A simple method for the removal of thiols on gold surfaces using an NH4OH-H2O2-H2O solution.

The removal behavior of self-assembled monolayers (SAMs) of thiol molecules on a gold substrate by an NH(4)OH-H(2)O(2)-H(2)O solution was studied using attenuated total reflectance infrared spectroscopy (ATR-IR) and atomic force microscopy (AFM). Furthermore, the impact of the concentration of NH(4)OH and H(2)O(2) in the solution and reaction temperature on the SAM removal rate and efficiency was explored. The SAM removal rate and efficiency were significantly influenced by the concentration of NH(4)OH rather than H(2)O(2). The solution containing the 2 : 1 molar ratio of NH(4)OH : H(2)O(2) among three different solutions showed the highest removal rate and efficiency in the removal of 11-mercapto-1-undecanol. The increase in the reaction temperature resulted in the enhancement on the SAM removal rate, but it led to the fast delamination of the gold layer. These results may be useful in the regeneration of sensor surfaces relying on gold/thiol chemistry.

[1]  D. Allara,et al.  Quantitative determination of molecular structure in multilayered thin films of biaxial and lower symmetry from photon spectroscopies. I. Reflection infrared vibrational spectroscopy , 1992 .

[2]  Rodolfo J. Romañach,et al.  Atomic force measurements of 16-mercaptohexadecanoic acid and its salt with CH , 2005 .

[3]  K. Uosaki,et al.  In Situ, Real-Time Monitoring of the Reductive Desorption Process of Self-Assembled Monolayers of Hexanethiol on Au(111) Surfaces in Acidic and Alkaline Aqueous Solutions by Scanning Tunneling Microscopy , 2001 .

[4]  T. Thundat,et al.  Microcantilever (MCL) Biosensing , 2006 .

[5]  H. Tompkins,et al.  Convenient calibration of FTIR peak ‘size’ for thin organic/polymer films , 2001 .

[6]  S. Pak,et al.  Reactions of hydroxyl radicals on titania, silica, alumina, and gold surfaces , 2000 .

[7]  Christopher G. Worley,et al.  Removing sulfur from gold using ultraviolet/ozone cleaning , 1995 .

[8]  A. Amirfazli,et al.  Kinetics of alkanethiol monolayer desorption from gold in air. , 2005, Chemical communications.

[9]  C. R. Helms,et al.  Effect of silicon surface cleaning procedures on oxidation kinetics and surface chemistry , 1987 .

[10]  D. Berk,et al.  Kinetics of GaAs Dissolution in H2O2−NH4OH−H2O Solutions , 1996 .

[11]  Robert Fedosejevs,et al.  Thermo-kinetics study of laser-induced desorption of self-assembled monolayers from gold: case of laser micropatterning. , 2005, The journal of physical chemistry. B.

[12]  A. Kell,et al.  Selective reductive desorption of a SAM-coated gold electrode revealed using fluorescence microscopy. , 2004, Journal of the American Chemical Society.

[13]  H. Torii,et al.  In Situ Investigation of Molecular Adsorption on Au Surface by Surface-Enhanced Infrared Absorption Spectroscopy , 2000 .

[14]  T. Ohsaka,et al.  Cathodic detection of H2O2 using iodide-modified gold electrode in alkaline media. , 2006, Analytical chemistry.

[15]  M. Morin,et al.  Studies of the Electrochemical Removal and Efficient Re-formation of a Monolayer of Hexadecanethiol Self-Assembled at an Au(111) Single Crystal in Aqueous Solutions , 1997 .

[16]  Frank Schreiber,et al.  Self-assembled monolayers: from ‘simple’ model systems to biofunctionalized interfaces , 2004 .

[17]  G. Leggett,et al.  Static Secondary Ion Mass Spectrometry Studies of Self-Assembled Monolayers: Influence of Adsorbate Chain Length and Terminal Functional Group on Rates of Photooxidation of Alkanethiols on Gold , 1998 .

[18]  A. Ulman,et al.  Formation and Structure of Self-Assembled Monolayers. , 1996, Chemical reviews.

[19]  U. Suter,et al.  Versatile Method for Chemical Reactions with Self-Assembled Monolayers of Alkanethiols on Gold , 2001 .