Design and Application of an Optical Sensor for Simultaneous Imaging of pH and Dissolved O2 with Low Cross-Talk

Visualization and quantification of analytes such as O2 or pH is essential in biological research. Here we present the design and application of a new optical dual-analyte sensor for imaging, optimized to have low cross-sensitivity between the two analytes O2 and pH. The used indicator and reference dyes were selected to match the different channels of a commercial 2CCD (RGB + NIR) camera. A red-light emitting O2-sensitive europium complex (Eu(HPhN)3dpp) with a dynamic range of 0–20% O2 in the finished sensor was combined with a near-infrared emitting pH indicator (OHButoxy-aza-BODIPY) with a dynamic range of pH 7.2–8.8. To enable ratiometric readout, an inert reference coumarin dye (Bu3Coum) was co-immobilized with the optical indicators. In order to maximize the sensor signal, inert diamond powder was added to one sensor layer as a simple way to increase scattering of light within the sensor. Furthermore, the addition of an optical isolation layer enabled measurements in highly fluorescent samples, such...