Highly Stable Core-Shell Structured Semiconducting Polymer Nanoparticles for FRET-Based Intracellular pH Imaging

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Traditional semiconducting polymer nanoparticles (SPNs) often suffer from photobleaching and material leakage, limiting their use in biological sensing.
• Fluorescence resonance energy transfer (FRET) systems using small molecules face challenges with quenching interference and stability.

Purpose of the Study:

• To develop highly stable semiconducting polymer nanoparticles (SPNs) with a novel core-shell structure for ratiometric sensing of intracellular pH.
• To overcome the limitations of existing SPN-based FRET systems by enhancing stability and minimizing interference.

Main Methods:

• Fabrication of poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) core and poly(fluorene-2,7-ylenevinylene-co-phenylene) (PFV)-dopamine (DA) shell SPNs.
• Characterization of the core-shell structure and optical properties of the PFO/PFV-DA NPs.
• Evaluation of the NPs' stability, pH sensitivity, and ratiometric imaging capabilities in aqueous media and live cells.

Main Results:

• Developed highly stable PFO/PFV-DA NPs with a unique core-shell architecture, spatially separating donor (PFO) and acceptor (PFV).
• Achieved minimized quenching interference and maximized pH sensitivity due to the thick PFV shell.
• Demonstrated quantitative, ratiometric response to pH changes and successful intracellular pH mapping via ratiometric imaging.

Conclusions:

• The novel core-shell SPNs provide enhanced structural and optical stability, addressing photobleaching and leakage issues.
• This PFO/PFV-DA NP platform enables highly sensitive and quantitative intracellular pH sensing.
• The developed ratiometric emission intensity strategy offers a generalizable approach for sensitive biological sensing using core-shell SPNs.