Effect of ordered gold surfaces on the insulating/conductive properties of tiolated molecular junctions

• Grant number: 18/21911-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2019
• End date: December 31, 2019
• Field of knowledge: Engineering - Materials and Metallurgical Engineering
• Principal Investigator: Paulo Roberto Bueno
• Grantee: Isabelle Zacarias
• Host Institution: Instituto de Química (IQ). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil
• Associated research grant: 17/24839-0 - Nanoelectronics and nanoscale electrochemistry: fundaments and applications, AP.TEM

Abstract

The construction of molecular junctions has several applications, among them biosensorsdesign. The use of these junctions, also known as SAMs (self-assembled monolayers), ishighlighted by its ease preparation. However, this process depends on the surfacecharacteristics (substrate), which can causes structural defects or pin-holes. In thiscontext, this work will focus on the use of different gold surfaces (for example, golddeposited on silicon wafer, electrodes obtained by the melting of the gold wire tip inhydrogen flame and microfabricated electrodes) as substrate, potential in obtainingelectrochemically stable monolayers with desired insulating/conductive properties. Asabsorbate, alkanethiols will be used because their chemical affinity with gold. In addition,since electroactive species such as ferrocene-thiol and ferrocene-modified peptides havebeen used to obtain electroactive surfaces with applications in biosensors, they will also beevaluated in the different proposed surfaces. Gold surface cleaning will be performed bydifferent combinations of methods: (i) Sigma cleaning solution, by (ii) using isopropylalcohol, (iii) ozone and by (iv) electrochemical process. In order to evaluate theinsulating/conductive properties of the molecular joints obtained in different gold surfaceswith respect to the presence of defects and, consequently, to relate to their stability andreproducibility, surface characterizations will be realized by AFM (atomic force microscopy)and by electrochemical techniques such as cyclic voltammetry (CV) and electrochemicalimpedance spectroscopy (EIS).