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Advisor(s)
Abstract(s)
A crescente preocupação com as mudanças climáticas e a necessidade de reduzir as emissões
de gases com efeito de estufa têm aumentado a procura por soluções energéticas mais limpas
e sustentáveis, assim como a utilização de materiais mais amigos do ambiente e reutilizáveis.
Neste contexto, a presente dissertação propõe o desenvolvimento de uma célula de
biocombustível enzimática de glicose/O₂ (EBFC), utilizando papel como substrato para os
elétrodos, minimizando e reduzindo o uso de material, com o intuito de aumentar a
sustentabilidade ambiental no fabrico de dispositivos analíticos. A EBFC é composta por dois
bioelétrodos, com imobilização das enzimas glicose desidrogenase (bioânodo) e bilirrubina
oxidase (biocátodo).
A seleção do nanomaterial adequado para a construção dos elétrodos foi realizada utilizando
voltametria cíclica (CV), uma técnica eletroquímica que permite comparar a eficiência de
diferentes nanomateriais em termos de transferência eletrónica e atividade de oxidaçãoredução.
Foram testados dois nanomateriais de carbono (carbono mesoporoso e negro de
fumo), bem como dois solventes diferentes na sua dispersão, nomeadamente N,Ndimetilformamida
(DMF) e dodecil sulfato de sódio (SDS) tendo-se verificado que o carbono
mesoporoso, dispersado em DMF, apresentou o melhor desempenho, sendo então selecionado
para a construção dos biossensores. Este material demonstrou uma capacidade superior de
imobilização de enzimas, facilitando a transferência direta de eletrões e aumentando a
eficiência dos processos redox.
Os bioelétrodos desenvolvidos com base neste nanomaterial foram inicialmente caracterizados
como biossensores para os seus substratos (glicose e O2) usando as técnicas CV e amperometria.
No caso do biossensor de glicose, foram alcançados resultado com uma sensibilidade de 3,33
μA/mM e um limite de deteção (LOD) de 0,049 mM. Já no biossensor de oxigénio, obteve-se
uma sensibilidade de 32,54 μA/mM, com um LOD de 0,002 mM.
A célula de combustível enzimática glicose/O2 foi então construída usando o bioelétrodo
papel(MC)/GDH, como ânodo, e bioelétrodo papel(MC)/BOx, como cátodo. As curvas de
polarização da célula de combustível permitiram analisar o seu desempenho energético. A potência máxima gerada pela célula foi de 0,13 μW na presença de glicose, um valor baixo, mas
suficiente para aplicações em biossensores de baixo consumo energético.
Apesar da potência gerada ser relativamente baixa, a EBFC desenvolvida demonstra um elevado
potencial para ser utilizada como um biossensor autossuficiente na determinação de glicose,
especialmente em dispositivos biomédicos portáteis. Esta tecnologia inovadora representa um
passo importante na criação de soluções sustentáveis e ecológicas para a monitorização de
saúde, alinhando-se com as exigências atuais de energias renováveis e dispositivos
autossustentáveis.
The growing concern about climate change and the need to reduce greenhouse gas emissions have increased the search for cleaner and more sustainable energy solutions, as well as the use of more environmentally friendly and reusable materials. In this context, this dissertation proposes the development of a glucose/O2 enzymatic biofuel cell (EBFC), using paper as a substrate for the electrodes, minimizing and reducing the use of material with the aim of increasing environmental sustainability in the manufacture of analytical devices. The EBFC was composed of two paper bioelectrodes, with immobilization of the enzymes glucose dehydrogenase (bioanode) and bilirubin oxidase (biocathode). The selection of the appropriate nanomaterial for the construction of the electrodes was carried out using cyclic voltammetry (CV), an electrochemical technique that allows the efficiency of different nanomaterials to be compared in terms of electron transfer and redox activity. Two carbon nanomaterials were tested (mesoporous carbon and carbon black), as well as two different solvents in their dispersion, namely N,N-dimethylformamide (DMF) and sodium dodecyl sulfate (SDS), and it was found that mesoporous carbon, dispersed in DMF, showed the best performance and was therefore selected for the construction of the biosensors. This material showed a superior capacity for immobilizing enzymes, facilitating the direct transfer of electrons and increasing the efficiency of redox processes. The bioelectrodes developed based on this nanomaterial were initially characterized as biosensors for their substrates (glucose and O2) using CV and amperometric techniques. In the case of the glucose biosensor, results were obtained with a sensitivity of 3.33 μA/mM and a limit of detection (LOD) of 0.049 mM. For the oxygen biosensor, a sensitivity of 32.54 μA/mM was obtained, with an LOD of 0.002 mM. The glucose/O2 enzymatic fuel cell was then constructed using the paper(MC)/GDH bioelectrode as the anode and the paper(MC)/BOx bioelectrode as the cathode. The polarization curves of the fuel cell allowed its energy performance to be analyzed. The maximum power generated by the cell was 0.13 μW in the presence of glucose, a low value, but sufficient for applications in low-energy biosensors. Although the power generated is relatively low, the EBFC developed has a high potential to be used as a self-sufficient biosensor for glucose determination, especially in portable biomedical devices. This innovative technology represents an important step in the creation of sustainable and ecological solutions for health monitoring, in line with current demands for renewable energies and self-sustaining devices.
The growing concern about climate change and the need to reduce greenhouse gas emissions have increased the search for cleaner and more sustainable energy solutions, as well as the use of more environmentally friendly and reusable materials. In this context, this dissertation proposes the development of a glucose/O2 enzymatic biofuel cell (EBFC), using paper as a substrate for the electrodes, minimizing and reducing the use of material with the aim of increasing environmental sustainability in the manufacture of analytical devices. The EBFC was composed of two paper bioelectrodes, with immobilization of the enzymes glucose dehydrogenase (bioanode) and bilirubin oxidase (biocathode). The selection of the appropriate nanomaterial for the construction of the electrodes was carried out using cyclic voltammetry (CV), an electrochemical technique that allows the efficiency of different nanomaterials to be compared in terms of electron transfer and redox activity. Two carbon nanomaterials were tested (mesoporous carbon and carbon black), as well as two different solvents in their dispersion, namely N,N-dimethylformamide (DMF) and sodium dodecyl sulfate (SDS), and it was found that mesoporous carbon, dispersed in DMF, showed the best performance and was therefore selected for the construction of the biosensors. This material showed a superior capacity for immobilizing enzymes, facilitating the direct transfer of electrons and increasing the efficiency of redox processes. The bioelectrodes developed based on this nanomaterial were initially characterized as biosensors for their substrates (glucose and O2) using CV and amperometric techniques. In the case of the glucose biosensor, results were obtained with a sensitivity of 3.33 μA/mM and a limit of detection (LOD) of 0.049 mM. For the oxygen biosensor, a sensitivity of 32.54 μA/mM was obtained, with an LOD of 0.002 mM. The glucose/O2 enzymatic fuel cell was then constructed using the paper(MC)/GDH bioelectrode as the anode and the paper(MC)/BOx bioelectrode as the cathode. The polarization curves of the fuel cell allowed its energy performance to be analyzed. The maximum power generated by the cell was 0.13 μW in the presence of glucose, a low value, but sufficient for applications in low-energy biosensors. Although the power generated is relatively low, the EBFC developed has a high potential to be used as a self-sufficient biosensor for glucose determination, especially in portable biomedical devices. This innovative technology represents an important step in the creation of sustainable and ecological solutions for health monitoring, in line with current demands for renewable energies and self-sustaining devices.
Description
Keywords
Fuel cell Self-powered biosensor Enzymes Glucose Paper electrodes Enzimas Célula de combustível Elétrodos de papel Biossensor auto-alimentado Glicose