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Study of the electrochemical behavior of keratin and its interaction with p-toluenediamine and p-aminophenol and their oxidation products mimicking reactions of permanent hair dye

Grant number: 18/12449-6
Support type:Scholarships abroad - Research Internship - Doctorate
Effective date (Start): November 26, 2018
Effective date (End): September 25, 2019
Field of knowledge:Physical Sciences and Mathematics - Chemistry
Principal Investigator:Maria Valnice Boldrin
Grantee:João Carlos de Souza
Supervisor abroad: Ana Maria Oliveira Brett
Home Institution: Instituto de Química (IQ). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil
Local de pesquisa : Universidade de Coimbra (UC), Portugal  
Associated to the scholarship:15/12998-1 - Chromatographic and electroanalytical methods applied in determination of p-toluenediamine and p-aminophenol in oxidative medium used in permanent hair dye, BP.DR

Abstract

Permanent hair dyeing is a process adopted by millions of people around the world, and involves complex oxidative reactions between precursor agents and couplers in alkaline oxidizing medium and involves the formation of dye within the hair. In this context, hairdressing salon effluent may contain not only these agents, but a large amount of byproducts formed during the oxidation process by the use of peroxide and ammonia during dyeing, the toxicity/mutagenicity of which is still poorly known. Within this context, in the first phase of the work the occurrence and mutagenicity of residues of p-toluenediamine and p-aminophenol, used as precursors in hair dyes, respectively, were evaluated. The studies pointed to the contamination of the hairdressing salon effluents and collection waters before and after treatment and the byproducts of the direct oxidation of p-toluenedidamine showed a proven mutagenic potential. Considering that human hair involves around 85% of keratin, it is proposed in this second phase of the work to investigate the potential of developing electrodes modified with keratin for the knowledge of the interactions and determination of the compounds involved in permanent dyeing by electrochemical sensors and the interactions of compounds with mutagenic characteristics with nitrogenous bases of the DNA. For this, it is proposed to develop part of the project under the supervision of Profesor Ana Maria Brett, specialist in the field of bioanalytical and application of her current research involving electrochemical study of proteins. The aim of this work is to investigate the electrochemical oxidation of keratin using the technique of atomic force microscopy and electrochemical techniques, focusing on the oxidative monitoring of the electroactive amino acids that make up keratin (cysteine, tyrosine, histidine, tryptophan and methionine) and their interactions with p-toluenediamine, p-aminophenol and their oxidation products. In the second part of the project, it is proposed the development of electrochemical sensors of these compounds, as well as to investigate the interaction of these precursors, couplers and their oxidation products with human DNA. This would be relevant in understanding the mechanisms of action of these compounds in hair and its biotransformations in the human body. In addition, these interactions could be useful for the development of economical, sensitive and selective electrochemical sensors in environmental matrices and biological fluids.