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

Abstract

Visualization and quantification of analytes such as O 2 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 O 2 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 O 2 -sensitive europium complex (Eu(HPhN) 3 dpp) with a dynamic range of 0−20% O 2 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 (Bu 3 Coum) 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 as algal biofilms. The sensor was tested in a marine photosynthetic microbial mat.

Oxygen Sensing Difluoroboron β-Diketonate Polylactide Materials with Tunable Dynamic Ranges for Wound Imaging

“…This may be due to interfering fluorescence intensity, as discussed above for F/P calibration and previously, for RGB curves. 45 This limitation is addressed with I-NPs , with very strong RTP versus F. Like hydrogen and bromide analogues, iodo nanoparticles show different total emission colors when purged with also gases ranging from 0–100% oxygen (Figure 3, left). And we will show below for wound imaging, I-NPs are ideal for ratiometric camera imaging.…”

A Fluorescence Intensity Ratiometric Fiber Optics–Based Chemical Sensor for Monitoring pH

“…Only some of these dyes have since been used to make optical sensors, and the reports of optical sensors have for a long period been dominated by fluorescein and hydroxypyrene . Recently, boron‐dipyromethene has been used to make sensors . Optodes with acceptable sensor performance have been achieved by immobilizing the dyes in sol–gels[11c,12b] and hydrogels.…”

“…Optodes with acceptable sensor performance have been achieved by immobilizing the dyes in sol–gels[11c,12b] and hydrogels. [11b,13a] But generally, they have been shown to leak dyes to the surrounding solution. As fluorescein dyes have poor photostability, they suffer from drift and a limited number of possible reads.…”

Luminescence Lifetime Imaging of O₂ with a Frequency-Domain-Based Camera System

“…The distribution and dynamics of dissolved gases and ions in sediments and soils provide key information on biogeochemical processes such as microbial respiration 1,2 , or radial oxygen loss from plant roots 3,4,5 , and the chemical microenvironment of microbes 6,7 , plant rhizospheres 5,8,9 and animal burrows 10,11,12 . Biological and chemical activity in such diffusion-limited environments can create steep gradients of chemical substrates or products of biogeochemical processes.…”

“…We would like to emphasize that this method is by no means limited to this application. Oxygen-sensitive optodes or sensor particles 27 in combination with various imaging methods have been used in medical research 32 , in bioprinting 33 , for pressure sensitive paints 34,35 , or to study photosynthetic systems 2,36,37 , just to name a few other fields of application.…”