Document type
Academic documents
Document subtype
Master's dissertation
Title
Preparação, Caracterização e Propriedades de Eléctrodos Modificados com Polímeros Condutores Funcionalizados para a Imobilização de DNA
Participants in the publication
Virgínia Clara Teixeira Ferreira (Author)
Dep. Química e Bioquímica
Dep. Química e Bioquímica
CQB
Summary
The purpose of this work was to study polymer modified electrodes containing free functional groups with DNA affinity and to evaluate the capacity of the immobilized biomolecules for the detection of heavy metal ions (Zn2+). \\nThe monomers 5-Amino-1-Naphthol (AN) and Thionine (TN) were investigated and their systematic study allowed to select the electropolymerisation conditions suitable to the objective of the work. Potentiodynamic electropolymerisation of AN in acidic media yielded films with good electroactivity and stability in this media. However, due to the weak electroactivity observed in neutral media, its use in the present study was not possible. The electroactivity of the synthesised polythionine (PTN) films in acidic medium depends on the experimental conditions. For the potentiostatic polymerisation the higher electroactivity has been achieved with the increase of the polarisation time and potential. Potentiodynamically, an increase of electroactivity was obtained for the film grown with 80 potential cycles at 20 mV s-1 between 0 and 1150 mV vs. SCE (PTN 80/20). Cyclic voltammetric and electrochemical quartz crystal microbalance (EQCM) studies revealed structural changes during electropolymerisation that were corroborated by atomic force microscopy (AFM). The redox behaviour of PTN films in different media and in a wide range of pH values was investigated; stability has been evaluated in biological compatible media and it was verified that electroactivity is affected by the nature and pH of the solution. By EQCM studies it was observed different mass changes with the film thickening and solution pH; the results suggest the contribution of distinct mechanisms, depending on the pH of the solution. \\nFree amino functions in the polymer structure enabled the nucleotides, dGTP e dG20-P, immobilisation onto the modified electrode – PTN 80/20 – which was enhanced by the presence of coupling agents N-hydroxisuccinimide (NHS) and N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC). Due to the metal ions affinity to DNA their electrochemical detection was possible in the PTN modified electrodes with ds-ADN.
Institution
FACULDADE DE CIÊNCIAS DA UNIVERSIDADE DE LISBOA
Publication Identifiers
Keywords
5-Amino-1-Naphthol
Thionine
Electropolymerisation
Electrochemical quartz crystal microbalance
Atomic force microscopy
Scanning electrochemical microscopy
Nucleotides immobilisation
Heavy ions
Notes
Nº aluno Ciências: 31155
Orientadores: Luisa Maria Abrantes
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