Submitted by Cláudia Bueno (claudiamoura18@gmail.com) on 2015-10-28T19:04:13Z No. of bitstreams: 2 Dissertação - Thiago Miguel Garcia Cardoso - 2014.pdf: 3179587 bytes, checksum: 5d358a40aa90ef1768cbb11668a1a1db (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-10-29T10:25:57Z (GMT) No. of bitstreams: 2 Dissertação - Thiago Miguel Garcia Cardoso - 2014.pdf: 3179587 bytes, checksum: 5d358a40aa90ef1768cbb11668a1a1db (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-10-29T10:25:57Z (GMT). No. of bitstreams: 2 Dissertação - Thiago Miguel Garcia Cardoso - 2014.pdf: 3179587 bytes, checksum: 5d358a40aa90ef1768cbb11668a1a1db (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-12-12 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / This current study describes the development of alternative technologies for the fabrication of microfluidic paper-based analytical devices (μPADs). The first technology refers to the manufacturing of a metal stamp for rapid prototyping of μPADs. Basically, the method uses the heating process to transfer wax to the paper surface. The wax is required to create a hydrophobic barriers thus delimiting microfluidic channels for the fluid transport through lateral flow effect. Some remarkable advantages of the metal stamping process include robustness, portability and simplicity. Paraffin is a hydrophobic and thermoplastic material that can be easily molded. Furthermore, it shows high chemical resistance when exposed to different aqueous and organic solutions. The stamping-based technology allows the fabrication of μPADs at very low cost. The proposed approach exhibited great reproducibility. The relative standard deviation (RSD) for the channel widths measured on 50 independent μPADs revealed a value of 3.5%. The analytical performance of the paper-based device associated with colorimetric detection was tested for the nitrite analysis in clinical, food and environmental samples. The limit of detection (LD) nitrite assays without preconcentration was 11.3 μM. In order to access the nitrite concentration in environmental samples, a preconcentration method was developed allowing to achieve a LD of 5.6 μM. The results obtained were compared to the spectrophotometric technique and the statistical test demonstrated no significant difference between both methodologies. The stamping process have demonstrated high potential to produce μPADs in laboratories with none or minimal instrumentation. Besides the stamping process, another fabrication approach based on the spraying of white glue mixed with a sensitizing agent was also proposed to produce μPADs. To create effective hydrophobic barriers, the white glue was first sprayed on the paper surface though a magnetic mask. Afterwards, the device was exposed to visible light for polymerization of the glue. In order to evaluate the fabrication methodology, 25 devices were produced and the RSD value achieved for the channel widths was 5.7%. The analytical feasibility of the μPADs fabricated with white glue was successfully demonstrated for qualitative assays dedicated to urinalysis (glucose, uric acid, nitrite, pH, BSA, urea, ketones bodies and bilirubin) and pancreatitis assay (amylase and lipase). Both alternative methods based on stamping and spraying has exhibited great potential to be used for production in mass. Moreover, the proposed devices revealed high potential to be broadly explored in biological/clinical, food and environmental applications. / O presente trabalho descreve o desenvolvimento de tecnologias alternativas para fabricação de dispositivos microfluídicos em papel. A primeira tecnologia se refere à confecção de um carimbo metálico para prototipagem de dispositivos microfluídicos em papel. Basicamente, a metodologia baseiase na transferência de parafina para a superfície do papel por um processo de aquecimento. O uso da parafina faz-se necessário para criação da barreira hidrofóbica, no qual delimita canais microfluídicos para o transporte do fluido através do fluxo lateral. As vantagens em utilizar o carimbo estão entre a facilidade de manuseio, a robutez e a portabilidade. Em relação ao uso da parafina, destaca-se como sendo um agente hidrofóbico e termoplástico, que pode ser facilmente moldado, além de ser um material altamente resistente a diferentes compostos químicos. A combinação do uso desses dois materiais, carimbo e parafina, possibilitou a fabricação rápida e barata dos dispositivos microfluídicos à base de papel (μPADs). Para avaliar o desempenho do processo de carimbagem foram fabricados 50 dispositivos no qual o desvio padrão relativo (DPR) encontrado para a largura do canal foi de 3,5%. O desempenho analítico dos μPADs associado a detecção colorimétrica foi avaliado na análise de nitrito em amostras clínicas, alimentícias e ambientais. O limite de detecção da análise de nitrito sem etapa de pré-concentração foi de 11,3 μM, para a análise de amostras ambientais foi desenvolvido uma etapa de pré-concentração, onde foi obtido um limite de detecção de 5,6 μM. Os resultados obtidos foram comparados à técnica de espectrofotometria e o teste estatístico demonstrou que não existe diferença significativa entre os dois métodos. O método de carimbagem demonstrou potencialidade para fabricação dos μPADs em laboratórios com recursos limitados, pois exige um mínimo de instrumentação. Além do processo de carimbagem, uma outra metodologia, também de baixo custo, foi explorada para fabricação dos μPADs. Essa medologia consiste no jateamente de cola branca misturada a um agente sensibilizante serigráfico para fabricação da barreira hidrofóbica. Basicamente, o processo consiste em jatear essa mistura sobre o substrato de papel que foi fixada a uma máscara magnética. Após o jateamento, o dispositivo foi exposto à radiação visível para polimerização da cola e obtenção das barreiras hidrofóbicas. A reprodutibilidade da largura dos canais foi avaliado em 25 microdispositivos e DPR encontrado foi de 5,7%. A potencialidade dos μPADs fabricados por essa metodologia foi avaliada na aplicação em teste para urinálise (glicose, ácido úrico, bilirrubina, nitrito, pH, albumina, ureia e corpos cetônicos) e pancreatite (amilase e lipase). Os dois métodos alternativos de fabricação apresentaram-se viáveis para fabricação dos μPADs e com grande potencialidade para produção em escala industrial. Além disso, demonstraram-se aplicáveis para análise biológicas, alimentícias e ambientais.

Due to an ever-increasing global population and limited resource availability, there is a constant need for detection of both natural and anthropogenic hazards in water, air, food, and material goods. Traditionally a different instrument would be used to detect each class of contaminant, often after a concentration or separation protocol to extract the analyte from its matrix. Raman spectroscopy is unique in its ability to detect organic or inorganic, airborne or waterborne, and embedded or adsorbed analytes within environmental systems. This ability comes from the inherent abilities of the Raman spectrometer combined with concentration, separation, and signal enhancement provided by drop coating deposition Raman (DCDR) and surface-enhanced Raman spectroscopy (SERS). Herein the capacity of DCDR to differentiate between cyanotoxin variants in aqueous solutions was demonstrated using principal component analysis (PCA) to statistically demonstrate spectral differentiation. A set of rules was outlined based on Raman peak ratios to allow an inexperienced user to determine the toxin variant identity from its Raman spectrum. DCDR was also employed for microcystin-LR (MC-LR) detection in environmental waters at environmentally relevant concentrations, after pre-concentration with solid-phase extraction (SPE). In a cellulose matrix, SERS and normal Raman spectral imaging revealed nanoparticle transport and deposition patterns, illustrating that nanoparticle surface coating dictated the observed transport properties. Both SERS spectral imaging and insight into analyte transport in wax-printed paper microfluidic channels will ultimately be useful for microfluidic paper-based analytical device (𝜇PAD) development. Within algal cells, SERS produced 3D cellular images in the presence of intracellularly biosynthesized gold nanoparticles (AuNP), documenting in detail the molecular vibrations of biomolecules at the AuNP surfaces. Molecules involved in nanoparticle biosynthesis were identified at AuNP surfaces within algal cells, thus aiding in mechanism elucidation. The capabilities of Raman spectroscopy are endless, especially in light of SERS tag design, coordinating detection of analytes that do not inherently produce strong Raman vibrations. The increase in portable Raman spectrometer availability will only facilitate cheaper, more frequent application of Raman spectrometry both in the field and the lab. The tremendous detection power of the Raman spectrometer cannot be ignored. / Ph. D.