Label-free human chorionic gonadotropin detection at picogram levels using oriented antibodies bound to graphene screen-printed electrodes

Human chorionic gonadotropin (hCG) is a key diagnostic marker of pregnancy and an important biomarker for cancers in the prostate, ovaries and bladder and therefore of great importance in diagnosis. For this purpose, a new immunosensor of screen-printed electrodes (SPEs) is presented here. The device was fabricated by introducing a polyaniline (PANI) conductive layer, via in situ electropolymerization of aniline, onto a screen-printed graphene support. The PANI-coated graphene acts as the working electrode of a three terminal electrochemical sensor. The working electrode is functionalised with anti-hCG, by means of a simple process that enabled oriented antibody binding to the PANI layer. The antibody was attached to PANI following activation of the –COOH group at the Fc terminal. Functionalisation of the electrode was analysed and optimized using Electrochemical Impedance Spectroscopy (EIS). Chemical modification of the surface was characterised using Fourier transform infrared, and Raman spectroscopy with confocal microscopy. The graphene–SPE–PANI devices displayed linear responses to hCG in EIS assays from 0.001 to 50 ng mL−1 in real urine, with a detection limit of 0.286 pg mL−1. High selectivity was observed with respect to the presence of the constituent components of urine (urea, creatinine, magnesium chloride, calcium chloride, sodium dihydrogen phosphate, ammonium chloride, potassium sulphate and sodium chloride) at their normal levels, with a negligible sensor response to these chemicals. Successful detection of hCG was also achieved in spiked samples of real urine from a pregnant woman. The immunosensor developed is a promising tool for point-of-care detection of hCG, due to its excellent detection capability, simplicity of fabrication, low-cost, high sensitivity and selectivity.

Specific label-free and real-time detection of oxidized low density lipoprotein (oxLDL) using an immunosensor with three monoclonal antibodies

Increased levels of plasma oxLDL, which is the oxidized fraction of Low Density Lipoprotein (LDL), are associated with atherosclerosis, an inflammatory disease, and the subsequent development of severe cardiovascular diseases that are today a major cause of death in modern countries. It is therefore important to find a reliable and fast assay to determine oxLDL in serum. A new immunosensor employing three monoclonal antibodies (mAbs) against oxLDL is proposed in this work as a quick and effective way to monitor oxLDL. The oxLDL was first employed to produce anti-oxLDL monoclonal antibodies by hybridoma cells that were previously obtained. The immunosensor was set-up by selfassembling cysteamine (Cyst) on a gold (Au) layer (4 mm diameter) of a disposable screen-printed electrode. Three mAbs were allowed to react with N-hydroxysuccinimide (NHS) and ethyl(dimethylaminopropyl)carbodiimide (EDAC), and subsequently incubated in the Au/Cys. Albumin from bovine serum (BSA) was immobilized further to ensure that other molecules apart from oxLDL could not bind to the electrode surface. All steps were followed by various characterization techniques such as electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV). The analytical operation of the immunosensor was obtained by incubating the sensing layer of the device in oxLDL for 15 minutes, prior to EIS and SWV. This was done by using standard oxLDL solutions prepared in foetal calf serum, in order to simulate patient's plasma with circulating oxLDL. A sensitive response was observed from 0.5 to 18.0 mg mL 1 . The device was successfully applied to determine the oxLDL fraction in real serum, without prior dilution or necessary chemical treatment. The use of multiple monoclonal antibodies on a biosensing platform seemed to be a successful approach to produce a specific response towards a complex multi-analyte target, correlating well with the level of oxLDL within atherosclerosis disease, in a simple, fast and cheap way.

A label-free DNA aptamer-based impedance biosensor for the detection of E. coli outer membrane proteins

A label-free DNA aptamer-based impedance biosensor for the detection of E. coli outer membrane proteins (OMPs) was developed. Two single stranded DNA sequences were tested as recognition elements and compared. The aptamer capture probes were immobilized, with and without 6-mercapto-1-hexanol (MCH) on a gold electrode. Each step of the modification process was characterized by Faradaic impedance spectroscopy (FIS). A linear relationship between the electron-transfer resistance (Ret) and E. coli OMPs concentration was demonstrated in a dynamic detection range of 1 × 10−7–2 × 10−6 M. Moreover, the aptasensor showed selectivity despite the presence of other possible water contaminates and could be regenerated under low pH condition. The developed biosensor shows great potential to be incorporated in a biochip and used for in situ detection of E. coli OMPs in water samples.

Label-free Detection of Microcystin-LR in Waters Using Real-Time Potentiometric Biosensors Based on Single-Walled Carbon Nanotubes Imprinted Polymers

Microcystin-LR (MC-LR) is a dangerous toxin found in environmental waters, quantified by high performance liquid chromatography and/or enzyme-linked immunosorbent assays. Quick, low cost and on-site analysis is thus required to ensure human safety and wide screening programs. This work proposes label-free potentiometric sensors made of solid-contact electrodes coated with a surface imprinted polymer on the surface of Multi-Walled Carbon NanoTubes (CNTs) incorporated in a polyvinyl chloride membrane. The imprinting effect was checked by using non-imprinted materials. The MC-LR sensitive sensors were evaluated, characterized and applied successfully in spiked environmental waters. The presented method offered the advantages of low cost, portability, easy operation and suitability for adaptation to flow methods.

Isoflavones in food supplements: chemical profile, label accordance and permeability study in Caco-2 cells

Consumers nowadays are playing an active role in their health-care. A special case is the increasing number of women, who are reluctant to use exogenous hormone therapy for the treatment of menopausal symptoms and are looking for complementary therapies. However, food supplements are not clearly regulated in Europe. The EFSA has only recently begun to address the issues of botanical safety and purity regulation, leading to a variability of content, standardization, dosage, and purity of available products. In this study, isoflavones (puerarin, daidzin, genistin, daidzein, glycitein, genistein, formononetin, prunetin, and biochanin A) from food supplements (n = 15) for menopausal symptoms relief are evaluated and compared with the labelled information. Only four supplements complied with the recommendations made by the EC on the tolerable thresholds. The intestinal bioavailability of these compounds was investigated using Caco-2 cells. The apparent permeability coefficients of the selected isoflavonoids across the Caco-2 cells were affected by the isoflavone concentration and product matrix.

Label-free detection of biomolecules with Ta2O5-based field effect devices

Dissertação para obtenção do Grau de Doutor em Nanotecnologias e Nanociências

Which characteristics, behaviours and perceptions influence the consumption of Nestum private label brands?

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics

“Private label products: A category analysis”

The presented dissertation was developed within a partnership between Nova School of Business and Economics and the Portuguese retailer Sonae MC. The main objective of the study was to develop an analysis for the confectionary category to identify potential development opportunities for new Private Label products. In order to do so, the starting point was to understand how the confectionery market was behaving, followed by and understanding of Continente’s performance in that market. Aiming to point out development opportunities, the analysis was split between the subcategories – Chocolate, Chewing Gums and Sweets. The Subcategory performance was assessed in terms of sales, number of SKU’s, Private Label weight and it market position in terms of share. For the potential development opportunities a comparison between the top selling Branded Product and the competitors’ position was developed, in order to establish a reasonable size and retail price for such products. Key Word: Private Label, Branded Products, Continente, Sonae MC, Retail, SKU’s, Sales, Price, Market Share,

A inovação, as marcas próprias e o private label no setor do calçado em Portugal

O sector do calçado português apresenta excelentes indicadores económicos e um desempenho competitivo assinalável. Os últimos quatro anos foram particularmente fortes, tendo Portugal atingido o 11º lugar entre os 15 maiores exportadores mundiais, com o segundo preço mais elevado por par de sapato vendido, superado apenas pela Itália. O artigo analisa o tipo de inovação realizada pelas empresas consideradas inovadoras dentro do sector do calçado em Portugal, de acordo com o manual de Oslo, e analisa a evolução que as empresas fizeram ao passarem de um regime dominado pelo private label para o desenvolvimento de produtos, de coleções e de marcas próprias. A pesquisa foi de natureza qualitativa, envolvendo sete empresas com inovação, sendo realizado estudos de caso através de entrevistas semi-estruturadas, análise de documentos e visitas às empresas e aos seus processos produtivos e de criação. Os resultados obtidos na investigação evidenciam uma relação entre os indicadores económicos e de desempenho e a existência de determinadas categorias de inovação. Evidencia ainda a relação existente entre o regime de produção e os indicadores económicos das empresas.

Sensitive label-free electron chemical capacitive transducer signal for D-dimer electroanalyses

Supplementary data associated with this article can be found, in the online version, at: http://dx.doi.org/10.1016/j.electacta.2015.09.169.

A multicenter, open-label study of the efficacy and safety of telmisartan in mild to moderate hypertensive patients

OBJECTIVE: To evaluate the efficacy and tolerability of telmisartan, given once a day to patients with mild to moderate hypertension, as well as to assess the 24-hour blood pressure profile with ABPM. METHODS: Initially, 163 patients over 18 were selected, regardless of sex, with blood pressure levels >140/90mmHg at visit 1, which was confirmed at visit 2. One hundred thirty-four patients completed the study. After a 4-week placebo run-in phase, telmisartan 40mg/daily was given for 6 weeks. In those patients whose blood pressure (BP) levels were lower than 140/90mmHg, the same dosage was kept for an additional period of 6 weeks. For those who had BP higher than 140/90mmHg, the dosage was increased to 80mg/daily. Sixty-two patients were included in a subgroup that underwent ABPM 3 different times during the study. RESULTS: In the overall group, blood pressure reduction ranged from 162.3±14.5/101.3±5.75 mmHg (baseline) to 147.3±20.1/90.8±10.9 mmHg (week 12) (p<0.05). Mean blood pressure decreases were 14.4mmHg for systolic BP and 10.3mmHg for diastolic BP, after 12 weeks of active treatment. A subanalysis showed that 47 (35%) patients took telmisartan 40mg throughout the study and 81 (65%) had the dosage increased to 80mg daily. Using ABPM, an 8-mmHg reduction in systolic BP as well as a 5-mmHg reduction in diastolic BP were observed, when compared with baseline values in the final 6 hours (18-24 hours after the last dose of study medication). CONCLUSION: Our results confirm that telmisartan given once a day is effective in reducing blood pressure levels in mild to moderate hypertensive patients. This reduction occurs in a sustained and gradual manner during a 24-hour period confirmed by ABPM.

Evaluación del uso “extra-label” de fluorquinolonas en llamas desde un enfoque plural: bienestar animal versus salud pública y ecotoxicología

La explotación comercial de la llama facilita la aparición de patologías bacterianas y parasitarias que producen importantes pérdidas económicas. Su prevención y el tratamiento exigen establecer regímenes terapéuticos eficaces y seguros que eviten la aparición de resistencias. La ausencia de especialidades farmacéuticas propias para esta especie y la falta de información científica sobre el comportamiento de los fármacos de uso habitual en llamas, obligan al veterinario a establecer pautas terapéuticas “fuera de prospecto”, a partir de su experiencia en otras especies. Esto conlleva el riesgo de alcanzar o bien niveles tóxicos o bien sub-terapéuticos, estos últimos facilitan la aparición de resistencias bacterianas transmisibles a otras poblaciones. Pretendemos describir el comportamiento cinético de dos antimicrobianos de amplio espectro y uso exclusivo en veterinaria (enrofloxacina y marbofloxacina). Los datos obtenidos nos permitirán evaluar la seguridad y eficacia de diferentes regímenes terapéuticos que puedan dar respuesta a las necesidades clínicas en esta especie. El proyecto que abordamos se encuentra en una línea de aprovechamiento de los recursos naturales dentro de un espíritu de compromiso social, desarrollo sostenible, bienestar animal y salud pública.

Label monitoring on document streams

Magdeburg, Univ., Fak. für Informatik, Diss., 2012

Eine Schule für alle - Inklusive Bildung als Vision, als Label oder als Korrektur

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