LSRE-LCM - Artigos em Livros de Atas (participação em conferências)
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- Permeation of chlorpyrifos in ex vivo pig skin – Experimental conditions to get closer to human exposurePublication . Silva, DorindaTrack 3: Environmental chemistry and exposure assessment: analysis, monitoring, fate and modeling 3.06.P-Tu151 Permeation of Chlorpyrifos in Ex Vivo Pig Skin - Experimental Conditions to Get Closer to Human Exposure to air pollutants is not limited to inhalation risk and dermal contact is gaining increasing interest with the possibility to represent a risky carcinogenic route. Chlorpyrifos is a broad-spectrum organophosphorus pesticide used for aerial and ground-based treatments with different permeation values being reported for human skin. Despite the recommendations of the organisation for economic co-operation and development (OECD) to use 50% of ethanol in the receptor fluid for skin permeation of lipophilic compounds (as chlorpyrifos), this condition was suggested to exaggerate its permeation.
- Use of Lipid Vesicles for Revealing the Potential Contribution of Cytochrome C in the Metabolism of Environmental ToxicantsPublication . Lopes, João M.; Marques-da-Silva, Dorinda; Videira, Paula A.; Lagoa, RicardoCytochrome c (Cc) is well-known as an electron carrier at mitochondria but can also catalyze peroxidase-like reactions. Although the reported catalytic abilities are low, the role of Cc in transforming environmental toxicants requires additional studies. We employed cardiolipin vesicles to stimulate the enzymatic activity of Cc and tested the catalytic system towards the dye methyl orange and the polycyclic aromatic hydrocarbons (PAHs) benzo[b]fluoranthene and benzo[a]pyrene. The results showed that cardiolipin-containing vesicles promoted dye decolorization and the oxidation of both PAHs by Cc, indicating that lipid membranes can be useful to further investigate Cc–mediated metabolism of toxicants.
- Synthetic Membranes as an Alternative to Animal Skin to Investigate Dermal Permeation of ChlorpyrifosPublication . Marques-da-Silva, Dorinda; Lagoa, RicardoChlorpyrifos is a pesticide revised as dangerous for human health. While dermal permeation of chlorpyrifos is still poorly investigated, alternatives to animal and/or human skin are demanded. In this work, the suitability of synthetic membranes as alternative models to study dermal permeation of chlorpyrifos was investigated. Silicone and STRAT-M® membranes were tested on Franz cells using different receptor compositions. By adapting the concentration of ethanol in the receptor fluid, the results of chlorpyrifos permeation through both membranes were close to those found in human skin studies, supporting the use of those membranes as non-animal skin-equivalent models.
- Oxidative Stress and Inflammatory Response of Skin Fibroblasts Exposed to ChlorpyrifosPublication . Silva, Zélia; Almeida, Danielle; Marques-da-Silva, Dorinda; Lagoa, Ricardo; Videira, Paula A.Chlorpyrifos (CPF) is a widely used insecticide. The aim of this work was to study the effect of CPF in skin fibroblasts exposed to concentrations detected in human skin and unleash underlying cellular mechanisms. Fibroblasts were exposed to different concentrations (0.36–250 µM) of CPF pure alone or in a commercial CPF mixture (Lethal 20) for 6 days. In conclusion, prolonged exposure to 250 µM of CPF pure and 125 µM of Lethal 20 caused a significant loss of the fibroblast´s viability. Moreover, the toxicity of this pesticide in fibroblasts is evidenced by the induction of oxidative stress and stimulation of the production of interleukin (IL)-6.
- Promotion of Dermal Permeation of Bioactive Compounds Using a Microneedle DevicePublication . Violante, Cristiana; Lagoa, Ricardo; Marques-da-Silva, DorindaSeveral natural bioactive compounds are described for their beneficial effects to skin. Nevertheless, for some compounds, dermal absorption is a challenge, demanding new methods to enhance skin penetration. In this work, pre-treatment with a microneedle device was tested to promote the permeation of caffeine and epicatechin through ex vivo pig skin. The results indicated that the microneedle pre-treatment increased the permeation of both compounds at a similar range. Compared to untreated skin, more than 20% higher amounts of caffeine and epicatechin crossed the treated skin. The data support the application of microneedle systems to promote the dermal delivery of bioactive compounds.
- Comparison of cytochrome c with conventional biocatalysts in the degradation of environmental toxicantsPublication . Lagoa, Ricardo; Lopes, João M.; Rodrigues, J. Rui; Marques-da-Silva, DorindaPeroxidases and laccases are amongst the most attractive enzymes for the degradation of concerning pollutants like polycyclic aromatic hydrocarbons (PAHs) and organic dyes. In spite of the availability of high activity enzymes, their applicability is hindered by specificity and stability limitations in real environmental conditions, so more suitable biocatalysts are demanded. Cytochrome c (Cc) is best known as a protein electron carrier at mitochondria, but it also displays (pseudo-)peroxidase activity. In this work, we aimed to evaluate the potential of Cc as biocatalyst of PAHs’ and azo dyes’ degradation and compare it with two more conventional enzymes - plant peroxidases and fungi laccases. The studies were carried out with Cc from horse heart, horseradish peroxidase (HRP) and laccase from Trametes versicolor. The enzymes were tested with two major PAHs, anthracene and benzo[a]pyrene (BaP), and with methyl orange (MO) as a model azo dye. The enzyme-catalyzed oxidation of PAHs was determined by HPLC, and MO decolorization was followed in spectrophotometric kinetic assays. Several degradation studies were performed to assess the catalytic capacity at different pH and the effect of the redox mediator ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate)). Peroxidase reactions of HRP and Cc were initiated with 100 μM H2O2 (in media containing 100 μM DTPA as metal chelator). In pH 5 acetate buffer, the specific ABTS-oxidizing activity of Cc was much lower than that of laccase and HRP. However, these two enzymes lost almost all activity at pH 7, while Cc exhibited catalytic activity even at pH 8 (phosphate buffer). Decolorization assays showed laccase alone to be a weak catalyst of MO degradation, although addition of ABTS to the reaction media greatly accelerated the transformation. On the contrary, both HRP and Cc directly catalyzed MO decolorization, including at neutral pH, and the redox mediator offered no advantage. As for the PAHs, HRP and laccase catalysis benefited from the presence of ABTS in the media, but again Cc oxidized anthracene and BaP directly. Indeed, 24h incubation of BaP (1 mg/L) with Cc (0.1 mg/mL) resulted in the transformation of 70±4% of the PAH and generation of major reaction products different of the BaP quinones produced by laccase- and HRP-ABTS systems. This work disclosed catalytic properties of Cc different from laccase and HRP that are relevant for the design of new enzymatic remediation processes.
- Summer production of lettuce grown in a hydroponic system using wastewaterPublication . Vieira, Judite; Vaz, Daniela C.; Santos, Ounísia; Pala, HelenaPopulation growth leads to an increasing need for food production, which causes negative impacts on the environment, namely a higher use of water, and fast depleting land. The search for more efficient technologies in the agricultural sector aims for sustainable production, reducing water consumption and waste, inducing wastewater reuse, and the use of soilless cropping systems as an alternative to traditional agriculture. The aim of this study was to evaluate the growth of lettuces in wastewater from an urban treatment plant in a small hydroponic system, without recirculation, during the summer period, when the scarcity of water is higher thus increasing the impacts of crop production with soil. The crop growth was studied under three different conditions: wastewater (after primary or secondary treatment); wastewater with potassium supplementation; and synthetic medium, as control. Physical and chemical parameters of the wastewater, crop growth, and the environmental conditions of the greenhouse were monitored. At end of the assay the crop fresh weight was determined, and toxicity analysis were carried out through cell viability assays with the Caco-2 cell line. Results point to a limited crop growth in the wastewater with a secondary treatment, due to low nutrients concentrations, which affects the plants fresh weight. Solids load, pH value and nitrite concentration in wastewater seem to affect crop growth. Wastewater with a primary treatment had a large organic load, and the system allowed the removal of over 98% of BOD5 and the removal of over 68% of COD. The system provided an improvement in the wastewater quality, allowing the removal of the nutrient load (minimum value) of 43% N, 53% K, and 46% P (total phosphorus). For extract percentages up to 1% (w/v) there is no evidence of toxicity associated with the lettuce culture from the hydroponic system. The reuse of urban wastewater in hydroponics seems to be a sustainable promising technology that may complement the lack of crop production in soil due to water scarce.
- Feasibility Study of the PET Fines Incorporation into Recycling ProcessesPublication . Nascimento, Bruna Guilherme do; Bozzola, Fernando; Vasco, Joel C.; Parnigoni, Milena; Capela, Carlos; Heleno, Lizete; Gaspar, Marcelo; Oliveira, Nelson S.Circular economy principles focus on the need to preserve natural resources and foster the use of environmentally sustainable practices. Concerning the use of plastics in a circular economy, increasingly demanding solutions have to be developed towards the zero-waste goal sought after by researchers and society alike. Particular attention has been put into the recycling of PET, mainly due to its wide spectrum of use and, consequently, to large volumes of related waste. The PET mechanical recycling process requires these waste materials to be shredded into PET flakes. Following such a procedure, these flakes are pelletized to be used again as feedstock. Considering the main stages of the mechanical recycling processes, which include plastic screening, shredding and washing, significant amounts of end waste materials are generated. This end-waste integrates small scale particles that are designated by plastic fines. Concerning the PET recycling process, the PET fines resulting from its mechanical recycling are not currently valued due to several technical issues, such as their high contamination level and the complexity of sorting them from other small-size particles. Current research focuses on the feasibility of incorporating these PET fines into the film/injection extruders, avoiding this way the need for an intermediate pelletization stage. To allow for such direct incorporation of PET fines into recycling processes, different decontamination and sorting solutions were implemented and tested. The current study is based on analyzing the mechanical properties of PET fines, using laboratory tests such as FTIR, DSC, MFI, moisture content, tensile tests and bending tests. Preliminary results allow foreseeing the successful direct incorporation of PET fines into PET recycling.
- Ink Removal on Plastic Films Printed by FlexographyPublication . Bozzola, Fernando; Nascimento, Bruna Guilherme do; Vasco, Joel C.; Silva, Nelson; Lagoa, Fernando; Capela, Carlos; Heleno, Lizete; Gaspar, Marcelo; Oliveira, Nelson S.Plastics are key engineering materials for our society and economy, mainly due to their multifunctionality and ease of processing. Nonetheless, their main drawback is related to the fact that when these cannot be reprocessed, they do generate waste, which leads to several environmental impacts. Therefore, considering plastics’ circularity, minimizing their waste, and the resulting impacts, stresses the need for these to be recyclable. One of the main challenges that concern their recyclability is the deinking of plastic films when printed by flexography. The current technology uses non-bio-based surfactants and non-renewable surfactants, which are harmful to the environment. Therefore, the main objective of current research is to develop an environmentally sustainable process for ink removal on printed post-industrial flexible plastic films using bio-based surfactants. This process focuses on obtaining a deinked plastic that may be reprinted, avoiding this way for inappropriate disposal or reprocessing problems. The value increase of upcycling such post-industrial waste makes it possible to match the quality of the virgin plastic, which is key to carrying out an effective cost analysis of recycled plastic when compared to the new plastic films. Dedicated laboratory deinking procedures were undertaken with transparent polyethylene films printed by flexography with different conditions. Preliminary results show the dedicated experimental ink removal procedure using bio-based surfactants to be effective and environmentally sustainable.
- Energy Efficiency and Sustainability in an Aquaponic Greenhouse Supported by IoTPublication . Galvão, João; Santos, Pedro; Aires, Luis; Ribeiro, Vânia; Neves, FilipeThe increasing demand for agricultural crops and the necessity to reduce environmental impacts from traditional agriculture have led to the emergence of sustainable production systems such as hydroponics and aquaponics. These soil and pesticide-free systems require less water and fertilizers but need electrical energy and controlled greenhouse environmental conditions to be highly productive. This work presents a monitoring and management system for environmental parameters inside an aquaponic greenhouse, that allows the manager to assess in real-time the working status of the aquaponic system, helping in the detection of critical conditions that require a quick decision. This system was developed to measure, through IoT sensors network, the temperature and the relative humidity of the air, the temperature, pH and the electrical conductivity of the water that contains the dissolved nutrients that feed the growth of the plants. It is possible to visualize the measured parameters via the Internet, on a dashboard, in a mobile application and store these variables in a database. To further increase the sustainability of the aquaponic greenhouse, the electricity consumed during its activity will be produced locally by photovoltaic technology. The technologies proposed in this work may promote the emergence of small models of greenhouses, implemented by communities and populations, reducing production energy costs and transportation resources.