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Dynamic behaviour of the silica-water-bio electrical double layer in the presence of a divalent electrolyte

Dynamic behaviour of the silica-water-bio electrical double layer in the presence of a divalent electrolyte
Dynamic behaviour of the silica-water-bio electrical double layer in the presence of a divalent electrolyte
Electronic devices are becoming increasingly used in chemical- and bio-sensing applications and therefore understanding the silica-electrolyte interface at the atomic scale is becoming increasingly important. For example, field-effect biosensors (BioFETs) operate by measuring perturbations in the electric field produced by the electrical double layer due to biomolecules binding on the surface. In this paper, explicit-solvent atomistic calculations of this electric field are presented and the structure and dynamics of the interface are investigated in different ionic strengths using molecular dynamics simulations. Novel results from simulation of the addition of DNA molecules and divalent ions are also presented, the latter of particular importance in both physiological solutions and biosensing experiments. The simulations demonstrated evidence of charge inversion, which is known to occur experimentally for divalent electrolyte systems. A strong interaction between ions and DNA phosphate groups was demonstrated in mixed electrolyte solutions, which are relevant to experimental observations of device sensitivity in the literature. The bound DNA resulted in local changes to the electric field at the surface; however, the spatial- and temporal-mean electric field showed no significant change. This result is explained by strong screening resulting from a combination of strongly polarised water and a compact layer of counterions around the DNA and silica surface. This work suggests that the saturation of the Stern layer is an important factor in determining BioFET response to increased salt concentration and provides novel insight into the interplay between ions and the electrical double layer.
1463-9076
2687-2701
Lowe, B. M.
69b560bf-d230-4b2a-b103-8e2b485c58a7
Maekawa, Y.
7691a2a6-4c4a-4cc0-8b34-319c116bc50b
Shibuta, Y.
33a766b2-ad0e-431a-8adc-ccebdccb6906
Sakata, T.
38e0a362-05f8-4ee9-b132-0cb1dbc2a407
Skylaris, C.-K.
8f593d13-3ace-4558-ba08-04e48211af61
Green, N. G.
d9b47269-c426-41fd-a41d-5f4579faa581
Lowe, B. M.
69b560bf-d230-4b2a-b103-8e2b485c58a7
Maekawa, Y.
7691a2a6-4c4a-4cc0-8b34-319c116bc50b
Shibuta, Y.
33a766b2-ad0e-431a-8adc-ccebdccb6906
Sakata, T.
38e0a362-05f8-4ee9-b132-0cb1dbc2a407
Skylaris, C.-K.
8f593d13-3ace-4558-ba08-04e48211af61
Green, N. G.
d9b47269-c426-41fd-a41d-5f4579faa581

Lowe, B. M., Maekawa, Y., Shibuta, Y., Sakata, T., Skylaris, C.-K. and Green, N. G. (2017) Dynamic behaviour of the silica-water-bio electrical double layer in the presence of a divalent electrolyte. Physical Chemistry Chemical Physics, 19 (4), 2687-2701. (doi:10.1039/C6CP04101A).

Record type: Article

Abstract

Electronic devices are becoming increasingly used in chemical- and bio-sensing applications and therefore understanding the silica-electrolyte interface at the atomic scale is becoming increasingly important. For example, field-effect biosensors (BioFETs) operate by measuring perturbations in the electric field produced by the electrical double layer due to biomolecules binding on the surface. In this paper, explicit-solvent atomistic calculations of this electric field are presented and the structure and dynamics of the interface are investigated in different ionic strengths using molecular dynamics simulations. Novel results from simulation of the addition of DNA molecules and divalent ions are also presented, the latter of particular importance in both physiological solutions and biosensing experiments. The simulations demonstrated evidence of charge inversion, which is known to occur experimentally for divalent electrolyte systems. A strong interaction between ions and DNA phosphate groups was demonstrated in mixed electrolyte solutions, which are relevant to experimental observations of device sensitivity in the literature. The bound DNA resulted in local changes to the electric field at the surface; however, the spatial- and temporal-mean electric field showed no significant change. This result is explained by strong screening resulting from a combination of strongly polarised water and a compact layer of counterions around the DNA and silica surface. This work suggests that the saturation of the Stern layer is an important factor in determining BioFET response to increased salt concentration and provides novel insight into the interplay between ions and the electrical double layer.

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More information

Accepted/In Press date: 18 October 2016
e-pub ahead of print date: 19 October 2016
Published date: 28 January 2017
Organisations: Nanoelectronics and Nanotechnology

Identifiers

Local EPrints ID: 401017
URI: http://eprints.soton.ac.uk/id/eprint/401017
ISSN: 1463-9076
PURE UUID: ecf48a44-2e72-4de1-a6fa-1a971fa33419
ORCID for C.-K. Skylaris: ORCID iD orcid.org/0000-0003-0258-3433
ORCID for N. G. Green: ORCID iD orcid.org/0000-0001-9230-4455

Catalogue record

Date deposited: 30 Nov 2016 10:01
Last modified: 15 Mar 2024 05:56

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Contributors

Author: B. M. Lowe
Author: Y. Maekawa
Author: Y. Shibuta
Author: T. Sakata
Author: C.-K. Skylaris ORCID iD
Author: N. G. Green ORCID iD

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