Fluoride-induced modulation of ionic transport in asymmetric nanopores functionalized with “caged” fluorescein moieties

Ali, Mubarak ; Ahmed, Ishtiaq ; Ramirez, Patricio ; Nasir, Saima ; Cervera, Javier ; Niemeyer, Christof M. ; Ensinger, Wolfgang :
Fluoride-induced modulation of ionic transport in asymmetric nanopores functionalized with “caged” fluorescein moieties.
[Online-Edition: http://dx.doi.org/10.1039/C6NR00292G]
In: Nanoscale, 8 (16) pp. 8583-8590. ISSN 2040-3364
[Artikel], (2016)

Offizielle URL: http://dx.doi.org/10.1039/C6NR00292G

Kurzbeschreibung (Abstract)

We demonstrate experimentally and theoretically a nanofluidic fluoride sensing device based on a single conical pore functionalized with "caged" fluorescein moieties. The nanopore functionalization is based on an amine-terminated fluorescein whose phenolic hydroxyl groups are protected with tert-butyldiphenylsilyl (TBDPS) moieties. The protected fluorescein (Fcn-TBDPS-NH2) molecules are then immobilized on the nanopore surface via carbodiimide coupling chemistry. Exposure to fluoride ions removes the uncharged TBDPS moieties due to the fluoride-promoted cleavage of the silicon-oxygen bond, leading to the generation of negatively charged groups on the fluorescein moieties immobilized onto the pore surface. The asymmetrical distribution of these groups along the conical nanopore leads to the electrical rectification observed in the current-voltage (I-V) curve. On the contrary, other halides and anions are not able to induce any significant ionic rectification in the asymmetric pore. In each case, the success of the chemical functionalization and deprotection reactions is monitored through the changes observed in the I-V curves before and after the specified reaction step. The theoretical results based on the Nernst-Planck and Poisson equations further demonstrate the validity of an experimental approach to fluoride-induced modulation of nanopore current rectification behaviour.

Typ des Eintrags:	Artikel
Erschienen:	2016
Autor(en):	Ali, Mubarak ; Ahmed, Ishtiaq ; Ramirez, Patricio ; Nasir, Saima ; Cervera, Javier ; Niemeyer, Christof M. ; Ensinger, Wolfgang
Titel:	Fluoride-induced modulation of ionic transport in asymmetric nanopores functionalized with “caged” fluorescein moieties
Sprache:	Englisch
Kurzbeschreibung (Abstract):	We demonstrate experimentally and theoretically a nanofluidic fluoride sensing device based on a single conical pore functionalized with "caged" fluorescein moieties. The nanopore functionalization is based on an amine-terminated fluorescein whose phenolic hydroxyl groups are protected with tert-butyldiphenylsilyl (TBDPS) moieties. The protected fluorescein (Fcn-TBDPS-NH2) molecules are then immobilized on the nanopore surface via carbodiimide coupling chemistry. Exposure to fluoride ions removes the uncharged TBDPS moieties due to the fluoride-promoted cleavage of the silicon-oxygen bond, leading to the generation of negatively charged groups on the fluorescein moieties immobilized onto the pore surface. The asymmetrical distribution of these groups along the conical nanopore leads to the electrical rectification observed in the current-voltage (I-V) curve. On the contrary, other halides and anions are not able to induce any significant ionic rectification in the asymmetric pore. In each case, the success of the chemical functionalization and deprotection reactions is monitored through the changes observed in the I-V curves before and after the specified reaction step. The theoretical results based on the Nernst-Planck and Poisson equations further demonstrate the validity of an experimental approach to fluoride-induced modulation of nanopore current rectification behaviour.
Titel der Zeitschrift, Zeitung oder Schriftenreihe:	Nanoscale
Band:	8
(Heft-)Nummer:	16
Verlag:	ROYAL SOC CHEMISTRY, CAMBRIDGE, ENGLAND
Fachbereich(e)/-gebiet(e):	11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Materialanalytik 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft 11 Fachbereich Material- und Geowissenschaften
Hinterlegungsdatum:	06 Jun 2016 12:07
Offizielle URL:	http://dx.doi.org/10.1039/C6NR00292G
ID-Nummer:	10.1039/C6NR00292G
Sponsoren:	M. A., S. N. and W. E. acknowledge the funding from the Hessen State Ministry of Higher Education, Research and the Arts, Germany, under the LOEWE project iNAPO., P. R. and J. C. acknowledge financial support by the Generalitat Valenciana (Program of Excellence Prometeo/GV/0069), the Spanish Ministry of Economic Affairs and Competitiveness (MAT2015-65011-P), and FEDER., I. A. and C. M. N. acknowledge the financial support through the Helmholtz programme BioInterfaces in Technology and Medicine.
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