Tailoring the DNA SAM surface density on different surface crystallographic features using potential assisted thiol exchange

Kaylyn K. Leung, Andrea Diaz Gaxiola, Hua Zhong Yu, Dan Bizzotto*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

10 Citations (Scopus)

Abstract

The influence of surface crystallography and applied potential on the thiol-exchange procedure to create mixed alkylthiol DNA SAMs is detailed. A single crystal gold bead and fluorophore labeled thiol modified DNA were used to characterize the resulting surface modifications. The thiol-exchange occurs with different efficiencies on the low index planes (111,100,110) as compared to 311 and 210. Positive applied potentials (>0/SCE) result in 10 × higher coverage than when compared to deposition at the open circuit potential (OCP) over the same 60 min time period. Negative potentials (<0/SCE) resulted in less uniform coverage with the 111 facet being significantly modified. The electrolyte used during the deposition was a 10 mM TRIS Buffer with 100 mM NaCl 500 mM MgCl2. The influence of [Cl] was studied showing it had a significant impact on the thiol-exchange at the positive potentials, where higher [Cl] resulted in higher DNA coverages and a more uniform coverage across the multi-crystalline surface. The local environment of the thiol-exchanged DNA SAMs were compared for different regions on the surface using potential driven DNA reorientation modulating the fluorescence intensity. These results showed a common behaviour from all surfaces suggesting that the DNA SAMs prepared by thiol-exchange were consistently prepared with a variable surface concentration controlled by potential and time.

Original languageEnglish
Pages (from-to)188-197
Number of pages10
JournalElectrochimica Acta
Volume261
DOIs
Publication statusPublished - 20 Jan 2018

Keywords

  • Electrodeposition
  • Fluorescence microscopy
  • Self-assembled monolayers
  • Surface crystallography
  • Thiol-exchange

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