Electrochemical Characterization of Protein Adsorption onto YNGRT-Au and VLGXE-Au Surfaces.

Hanna Trzeciakiewicz,Jose Esteves-Villanueva,Sanela Martic-Milne,Kamaljit Kaur,Rania Soudy

doi:10.3390/s150819429

Hanna Trzeciakiewicz, Jose Esteves-Villanueva + Show 3 more

Open Access

https://doi.org/10.3390/s150819429

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Abstract

The adsorption of the proteins CD13, mucin and bovine serum albumin on VLGXE-Au and YNGRT-Au interfaces was monitored by electrochemical impedance spectroscopy in the presence of [Fe(CN)6]3−/4−. The hydrophobicity of the Au surface was tailored using specific peptides, blocking agents and diluents. The combination of blocking agents (ethanolamine or n-butylamine) and diluents (hexanethiol or 2-mercaptoethanol) was used to prepare various peptide-modified Au surfaces. Protein adsorption onto the peptide-Au surfaces modified with the combination of n-butylamine and hexanethiol produced a dramatic decrease in the charge transfer resistance, Rct, for all three proteins. In contrast, polar peptide-surfaces induced a minimal change in Rct for all three proteins. Furthermore, an increase in Rct was observed with CD13 (an aminopeptidase overexpressed in certain cancers) in comparison to the other proteins when the VLGXE-Au surface was modified with n-butylamine as a blocking agent. The electrochemical data indicated that protein adsorption may be modulated by tailoring the peptide sequence on Au surfaces and that blocking agents and diluents play a key role in promoting or preventing protein adsorption. The peptide-Au platform may also be used for targeting cancer biomarkers with designer peptides.

Highlights

Organized self-assembled monolayers on conductive surfaces represent a powerful approach to tuning the electrical and chemical properties of interfaces
Hydrophobic proteins such as human serum albumin adsorbs onto hydrophobic surfaces [6], while β-casein protein adsorbs onto hydrophilic surfaces [7]
The adsorption mechanism for proteins including bovine serum albumin (BSA), myoglobin, fibrinogen, and lysozyme, were studied on the hydrophobic alkanethiol self-assembled monolayers using a range of techniques such as surface-plasmon resonance, quartz crystal microbalance, and field-effect transistor [8]

Summary

Introduction

Organized self-assembled monolayers on conductive surfaces represent a powerful approach to tuning the electrical and chemical properties of interfaces. The adsorption mechanism for proteins including bovine serum albumin (BSA), myoglobin, fibrinogen, and lysozyme, were studied on the hydrophobic alkanethiol self-assembled monolayers using a range of techniques such as surface-plasmon resonance, quartz crystal microbalance, and field-effect transistor [8]. Protein adsorption onto metallic surfaces may increase electron transfer due to corrosion of the metal [22,23]. Cyclic voltammetry (CV) and EIS were used to monitor the surface properties of peptide films and protein adsorption via electron transfer perturbations on Au surfaces. We demonstrated that the electron transfer of [Fe(CN)6]3−/4− may be modulated by protein adsorption onto peptide-modified Au surfaces (VLGXE-Au and YNGRT-Au). The enhancement or depletion of the electron transfer, due to protein adsorption, was achieved by tailoring the surface hydrophobicity and peptide content

Experimental Section

Preparation of Peptide-Au Films

Electrochemical Measurements

Preparation and Characterization of Peptide-Au Surfaces

Protein Binding to Peptide-Au Surfaces

Effects of Surface Composition on Protein Adsorption