A targeted fluorescent nanosensor for ratiometric pH sensing at the cell surface

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Cell Biology

Background:

• Altered extracellular pH (pH_e) is linked to diseases like cancer and inflammation.
• Current bulk pH measurements lack spatial resolution at the cell surface.
• Limited tools exist for high-resolution extracellular pH monitoring.

Purpose of the Study:

• To develop a versatile nanosensor for accurate extracellular pH measurement.
• To enable in-situ monitoring of pH at the cell surface.
• To provide a robust tool for biomedical research.

Main Methods:

• Fabrication of biocompatible polystyrene nanoparticles.
• Loading nanoparticles with pH-inert Nile red and pH-responsive fluorescein dyes.
• Surface functionalization with a cell-targeting moiety for membrane adhesion.

Main Results:

• The nanosensor provides sensitive ratiometric pH response (5.5-9.0) with a pKa of 7.47.
• Demonstrated cell membrane targeting and in-situ extracellular pH measurement.
• Exhibited robustness, reversibility, and biocompatibility for extended use.

Conclusions:

• The developed nanosensor enables precise, high-resolution extracellular pH measurement.
• It is well-suited for studying cellular microenvironments in health and disease.
• This technology has potential to advance research in cancer and metabolic disorders.