Single-chromophore-based ratiometric O₂ sensor for quantitative intracellular O₂ mapping.

Area of Science:

• Biomedical Engineering
• Chemical Biology
• Analytical Chemistry

Background:

• Accurate in-situ intracellular oxygen (O2) measurements are crucial for understanding O2-related physiology and pathology.
• Existing ratiometric luminescent O2 probes often use dual-chromophore systems, leading to large molecular size and photobleaching issues.

Purpose of the Study:

• To develop a novel, single-chromophore-based dual-emission probe for accurate intracellular O2 sensing.
• To overcome the limitations of traditional dual-chromophore O2 probes.

Main Methods:

• Synthesis and characterization of a single-chromophore Pt(II) complex, PtQTAC.
• Demonstration of simultaneous fluorescence and phosphorescence emission upon single excitation.
• Incorporation of PtQTAC into nanoparticles for cellular uptake and intracellular O2 detection using confocal microscopy.

Main Results:

• PtQTAC exhibits well-separated dual emission spectra with balanced intensities and a ratiometric response to O2 levels, fitting the Stern-Volmer equation.
• The nanoparticle-incorporated probe maintains O2 sensitivity and is readily internalized by cells.
• Precise mapping and quantification of intracellular O2 concentrations were achieved after calibration.

Conclusions:

• PtQTAC represents the first single-chromophore-based luminescent probe for intracellular O2 concentration quantification.
• This novel probe offers a simplified design, improved photostability, and accurate O2 sensing capabilities for biological studies.