Steam‐Sterilizable, Fluorescence Lifetime‐Based Sensing Film for Dissolved Carbon Dioxide

Abstract

An autoclavable sensing film was developed for monitoring dissolved CO2. The sensing film, based on fluorescence resonance energy transfer (FRET), consisted of a fluorescent donor, an acceptor, and a quaternary ammonium hydroxide, which were doped in a two-component silicone film. As no aqueous solution was used in the sensing film matrix, the sensing film was unaffected by osmotic pressure. Fluorescence lifetime was selected as the sensing parameter, and measured in frequency domain using phase fluorometry. Upon exposure to 20% CO2-saturated water, a 43 degrees increase in phase angle was observed at 100 MHz. The process was fully reversible when the sensing film was exposed to nitrogen-saturated water. The estimated response and recovery times for 90% signal change were 1 min (for a step change from 0 to 6.7% CO2-saturated water) and 1.5 min (for a step change from 6.7 to 3.3% CO2-saturated water). When used for on-line monitoring of dissolved CO2 produced by a culture of Escherichia coli, the sensing film showed a similar trend to that obtained from off-line measurements using a wet chemistry analyzer.

Monitoring and Controlling the Dissolved Oxygen (DO) Concentration within the High Aspect Ratio Vessel (HARV)

“…The reason for the observed loss of signal may be the effect of additional curing of the polymer support matrix that increases its opacity. These results are consistent with previous findings demonstrating that fluorescent-based dissolved gas sensors can be autoclaved (6,10). should be linear for dynamic quenching in a homogeneous matrix.…”

Fluorescent Carbon Dioxide Indicators

“…The rather elegant work of Chang et al 50 appears to lend support to this proposal, in their study of steam sterilisable fluorescence lifetime-based sensing films for carbon dioxide. Thus, by comparing films containing the same quantity but different quaternary ammonium hydroxides, these workers found that the order of sensor film stability (with number of β-hydrogens in parenthesis) was: TOAH (8) < CTAH (2) < TMAH (0).…”

“…A number of studies, carried out using dry and wet luminescent optical sensors for carbon dioxide, have illustrated the efficacy of these indicators for the detection and measurement of carbon dioxide in: blood 24 , food packages 69 , bioreactors 26,50 and seawater 30 . However, despite this success and promise, these sensors have been slow to take off as commercial products and the detection and analysis of carbon dioxide is still dominated by the Severinghaus electrode (dissolved work) and infrared spectroscopy (gaseous work).…”

Real‐time monitoring of shake flask fermentation and off gas using triple disposable noninvasive optical sensors

“…With the invention of disposable noninvasive sensors, this situation might be changed quickly in the future. The disposable noninvasive sensors for pH, DO, and CO 2 used in this study were developed by the authors' laboratory 10–20. All patches share a similar multilayer structure with a sensitive dye immobilized in the responsive layer of the sensing patch.…”