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Fiber-optic pH Detection in Small Volumes of Biosamples

Fiber-optic pH Detection in Small Volumes of Biosamples

I Kasik, J Mrazek, T Martan, M Pospisilova, O Podrazky, V Matejec, K Hoyerova, M Kaminek

Anal Bioanal Chem. 2010 Nov;398(5):1883-9.

PMID: 20835818

Abstract:

Determining the pH values of microscopic plant samples may help to explain complex processes in plants, so it is an area of interest to botanists. Fiber-optic probes with small dimensions can be used for this purpose. This paper deals with the fiber-optic detection of the pH values of droplets of plant xylem exudate based on ratiometric fluorescence intensity measurements with an internal reference. For this purpose, novel V-taper sensing probes with a minimum diameter of around 8 μm were prepared that enable the delivery of fluorescence signal from the detection site on the taper tip to the detector. The taper tips were coated with pH-sensitive transducer (8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt; HPTS) and a reference [dichlorotris-(1,10-phenanthroline) ruthenium (II) hydrate (Ru-phen dichloride)] immobilized in a xerogel layer of propyltriethoxysilane and (3-glycidoxy)propyl trimethoxysilane. The prepared probes were sensitive to pH values mainly in the range from 6.0 to 9.0. In the pH range 6-9, the results were limited by measurement errors of about 0.2 pH units, and in the pH range 5-6 by measurement errors of about 0.5 pH units. Using the developed V-taper sensing probes, the pH values of in vivo and in vitro samples of small volumes (~6 μl) of exudate were measured. The results were validated by comparison with conventional electrochemical pH measurements.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP207802457	Dichlorotris(1,10-phenanthroline)ruthenium(II) hydrate		207802-45-7	Price

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