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Projeto de investigação
NanoSERS Microfluidics cytometry platform for expeditious cells phenotyping
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NanoSERS Microfluidics platform for rapid screening for infectious diseases
Publication . Oliveira, Maria João Quitoles De; Águas, Hugo; Tavares, José; Byrne, Hugh
Early and accurate disease detection is critical for clinical diagnosis and ultimately
determining patient outcomes. Point-of-care testing (POCT) platforms are needed in low-
resource settings and also to help the decentralisation of healthcare centres. Immunoas-
says using Surface-Enhanced Raman Spectroscopy (SERS) are especially interesting for
their increased sensitivity and specificity. Additionally, SERS can be easily translated
into POCT formats with microfluidics. In this work, a sensitive, selective, capable of
multiplexing, and reusable SERS-based biosensor was developed. The SERS immunoas-
say relies on a sandwich format, whereby a capture platform and SERS immunotags can
capture and detect a specific antigen, respectively. The SERS immunotags consisted of
gold nanostars, allowing exceptionally intense SERS signals from attached Raman re-
porters, and the covalent attachment of antibodies provided a stable antigen-antibody
binding activity. As a capture platform, a regenerated cellulose-based hydrogel provided
a robust design and the added advantage of environmental friendliness. Besides being a
transparent material with low background fluorescence and Raman signal, its high-water
retention capacity was particularly suited for preserving the high activity of covalently
bound antibodies, improving the assay time-stability. This SERS-based immunoassay was
then integrated into a microfluidic device, allowing high-throughput sample screening
allied with the high sensitivity and multiplexing features of the developed assay. The de-
vice was fabricated in less than 30 minutes by exploring direct patterning on shrinkable
polystyrene sheets for the construction of adaptable complex three-dimensional microflu-
idic chips. Finally, to validate the microfluidic system, Plasmodium falciparum infected
red blood cell culture samples were tested for malaria biomarker detection. The discrimi-
nation of SERS immunotags signals from the background was made through the direct
classical least squares method. As a result, better data fitting was achieved, compared
to the commonly used peak integral method. Considering these features, the proposed SERS-based immunoassay notably improved the detection limits of traditional enzyme-
linked immunosorbent assay approaches. Its performance was better or comparable to
existing SERS-based immunosensors. Moreover, this approach successfully overcame the
main challenges for application at POCT, including increasing reproducibility, sensitivity,
and specificity. Hence, the microfluidic SERS system represents a powerful technology
which can contribute to early diagnosis of infectious diseases, a decisive step towards
lowering their still substantial burden on health systems worldwide.
High UV and sunlight photocatalytic performance of porous ZnO nanostructures synthesized by a facile and fast microwave hydrothermal method
Publication . Ferreira, Sofia Henriques; Morais, Maria; Nunes, Daniela; Oliveira, Maria João; Rovisco, Ana; Pimentel, Ana; Águas, Hugo; Fortunato, Elvira; Martins, Rodrigo; DCM - Departamento de Ciência dos Materiais; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; Molecular Diversity Preservation International (MDPI)
The degradation of organic pollutants in wastewaters assisted by oxide semiconductor nanostructures has been the focus of many research groups over the last decades, along with the synthesis of these nanomaterials by simple, eco-friendly, fast, and cost-effective processes. In this work, porous zinc oxide (ZnO) nanostructures were successfully synthesized via a microwave hydrothermal process. A layered zinc hydroxide carbonate (LZHC) precursor was obtained after 15 min of synthesis and submitted to different calcination temperatures to convert it into porous ZnO nanostructures. The influence of the calcination temperature (300, 500, and 700 °C) on the morphological, structural, and optical properties of the ZnO nanostructureswas investigated. All ZnO samples were tested as photocatalysts in the degradation of rhodamine B (RhB) under UV irradiation and natural sunlight. All samples showed enhanced photocatalytic activity under both light sources, with RhB being practically degraded within 60 min in both situations. The porous ZnO obtained at 700 °C showed the greatest photocatalytic activity due to its high crystallinity, with a degradation rate of 0.091 and 0.084 min-1 for UV light and sunlight, respectively. These results are a very important step towards the use of oxide semiconductors in the degradation of water pollutants mediated by natural sunlight.
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Fundação para a Ciência e a Tecnologia
Programa de financiamento
OE
Número da atribuição
SFRH/BD/132057/2017