FRET-Based Semiconducting Polymer Dots for pH Sensing.

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Förster resonance energy transfer (FRET)-based polymer dots (Pdots) are promising but underutilized for pH sensing.
• Semiconducting polymers offer excellent properties for Pdot fabrication.
• Systematic exploitation of Pdot-based pH sensors remains limited.

Purpose of the Study:

• To construct and characterize FRET-based blend polymer dots for sensitive pH detection.
• To investigate the influence of pH on Pdot fluorescence properties and energy transfer efficiency.
• To explore the potential applications of these Pdots in various sensing scenarios.

Main Methods:

• Fabrication of blend polymer dots using specific donor (PFV) and acceptor (BDMO-PPV) semiconducting polymers, and surface functionalization with PS-PEG-COOH for carboxyl groups.
• Utilizing the Förster resonance energy transfer (FRET) process within the Pdots for sensing.
• Analyzing changes in fluorescence spectra, intensity, and fluorescence lifetime in response to varying pH levels, particularly in acidic conditions.

Main Results:

• The developed Pdots exhibit high sensitivity to pH changes, especially in low pH environments (pH 1-2).
• Decreasing pH leads to simultaneous spectral and intensity changes, alongside alterations in fluorescence lifetime.
• Observed spectral changes include sharpening of the ~524 nm emission peak and weakening/blue shifts of the ~573 nm band, indicating reduced FRET efficiency due to polymer chain conformational changes.
• Time-resolved fluorescence measurements confirm the suggested FRET efficiency decrease.

Conclusions:

• The constructed FRET-based blend Pdots are effective and sensitive pH sensors, particularly for acidic conditions.
• The observed fluorescence property changes are linked to pH-induced polymer chain conformational alterations affecting FRET efficiency.
• These Pdots hold significant potential for applications in industrial wastewater monitoring, in vitro/intracellular pH measurements, and DNA detection.