Subcellular distribution-based reference-free cancer cell discrimination with a novel AIE cationic probe

Area of Science:

• Biomedical Engineering
• Chemical Biology
• Molecular Imaging

Background:

• Conventional cancer cell discrimination relies on intensity-based fluorescent probes, which are prone to errors from environmental and probe concentration variations.
• Existing methods require reference controls, limiting their reliability and practical application in diagnostics.
• There is a critical need for intensity-independent analytical methods for robust cancer cell discrimination.

Purpose of the Study:

• To develop a novel fluorescent probe for reliable cancer cell discrimination.
• To establish a new analytical strategy that circumvents the limitations of intensity-based measurements.
• To create a reference-free modality for advancing cancer diagnostics.

Main Methods:

• Design and synthesis of TPC-CD, a cationic fluorescent probe with a D-π-A structure and Aggregation-Induced Emission (AIE) properties.
• Exploitation of differential membrane surface charge density between cancer and normal cells for probe targeting.
• Validation of the charge-dependent mechanism by altering membrane charge and observing probe internalization and subcellular localization.

Main Results:

• TPC-CD exhibits desirable photophysical properties including near-infrared emission and a large Stokes shift.
• The probe selectively binds to the negatively charged membranes of cancer cells, leading to accumulation on the cell surface.
• Normal cells, with less negative surface charge, readily internalize TPC-CD, resulting in diffuse cytoplasmic fluorescence, enabling clear visual discrimination.
• Subcellular distribution of TPC-CD directly correlates with the cell's surface charge state.

Conclusions:

• A novel subcellular distribution-based strategy provides robust, reference-free cancer cell discrimination, overcoming intensity-dependent errors.
• TPC-CD offers a powerful new tool for fluorescence imaging and analysis in cancer diagnostics.
• The study presents a new design principle for next-generation smart fluorescent probes.