Mapping O₂ concentration in ex-vivo tissue samples on a fast PLIM macro-imager

Area of Science:

• Biomedical Optics
• Microscopy Technology
• Oxygen Sensing

Background:

• Existing phosphorescence lifetime imaging microscopy (PLIM) platforms face challenges in sensitivity, speed, accuracy, and usability.
• Accurate oxygen (O2) mapping is crucial for understanding tissue metabolism and disease states.

Purpose of the Study:

• To develop and validate a new PLIM imager based on the Timepix3 camera (Tpx3cam) for enhanced O2 concentration imaging.
• To assess the performance of the new imager using a nanoparticle-based probe (NanO2-IR) in various ex vivo and in vivo animal tissue models.

Main Methods:

• Utilized a Timepix3 camera-based PLIM imager for O2 concentration mapping.
• Employed NanO2-IR probe for passive staining or microinjection into mouse brain, lung, and intestinal tissues.
• Evaluated O2 imaging at depths up to 0.5 mm following subcutaneous probe injection.

Main Results:

• Achieved robust phosphorescence signals for O2 mapping in tissues within 20 seconds.
• Demonstrated accurate O2 level changes with inhibited respiration or limited O2 diffusion.
• Quantified a significant O2 gradient (approx. 140 µM) between the colonic lumen and serosal surface.

Conclusions:

• The new Tpx3cam-based PLIM imager offers superior performance for O2 imaging compared to existing platforms.
• The system enables rapid and sensitive metabolic imaging in diverse ex vivo animal tissue models.
• The developed imager shows potential for future applications in live animal studies.