Enhanced and tunable white light emission from Ag nanoclusters and Eu3+-co-doped CaBAl glasses.

Noble metal embedded glasses have been studied as promising candidates for a variety of technological applications, mainly due to their ability to enhance rare earth luminescence properties. In this work, Ag:Eu-co-doped calcium boroaluminate glasses were prepared and submitted to further heat treatment to form different Ag species. The optical and luminescence properties were investigated in terms of heat treatment times. Absorption spectra showed a successful Eu and Ag ion incorporation in the host, as well as Ag nanoparticle precipitation induced by heat treatment. Upon UV-light excitation, the co-doped glasses exhibited an intense wide emission band centered at about 500 nm, attributed to molecule-like silver species, which combined with the Eu3+ characteristic emission reaches a white light resultant emission. A new excitation band for Eu3+ at 335 nm and a silver luminescence lifetime decrease suggest an energy transfer process from molecule-like Ag to Eu3+ as being responsible for the enhanced PL properties in these glasses. An appropriate combination of a violet LED with the sample emission provides a route to achieve the ideal white light CIE color parameters. The relevant quality color results qualify these glasses as phosphors with high potential for white light emitting devices.

Ultraviolet (UVB and UVA) photoprotector activity and percutaneous penetration of extracts obtained from Arrabidaea chica.

The aim of this work is to investigate the photoprotection activity and toxicity level of formulations containing the extract and its fractions obtained from leaves of Arrabidaea chica. The ex vivo percutaneous penetration of the extract was evaluated using the photoacoustic spectroscopy technique. The formulation presented optical absorption in the ultraviolet region, including UVA and UVB. This formulation was obtained without adding inorganic UV filters, as is frequently used in commercial sunscreens. The results showed a penetration rate similar to those of commercial sunscreens with its presence on the skin surface at least 180 min after the application. This formulation presented no toxic effects evaluated using hematological, biochemical, and histological assays. The results suggest that the formulation from the leaves of A. chica provides substantial protection against UVA + UVB radiation with a possible advantage of being natural and free of inorganic compounds compared with the majority of available commercial sunscreens.

Evidence of deep percutaneous penetration associated with anti-inflammatory activity of topically applied Helicteres gardneriana extract: a photoacoustic spectroscopy study.

PURPOSE: To apply the photoacoustic spectroscopy technique to investigate the penetration rate of topically applied Helicteres gardneriana extract used as anti-inflammatory agent. METHODS: Experiments were performed ex vivo in a well-controlled group of mice. The crude extract was obtained from leaves of the plant Helicteres gardneriana. Croton oil was applied into the ventral surface of the mouse's right and left auricles in order to induce an inflammatory response. The left auricle was treated with crude extract, while the right one served as the control. After 6 h, the auricles were sectioned for measurements of edema intensity, myeloperoxidase activity and the formulation penetration rate. RESULTS: Croton oil induced inflammatory response in both auricles. The application of Helicteres gardneriana extract reduced significantly the edema of the auricle and inhibited the activity of the myeloperoxidase enzyme. The photoacoustic data showed that the propagation of the formulation was efficient to reach the deep region of the auricle, crossing the cartilage. The strong anti-inflammatory effect was associated with the observed deep penetration of the formulation. CONCLUSION: This pre-clinical study showed the anti-inflammatory effect of Helicteres gardneriana extract. The photoacoustic technique was useful to demonstrate that this anti-inflammatory activity was associated with deep percutaneous penetration.