Sebastião Pratavieira

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Light at wavelengths in the near-infrared (NIR) region allows for deep penetration and minimal absorption through high scattering tissue media. NIR light has been conventionally used through the first NIR optical tissue window with wavelengths from 650 to 950 nm. Longer NIR wavelengths had been overlooked due to major water absorption peaks and a lack of(More)
Tryptophan is investigated as the key native marker in cells to determine the level of metastasis competence in breast cell lines using native fluorescence spectroscopy. The ratio of fluorescence intensity at 340 nm to intensity at 460 nm is associated with aggressiveness of the cancer cells. We found that the fluorescence of aggressive breast cancer cell(More)
Spatially coherent multicolored optical vector vortex beams were created using a tunable liquid crystal q-plate and a supercontinuum light source. The feasibility of the q-plate as a tunable spectral filter (switch) was demonstrated, and the polarization topology of the resulting vector vortex beam was mapped. Potential applications include multiplexing for(More)
Chlorin-e6 (chl-e6) and a hydrogenated derivative (chl-e6H) were semi-synthesized, and their photophysical properties and photodynamic activity against Escherichia coli, Staphylococcus aureus and Candida albicans evaluated. Methyl pheophorbide-a (Mepheo-a) was obtained from S. maxima using methanolic extraction with acid catalysis (CH3OH–H2SO4). Chlorin-e6(More)
One of the clinical limitations of the photodynamic therapy (PDT) is the reduced light penetration into biological tissues. Pulsed lasers may present advantages concerning photodynamic response when compared to continuous wave (CW) lasers operating under the same average power conditions. The aim of this study was to investigate PDT-induced response when(More)
The aims of this study were to determine the spatial and temporal theoretical distribution of the concentrations of Protoporphyrin IX, 3O2 and doses of 1O2. The type II mechanism and explicit dosimetry in photodynamic therapy were used. Furthermore, the mechanism of respiration and cellular metabolism acting on 3O2 were taken into account. The dermis was(More)
Photodynamic Inactivation (PDI) is based on the use of a photosensitizer (PS) and light that results mainly in the production of reactive oxygen species, aiming to produce microorganism cell death. PS incubation time and light dose are key protocol parameters that influence PDI response; the correct choice of them can increase the efficiency of(More)
Actinic cheilitis is a potentially malignant disorder of the lips. Its first cause is believed to be UV sun radiation. The lesion is highly heterogeneous, making the choice of area to be biopsied difficult. This study exploits the capabilities of time-resolved fluorescence spectroscopy for the identification of the most representative area to be biopsied. A(More)
OBJECTIVE In this study, we aim to compare the photodynamic inactivation (PDI) effects of two different photosensitizers (PS), Photogem® and Natural Curcumin, irradiated with light-emitted diodes (LED) at 630 and 450 nm, respectively. BACKGROUND The current antimicrobial mouthwash for oral hygiene has several drawbacks. In this context, PDI is an(More)
In this communication, we present that wide-field optical fluorescence might be useful for: the screening of oral lesions that are imperceptible to the naked eye, determination of biopsy area, better definition of treatment, and previous and post-treatment follow-up.