O<sub>2</sub>-Sensitive Inks for Measuring Total (Aerobic) Viable Count Using Micro-Respirometry
The popular method of micro-respirometry (μR) for measuring total viable (aerobic) count (TVC) utilises luminescence-based O<sub>2</sub> sensors that are difficult to fabricate and therefore expensive. A simple method is described for making inexpensive, ink-based potential substitutes t...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-09-01
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| Series: | Chemosensors |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2227-9040/12/9/190 |
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| Summary: | The popular method of micro-respirometry (μR) for measuring total viable (aerobic) count (TVC) utilises luminescence-based O<sub>2</sub> sensors that are difficult to fabricate and therefore expensive. A simple method is described for making inexpensive, ink-based potential substitutes that utilise the same O<sub>2</sub>-sensitive dyes. The sensitivity of such inks is readily increased by using dyes with a long lifetime in the absence of O<sub>2</sub>, τ<sub>o</sub>, and/or an ink resin/polymer with a high O<sub>2</sub> permeability, P<sub>m</sub>(O<sub>2</sub>). Response modelling of the μR-based TVC system and subsequent testing using a range of O<sub>2</sub> sensors of different sensitivity show that there is little to be gained by making the O<sub>2</sub> sensor either very sensitive or insensitive, and that the best O<sub>2</sub> sensors are dyes such as Pt(II) tetraphenyltetrabenzoporphyrin (PtBP), with τ<sub>o</sub> = ca. 40–50 μs. Further work shows that a simple-to-make PtBP ink can be used as a direct replacement for the expensive O<sub>2</sub> sensor used in commercial instruments for measuring TVC based on μR. In addition, the PtBP can be replaced by an even less expensive O<sub>2</sub>-sensitive dye, Pt(II) meso-tetra(pentafluorophenyl)porphyrin (PtTFPP). The potential use of inexpensive O<sub>2</sub>-sensitive inks as an alternative to any expensive commercial counterpart based on the same O<sub>2</sub>-sensitive dye is discussed briefly. |
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| ISSN: | 2227-9040 |