Browsing by Author "Monteiro, Tiago"
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- Construction of effective disposable biosensors for point of care testing of nitritePublication . Monteiro, Tiago; Rodrigues, Patrícia R.; Gonçalves, Ana Luisa; Moura, José J.G.; Jubete, Elena; Añorga, Larraitz; Piknova, Barbora Piknova; Schechter, Alan N.; Silveira, Célia M.; Almeida, M. Gabriela"In this paper we aim to demonstrate, as a proof-of-concept, the feasibility of the mass production of effective point of care tests for nitrite quantification in environmental, food and clinical samples. Following our previous work on the development of third generation electrochemical biosensors based on the ammonia forming nitrite reductase (ccNiR), herein we reduced the size of the electrodes’ system to a miniaturized format, solved the problem of oxygen interference and performed simple quantification assays in real samples. In particular, carbon paste screen printed electrodes (SPE) were coated with a ccNiR/carbon ink composite homogenized in organic solvents and cured at low temperatures. The biocompatibility of these chemical and thermal treatments was evaluated by cyclic voltammetry showing that the catalytic performance was higher with the combination acetone and a 40 °C curing temperature. The successful incorporation of the protein in the carbon ink/solvent composite, while remaining catalytically competent, attests for ccNiR’s robustness and suitability for application in screen printed based biosensors. Because the direct electrochemical reduction of molecular oxygen occurs when electroanalytical measurements are performed at the negative potentials required to activate ccNiR (ca. -0.4 V vs Ag/AgCl), an oxygen scavenging system based on the coupling of glucose oxidase and catalase activities was successfully used. This enabled the quantification of nitrite in different samples (milk, water, plasma and urine) in a straightforward way and with small error (1 – 6%). The sensitivity of the biosensor towards nitrite reduction under optimized conditions was 0.55 A M-1 cm-2 with a linear response range 0.7 – 370 μM."
- Development of new analytical tools for monitoring of cardiovascular disease markers – towards the detection of homocysteine-thiolactonePublication . Monteiro, Tiago; Oliveira, Francisco; Silveira, Célia M.; Pereira, Sofia A.; Almeida, M. Gabriela
- Inhibition-based biosensor for cyanide detection – a preliminary studyPublication . Coelho, Ana R.; Monteiro, Tiago; Viana, Ana S.; Almeida, M. Gabriela
- New PON1-based biosensor for the detection of homocysteine-thiolactone in human plasmaPublication . Monteiro, Tiago; Oliveira, Francisco; Silveira, Célia M.; Pereira, Sofia A.; Almeida, M. Gabriela
- O papel das organizações africanas na resposta ao fenómeno da pirataria e do assalto armado no mar contemporâneo, na região do Golfo da GuinéPublication . Monteiro, TiagoApós a resposta global à pirataria na costa da Somália, as atenções viraram-se para o Golfo da Guiné na última década. Ao tornar-se a zona marítima mais perigosa do continente africano, em termos de ataques, sequestros e outros atos ilícitos, o Conselho de Segurança das Nações Unidas adotou as Resoluções 2018 e 2039, onde expressa a preocupação com a insegurança marítima e as suas consequências globais e regionais. Foi no seguimento das Resoluções que as Comunidades Económicas da África Ocidental e Central criaram um mecanismo cooperativo entre os 25 Estados-membro, chamado Arquitetura de Segurança Marítima de Yaoundé. Considerando o impacto que uma resposta regional coordenada pode ter no combate a este fenómeno, importa analisar e compreender os progressos conseguidos pela Arquitetura e de que forma contribui para a diminuição da atividade da pirataria e assalto armado no mar. A investigação seguiu um raciocínio indutivo, baseado numa estratégia de investigação qualitativa, recorrendo-se à análise documental e a entrevistas semiestruturadas. Da investigação resultou que a Arquitetura, tirando proveito do apoio de organizações internacionais, integra um conjunto de projetos importantes, relativamente às dimensões da proteção, segurança e partilha de informações. No entanto, carece de um esforço regional para responder às necessidades de governança no domínio judicial. Abstract: Following the global response to piracy off the coast of Somalia, attention has turned to the Gulf of Guinea over the past decade. By becoming the most dangerous maritime zone on the African continent with attacks, kidnappings and other illicit acts, the United Nations Security Council adopted Resolutions 2039 and 2018, which expresses concerns about maritime insecurity and its global and regional consequences. It was following the Resolutions that the Economic Communities of West and Central Africa created a cooperative mechanism between the 25 Member States, called the Yaoundé Architecture. Considering the impact that a coordinated regional response can have in combating this phenomenon, it is important to analyze and understand the progress achieved by Architecture and how it contributes to the decrease of piracy and armed robbery at sea. The investigation followed an inductive reasoning, based on a qualitative research strategy, using document analysis and semi-structured interviews. The research concluded that the Architecture, taking benefit of the support of international organizations, integrates a set of important projects, regarding the dimensions of protection, security and information sharing. However, it lacks a regional effort to respond to governance needs in the judicial domain.