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Aref M, Ranjbari E, García-Guzmán JJ, Hu K, Lork A, Crespo GA, Ewing AG, Cuartero M. Potentiometric pH Nanosensor for Intracellular Measurements: Real-Time and Continuous Assessment of Local Gradients. Anal Chem 2021; 93:15744-15751. [PMID: 34783529 PMCID: PMC8637545 DOI: 10.1021/acs.analchem.1c03874] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
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We present a pH nanosensor
conceived for single intracellular measurements.
The sensing architecture consisted of a two-electrode system evaluated
in the potentiometric mode. We used solid-contact carbon nanopipette
electrodes tailored to produce both the indicator (pH nanosensor)
and reference electrodes. The indicator electrode was a membrane-based
ion-selective electrode containing a receptor for hydrogen ions that
provided a favorable selectivity for intracellular measurements. The
analytical features of the pH nanosensor revealed a Nernstian response
(slope of −59.5 mV/pH unit) with appropriate repeatability
and reproducibility (variation coefficients of <2% for the calibration
parameters), a fast response time (<5 s), adequate medium-term
drift (0.7 mV h–1), and a linear range of response
including physiological and abnormal cell pH levels (6.0–8.5).
In addition, the position and configuration of the reference electrode
were investigated in cell-based experiments to provide unbiased pH
measurements, in which both the indicator and reference electrodes
were located inside the same cell, each of them inside two neighboring
cells, or the indicator electrode inside the cell and the reference
electrode outside of (but nearby) the studied cell. Finally, the pH
nanosensor was applied to two cases: (i) the tracing of the pH gradient
from extra-to intracellular media over insertion into a single PC12
cell and (ii) the monitoring of variations in intracellular pH in
response to exogenous administration of pharmaceuticals. It is anticipated
that the developed pH nanosensor, which is a label-free analytical
tool, has high potential to aid in the investigation of pathological
states that manifest in cell pH misregulation, with no restriction
in the type of targeted cells.
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Affiliation(s)
- Mohaddeseh Aref
- Department of Chemistry, School of Engineering Science in Chemistry, Biochemistry and Health, Royal Institute of Technology, KTH, Stockholm SE-100 44, Sweden
| | - Elias Ranjbari
- Department of Chemistry and Molecular Biology, University of Gothenburg, Kemivägen 10, Gothenburg 41296, Sweden
| | - Juan José García-Guzmán
- Department of Chemistry, School of Engineering Science in Chemistry, Biochemistry and Health, Royal Institute of Technology, KTH, Stockholm SE-100 44, Sweden
| | - Keke Hu
- Department of Chemistry and Molecular Biology, University of Gothenburg, Kemivägen 10, Gothenburg 41296, Sweden
| | - Alicia Lork
- Department of Chemistry and Molecular Biology, University of Gothenburg, Kemivägen 10, Gothenburg 41296, Sweden
| | - Gaston A Crespo
- Department of Chemistry, School of Engineering Science in Chemistry, Biochemistry and Health, Royal Institute of Technology, KTH, Stockholm SE-100 44, Sweden
| | - Andrew G Ewing
- Department of Chemistry and Molecular Biology, University of Gothenburg, Kemivägen 10, Gothenburg 41296, Sweden
| | - Maria Cuartero
- Department of Chemistry, School of Engineering Science in Chemistry, Biochemistry and Health, Royal Institute of Technology, KTH, Stockholm SE-100 44, Sweden
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