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Projeto de investigação
Development of Nanostrutures for Detection of Triclosan Traces on Aquatic Environments
Financiador
Autores
Publicações
Desenvolvimento de um sensor de triclosan em meio aquoso complexo
Publication . Marques, Inês Correia Gonçalves; Raposo, Maria de Fátima
Sendo a água um recurso essencial para a vida, é fundamental prevenir a sua contaminação. As estações de tratamento de águas residuais (ETAR) são pontos fulcrais na manutenção da qualidade da água, uma vez que permitem remover poluentes da água antes que esta seja descarregada. No entanto, alguns Produtos Farmacêuticos e de Cuidado Pessoal (PPCPs), abundantemente utilizados por todos nós, chegam às águas residuais e às ETAR, não sendo eliminados durante os processos de tratamento. O triclosan, inserido nesta classe de produtos, pode levar a resíduos de longa duração, dado ser um composto estável e lipofílico, promovendo efeitos adversos nos organismos. Deste modo, pretende-se desenvolver sistemas sensoriais que possam detectar este poluente em água a baixas concentrações. Neste trabalho, recorreu-se ao conceito de Língua Eletrónica através da técnica de Espectroscopia de impedância para desenvolver um protótipo que permita detectar em água pequenas quantidades de triclosan em concentrações de 10-6 M a 10-12 M. Para tal protótipo fizeram-se filmes finos pelas técnicas de Camada-sobre-Camada (LbL) e de sputtering, após selecção de moléculas que se adequem à detecção de triclosan, aumentando a afinidade e sensibilidade do sensor. Foram analisadas soluções com diferentes concentrações de triclosan e de cloreto de sódio, de modo a garantir que os eléctrodos, sem quaisquer revestimentos, são funcionais e indiciam a presença das moléculas-alvo. Para fazer a caracterização dos filmes recorreu-se a uma análise microscópica e a técnicas de espectrofotometria de ultravioleta-visível antes e após o contacto com triclosan. Os resultados dos espectros de impedância foram obtidos através do analisador HAMEG Programmable LCR Bridge HM8118, sendo posteriormente analisados estatísticamente através de Análise de Componentes Principais, permitindo a sua interpretação. Foi possível assim concluir que as propriedades eléctricas dos filmes fabricados têm uma dependência com a concentração de triclosan em água, na gama de concentrações utilizada.
Liposomes encapsulating catechins: a biophysical approach for skin cancer therapy
Publication . Pires, Ana Filipa Soares; Raposo, Maria de Fátima
Every year, a large number of skin cancer cases caused by a prolonged ultraviolet
radiation exposure, are diagnosed around the world. Epigallocatechin–3–
gallate (EGCG) derived from green tea leaves, display protective effect against
oxidative stress which reduce the risk of contracting skin cancer. However, frequently,
the antioxidant and anti–inflammatory activities of EGCG in are compromised
because this molecule is extremely unstable and rapidly degraded in
physiological conditions. Considering these issues, the main goal of this thesis
was developed a stable liposomal nanocarrier for topical/transdermal delivery of
EGCG, firstly, to increase its bioavailability and, secondly, to offer an desirable
skin protection against harmful effects of UV radiation. Primarily, the molecular
mechanisms between EGCG and different phospholipids were studied using
Langmuir experiments, revealling the affinity and localization of EGCG on each
lipidic membrane, which according to the results depends on the molecular organization
of lipidic monolayer (functional groups anchored at headgroup) and of
the degree of protonation of EGCG. EGCG establishes electrostatic and hydrogenbonding
interactions with zwitterionic (DMPC, DPPC) and anionic (DPPG and
DPPS) phospholipids, which condense the monolayers and alter the membrane’s
potential and compressibility. Regarding the irradiation experiments, the results
indicated that EGCG efficiently slows down the oxidant events in monolayers and
in lipid bilayers, which were produced by blue and ultraviolet radiation exposure,
respectively. Lastly, the nanofibers meshes containing EGCG-loaded liposomes
are biocompatible, support human fibroblasts adhesion and scavenge the oxidant
species generated by UV radiation, which guarantees a higher cell survival.
Ammonia Detection by Electronic Noses for a Safer Work Environment
Publication . Reis, Tiago; Moura, Pedro Catalão; Gonçalves, Débora; Ribeiro, Paulo A.; Vassilenko, Valentina; Fino, Maria Helena; Raposo, Maria; DF – Departamento de Física; LIBPhys-UNL; DEE - Departamento de Engenharia Electrotécnica e de Computadores; CTS - Centro de Tecnologia e Sistemas; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; MDPI - Multidisciplinary Digital Publishing Institute
Providing employees with proper work conditions should be one of the main concerns of any employer. Even so, in many cases, work shifts chronically expose the workers to a wide range of potentially harmful compounds, such as ammonia. Ammonia has been present in the composition of products commonly used in a wide range of industries, namely production in lines, and also laboratories, schools, hospitals, and others. Chronic exposure to ammonia can yield several diseases, such as irritation and pruritus, as well as inflammation of ocular, cutaneous, and respiratory tissues. In more extreme cases, exposure to ammonia is also related to dyspnea, progressive cyanosis, and pulmonary edema. As such, the use of ammonia needs to be properly regulated and monitored to ensure safer work environments. The Occupational Safety and Health Administration and the European Agency for Safety and Health at Work have already commissioned regulations on the acceptable limits of exposure to ammonia. Nevertheless, the monitoring of ammonia gas is still not normalized because appropriate sensors can be difficult to find as commercially available products. To help promote promising methods of developing ammonia sensors, this work will compile and compare the results published so far.
Advances in applied electrokinetics: Treatment, by-products reuse and sensors’ system
Publication . Magro, Cátia Joana Costa; Mateus, Eduardo; Ribeiro, Alexandra; Paz-Garcia, Juan
Some of the barriers for a paradigm change on water reuse solutions are related to their maturing
technology level, to the removal of emerging organic contaminants and to the availability of rapid,
reliable and cost-effective monitoring tools. Thus, in this dissertation, electro-based techniques were
applied to secondary effluents aiming to promote water reuse through the (i) removal of triclosan and
inorganic contaminants, (ii) development and test of electronic tongue sensors that may be used as
complementary monitoring tools coupled with degradation processes, and (iii) enhancing of the
technology maturity level with the recovery of self-produced hydrogen and freshwater replacement in
the production of construction materials.
With these objectives, the main findings in this PhD project are described hereunder:
(i)
Electrochemical reactors are effective for degrading triclosan and its by-products. The
type of electrodes is an important variable that strongly impacts the degradation
efficiency, the kinetics and the by-products generated after treatment;
GC/MS/MS selectivity and sensitivity allows, after operational optimization, the
detection and quantification of triclosan, without the analyte derivatization, in the
effluent at ng/L level, showing that standard methods should be adjusted “case-bycase”.
(ii)
Electronic tongues coated with organic polyelectrolyte thin films are able to distinguish
at pico-molar resolution, by means of principal component analysis, between mineral
water and secondary effluent matrices and discriminating triclosan at different
concentrations;
The coating’s stability is affected by characteristics of the water to be analysed (e.g.
such as pH and elements content), rather than by the molecule to be detected; Due to
this dependency, sputtering thin films, more robust and stable, should be added to the
electronic tongue array;
A customized electronic tongue proved be a potential complementary monitoring tool
to follow the degradation pathway of the target compounds across the treatment,
when coupled to a dynamic electrochemical reactor; It was possible to semi-quantify
methyl-triclosan and triclosan using the array, whereas for phenolic compounds (2,4-dichlorophenol and 2,4,6-trichlorophenol) best results were obtained by using a single
sensor and thinner film as coating.
(iii)
The remediation process by-product, hydrogen, showed, on a proof of concept level,
its potential to be stored, reused or used as fuel in a proton-exchange membrane fuel
cell, to generate energy;
The use of electro-treated effluent showed to be sustainable for replacing freshwater
in construction materials production. This replacement can provide high quality
materials with features that are valued by construction materials industry, increasing
the market value of the reactor developed.
Unidades organizacionais
Descrição
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Contribuidores
Financiadores
Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
3599-PPCDT
Número da atribuição
PTDC/FIS-NAN/0909/2014