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- Title
Inkjet-printed pH-independent paper-based calcium sensor with fluorescence signal readout relying on a solvatochromic dye.
- Authors
Shibata, Hiroyuki; Ikeda, Yuma; Hiruta, Yuki; Citterio, Daniel
- Abstract
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 Ca2+ concentration-dependent response curves not affected by the sample pH (pH 6.0, 7.0, and 8.0). The dynamic range obtained for Ca2+ 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 Ca2+ in mineral water has been achieved without the pH-buffering process required for conventional cation-exchange ISOs.
- Subjects
INTERNATIONAL Organization for Standardization; OPTICAL transducers; FLUORESCENCE; CALCIUM; MINERAL waters; DETECTORS; PHOTOMULTIPLIERS
- Publication
Analytical & Bioanalytical Chemistry, 2020, Vol 412, Issue 14, p3489
- ISSN
1618-2642
- Publication type
Article
- DOI
10.1007/s00216-019-02218-x