Simplified Fabrication for Ion-Selective Optical Emulsion Sensor with Hydrophobic Solvatochromic Dye Transducer: A Cautionary Tale

Article Article scientifique Article Simplified Fabrication for Ion-Selective Optical Emulsion Sensor with Hydrophobic Solvatochromic Dye Transducer: A Cautionary Tale eng 2019 author Wang Lu 838433 author Sadler Stéphanie Deeka-Marie 892437 author Cao Tianchi 826543 author Xie Xiaojiang author Moser Von Filseck Joachim 831691 author Bakker Eric 716236 8973-8978 10.1021/acs.analchem.9b01145 0003-2700 https://pubs.acs.org/doi/10.1021/acs.analchem.9b01145 It has recently been reported that polystyrene microbeads may be modified to realize plasticizer-free ion-selective optical sensors (optodes) on the basis of solvatochromic dye transducers. We show here that the functionalized microbeads, individually isolated by flow cytometry, exhibit unexpectedly poor fluorescent properties and that the sensor response is instead attributed to the supernatant. A more thorough study reveals that such optical microemulsion sensors can be made operationally functional and chemically selective, seemingly in the absence of any solvent matrix or added surfactant. Instead, it is shown that residual THF used in the fabrication of the emulsified sensors may solubilize the sensing components and give a functional optode response. To evaluate this further, the number of sensing components was stepwise simplified to assess their need. Variation of residual THF levels has no effect on the ion optode response when plasticizer is present, in support of established results. Lipophilic solvatochromic dye transducers are also shown not to require an added surfactant as their nature already endows the emulsified sensors with a stabilizing ionic surface charge. The ionophores are shown to exhibit much larger stability constants in the surfactant-free formulations than surfactant-based ones (Valionomycin: log!>9.2 compared to 6.1; Na+-ionophore X: 6.7 vs. 4.7), which is attributed to a less polar solvent environment for the ionophore. Potassium, sodium and calcium-selective sensors were used as model systems in this study. Dewey 540 Swiss National Science Foundation Ion Recognition by Extraction and Thin Layer Electrochemistry 175622 CH Project funding 39 Département de biochimie 144 40 Département de chimie minérale, analytique et appliquée 145 false 772 Groupe Bakker 769 Groupe Roux Analytical chemistry 91 14 8c9f88bc-5bc4-489d-8e8c-fe434b62be95 Article (Accepted version) Public 10.1021acs.analchem.9b01145.pdf 3436851 application/pdf Restricted 2020-06-28 openAccess Faculté des sciences / Section de chimie et biochimie / Département de biochimie Faculté des sciences / Section de chimie et biochimie / Département de chimie minérale, analytique et appliquée

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Simplified Fabrication for Ion-Selective Optical Emulsion Sensor with Hydrophobic Solvatochromic Dye Transducer: A Cautionary Tale	Analytical chemistry			2019	389	149

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Sadler, Stéphanie Deeka-Marie