Electrochemical behavior of non-functionalized and sulfonated melanins at different pH values

Author(s)

Guerra, Nayrim Brizuela ; Lima, Joao Victor Morais ; Paulin, Joao Vitor ; Nozella, Natan Luiz ; Boratto, Miguel Henrique ; Nogueira, Gabriel Leonardo ; Bufon, Carlos Cesar Bof ; Graeff, Carlos Frederico de Oliveira

• Document type: Journal article
• Source: Polymer International; v. 73, n. 11, p. 9-pg., 2024-07-12.

Abstract

Melanins are macromolecular pigments widely spread in many living organisms, with unique physical and chemical properties. Specifically, their conductive properties have drawn attention for applications in different devices; however, the electrochemical response is equally necessary for designing technologies in sustainable bioelectronics. In this sense, we report a comparative study of the redox electrochemical properties of non-functionalized and sulfonated melanins in different pH environments. The electrochemical response was investigated using cyclic voltammetry, electrochemical impedance spectroscopy, dielectric permittivity and AC/DC conductivity at pH 3, 5 and 7. The voltammetric currents were higher at low pH, in agreement with the known proton transport properties of melanins. The effect of pH on electrochemical properties was slightly more significant in non-functionalized pigments. Melanins with a higher 5,6-dihydroxyindole carboxylic acid/5,6-dihydroxyindole ratio showed high DC current and low impedance. No significant difference was observed in the dielectric relaxation process between the different samples. (c) 2024 Society of Chemical Industry. (AU)

• FAPESP's process: 20/15869-6 - Rolled-up drain vertical organic transistors towards bioelectronic and neuromorphic applications
• Grantee: João Vitor Paulin
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 17/20809-0 - Study of organic devices for application in bioelectronics
• Grantee: Miguel Henrique Boratto
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 22/00410-3 - Obtation and characterization of organic electrochemical transistors based on melanin
• Grantee: Natan Luis Nozella
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 21/09207-3 - Fabrication of electrochemical transistors based on doped melanin with improved ionic and electronic conductivity
• Grantee: Nayrim Brizuela Guerra
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 20/04721-8 - PEDOT:PSS and melanin as active layers in neuromorphic devices
• Grantee: Miguel Henrique Boratto
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• FAPESP's process: 21/03379-7 - Application of New Materials as Electrodes in Flexible Supercapacitors
• Grantee: João Victor Morais Lima
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 14/25979-2 - Fabrication and characterization of devices and systems based on hybrid nanomembranes
• Grantee: Carlos César Bof Bufon
• Support Opportunities: Research Grants - Young Investigators Grants