Precise molecular spacer engineering for tumor-responsive pK_a tuning: a pan-cancer imaging platform for evaluating...

Area of Science:

• Chemical Biology
• Molecular Imaging
• Biomedical Engineering

Background:

• Precise pK_a regulation of pH-sensing probes is crucial for accurate tumor visualization but remains challenging.
• Existing molecular engineering strategies primarily focus on the fluorophore, with limited long-distance regulation methods reported.

Purpose of the Study:

• To develop an innovative spacer-based strategy for precise pK_a regulation of pH-sensing probes.
• To demonstrate the probe's capability for pan-tumor visualization, metastasis detection, and drug screening.

Main Methods:

• Development of a spacer-based pK_a regulation strategy using a mesoamino-substituted sulfone-xanthene fluorophore.
• Density Functional Theory (DFT) calculations to elucidate the mechanism of pK_a modulation.
• In vivo validation using orthotopic tumor models, metastasis models, and fluorescence-based high-throughput screening.

Main Results:

• The spacer efficiently regulated pK_a values to 5.87, 5.37, and 3.73 with varying numbers of spacers.
• The optimized probe (J-S-BCF₃) accurately visualized tumor boundaries, microlymph node, and lung metastases.
• Reserpine identified as a V-ATPase inhibitor, and its effect on tumor microenvironment reprogramming was monitored.

Conclusions:

• The novel spacer design offers an effective long-distance regulation strategy for constructing high-performance fluorescent probes.
• This approach broadens the scope for developing probes with tailored properties for biomedical applications.
• The developed probe shows high potential for detecting multiple tumors and metastases, facilitating clinical translation.