Development of nanostructured sensors for monitoring emerging pollutants

• Autor(a) principal: Moura, Tiago Alexandre Peres
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/141399
• topic: environmental monitoring; macrolides; nanostructered sensors; metal oxides; polyelectrolytes; electronic tongue; Domínio/Área Científica::Engenharia e Tecnologia::Outras Engenharias e Tecnologias

Antibiotics represent a class of pharmaceuticals used to treat bacterial infections. How- ever, the ever growing use of antibiotics in agriculture, human and veterinary medicine, has lead to great concern regarding the outbreak of microbe strains resistant to antimicro- bial drugs. Azithromycin, clarithromycin, and erythromycin are macrolides, a group of molecules with a broad spectrum of antibiotic properties, and are included in a watch list of emerging pollutants that emphasises the importance of understanding their occurrence and fate in the aquatic environment, and developing reliable monitoring tools for their detection and quantification. Sensors provide many advantages compared to traditional analytical techniques such as fast response time, simple operation, cost effectiveness, and the ability to perform real-time, in situ monitoring. In this dissertation project, an ensem- ble of nanostructured sensors formed by metal oxide and polyelectrolyte thin films de- posited on ceramic substrates with gold interdigitated electrodes was produced and tested. The morphological characterization of the thin films was achieved by scanning electron microscopy. Impedance spectroscopy was employed as the transducing method for the devices’ electrical signal, producing multivariate datasets subsequently analysed by prin- cipal component analysis. The ZnO and TiO2 based sensors deposited with 50% and 100% O2, respectively, presented the most satisfactory results regarding the detection and quantification of the three macrolides, by principal component analysis, in concentrations between 10−15 M and 10−5 M in mineral water. Regarding the river water matrix, all the metal oxide thin films were capable of discriminating non-doped and doped samples, and sorting the different concentrations of azithromycin, clarithromycin, and erythromycin. The electronic tongue, an array of sensors composed of the metal oxide and polyelectrolyte thin film sensors, and one uncoated sensor, was capable of detection and quantification of the three macrolides in river water, with a sensitivity of 4.9±0.6, 5.8±0.4, and 4.7±0.6 per decade to azithromycin, clarithromycin, and erythromycin concentration, respectively.