Colorimetric paper-based sensors against cancer biomarkers

Cancer is a major cause of mortality and morbidity worldwide. Detection and quantification of cancer biomarkers plays a critical role in cancer early diagnosis, screening, and treatment. Clinicians, particularly in developing countries, deal with high costs and limited resources for diagnostic systems. Using low-cost substrates to develop sensor devices could be very helpful. The interest in paper-based sensors with colorimetric detection increased exponentially in the last decade as they meet the criteria for point-of-care (PoC) devices. Cellulose and different nanomaterials have been used as substrate and colorimetric probes, respectively, for these types of devices in their different designs as spot tests, lateral-flow assays, dipsticks, and microfluidic paper-based devices (μPADs), offering low-cost and disposable devices. However, the main challenge with these devices is their low sensitivity and lack of efficiency in performing quantitative measurements. This review includes an overview of the use of paper for the development of sensing devices focusing on colorimetric detection and their application to cancer biomarkers. We highlight recent works reporting the use of paper in the development of colorimetric sensors for cancer biomarkers, such as proteins, nucleic acids, and others. Finally, we discuss the main advantages of these types of devices and highlight their major pitfalls.This research was funded by Portuguese Foundation for Science and Technology (FCT), under the scope of the strategic funding of UIDB/04469/2020 unit and through Mariana Carneiro PhD grant reference SFRH/BD/131959/2017.info:eu-repo/semantics/publishedVersio

Test-strips for monitoring cancer biomarkers in point-of-care

Authors acknowledge funding to Fundação para a Ciência e Tecnologia, I.P., through the PhD grant reference SFRH/BD/131959/2017info:eu-repo/semantics/publishedVersio

Saliency-driven system models for cell analysis with deep learning.

Background and objectivesSaliency refers to the visual perception quality that makes objects in a scene to stand out from others and attract attention. While computational saliency models can simulate the expert's visual attention, there is little evidence about how these models perform when used to predict the cytopathologist's eye fixations. Saliency models may be the key to instrumenting fast object detection on large Pap smear slides under real noisy conditions, artifacts, and cell occlusions. This paper describes how our computational schemes retrieve regions of interest (ROI) of clinical relevance using visual attention models. We also compare the performance of different computed saliency models as part of cell screening tasks, aiming to design a computer-aided diagnosis systems that supports cytopathologists.MethodWe record eye fixation maps from cytopathologists at work, and compare with 13 different saliency prediction algorithms, including deep learning. We develop cell-specific convolutional neural networks (CNN) to investigate the impact of bottom-up and top-down factors on saliency prediction from real routine exams. By combining the eye tracking data from pathologists with computed saliency models, we assess algorithms reliability in identifying clinically relevant cells.ResultsThe proposed cell-specific CNN model outperforms all other saliency prediction methods, particularly regarding the number of false positives. Our algorithm also detects the most clinically relevant cells, which are among the three top salient regions, with accuracy above 98% for all diseases, except carcinoma (87%). Bottom-up methods performed satisfactorily, with saliency maps that enabled ROI detection above 75% for carcinoma and 86% for other pathologies.ConclusionsROIs extraction using our saliency prediction methods enabled ranking the most relevant clinical areas within the image, a viable data reduction strategy to guide automatic analyses of Pap smear slides. Top-down factors for saliency prediction on cell images increases the accuracy of the estimated maps while bottom-up algorithms proved to be useful for predicting the cytopathologist's eye fixations depending on parameters, such as the number of false positive and negative. Our contributions are: comparison among 13 state-of-the-art saliency models to cytopathologists' visual attention and deliver a method that the associate the most conspicuous regions to clinically relevant cells

Nanocellulose- based biosensor for colorimetric detection of glucose

This work reports for the first time a colorimetric based biosensor using nanocellulose (NC) based supports drop-deposited onto a cellulose paper substrate for glucose detection in point-of-care. For this purpose, microcrystalline cellulose (MCC) samples were oxidized with 2,2,6,6-tetramethylpiperidine-N-oxyl radical (TEMPO), sodium hypochlorite, and potassium bromide, to produce NC that corresponded to carboxyl- NC. For the characterization, we used several methods: TEM, FTIR and conductometric titration. In all samples, the primary alcohol groups were selectively oxidized into carboxyl groups, provided the sodium hypochlorite is added dropwise and the reaction is performed at constant pH?10. Carboxyl- NC was further casted on a cellulose substrate and used as support for glucose oxidase (GOx), horseradish peroxidase (HRP) and 2,2?-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) reactions, aiming to yield a coloured detection system for glucose. The sensing system was generated by integrating GOx on the carboxyl- NC /cellulose substrate. Upon reaction with glucose, the enzyme produced hydrogen peroxide, which was converted into a blue-coloured product by reaction with HRP and the chromogenic reagent ABTS. The test-strip was calibrated by incubating it in different concentrations of glucose. The colours obtained were further analysed by a suitable image analysis software. Linear response for glucose ranged 1.5 to 13.0?mM. Overall, this new test-strip used renewable material for glucose determination, which is an advantage when compared to other systems that require more complex technological approaches. Moreover, it was found that Carboxyl- NC improved the colour homogeneity of the test-strip and the intrinsic linear response of concentration range.The Portuguese Science and Technology Foundation, I.P. (FCT), isacknowledged for the financial support through the project reference P2020 -PTDC/AAG-TEC/5400/2014 (also POCI-01-0145-FEDER-016637, FEDER, COMPETE, POCI) and POCTEP/INTERREG is also acknowledged through the project 2QBioneuro, Impulso de una red deI + i en química biológica para diagnóstico y tratamiento de enfermedades neurológicas. MCCGC acknowledges FCT for the PhD grant SFRH/BD/131959/2017. The Portuguese Foundation for Science andTechnology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit and BioTecNorteoperation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund underthe scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Casbane diterpene as novel and natural antimicrobial agent against biofilm infections

Croton nepetaefolius is a plant native from northeastern Brazil and belongs to Euphorbiaceae family. The essential oil of this plant is widely used in folk medicine from the treatment of gastrointestinal disorders to the use as an antiseptic agent, with an antifungal action scientifically proven. The action of this plant has been extensively explored by the scientific community, being the secondary metabolites, which are responsible for their properties, alkaloids, diterpenes, and triterpenes. The aim of this study was to evaluate the ability of the secondary metabolite, casbane diterpene (CD) (isolated of the species mentioned above), to inhibit microbial growth and biofilm formation of several clinical relevant species (about 15 species among bacteria and fungi). Minimal inhibitory concentration was assessed by the standard technique of microdilution and biofilm inhibition was tested using microtiter plates with biomass quantification by crystal violet staining method. It was found that the CD possessed biocidal and biostatic activity for the majority of the species screened, with the minimal concentration active between 125 and 500 mg/L. Moreover, CD anti-biofilm action was also observed for some of the species. In addition, it was noticed some biofilm formation inhibition even when the planktonic growth was not significantly affected. In conclusion it can be speculated that casbane diterpene shows potential to be a natural tool for the treatment of diseases caused by different infectious microorganisms

Surface functionalization of 3D printed structures: Aesthetic and antibiofouling properties

Additive manufacturing (AM) is a hot topic nowadays, having a first order in importance in research trends, improving existent technologies and carrying them further. AM can be applied to ceramics, which have importance in current technologies. Their capability to maintain functional properties for long time periods, combined with the easiness to process and the abundance of raw materials, make them a fundamental part of mankind development. Within ceramics, stoneware has a wide range of uses but in some conditions, it can be affected by biofouling. Ti(O)N and Ag-Ti(O)N coatings over 3D printed stoneware, were presented as multifunctional solution, linking aesthetical and antimicrobial properties. Films were developed by reactive direct current (DC) magnetron sputtering and characterized physical, chemical and morphologically, as well as regarding their colour variation. Moreover roughness, wettability, antibacterial and antibiofouling were also evaluated. The results revealed that the Ag doped coatings (with or without oxygen addition) had an enhanced multifunctionality compared to control samples (without Ag). Ag nanoparticles addition created a surface with potential antibacterial and antibiofouling activities, in order to resist outdoors and aqueous environments, making these films able to be applied in architectural pieces as sculptures or other decorative parts, maintaining their properties with good aesthetical properties.The authors acknowledge to MIT Portugal-2017 program by thefinancial support through FCT/MCTES for this exploratory researchproject with the reference MIT-EXPL/ISF/0006/2007 and PhysicsCenter of University of Minho and University of Porto (CFUM-UP) by itssupport though the strategical project (UID/FIS/04650/2019). Thisstudy was supported by the Portuguese Foundation for Science andTechnology (FCT) under the scope of the strategic funding of UID/FIS/04650/2019 and UID/BIO/04469/2019 unit and BioTecNorte opera-tion (NORTE-01-0145-FEDER-000004) funded by the EuropeanRegional Development Fund under the scope of Norte2020—ProgramaOperacional Regional do Norte and, in the framework of the ATRITO-0(co-financed via FEDER (PT2020) POCI-01-0145-FEDER-030446 andFCT (PIDDAC)) and the On-SURF (co-financedvia FEDER (PT2020)POCI-01-0247-FEDER-024521) projects.info:eu-repo/semantics/publishedVersio

Estudos sobre a paz e cultura da paz

Segundo o autor, a cultura da paz implica uma mudança quer na forma como a “alta cultura” lida com a realidade quer no tipo de abordagem que o senso comum faz às relações sociais, sendo que a ruptura com a ideologia conservadora, ou seja, com o senso comum realista só é possível graças a estas alterações. O autor realça tanto a importância que os estudos sobre a paz têm para o surgimento de um conceito amplo de paz, desenvolvido por Johan Galtung, como o facto destes estarem estrategicamente orientados para a transformação do sistema internacional. Sequentemente, conclui que a paz é uma categoria moral e cultural que só pode ser alcançada através do comportamento quotidian

Feasibility and Environmental Sustainability of a 103.5 kWp floating Photovoltaic Electrical System with a Case Study in a Hydroelectric Power Plant, Santa Clara Hpp, Located in the South of Brazil Region

Typical environmental problems associated with the implementation of solar photovoltaic systems for the generation of peak electrical energy, on a larger scale, such as on the order of 1 MWp, is in the occupied area, usually more than 3 km2. This can be minimized by the use of water parks or water dam’s reservoir, small and large hydroelectric power plants dams. Both the terrestrial and aquatic systems can impact the site, the first one, for the need to promote earthworks, removal of extensive green areas in the surroundings, installation of new transmission line, among others; and the second, despite the fact that a flat surface is already used and that there is no need for new civil procedures for its installation and can normally take advantage of the existing power transmission line, may cause changes in the biota of the reservoir, depending on the shading areas on the surface of the lake. Due to these facts, this research was proposed to investigate, parameterize and tropicalize an electric power generation system based on floating silicon photovoltaic cell panels installed in the Santa Clara HPP reservoir, in terms of peak power, durability, aspects and environmental impacts, with the study of possible evolutionary improvements of the project such as "tracking" or solar tracking, as well as dynamism of the structure, allowing the shadow area to be shifted over time, minimizing its effects in the local biota

Isolation and characterization of novel chlorella vulgaris mutants with low chlorophyll and improved protein contents for food applications

Microalgae are widely used as food supplements due to their high protein content, essential fatty acids and amino acids as well as carotenoids. The addition of microalgal biomass to food products (e.g., baked confectioneries) is a common strategy to attract novel consumers. However, organoleptic factors such as color, taste and smell can be decisive for the acceptability of foods supplemented with microalgae. The aim of this work was to develop chlorophyll-deficient mutants of Chlorella vulgaris by chemically induced random mutagenesis to obtain biomass with different pigmentations for nutritional applications. Using this strategy, two C. vulgaris mutants with yellow (MT01) and white (MT02) color were successfully isolated, scaled up and characterized. The changes in color of MT01 and MT02 mutant strains were due to an 80 and 99% decrease in their chlorophyll contents, respectively, as compared to the original wild type (WT) strain. Under heterotrophic growth, MT01 showed a growth performance similar to that of the WT, reaching a concentration of 5.84 and 6.06 g L-1, respectively, whereas MT02 displayed slightly lower growth (4.59 g L-1). When grown under a light intensity of 100 μmol m-2 s-1, the pigment content in MT01 increased without compromising growth, while MT02 was not able to grow under this light intensity, a strong indication that it became light-sensitive. The yellow color of MT01 in the dark was mainly due to the presence of the xanthophyll lutein. On the other hand, phytoene was the only carotenoid detected in MT02, which is known to be colorless. Concomitantly, MT02 contained the highest protein content, reaching 48.7% of DW, a 60% increase as compared to the WT. MT01 exhibited a 30% increase when compared to that of the WT, reaching a protein content of 39.5% of DW. Taken together, the results strongly suggest that the partial abrogation of pigment biosynthesis is a factor that might promote higher protein contents in this species. Moreover, because of their higher protein and lower chlorophyll contents, the MT01 and MT02 strains are likely candidates to be feedstocks for the development of novel, innovative food supplements and foods.FCT: UIDB/04085/2020info:eu-repo/semantics/publishedVersio