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

Ali, Mubarak and Ahmed, Ishtiaq and Ramirez, Patricio and Nasir, Saima and Cervera, Javier and Niemeyer, Christof M. and 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
[Article] , (2016)

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

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.

Item Type:	Article
Erschienen:	2016
Creators:	Ali, Mubarak and Ahmed, Ishtiaq and Ramirez, Patricio and Nasir, Saima and Cervera, Javier and Niemeyer, Christof M. and Ensinger, Wolfgang
Title:	Fluoride-induced modulation of ionic transport in asymmetric nanopores functionalized with “caged” fluorescein moieties
Language:	English
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.
Journal or Publication Title:	Nanoscale
Volume:	8
Number:	16
Publisher:	ROYAL SOC CHEMISTRY, CAMBRIDGE, ENGLAND
Divisions:	11 Department of Materials and Earth Sciences > Material Science > Material Analytics 11 Department of Materials and Earth Sciences > Material Science 11 Department of Materials and Earth Sciences
Date Deposited:	06 Jun 2016 12:07
Official URL:	http://dx.doi.org/10.1039/C6NR00292G
Identification Number:	doi:10.1039/C6NR00292G
Funders:	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.
Export:

Optionen (nur für Redakteure)

View Item