Browsing by Author "Algarra, Manuel"
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- Biochemical changes in cancer cells induced by photoactive nanosystem based on carbon dots loaded with Ru-complexPublication . Nesic, Maja D.; Ducic, Tanja; Gonçalves, Mara; Stepić, Milutin; Algarra, Manuel; Soto, Juan; Gemović, Branislava; Bandosz, Teresa J.; Petkovic, MarijanaCarbon dots (CDs) and N-carbon dots (N-CDs) loaded with Ru-complex (CDs@RuCN, N-CDs@RuCN, respec tively) were investigated as media imposing biochemical changes induced by UV illumination of ovarian cancer, A2780, and osteosarcoma, CAL72, cells. Synchrotron radiation-based Fourier Transform Infrared Spectroscopy was performed, and the spectra were subjected to a Principal Component Analysis. The CDs@RuCN and N CDs@RuCN effects on cancer cells were analyzed by the theoretical modelling of the stability of the composite systems and a protein database search. Moreover, a detailed evaluation of surface and optical properties of CDs@RuCN and N-CDs@RuCN was carried out. Results demonstrated selective action of the CDs@RuCN and N CDs@RuCN-based photodynamic therapy, with N-CDs@RuCN being the most active in inducing changes in A2780 and CDs@RuCN in CAL72 cells. We assume that different surface charges of nanoparticles led to direct interactions of N-CDs@RuCN with a Wnt signalling pathway in A2780 and those of CDs@RuCN with PI3–K/Akt in CAL72 cells and that further biochemical changes occurred upon light illumination.
- Chemically heterogeneous carbon dots enhanced cholesterol detection by MALDI TOF mass spectrometryPublication . Houdová, Dominika; Soto, Juan; Castro, Rita; Rodrigues, João; Soledad Pino-González, Mª; Petković, Marijana; Bandosz, Teresa J; Algarra, ManuelA binary system composed of carbon dots (CDs) and N-doped CDs (N-CDs) embedded in an organic matrix was used for the analysis of cholesterol by MALDI (matrix-assisted laser desorption and ionization time of-flight) mass spectrometry, as a model for detection of small, biologically relevant molecules. The results showed that both CDs are sensitive to the cholesterol and can be used either alone or in a binary system with 2,5-dihydroxybenzoic acid (DHB) to enhance the detection process. It was found that both COOH and NH2 groups on CDs surface contributed to the enhancement in the cholesterol detection by MALDI mass spectrometry in the presence of inorganic cations. Nevertheless, in the presence of NaCl, N-CDs led to a better reproducibility of results. It was due to the coexistence of positive and negative charge on N-CDs surface that led to a homogeneous analyte/substrate distribution, which is an important detection parameter. The enhancing effect of carbon dots was linked to a negative Gibbs energy of the complex formation between CDs, Na+ , cholesterol and DHB, and it was supported by theoretical calcula tions. Moreover, upon the addition of CDs/N-CDs, such features as a low ionization potential, vertical excitation, dipole moment and oscillator strength positively affected the cholesterol detection by MALDI in the presence of Na+.
- Comprehensive insight from phthalates occurrence: from health outcomes to emerging analytical approachesPublication . Luís, Catarina; Algarra, Manuel; Câmara, José S.; Perestrelo, RosaPhthalates are a group of chemicals used in a multitude of important industrial products (e.g., medical devices, children’s toys, and food packages), mainly as plasticizers to improve me chanical properties such as flexibility, transparency, durability, and longevity of polyvinyl chloride (PVC). The wide occurrence of phthalates in many consumer products, including foods (e.g., bottled water, soft drinks, wine, milk, and meat) brings that most people are exposed to phthalates every day, which raises some concerns. Adverse health outcomes from phthalates exposure have been associated with endocrine disruption, deformities in the human reproductive system, increased risk of preterm birth, carcinogen exposure, among others. Apprehension related to the health risks and ubiquitous incidence of phthalates in foods inspires the development of reliable analytical approaches that allow their detection and quantification at trace levels. The purpose of the current review is to provide information related to the presence of phthalates in the food chain, highlighting the health risks associated with their exposure. Moreover, an overview of emerging extraction procedures and high-resolution analytical approaches for a comprehensive quantification of phthalates is presented.
- Detection of Ru potential metallodrug in human urine by MALDI-TOF mass spectrometry: validation and options to enhance the sensitivityPublication . Nunes, Nádia; Popović, Iva; Abreu, Elder; Maciel, Dina; Rodrigues, João; Soto, Juan; Algarra, Manuel; Petkovic, MarijanaWe studied the possibility of detection of [Ru(η5 -C5H5)(PPh3)2Cl] (abbreviated by RuCp) complex as a model system for Ru-based metallodrugs in human urine by using matrix-assisted laser desorption/ionization time-of flight mass spectrometry (MALDI-TOF MS) without previous purification or removal of inorganic salts. Inorganic salts might prevent the detection of RuCp by MALDI-TOF MS, most likely through the increased number and intensity of background/organic matrix signals. This problem might be overcome by the acquisition of matrix free spectra and the addition of nanoparticles, such as carbon dots, to the urine solution. Our results suggest that RuCp is easily detectable by MALDI-TOF MS in all acquisition conditions, with the CHCA matrix being the best for acquisition in phosphate-containing solutions, whereas in urine, DHB and matrix-free approach demonstrated the highest sensitivity, precision, and reproducibility. The sensitivity of matrix-free MALDI detection of RuCp could be increased by the addition of carbon dots to the urine. Based on theoretical calcu lations for all matrix/analyte combinations, the model for the interaction of RuCp with carbon dots was established, and higher sensitivity explained.
- Evaluation of the occurrence of phthalates in plastic materials used in food packagingPublication . Perestrelo, Rosa; Silva, Catarina L.; Algarra, Manuel; Câmara, José S.Phthalates are multifunctional synthetic chemicals found in a wide array of consumer and industrial products, mainly used to improve the mechanical properties of plastics, giving them flexibility and softness. In the European Union, phthalates are prohibited at levels greater than 0.1% by weight in most food packaging. In the current study, headspace solid-phase microextraction (HS SPME) combined with gas chromatography-mass spectrometry (GC-MS) was optimized, through the multivariate optimization process, and validated to evaluate the occurrence of four common phthalates, di-iso-butyl phthalate (DIBP), butyl-benzyl phthalate (BBP), di-n-octyl phthalate (DOP), and 2,2,4,4-tetrabromodiphenyl (BDE), in different food packaging. The best extraction efficiency was achieved using the polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber at 80 ◦C for 30 min. The validated method showed good linearity, precision (RSD < 13%), and recoveries (90.2 to 111%). The limit of detection (LOD) and of quantification (LOQ) ranged from 0.03 to 0.08 µg/L and from 0.10 to 0.24 µg/L, respectively. On average, the phthalates concentration varied largely among the assayed food packaging. DIBP was the most predominant phthalate in terms of occurrence (71.4% of analyzed simples) and concentration (from 3.61 to 10.7 µg/L). BBP was quantified in only one sample and BDE was detected in trace amounts (
- Lipid Status of A2780 Ovarian Cancer Cells after Treatment with Ruthenium Complex Modified with Carbon Dot Nanocarriers: A Multimodal SR-FTIR Spectroscopy and MALDI TOF Mass Spectrometry StudyPublication . Nesic, Maja D.; Ducic, Tanja; Algarra, Manuel; Popović, Iva; Stepić, Milutin; Gonçalves, Mara; Petkovic, MarijanaIn the last decade, targeting membrane lipids in cancer cells has been a promising approach that deserves attention in the field of anticancer drug development. To get a comprehensive un derstanding of the effect of the drug [Ru(η 5 -Cp)(PPh3 )2CN] (RuCN) on cell lipidic components, we combine complementary analytical approaches, matrix-assisted laser desorption and ionization time of-flight mass spectrometry (MALDI TOF MS) and synchrotron radiation-based Fourier transform infrared (SR-FTIR) spectroscopy. Techniques are used for screening the effect of potential metallodrug, RuCN, without and with drug carriers (carbon dots (CDs) and nitrogen-doped carbon dots (N-CDs)) on the lipids of the human ovarian cancer cell line A2780. MALDI TOF MS results revealed that the lysis of ovarian cancer membrane lipids is promoted by RuCN and not by drug carriers (CDs and N-CDs). Furthermore, SR-FTIR results strongly suggested that the phospholipids of cancer cells undergo oxidative stress after the treatment with RuCN that was accompanied by the disordering of the fatty acid chains. On the other hand, using (N-)CDs as RuCN nanocarriers prevented the oxidative stress caused by RuCN but did not prevent the disordering of the fatty acid chain packing. Finally, we demonstrated that RuCN and RuCN/(N-)CDs alter the hydration of the membrane surface in the membrane–water interface region.
- Monitoring phthalates in table and fortified wines by headspace solid-phase microextraction combined with gas chromatography–mass spectrometry analysisPublication . Perestrelo, Rosa; Silva, Catarina L.; Algarra, Manuel; Câmara, José S.Phthalates are a class of endocrine disruptors extensively used in plastic production as plasticizers, and as a result, they can be found in foods as a result of their migration ability. The occurrence of phthalates was monitored in 20 Portuguese wines using a simple, reliable, and environmentally friendly analytical method, headspace solid-phase microextraction combined with gas chromatography−mass spectrometry. Satisfactory figures of merit of method, linearity (correlation coefficient of ≥0.992), recovery (80.3−107.6%), precision (relative standard deviation of <13%), and limits of detection (0.03−0.11 μg/L) and quantification (0.09−0.36 μg/L) were achieved. Dibutyl phthalate and di-n-octyl phthalate were found in measurable quantities in table and fortified wines. The obtained results revealed that these wines do not represent any concern for human exposure, because their concentrations were lower than the tolerable daily intakes established by the European Food Safety Authority.