Inkjet-printed pH-independent paper-based calcium sensor with fluorescence signal readout relying on a solvatochromic dye

A challenge for paper-based cation sensors relying on classical carrier-based ion-selective optodes (ISOs) is their pH-cross response caused by the use of H + -sensitive chromoionophores as optical signal transducers. This work demonstrates fully pH-independent fluorescence-based calcium detection w...

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Veröffentlicht in:Analytical and bioanalytical chemistry 2020-05, Vol.412 (14), p.3489-3497
Hauptverfasser: Shibata, Hiroyuki, Ikeda, Yuma, Hiruta, Yuki, Citterio, Daniel
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Sprache:eng
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Zusammenfassung:A challenge for paper-based cation sensors relying on classical carrier-based ion-selective optodes (ISOs) is their pH-cross response caused by the use of H + -sensitive chromoionophores as optical signal transducers. This work demonstrates fully pH-independent fluorescence-based calcium detection with a paper-based plasticizer-free ISO. To achieve a pH-independent assay, a solvatochromic dye (SD) instead of a traditional H + -sensitive chromoionophore has been applied to the paper-based ISO by means of inkjet printing technology. The detection principle depends on an ionophore-driven phase-transfer ion-exchange reaction between target cations and the positively charged SD, which no longer involves H + in the optical signal transduction process. The developed paper-based ISOs with the SD resulted in Ca 2+ concentration-dependent response curves not affected by the sample pH (pH 6.0, 7.0, and 8.0). The dynamic range obtained for Ca 2+ detection was from 10 −5 to 1 mol L −1 with a detection limit of 19.3 μmol L −1 . Additionally, excellent selectivity derived from the used ionophore has been confirmed. As a simple practical application, the determination of Ca 2+ in mineral water has been achieved without the pH-buffering process required for conventional cation-exchange ISOs.
ISSN:1618-2642
1618-2650
DOI:10.1007/s00216-019-02218-x