Publications

Abstract Self-assembled vesicles composed of amino acid-based cationic/anionic surfactant mixtures show promise as novel effective drug nanocarriers. Here, we report the in vitro performance of vesicles based on cationic (16Ser) and anionic (8-8Ser) serine-based surfactants using a cancer cell model for the delivery of the anticancer drug doxorubicin (DOX). This catanionic mixture yields both negatively (0.20 in the cationic surfactant molar fraction, x(16Ser)) and positively (x(16Ser) '= 0.58) charged vesicles, hence providing a surface charge tunable system. Low toxicity is confirmed for concentration ranges below 32 mu M in both formulations. DOX is successfully encapsulated in the vesicles, resulting in a surface charge switch to negative for the (0.58) system, making both (0.20) and (0.58) DOX-loaded vesicles highly interesting for systemic administration. High uptake by cells was demonstrated using flow cytometry and confocal microscopy. Drug accumulation results in an increase of cell uptake up to 250% and 200% for the (0.20) and (0.58) vesicles, respectively, compared to free DOX and with localizations near the nuclear regions in the cells. The in vitro cytotoxicity studies show that DOX-loaded vesicles induce cell death, confirming the therapeutic potential of the formulations. Furthermore, the efficient accumulation of the drug inside the cell compartments harbors the potential for optimization strategies including phased delivery for prolonged treatment periods or even on-demand release.

Abstract In this study we focused on the social representations of digital teaching among Higher Education agents, considering their reported experience (more or less diversified) and type of access (mobile devices or not, large-screen devices or small screen-devices). The context of the study was a public Higher Education institution in the North of Portugal in which the Moodle was adopted years ago to support learning activities. The participants were 36 teachers (39% males, 61% females), aged between 25 and 55 years old, and 144 freshmen students (19% males, 81% females), aged between 18 and 57 years old, enrolled in different programs in the area of Health care. They answered to a questionnaire that consisted of: free association tasks around stimuli such as digital teaching and Moodle; a semantic differentiation scale on the attitudes towards Moodle; multiple choice questions about the levels of use and type of access to the platform; and demographic questions, including age and sex. A content-analysis of the qualitative data was conducted, using a macro developed in Excel. Words evoked by the participants were reduced to their most common form and phases rewritten to their common theme. Words and themes were then grouped under overarching categories. A descriptive analysis of the quantitative data was also performed. Results revealed that whereas for the teachers the semantic field of digital teaching consisted of the categories accessibility (47%), evolution (42%), and distance (39%); for the students it consisted of technology (97%), evolution (59%), and easiness (37%). The Moodle was seen as a kind of repository by the majority of the students (89%). Such an image is shared by less than one-half of teachers (36%), and it was more common among those who declared to use more functionalities of the learning management system (LMS). It is worth mentioning that almost one-half of students associated the Moodle with knowledge (49%). Errors and the dependency on the Internet were pointed out as the main constraints of the LMS, while accessibility and easiness of use were the main advantages. Concerning access, the portable computer was the device most used by both teachers and students (90%). Desktops were used by more than 80% of teachers and by less than 20% of students, while the reverse picture was found in the access by mobile phone (around 20% of teachers and around 70% of students). This study provides clues about the relation among the social position of the agents, their practices and their representations. The social representations seem to be more homogeneous among students than among teachers, suggesting that there is a relation with practices. The fact that the image of the Moodle as a repository is more present among the teachers who reported having used more functionalities of the Moodle is somewhat counter-intuitive and urges for more studies. It is also very suggestive that the agents use different anchors to represent digital teaching: distance in the case of the teachers and technology in the case of the students, though they converge in seeing it as a sign of evolution. Although mobile access seems to be more frequent among students, big screen devices are more used than small screen devices. These results do not support the idea of a screen-device gap among the participants, but should nevertheless open a discussion about what kind of affordances are being explored in digital teaching.

Abstract Stimuli-sensitive self-assembled nanostructures are of great relevance for the templating of nanomaterials and the design of efficient systems for the controlled delivery of molecules. Amino acid-based surfactants often display such fascinating self-assembly due to a combination of molecular features such as critical packing parameter, chirality and H-bonding interactions. Herein, we focus on a family of newly synthesized double-chained alkylcarboxylates derived from L-lysine, and designated by 8Lysn, mLys8, with n, m = 12, 14 and 16, and 12Lys16 and 16Lys12, where the numbers represent the number of C atoms in each hydrocarbon chain. The effects of the chain length asymmetry and structural isomerism of the surfactants on their interfacial properties, thermal behavior and self-assembly in water were investigated by a comprehensive toolbox, including surface tension, DSC, imaging (light microscopy, SEM, TEM and AFM) and SAXS. All the surfactants below their Krafft temperature self-organize into tubular structures of various morphologies (flat structures, twisted and coiled ribbons and hollow tubes), forming hydrogels at low surfactant concentration. Upon the solubilization phase transition, micelles or vesicles are formed depending on the surfactant structure, and the tubule-micelle or tubule-vesicle transition is thermoreversible. A molecular-level rationalization of the observed self-assembly and phase transition features is put forth.

Abstract A library of 4-[(3-methyl-4-aryl-2,3-dihydro-1,3-thiazol-2-ylidene)amino]benzene-1-sulphonamides (EMAC8002a–m) was designed and synthesised to evaluate the effect of substituents in the positions 3 and 4 of the dihydrothiazole ring on the inhibitory potency and selectivity toward human carbonic anhydrase isoforms I, II, IX, and XII. Most of the new compounds preferentially inhibit the isoforms II and XII. Both electronic and steric features on the aryl substituent in the position 4 of the dihydrothiazole ring concur to determine the overall biological activity of these new derivatives.

Abstract An experimental study of the vapour pressures and related thermodynamic properties of three phenyl derivatives of maleic anhydride and oxazole is reported. The vapour pressures of the crystalline phase of these compounds were measured at different temperatures using the Knudsen mass-loss effusion method, enabling the determination of the standard (p degrees = 0.1 MPa) molar enthalpies, entropies and Gibbs energies of sublimation. The enthalpies and temperatures of fusion were determined from DSC experiments. Quantum chemical calculations were used to calculate gas-phase isobaric heat capacities and absolute entropies. (C) 2018 Elsevier Ltd.

Abstract Gemini surfactants and bile acid salts are interesting amphiphiles owing to their unconventional and versatile molecular structure, and consequent unusual aggregation properties. In this work, we investigated the phase behavior of binary surfactant/water systems for the cationic bis-quat gemini surfactants 12-2-12 (short spacer) and 12-6-12 (intermediate spacer) and subsequently catanionic mixtures of each gemini surfactant and the bile salt sodium taurodeoxycholate, STDC The phase diagrams and phase structure were unraveled by polarized light microscopy, differential scanning calorimetry, deuterium NMR and small angle X-ray scattering. The 12-2-12 and 12-6-12 gemini form a micellar-lamellar-cubic and micellar-hexagonal-cubic phase sequence, respectively, denoting the strong influence of the spacer length on the self-assembly properties. Both the catanionic 12-212/STDC/water and 12-6-12/STDC/water systems display a rich mesomorphic behavior. One of the most striking features is that the STDC micelles are able to incorporate enormous amounts of gemini surfactant, forming an extremely wide solution region of mixed micellar structures. By contrast, the gemini micelles can only solubilize limited amounts of STDC. The liquid crystalline phases from the binary systems incorporate sizeable amounts of the counterpart surfactant, forming mixed catanionic aggregates at high concentration. Interestingly, the dilute region of both systems is dominated by liquid-liquid phase separation implying the formation of aqueous twophase micellar systems. The observed features are qualitatively rationalized in terms of packing and electrostatic effects between the surfactants at play.

Abstract In formal education, evaluation is often an intrinsic part of learning. However, in non-formal contexts, such as science centers and museums, evaluation methods are usually invasive and conflicting with visitors' agendas. The I SEA project - a science communication project - intends to develop an immersive virtual reality experience (VRE - I SEA), combining science communication and its evaluation in the same experience, becomes a meaningful procedure for both visitors and institutions. The VRE - I SEA will be hosted at two Portuguese science centers (Planetarium and Expolab). Fieldwork on these centers was developed with the following goals: characterizing each center (i.e., mission, public, models of science communication), perceiving expectations and conditions for integrating the VRE - I SEA, acknowledging experience with virtual reality (VR), and learning their vision about communicating deep seas ecosystems contents. An interview script was developed to cover these themes. Two researchers visited both centers, interviewing a total of 10 intervenients (5 percent), among stakeholders, staff members, and visitors. Data were analyzed with NVivo and cross-compared to participant observation, field notes, and audiovisual records. Results point out different visions concerning the integration of the VRE - I SEA. In the Planetarium, a science center focused on space - astronomy contents, in Porto, most participants identified common characteristics in space and deep seas ecosystems exploration and between the immersiveness of the Planetarium's sessions and the technology to be used in the VRE - I SEA. In Expolab, an Azorean science and technology center, the location was one of the main themes referred by the interviewed when discussing deep-sea ecosystems. In addition, VR is familiar to this center, as Expolab provides VR applications to several science subjects. As for science communication, the analysis of the interviews and the activities available at the time of the visits show a prevalence of a deficit and a contextual model. In fact, personnel from both centers highlight the public's search for contact with the experts and the development of the public's scientific literacy as key points in their mission. Inferring from the viewpoints of the interviewees, what distinguishes science centers from formal education is exactly the absence of systematic evaluation. In addition, science evaluation is sometimes confounded as feedback, which neither of the centers seems to have implemented in a systematic manner. However, there are several attempts for public dialogue (through interactions at the end of science sessions) and obtaining of informal feedback. In sum, the centers' flexibility in integrating and justifying a new theme of deep-sea ecosystems is remarkable, however, considering that one of the I SEA project's purpose is to incorporate a method for science communication evaluation in non-formal contexts, these results lead us to challenge the current communication models in both centers. The I SEA project leads us to rethink the purpose of science communication evaluation, through the development of non-invasive methods, with benefits for both science centers and visitors. Also, the integration of science communication evaluation into the science communication channels may present an essential component towards a more dialogical communication model for science centers, replicable in other non-formal contexts such as museums.

Abstract The standard molar enthalpies of formation in the gaseous state, at T= 298.15 K, of the 2-cyclopentenone and 3-methyl-2-cyclopentenone were derived from their standard molar energies of combustion and from their standard molar enthalpies of vaporization, obtained from static-bomb combustion calorimetry measurements and high-temperature Calvet microcalorimetry, respectively. The enthalpies of hydrogenation of the two cyclopentenones were derived from their gas-phase enthalpies of formation and the gas-phase enthalpies of formation of the corresponding cycloalkanones. The gas-phase standard molar enthalpy of formation of the compounds studied were also obtained using high level ab initio calculations and are in very good agreement with the experimental ones. In addition, thermochemical parameters associated to 2-cyclopentenone and 3-methyl-2-cyclopentenone transformations were investigated using the G3(MP2)//B3LYP level of theory. The conversions of both compounds to longer chain alkanes were found to be thermodynamically favourable. (C) 2019 Elsevier Ltd.

Abstract This work is a contribution to the thermochemical characterization of bicyclic hydrocarbons, reporting the study of six indane derivatives: 4-aminoindane, 5-aminoindane, 5-methoxyindane, 1-indanol, 2-indanol, and 5-indanol. The combustion calorimetry technique was used to measure the massic energy of combustion of each compound in the condensed state, which has been used to derive the corresponding standard (p degrees = 0.1 MPa) molar enthalpy of formation, at 298.15 K. The standard molar enthalpies of sublimation or vaporization of the compounds were determined by high-temperature Calvet microcalorimetry. For each indane derivative, the results obtained for those two properties, allowed to derive the respective value of standard molar enthalpy of formation, in the gaseous phase. Additionally, a theoretical study at the G3(MP2)//B3LYP level has been carried out, and the calculated enthalpies of formation have been compared with the experimental values. The values of the enthalpy of formation, in the gaseous phase, were analysed in terms of correlations between the structural (different substituents in the indane core) and energetics characteristics.