including Suzuki and (for the first time with these types of dyes) Sonogashira cross-couplings. Photophysical properties such as absorbance maxima, brightness, and photostability are highly dependent on the molecular structure. Selected modified cyanines were conjugated to folic acid for cancer cell targeting. Several conjugates display a favorable combination of high fluorescence brightness and photostability with high affinity to FR-positive cancer cells, and enable the selective imaging of these cells with low background.
Insights
Researchers developed novel near-infrared cyanine dyes for folate receptor (FR) targeted cancer imaging. These dyes show high brightness and photostability, enabling selective imaging of FR-positive cancer cells.
Area of Science:
- * Chemical biology
- * Molecular imaging
- * Cancer diagnostics
Background:
- * Folate receptor (FR) is overexpressed on many cancer cells, making it a key target for cancer imaging agents.
- * Near-infrared (NIR) cyanine dye conjugates targeting FR are valuable for fluorescence-guided surgery and molecular imaging.
- * Limited evaluation of FR-targeted conjugates necessitates structure-performance analysis for optimization.
Purpose of the Study:
- * To develop convenient synthetic routes for structurally diverse NIR-emissive cyanine dyes for folic acid conjugation.
- * To investigate the structure-performance relationships of these novel cyanine dyes.
- * To create effective FR-targeted imaging agents for cancer detection.
Main Methods:
- * Synthesis of structurally diverse NIR-emissive cyanine dyes using Suzuki and Sonogashira cross-coupling reactions.
- * Modification of cyanine precursors to alter photophysical properties.
- * Conjugation of selected cyanine dyes with folic acid.
- * Evaluation of FR-positive cancer cell targeting and imaging capabilities.
Main Results:
- * Successful synthesis of structurally varied NIR cyanine dyes with tunable photophysical properties.
- * Conjugates demonstrated high fluorescence brightness and photostability.
- * Several conjugates exhibited high affinity for FR-positive cancer cells.
- * Selective imaging of FR-positive cancer cells with low background was achieved.
Conclusions:
- * Novel NIR cyanine dyes offer a promising platform for FR-targeted cancer imaging.
- * Structural modifications significantly influence dye performance, enabling tailored agent development.
- * These conjugates facilitate precise and selective visualization of FR-positive tumors.
