title: Fiber-optic pH detection in small volumes of biosamples.
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.
authors.affiliation: Institute of Photonics and Electronics ASCR, v.v.i., Chaberska 57, 182 51 Prague 8, Czech Republic. kasik@ufe.cz
authors.forename: I
authors.initials: I
authors.lastname: Kasik
authors.forename: J
authors.initials: J
authors.lastname: Mrazek
authors.forename: T
authors.initials: T
authors.lastname: Martan
authors.forename: M
authors.initials: M
authors.lastname: Pospisilova
authors.forename: O
authors.initials: O
authors.lastname: Podrazky
authors.forename: V
authors.initials: V
authors.lastname: Matejec
authors.forename: K
authors.initials: K
authors.lastname: Hoyerova
authors.forename: M
authors.initials: M
authors.lastname: Kaminek
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D048429:Cell Size; D005336:Fiber Optic Technology / Q000379:methods*; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D052584:Xylem / Q000737:chemistry
chemical_list: D005456:Fluorescent Dyes