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O desenvolvimento de tecnologias de diagnóstico de rápida deteção tem sido alvo de grande interesse e investigação, sobretudo quando se refere a doenças neurológicas. Assim sendo, o objetivo principal deste trabalho consistiu no desenvolvimento de sensores eletroquímicos com base em polímeros de impressão molecular (MIP) desenvolvidos em suportes sustentáveis, como a cortiça, para a determinação de um biomarcador associado a processos neuroinflamatórios, a Interleucina 6 (IL6). Numa primeira parte do trabalho, foram otimizadas as condições experimentais para a construção do biossensor, nomeadamente com a escolha criteriosa do monómero a utilizar, de forma a interagir adequadamente com a molécula alvo definida, IL6. A determinação seletiva deste biomarcador foi conseguida utilizando um mecanismo de polimerização eletroquímica com remoção da proteína da matriz polimérica criada, através do ácido sulfúrico. Toda a evolução das diferentes etapas da construção do biossensor foi seguida por técnicas eletroquímicas, nomeadamente, impedância eletroquímica (EIS) e voltametria cíclica (CV). A otimização do biossensor foi efetuada em elétrodos de carbono convencionais descartáveis (SPE), em suporte em cerâmica. Por fim, o desempenho do sensor foi avaliado com a incubação de diferentes padrões de IL6, em solução tampão (PBS) inicialmente, e posteriormente, num sistema próximo do real, neste caso com a deteção de IL6 em amostra de soro comercial. Foi testada a seletividade do sensor eletroquímico na presença de compostos como a ureia, glicose, entre outros, que coexistem em excesso em amostras biológicas. Numa segunda parte do trabalho, após o estudo de condições ótimas e análise de parâmetros eletroquímicos do biossensor, o biossensor foi sintetizado com a mesma metodologia em elétrodos de carbono descartáveis em suporte de cortiça. Posteriormente, procedeu-se à avaliação do seu desempenho analítico. Em concordância com os resultados analíticos em elétrodos comerciais, concluiu-se que o sensor molecularmente impresso (MIP) em suporte de cortiça, obteve um bom desempenho analítico com gama de linearidade entre 0,001 a 10 ng/mL e coeficientes de correlação acima de 0,97 para curvas de calibração em tampão e em amostras de soro. Estes valores englobam os valores fisiológicos da proteína no soro de pacientes com a doença de Alzheimer (DA). Os polímeros sem impressão molecular (NIPs), tiveram uma resposta analítica muito baixa, concordante com o esperado devido à ausência de proteína. Em resumo, os biossensores desenvolvidos em suportes de cortiça apresentaram um bom desempenho analítico, que comparativamente aos sensores tradicionais, considerou-se igualável. Estes resultados demonstram ser possível aplicar (bio)materiais em qualquer área, incluindo a área médica, e melhorar a preservação pelo meio ambiente. Seria interessante mais alguns estudos e otimizações neste dispositivo desenvolvido para testar esta tecnologia em escala piloto. Uma das grandes vantagens desta estratégia proposta é uma ferramenta que permite a deteção no local, de resposta rápida, baixo custo associado e com redução de impactos ambientais causados.
The development of rapid detection diagnostic technologies has been the subject of great interest and research, especially when it comes to neurological diseases. Therefore, the main objective of this work consisted in the development of electrochemical sensors based on molecular imprint polymers (MIP) developed on sustainable supports, such as cork, for the determination of a biomarker associated with neuro-inflammatory processes, Interleukin 6 (IL6). In a first part of the work, the experimental conditions for the construction of the biosensor were optimized, namely with the careful choice of the monomer to be used, in order to properly interact with the defined target molecule, IL6. The selective determination of this biomarker was achieved using an electrochemical polymerization mechanism with removal of the protein from the created polymer matrix, through sulfuric acid. The entire evolution of the different stages of the biosensor construction was followed by electrochemical techniques, namely, electrochemical impedance (EIS) and cyclic voltammetry (CV). The biosensor optimization was performed using conventional disposable carbon electrodes (SPE) on a ceramic support. Finally, the sensor performance was evaluated with the incubation of different IL6 standards, in buffer solution (PBS) initially, and later, in a system close to the real one, in this case with the detection of IL6 in a commercial human serum sample. The selectivity of the electrochemical sensor was tested in the presence of compounds such as urea, glucose, among others, which coexist in excess in biological samples. In a second part of the work, after studying the optimal conditions and analyzing the electrochemical parameters of the biosensor, the biosensor was synthesized with the same methodology in disposable carbon electrodes on a cork support. Subsequently, its analytical performance was evaluated. In agreement with the analytical results in commercial electrodes, it was concluded that the molecularly printed sensor (MIP) on cork support, obtained a good analytical performance with a linearity range between 0,001 to 10 ng/mL and correlation coefficients above 0,97 for calibration curves in buffer and in serum samples. These values encompass the physiological values of protein in the serum of patients with Alzheimer's disease (DA). Non-molecular imprint polymers (NIPs) had a very low analytical response, in agreement with what was expected due to the absence of protein. In summary, the biosensors developed in cork supports presented a good analytical performance, which, compared to traditional sensors, was considered equal. These results demonstrate that it is possible to apply (bio)materials in any area, including the medical area, and improve preservation by the environment. It would be interesting to have some more studies and optimizations in this device developed to test this technology on a pilot scale. One of the great advantages of this proposed strategy is a tool that allows on-site detection, quick response, low associated cost and reduced environmental impacts.
The development of rapid detection diagnostic technologies has been the subject of great interest and research, especially when it comes to neurological diseases. Therefore, the main objective of this work consisted in the development of electrochemical sensors based on molecular imprint polymers (MIP) developed on sustainable supports, such as cork, for the determination of a biomarker associated with neuro-inflammatory processes, Interleukin 6 (IL6). In a first part of the work, the experimental conditions for the construction of the biosensor were optimized, namely with the careful choice of the monomer to be used, in order to properly interact with the defined target molecule, IL6. The selective determination of this biomarker was achieved using an electrochemical polymerization mechanism with removal of the protein from the created polymer matrix, through sulfuric acid. The entire evolution of the different stages of the biosensor construction was followed by electrochemical techniques, namely, electrochemical impedance (EIS) and cyclic voltammetry (CV). The biosensor optimization was performed using conventional disposable carbon electrodes (SPE) on a ceramic support. Finally, the sensor performance was evaluated with the incubation of different IL6 standards, in buffer solution (PBS) initially, and later, in a system close to the real one, in this case with the detection of IL6 in a commercial human serum sample. The selectivity of the electrochemical sensor was tested in the presence of compounds such as urea, glucose, among others, which coexist in excess in biological samples. In a second part of the work, after studying the optimal conditions and analyzing the electrochemical parameters of the biosensor, the biosensor was synthesized with the same methodology in disposable carbon electrodes on a cork support. Subsequently, its analytical performance was evaluated. In agreement with the analytical results in commercial electrodes, it was concluded that the molecularly printed sensor (MIP) on cork support, obtained a good analytical performance with a linearity range between 0,001 to 10 ng/mL and correlation coefficients above 0,97 for calibration curves in buffer and in serum samples. These values encompass the physiological values of protein in the serum of patients with Alzheimer's disease (DA). Non-molecular imprint polymers (NIPs) had a very low analytical response, in agreement with what was expected due to the absence of protein. In summary, the biosensors developed in cork supports presented a good analytical performance, which, compared to traditional sensors, was considered equal. These results demonstrate that it is possible to apply (bio)materials in any area, including the medical area, and improve preservation by the environment. It would be interesting to have some more studies and optimizations in this device developed to test this technology on a pilot scale. One of the great advantages of this proposed strategy is a tool that allows on-site detection, quick response, low associated cost and reduced environmental impacts.
Description
Keywords
Alzheimer Interleucina 6 Polímero de Impressão Molecular Sensor Eletroquímico Sustentabilidade Interleukin 6 Molecular Imprinted Polymers Electrochemical sensor Sustainability