Publications

Abstract Photodynamic therapy (PDT) of cancer is known for its limited number of side effects, and requires light, oxygen and photosensitizer. However, PDT is limited by poor penetration of light into deeply localized tissues, and the use of external light sources is required. Thus, researchers have been studying ways to improve the effectiveness of this phototherapy and expand it for the treatment of the deepest cancers, by using chemiluminescent or bioluminescent formulations to excite the photosensitizer by intracellular generation of light. The aim of this Minireview is to give a precis of the most important general chemi-/bioluminescence mechanisms and to analyze several studies that apply them for PDT. These studies have demonstrated the potential of utilizing chemi-/bioluminescence as excitation source in the PDT of cancer, besides combining new approaches to overcome the limitations of this mode of treatment.

Abstract In the original article[1] there is an error in the structure of compound 3j (the methyl group should be attached to the β-position and not to the α-position) and in some NMR resonances; also the name of compound 3g and two of its NMR assignments are erroneous. Correct versions are given below in Scheme 1, Figure 2, and the two related paragraphs of the Exp. Sect. An amended file of the Supporting Information is also available. (Figure presented.) © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Abstract Gas-phase electronic and structural properties of the room temperature ionic liquid 1-ethyl-3-methylimidazolium tris(perfluoroethyl) trifluorophosphate ([EMIM][FAP]) were studied using density functional theory, and confirmed with results from infrared spectroscopy. A conformational analysis allowed the identification of several plausible conformers of the ion pairs. For the detected conformers, the infrared spectra were predicted and their thermodynamic properties were evaluated. The topology of the electronic density of the most stable conformers of [EMIM][FAP] ion pairs were characterised using the quantum theory of atoms in molecules. A number of possible hydrogen bonds between the cations and anions of the ionic liquid were identified. Excellent correspondence was found between the predicted spectra of gas-phase [EMIM][FAP] conformers and the experimental infrared spectrum, which in turn allowed a clear attribution of the vibration modes of [EMIM][FAP]. Finally, the contribution of the various conformers of both isomers of the [FAP](-) anion to the ionic liquid macro-properties is shown.

Abstract Highly and stable fluorescent carbon dots (CQDs), with lambda(ex)/lambda(em) = 350/465 nm were obtained using a strong acid oxidation of activated carbon in aqueous suspension. The nanoparticles had a mean size of 12 nm and quantum yield of 3.94%. After functionalization with amine groups by PAMAM-NH2 dendrimer (CQDs@PAMAM-NH2), the size of particles increased and aggregates of 65 nm were formed. Quantum yield also increased to 6.33%. CQDs were characterized by various analytical techniques including ATR-FTIR, Raman, XPS and fluorescence spectroscopies. The prepared CQDs@PAMAM-NH2 were used as fluorescent ratiometric nanosensor of 4-chloro-2,6-dinitroaniline, which is a constituent of explosives. As a result of interactions, the fluorescence at 465 nm was quenched. Moreover, a new band at 507 nm emerged and it is linked to a charge transfer and the formation of a Meisenheimer complex. A ratio of fluorescence intensities at 465 and 507 nm (I-465/I-507) is used for a ratiometric fluorescence sensing. A linear detection ranges from 1.0 x 10(-5) to 6.0 x 10(-4) M with a detection limit of 2 mu M and accuracy of 0.85% as standard relative deviation (RSD, n = 10). The detection accuracy in the presence of other nitrocompounds was 2.80% as RSD.

Abstract In this work, we combined various parameters found in the literature for the choline cation, chloride anion, and ethylene glycol to set up force field models (FFMs) for a eutectic mixture, namely, ethaline (1:2 choline chloride/ethylene glycol (ChCl:2EG)). The validation of these models was carried out on the basis of physical and chemical properties, such as the density, expansion coefficient, enthalpy of vaporization, self-diffusion coefficients, isothermal compressibility, surface tension, and shear viscosity. After the initial evaluation of the FFMs, a refinement was found necessary and accomplished by taking into account polarization effects in a mean-field manner. This was achieved by rescaling the electrostatic charges of the ions based on partial charges derived from ab initio molecular dynamics (MD) simulations of the bulk system. Classical all-atom MD simulations performed over a large range of temperatures (298.15-373.15 K) using the refined FFMs clearly showed improved results, allowing a better prediction of experimental properties. Specific structural properties (radial distribution functions and hydrogen bonding) were then analyzed in order to support the adequacy of the proposed refinement. The final selected FFM leads to excellent agreement between simulated and experimental data on dynamic and structural properties. Moreover, compared to the previously reported force field model (Perkins, S. L.; Painter, P.; Colina, C. M. Experimental and Computational Studies of Choline Chloride-Based Deep Eutectic Solvents. J. Chem. Eng. Data 2014, 59, 3652-3662), a 10% improvement in simulated transport properties, i.e., self-diffusion coefficients, was achieved. The isothermal compressibility, surface tension, and shear viscosity for ethaline are accessed in MD simulations for the first time.

Abstract Cadmium-based quantum dots (QDs) are increasingly applied in existent and emerging technologies, especially in biological applications due to their exceptional photophysical and functionalization properties. However, they are very toxic compounds due to the high reactive and toxic cadmium core. The present study aimed to determine the toxicity of three different QDs (CdS 380, CdS 480 and CdSeS/ZnS) before and after the exposure of suspensions to sunlight, in order to assess the effect of environmentally relevant irradiation levels in their toxicity, which will act after their release to the environment. Therefore, a battery of ecotoxicological tests was performed with organisms that cover different functional and trophic levels, such as Vibrio fischeri, Raphidocelis subcapitata, Chlorella vulgaris and Daphnia magna. The results showed that core-shell type QDs showed lower toxic effects to V. fischeri in comparison to core type QDs before sunlight exposure. However, after sunlight exposure, there was a decrease of CdS 380 and CdS 480 QD toxicity to bacterium. Also, after sunlight exposure, an effective decrease of CdSeS/ZnS and CdS 480 toxicity for D. magna and R. subcapitata, and an evident increase in CdS 380 QD toxicity, at least for D. magna, were observed. The results of this study suggest that sunlight exposure has an effect in the aggregation and precipitation reactions of larger QDs, causing the degradation of functional groups and formation of larger bulks which may be less prone to photo-oxidation due to their diminished surface area. The same aggregation behaviour after sunlight exposure was observed for bare QDs. These results further emphasize that the shell of QDs seems to make them less harmful to aquatic biota, both under standard environmental conditions and after the exposure to a relevant abiotic factor like sunlight.

Abstract In the past few years a large effort is being made aiming at the development of fast and reliable tests for cancer biomarkers. Protein imprinted sensors can be a fast and reliable strategy to develop tailor made sensors for a large number of relevant molecules. This work aims to produce, optimize and use in biological samples a biosensor for microseminoproteinbeta (MSMB). Caffeic acid (CAF) electropolimerization was performed in the presence of microseminoprotein-beta (MSMB) creating target protein specific cavities on the surface of a screen-printed carbon. Dopamine was introduced as charged monomer labelling the binding site and was allowed to self-organize around the protein. The subsequent electropolimerization was made by applying a constant potential of +2.0 V, for 30s, on a carbon screen-printed electrode, immersed in a solution of protein and CAF prepared in phosphate buffer. The sensor with charged monomers showed a more sensitive response, with an average slope of -7.59 mu A/decade, linear concentration range of 0.5-100 ng/mL and a detection limit of 0.12 ng/mL. The corresponding non-imprinted sensor displayed an inconsistent response over the range of the calibration curve. The biosensor was successfully applied to the analysis of MSMB in serum and urine samples.

Abstract The ultraviolet-visible spectroscopy has been assessed as a technique for the evaluation of the strength of template-precursor adduct in the development of molecular imprints of the non-steroidal anti-inflammatory drug naproxen (NAP). The commonly employed approach relies on the collection of UV spectra of drug + precursor mixtures at different proportions, the spectra being recorded against blanks containing the same concentration of the precursor. The observation of either blue or red band-shifts and abatement of a major band are routinely attributed to template-precursor adduct formation. Following the described methodology, the precursors 1-(triethoxysilylpropyl)-3-(trimethoxysilylpropyl)-4,5-dihydroimidazolium iodide (AO-DHI+) and 4-(2-(trimethoxysilyl)ethyl)pyridine (PETMOS) provoked a blue-shift and band abatement effect on the NAP spectrum. Molecular dynamics simulations indicated a reasonable affinity between NAP and these precursors (coordination numbers 033 for AO-DHI+ and 0.18 for PETMOS), hence showing that NAP-precursor complexation is in fact effective. However, time dependent density functional theory (TD-DFT) calculations of the spectra of both free and precursor-complexed NAP were identical, thus providing no theoretical basis for the complexation-induced effects observed. We realized that the intense spectral bands of AO-DHI+ and PETMOS (at around 265 nm) superimpose partially with the NAP bands, and the apparent "blue-shifting" in the NAP spectra when mixed with AO-DHI + and PETMOS was in this case a spurious effect of the intense background subtraction. Therefore, extreme care must be taken when interpreting other spectroscopic results obtained in a similar fashion.

Abstract For the first time, a glassy carbon electrode (GCE) modified with novel N-doped carbon nanotubes (CNTN) functionalized with MnFe2O4 nanoparticles (MnFe2O4@CNT-N) has been prepared and applied for the electrochemical determination of caffeine (CF), acetaminophen (AC) and ascorbic acid (AA). The electrochemical behaviour of CF, AC and AA on the bare GCE, CNT-N/GCE and MnFe2O4@CNT-N/GCE were carefully investigated using cyclic voltammetry (CV) and square-wave voltammetry (SWV). Compared to bare GCE and CNT-N modified electrode, the MnFe2O4@CNT-N modified electrode can remarkably improve the electrocatalytic activity towards the oxidation of CF, AC and AA with an increase in the anodic peak currents of 52%, 50% and 55%, respectively. Also, the SWV anodic peaks of these molecules could be distinguished from each other at the MnFe2O4@CNT-N modified electrode with enhanced oxidation currents. The linear response ranges for the square wave voltammetric determination of CF, AC and AA were 1.0 x 10(-6) to 1.1 x 10(-3) mol dm(-3), 1.0 x 10(-6) to 1.0 x 10(-3) mol dm(-3) and 2.0 x 10(-6) to 1.0 x 10(-4) mol dm(-3) with detection limit (S/N= 3) of 0.83 x 10(-6), 0.83 x 10(-6) and 1.8 x 10(-6) mol dm(-3), respectively. The sensitivity values at the MnFe2O4@CNT-N/GCE for the individual determination of AC, AA and CF and in the presence of the other molecules showed that the quantification of AA and CF show no interferences from the other molecules; however, AA and CF interfered in the determination of AC, with the latter molecule showing the strongest interference. Nevertheless, the obtained results show that MnFe2O4@CNT-N composite material acted as an efficient electrochemical sensor towards the selected biomolecules.