Chemistry of Cysteine Assembly on Au(100): Electrochemistry, in situ STM and Molecular Modeling

Christian Engelbrekt, Renat R. Nazmutdinov, Tamara Zinkicheva, Dmitrii Glukhov, Jiawei Yan, Bingwei Mao, Jens Ulstrup, Jingdong Zhang*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Cysteine (Cys) is an essential amino acid with a carboxylic acid, an amine and a thiol group. We have studied the surface structure and adsorption dynamics of L-cysteine adlayers on Au(100) from aqueous solution using electrochemistry, high-resolution electrochemical scanning tunnelling microscopy (in situ STM), and molecular modelling. Cys adsorption on this low-index Au-surface has been much less studied than Cys adsorption on Au(111)- and Au(110)-electrode surfaces. Chronopotentiometry was employed to monitor the adsorption dynamics at sub-second resolution and showed that adsorption is completed in 30 minutes at Cys concentrations above 100 μM. Two consecutive steps could be fitted to these data. Two separate reductive desorption peaks of Cys adlayers on Au(100) with a total coverage of 2.52 (±0.15) × 10-10 mol/cm2 were observed. In situ STM showed that adsorbed Cys is organized in stripes with “fork-like” features which co-exist in (11×2)-2Cys and (7×2)-2Cys lattices, quite differently from Cys adsorption on Au(111)-electrode surfaces. Stripe structures with bright STM contrast in the center suggest that a second Cys adlayer on top of a first adlayer is formed, supporting the dual-peak reductive desorption of Cys adlayers. In addition, monolayers of both pure L-Cys, pure D-Cys and a 1:1 racemic mixture of L- and D-Cys on Au(100) were studied. Virtually identical macroscopic electrochemical features were found, but in situ STM discloses many more defects for the racemic mixture than for the pure enantiomers due to structural mismatch of L- and D-Cys. Density functional theory (DFT) calculations combined with a cluster model for the Au(100) surface were carried out to investigate the adsorption energy and geometry of adsorbed monomer and dimer Cys species in different orientations, with detailed attention to the chirality effects. Optimized DFT geometries were used to construct model STM images, and kinetic Monte Carlo simulations undertaken to illuminate the growth of adsorbate rows and the mechanism of the adlayer formation as well as the Cys adsorption patterns specific to the Au(100)-electrode surface.
Original languageEnglish
JournalNanoscale
Volume11
Issue number37
Pages (from-to)17235-17251
Number of pages17
ISSN2040-3364
DOIs
Publication statusPublished - 2019

Cite this

Engelbrekt, Christian ; Nazmutdinov, Renat R. ; Zinkicheva, Tamara ; Glukhov, Dmitrii ; Yan, Jiawei ; Mao, Bingwei ; Ulstrup, Jens ; Zhang, Jingdong. / Chemistry of Cysteine Assembly on Au(100): Electrochemistry, in situ STM and Molecular Modeling. In: Nanoscale. 2019 ; Vol. 11, No. 37. pp. 17235-17251.
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title = "Chemistry of Cysteine Assembly on Au(100): Electrochemistry, in situ STM and Molecular Modeling",
abstract = "Cysteine (Cys) is an essential amino acid with a carboxylic acid, an amine and a thiol group. We have studied the surface structure and adsorption dynamics of L-cysteine adlayers on Au(100) from aqueous solution using electrochemistry, high-resolution electrochemical scanning tunnelling microscopy (in situ STM), and molecular modelling. Cys adsorption on this low-index Au-surface has been much less studied than Cys adsorption on Au(111)- and Au(110)-electrode surfaces. Chronopotentiometry was employed to monitor the adsorption dynamics at sub-second resolution and showed that adsorption is completed in 30 minutes at Cys concentrations above 100 μM. Two consecutive steps could be fitted to these data. Two separate reductive desorption peaks of Cys adlayers on Au(100) with a total coverage of 2.52 (±0.15) × 10-10 mol/cm2 were observed. In situ STM showed that adsorbed Cys is organized in stripes with “fork-like” features which co-exist in (11×2)-2Cys and (7×2)-2Cys lattices, quite differently from Cys adsorption on Au(111)-electrode surfaces. Stripe structures with bright STM contrast in the center suggest that a second Cys adlayer on top of a first adlayer is formed, supporting the dual-peak reductive desorption of Cys adlayers. In addition, monolayers of both pure L-Cys, pure D-Cys and a 1:1 racemic mixture of L- and D-Cys on Au(100) were studied. Virtually identical macroscopic electrochemical features were found, but in situ STM discloses many more defects for the racemic mixture than for the pure enantiomers due to structural mismatch of L- and D-Cys. Density functional theory (DFT) calculations combined with a cluster model for the Au(100) surface were carried out to investigate the adsorption energy and geometry of adsorbed monomer and dimer Cys species in different orientations, with detailed attention to the chirality effects. Optimized DFT geometries were used to construct model STM images, and kinetic Monte Carlo simulations undertaken to illuminate the growth of adsorbate rows and the mechanism of the adlayer formation as well as the Cys adsorption patterns specific to the Au(100)-electrode surface.",
author = "Christian Engelbrekt and Nazmutdinov, {Renat R.} and Tamara Zinkicheva and Dmitrii Glukhov and Jiawei Yan and Bingwei Mao and Jens Ulstrup and Jingdong Zhang",
year = "2019",
doi = "10.1039/C9NR02477H",
language = "English",
volume = "11",
pages = "17235--17251",
journal = "Nanoscale",
issn = "2040-3364",
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Chemistry of Cysteine Assembly on Au(100): Electrochemistry, in situ STM and Molecular Modeling. / Engelbrekt, Christian; Nazmutdinov, Renat R.; Zinkicheva, Tamara; Glukhov, Dmitrii; Yan, Jiawei; Mao, Bingwei; Ulstrup, Jens; Zhang, Jingdong.

In: Nanoscale, Vol. 11, No. 37, 2019, p. 17235-17251.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Chemistry of Cysteine Assembly on Au(100): Electrochemistry, in situ STM and Molecular Modeling

AU - Engelbrekt, Christian

AU - Nazmutdinov, Renat R.

AU - Zinkicheva, Tamara

AU - Glukhov, Dmitrii

AU - Yan, Jiawei

AU - Mao, Bingwei

AU - Ulstrup, Jens

AU - Zhang, Jingdong

PY - 2019

Y1 - 2019

N2 - Cysteine (Cys) is an essential amino acid with a carboxylic acid, an amine and a thiol group. We have studied the surface structure and adsorption dynamics of L-cysteine adlayers on Au(100) from aqueous solution using electrochemistry, high-resolution electrochemical scanning tunnelling microscopy (in situ STM), and molecular modelling. Cys adsorption on this low-index Au-surface has been much less studied than Cys adsorption on Au(111)- and Au(110)-electrode surfaces. Chronopotentiometry was employed to monitor the adsorption dynamics at sub-second resolution and showed that adsorption is completed in 30 minutes at Cys concentrations above 100 μM. Two consecutive steps could be fitted to these data. Two separate reductive desorption peaks of Cys adlayers on Au(100) with a total coverage of 2.52 (±0.15) × 10-10 mol/cm2 were observed. In situ STM showed that adsorbed Cys is organized in stripes with “fork-like” features which co-exist in (11×2)-2Cys and (7×2)-2Cys lattices, quite differently from Cys adsorption on Au(111)-electrode surfaces. Stripe structures with bright STM contrast in the center suggest that a second Cys adlayer on top of a first adlayer is formed, supporting the dual-peak reductive desorption of Cys adlayers. In addition, monolayers of both pure L-Cys, pure D-Cys and a 1:1 racemic mixture of L- and D-Cys on Au(100) were studied. Virtually identical macroscopic electrochemical features were found, but in situ STM discloses many more defects for the racemic mixture than for the pure enantiomers due to structural mismatch of L- and D-Cys. Density functional theory (DFT) calculations combined with a cluster model for the Au(100) surface were carried out to investigate the adsorption energy and geometry of adsorbed monomer and dimer Cys species in different orientations, with detailed attention to the chirality effects. Optimized DFT geometries were used to construct model STM images, and kinetic Monte Carlo simulations undertaken to illuminate the growth of adsorbate rows and the mechanism of the adlayer formation as well as the Cys adsorption patterns specific to the Au(100)-electrode surface.

AB - Cysteine (Cys) is an essential amino acid with a carboxylic acid, an amine and a thiol group. We have studied the surface structure and adsorption dynamics of L-cysteine adlayers on Au(100) from aqueous solution using electrochemistry, high-resolution electrochemical scanning tunnelling microscopy (in situ STM), and molecular modelling. Cys adsorption on this low-index Au-surface has been much less studied than Cys adsorption on Au(111)- and Au(110)-electrode surfaces. Chronopotentiometry was employed to monitor the adsorption dynamics at sub-second resolution and showed that adsorption is completed in 30 minutes at Cys concentrations above 100 μM. Two consecutive steps could be fitted to these data. Two separate reductive desorption peaks of Cys adlayers on Au(100) with a total coverage of 2.52 (±0.15) × 10-10 mol/cm2 were observed. In situ STM showed that adsorbed Cys is organized in stripes with “fork-like” features which co-exist in (11×2)-2Cys and (7×2)-2Cys lattices, quite differently from Cys adsorption on Au(111)-electrode surfaces. Stripe structures with bright STM contrast in the center suggest that a second Cys adlayer on top of a first adlayer is formed, supporting the dual-peak reductive desorption of Cys adlayers. In addition, monolayers of both pure L-Cys, pure D-Cys and a 1:1 racemic mixture of L- and D-Cys on Au(100) were studied. Virtually identical macroscopic electrochemical features were found, but in situ STM discloses many more defects for the racemic mixture than for the pure enantiomers due to structural mismatch of L- and D-Cys. Density functional theory (DFT) calculations combined with a cluster model for the Au(100) surface were carried out to investigate the adsorption energy and geometry of adsorbed monomer and dimer Cys species in different orientations, with detailed attention to the chirality effects. Optimized DFT geometries were used to construct model STM images, and kinetic Monte Carlo simulations undertaken to illuminate the growth of adsorbate rows and the mechanism of the adlayer formation as well as the Cys adsorption patterns specific to the Au(100)-electrode surface.

U2 - 10.1039/C9NR02477H

DO - 10.1039/C9NR02477H

M3 - Journal article

VL - 11

SP - 17235

EP - 17251

JO - Nanoscale

JF - Nanoscale

SN - 2040-3364

IS - 37

ER -