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 |
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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. |
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ISSN: | 1618-2642 1618-2650 |
DOI: | 10.1007/s00216-019-02218-x |