A Nonenzymatic Biosensor Based on Gold Electrodes Modified with Peptide Self-Assemblies for Detecting Ammonia and Urea Oxidation

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• 作者：Roberta C. Bianchi ; Emerson Rodrigo da Silva ; Luiz H. Dall鈥楢ntonia ; Fabio Furlan Ferreira ; Wendel Andrade Alves
• 刊名：Langmuir
• 出版年：2014
• 出版时间：September 30, 2014
• 年：2014
• 卷：30
• 期：38
• 页码：11464-11473
• 全文大小：522K
• ISSN：1520-5827

文摘

We have developed a nonenzymatic biosensor for the detection of ammonia and urea oxidation based on the deposition of peptide microstructures onto thiolated gold electrodes. FF-MNSs/MCP/Au assemblies were obtained by modifying gold substrates with 4-mercaptopyridine (MCP), followed by coating with <span class="smallcaps">lspan>,<span class="smallcaps">lspan>-diphenylalanine micro/nanostructures (FF-MNSs) grown in the solid-vapor phase. Benzene rings and amide groups with peptide micro/nanostructures interact with synthetic NH<sub>4sub><sup>+sup> receptors through cation鈭捪€ and hydrogen bonding. AuOH clusters on the Au surface provided the catalytic sites. The application of a predetermined concentration of analytes at the peptide interfaces activated the catalytic sites. We observed a relationship between the stability of films and the crystal structure of peptides, and we organized the FF-MNSs into an orthorhombic symmetry that was the most suitable assembly for creation of our biosensors. At 0.1 mol L<sup>鈥?sup> NaOH, these FF-MNSs/MCP/Au electrodes have electrocatalytic properties regarding ammonia and urea oxidation that are comparable to those of enzyme-based architectures. Under optimal conditions, the electrocatalytic response is proportional to the ammonia and urea concentration in the range 0.1鈥?.0 mmol L<sup>鈥?sup>. The sensitivity was calculated as 2.83 and 81.3 渭A mmol L<sup>鈥?sup> cm<sup>鈥?sup> for ammonia and urea, respectively, at +0.40 V (vs SCE). Our detection method is easy to follow, does not require a mediator or enzyme, and has strong potential for detecting urea via nonenzymatic routes.