DSpace Collection:https://hdl.handle.net/10171/167462024-03-28T13:41:26Z2024-03-28T13:41:26ZPhotocatalytic and antibacterial performance of β-cyclodextrin-TiO2 nanoparticles loading sorbic and benzoic acidshttps://hdl.handle.net/10171/683232024-01-15T06:04:56Z2023-01-01T00:00:00ZTitle: Photocatalytic and antibacterial performance of β-cyclodextrin-TiO2 nanoparticles loading sorbic and benzoic acids
Abstract: TiO2 nanoparticles (NPs) have been modified with β-cyclodextrin (βCD)-food preservative complexes. The susceptibility of Escherichia coli and Staphylococcus aureus to TiO2 NPs, sorbic acid (SA), benzoic acid (BA), and β-Cyclodextrin-TiO2 NPs including SA or BA, was studied. At 0.5 mg mL−1, TiO2 NPs were more effective in the inhibition of bacterial growth than modified-TiO2 NPs, achieving 71% inhibition rate. At the higher concentration of 3 mg mL−1 there were no significant differences between treatments, being all of them highly effective reaching 90% inhibition. Higher treatment-doses were related to slower growth rates. Flow cytometry findings suggested efficient NPs interaction with bacteria, being more noticeable in the case of TiO2 NPs. Regarding the photocatalytic activity, under 0.600 mW cm−2 irradiation, TiO2 NPs reached 95% methylene-blue dye degradation after 150 min, while βCD-TiO2 NPs showed 3-times lower kinetic constant. Overall results suggest potential application of the new systems in active packages to protect food from microbial spoilage.2023-01-01T00:00:00ZGliadin nanoparticles for oral administration of bioactives: Ex vivo and in vivo investigationshttps://hdl.handle.net/10171/682872024-01-15T06:05:02Z2023-01-01T00:00:00ZTitle: Gliadin nanoparticles for oral administration of bioactives: Ex vivo and in vivo investigations
Abstract: This study aims to provide a thorough characterization of Brij O2-stabilized gliadin nanoparticles to be used for
the potential oral administration of various compounds. Different techniques were used in order to evaluate their
physico-chemical features and then in vivo studies in rats were performed for the investigation of their biodistribution and gastrointestinal transit profiles. The results showed that the gliadin nanoparticles accumulated
in the mucus layer of the bowel mucosa and evidenced their ability to move along the digestive systems of the
animals. The incubation of the nanosystems with Caenorhabditis elegans, used as an additional in vivo model,
confirmed the intake of the particles and evidenced their presence along the entire gastrointestinal tract of these
nematodes. The gliadin nanoparticles influenced neither the egg-laying activity of the worms nor their metabolism of lipids up to 10 μg/mL of nanoformulation. The systems decreased the content of the age-related lipofuscin pigment in the nematodes in a dose-dependent manner, demonstrating a certain antioxidant activity.
Lastly, dihydroethidium staining showed the absence of oxidative stress upon incubation of the worms together
with the formulations, confirming their safe profile. This data paves the way for the future application of the
proposed nanosystems regarding the oral delivery of various bioactives.2023-01-01T00:00:00ZValidation of an efficiency calibration procedure for a coaxial n-type and a well-type HPGe detector used for the measurement of environmental radioactivityhttps://hdl.handle.net/10171/682172024-01-15T06:05:03Z2016-01-01T00:00:00ZTitle: Validation of an efficiency calibration procedure for a coaxial n-type and a well-type HPGe detector used for the measurement of environmental radioactivity
Abstract: To obtain reliable measurements of the environmental radionuclide activity using HPGe (High Purity
Germanium) detectors, the knowledge of the absolute peak efficiency is required. This work presents a
practical procedure for efficiency calibration of a coaxial n-type and a well-type HPGe detector using
experimental and Monte Carlo simulations methods. The method was performed in an energy range
from 40 to 1460 keV and it can be used for both, solid and liquid environmental samples. The calibration
was initially verified measuring several reference materials provided by the IAEA (International Atomic
Energy Agency). Finally, through the participation in two Proficiency Tests organized by IAEA for the
members of the ALMERA network (Analytical Laboratories for the Measurement of Environmental
Radioactivity) the validity of the developed procedure was confirmed. The validation also showed that
measurement of 226Ra should be conducted using coaxial n-type HPGe detector in order to minimize the
true coincidence summing effect.2016-01-01T00:00:00ZThermal characterization, polymorphism, and stability evaluation of Se-NSAID derivatives with potent anticancer activityhttps://hdl.handle.net/10171/681682024-02-26T08:46:21Z2023-01-01T00:00:00ZTitle: Thermal characterization, polymorphism, and stability evaluation of Se-NSAID derivatives with potent anticancer activity
Abstract: Stability, thermal characterization, and identification of possible polymorphism are relevant in the development of novel
therapeutic drugs. In this context, thirty new nonsteroidal anti-inflammatory drug (NSAID) derivatives containing selenium
(Se) as selenoesters or diacyl diselenides with demonstrated anticancer activity were thermally characterized in order to
establish thermal stability criteria and detect possible polymorphic forms. Compounds were analyzed by a combination
of thermogravimetry, differential scanning calorimetry, and X-ray diffraction techniques, and five different calorimetric
behaviors were identified. Two compounds based on naproxen (I.3d and I.3e) and an indomethacin-containing derivative
(II.2) presented two crystalline forms. The stability under acid, alkaline and oxidative conditions of selected polymorphs
was also assessed using high-performance liquid chromatography. In addition, the cytotoxic activity of Se-NSAID crystal-
line polymorphs was studied in several cancer cell lines in vitro. Remarkably, no significant differences were found among
the polymorphic forms tested, thus proving that these compounds are thermally qualified for further drug development.2023-01-01T00:00:00Z