Publications

Abstract Microalgae and cyanobacteria have received ample attention in the last few decades due to their environmental and biotechnological applications. Co-cultures of these microorganisms may present benefits particularly on wastewater bioremediation and biomass production. However, the understanding on the interactions between photosynthetic microorganisms is still in an early stage of knowledge. In this line, the aim of the present study was the evaluation of the growth dynamics of co-cultures of a cyanobacterium, Synechocystis salina, and a microalga, Pseudokirchneriella subcapitata, under low phosphate-phosphorus concentrations. Kinetic growth parameters were determined through the Monod and modified Gompertz models and evidence of allelochemical production was confirmed through metabolomic analysis of the supernatant obtained from the co-cultures using GC-MS and 1D-NMR. Kinetic growth parameters have shown that P. subcapitata was better adapted to grow under low phosphorus concentrations. Co-cultivation of these microorganisms did not influence P. subcapitata growth; however, S. salina growth was strongly inhibited. The modified Gompertz model has shown that growth inhibition of S. salina in co-cultures may be related to the activity of allelochemicals produced by P. subcapitata. This assumption was corroborated by the assessment of the antimicrobial potential of lactic acid (2-hydroxypropanoic acid), an organic acid identified in the supernatant from the co-cultures with growth inhibitory effects against S. salina.

Abstract The development of new chemical entities represents an important challenge in pharmaceutical industry, being the use of privileged scaffolds for library design and drug discovery a valuable approach. Among the panoply of privileged structures, our research group has focused its attention on the chromone (4H-benzopyran-4-one) scaffold due to its chemical versatility and ability to bind to multiple targets. With this endeavour we report an expedite two-step procedure for the synthesis of novel 6-aryl/heteroaryl-4-oxo-4H-chromene-2-carboxylic ethyl ester. The new chromones were synthesized by a C-C Suzuki cross-coupling microwave-assisted reaction, using Pd(OAc)(2) as a catalyst, and a classic Claisen condensation followed by an intramolecular cyclization process.

Abstract The development of fast and reliable methods for protein determination are of great relevance to a diversity of areas from industry to diagnostics. Molecular Imprinted Materials (MIM) has proved to be an interesting methodology for protein analysis however further studies of the effect of the experimental parameters and starting materials in the performance of the MIM are still required. Caffeic acid (CAF) is employed for the first time as a monomer to tailor a synthetic receptor for a protein target. This was done by bulk-electropolymerization, applying a constant potential of +2.0 V, for 30 s, on a carbon screen printed electrode, immersed in a solution of protein and CAF prepared in phosphate buffer. Annexin A3 (ANXA3) was selected as protein target due to the fact that this is an emerging biomarker in prostate cancer. The assembly of the protein imprinted material (PIM) was followed by Electrochemical Impedance Spectroscopy (EIS) and Raman Spectroscopy. A non-imprinted material (NIM) was prepared in parallel as control. Square wave voltammetry (SWV) was used to monitor the electrochemical signal of the [Fe(CN)(6)](3-)/[Fe(CN)(6)](4-) redox for the quantification of ANXA3. The optimized PIM-based device showed average detection limits (LOD) of 0.095 ng/mL, a linear behavior against log (concentration) between 0.10, and 200 ng/mL and good selectivity. The NIM-based device showed random behavior against protein concentration. Finally, the PIM-sensor was successfully applied to the analysis of ANXA3 in spiked urine samples.

Abstract Nanotechnology offers substantial prospects for the development of innovative products and it is expected that the number of nanotechnology-based products will increase in the future. A number of promising applications are emerging, such as, smart packaging, nanosensors for pathogen detection, agrochemical nanoformulations, and nanoencapsulation of food ingredients for chemical preservation and shelf life extension. In this chapter, a special attention is given on how nanotechnology can mitigate the chemical changes of bioactive compounds, mainly those with nutritional value, occurring in food industry chain. Within this framework, an overview of the main external (oxygen, temperature, and light) factors that cause chemical degradation of some bioactive compounds present in food and affect food quality, and consequently contribute to food spoilage, and safety is also presented. © 2017 Elsevier Inc. All rights reserved.

Abstract Purpose: There is nowadays extensive experimental and computational investigation on the pathophysiology of atherosclerosis, searching correlations between its focal nature and local hemodynamic environment. The goal of this work is to present a methodology for patient-specific hemodynamics study of the carotid artery bifurcation based on the use of ultrasound (US) morphological and blood flow velocity patient data. Materials/methods: Subject-specific studies were performed for two patients, using a developed finite element code. Geometrical models were obtained from the acquisition of longitudinal and sequential cross-sectional ultrasound images and boundary conditions from Doppler velocity measurements at the common carotid artery. Results: There was a good agreement between ultrasound imaging data and computational simulated results. For a normal and a stenosed carotid bifurcation the velocity, wall shear stress (WSS) and WSS descriptors analysis illustrated the extremely complex hemodynamic behavior along the cardiac cycle. Different patterns were found, associated with morphology and hemodynamic patient-specific conditions. High values of time-averaged WSS (TAWSS) were found at stenosis site and for both patients TAWSS fields presented low values within areas of high oscillating shear index and relative residence time values, corresponding to recirculation zones. Conclusion: Simulated hemodynamic parameters were able to capture the disturbed flow conditions in a normal and a stenosed carotid artery bifurcation, which play an important role in the development of local atherosclerotic plaques. Computational simulations based on clinic US might help improving diagnostic and treatment management of carotid atherosclerosis.

Abstract A strategy based on water-in-oil emulsion for the dispersion of a sol-gel mixture into small droplets was employed with the view of the production of naproxen-imprinted micro- and nanospheres. The procedure, aiming at a surface imprinting process, comprised the synthesis of a naproxen-derived surfactant. The imprinting process occurred at the interface of the emulsions or microemulsions, by the migration of the NAP-surfactant head into the sol-gel drops to leave surficial imprints due mainly to ion-pair interaction with a cationic group contained within the growing sol-gel network. The surface imprinted microspheric particles exhibited a log-normal size distribution with geometric mean diameter of 3.1 mu m. Amesoporous texture was found from measurements of the specific surface area (206 m(2)/g) and pore diameter (D-P 2 nm). Evaluation of the microspheres as packed HPLC stationary phases resulted in the determination of the selectivity factor against ibuprofen (alpha=2.1), demonstrating the successful imprinting. Chromatographic efficiency, evaluated by the number of theoretical plates (222 plates cm(-3)), emerged as an outstanding feature among the set of all relatable formats produced before, an advantage intrinsic to the location of the imprinted sites on the surface. The material presented a capacity of 3.2 mu mol g(-1). Additionally, exploratory work conducted on their nanoscale counterparts resulted in the production of nanospheres in the size order of 10 nm providing good indications of a successful imprinting process.

Abstract Electrified double-layer (EDL) of ionic liquids electrode interfaces have been attracting considerable interest both from the fundamental and applied points of view. So far from the large set of ionic liquids synthetized only a very limited number has been electrochemically studied. As a consequence, the effect of complex shape and chemical properties of the ions and surface morphology on the structure and mechanism of formation of EDL is far from being understood. Binary mixtures of ionic liquids with a common cation (1-ethyl-3-methylimidazolium) paired with two different anions (bis(trifuoromethylsulfonyl) imide, [Tf N-2](-) and tris(pentafluoroethyl)trifluorophosphate, [FAP](-)) were prepared and their molecular mixing behavior was followed through the changes in their vibrational structure by Fourier transform infrared (ATR-FT-IR) spectroscopy. The interface at Hg and each of the binary mixture was followed by electrochemical impedance spectroscopy and drop time measurements. Differential capacitance and charge-potential curves were obtained and compared with those corresponding to the pure liquids. The data is interpreted as suggesting the coexistence at the interface of a mixture of two limiting structures each of which containing essentially one of the anions and sharing the common cation in a co-network.

Abstract This work describes the state of the art of electrochemical devices for the detection of an important class of neurotransmitters: the catecholamines. This class of biogenic amines includes dopamine, noradrenaline (also called norepinephrine) and adrenaline (also called epinephrine). Researchers have focused on the role of catecholamine molecules within the human body because they are involved in many important biological functions and are commonly associated with several diseases, such as Alzheimer's and Parkinson. Furthermore, the release of catecholamines as a consequence of induced stimulus is an important indicator of reward-related behaviors, such as food, drink, sex and drug addiction. Thus, the development of simple, fast and sensitive electroanalytical methodologies for the determination of catecholamines is currently needed in clinical and biomedical fields, as they have the potential to serve as clinically relevant biomarkers for specific disease states or to monitor treatment efficacy. Currently, three main strategies have used by researchers to detect catecholamine molecules, namely: the use electrochemical materials in combination with, for example, HPLC or FIA, the incorporation of new materials/layers on the sensor surfaces (Tables 1-7) and in vivo detection, manly by using FSCV at CFMEs (Section 10). The developed methodologies were able not only to accurately detect catecholamines at relevant concentration levels, but to do so in the presence of co-existing interferences in samples detected (ascorbate, for example). This review examines the progress made in electrochemical sensors for the selective detection of catecholamines in the last 15 years, with special focus on highly innovative features introduced by nanotechnology. As the literature in rather extensive, we try to simplify this work by summarizing and grouping electrochemical sensors according to the manner their substrates were chemically modified. We also discuss the current and future of electrochemical sensors for catecholamines in terms of the analytical performance of the devices and emerging applications.

Abstract One of the earliest synthetic antimalarial drugs, quinacrine, was recently reported as interesting for the treatment of acute myeloid leukemia. Inspired by this and similar findings, we evaluated a set of quinacrine analogues against gastric (MKN28), colon (Caco-2), and breast (MFC-7) cancer cell lines and one normal human fibroblast cell line (HFF-1). All the compounds, previously developed by us as dual-stage antimalarial leads, displayed antiproliferative activity, and one of the set stood out as selective toward the gastric cancer cell line, MKN-28. Interestingly, this compound was transported across an in vitro MKN-28 model cell line in low amounts, and approximately 80% was trapped inside those cells. Nuclear targeting of the same compound and its interactions with calf thymus DNA were assessed through combined fluorescence microscopy, spectroscopy, and calorimetry studies, which provided evidence for the compound's ability to reach the nucleus and to interact with DNA.