In vitro Assessment of Solar Filters for Erythropoietic Protoporphyria in the Action Spectrum of Protoporphyrin IX.

Introduction: Subjects with erythropoietic protoporphyria rely on broad-spectrum sunscreens with high sun protection factor, which is not informative on efficacy in the absorption spectrum of protoporphyrin IX, spanning visible radiation and peaking around 408 nm. Photoactivation of protoporphyrin IX is responsible for painful skin photosensitivity in erythropoietic protoporphyria. The authors assessed the protective efficacy of six sunscreens in vitro in the absorption spectrum of protoporphyrin IX. Method: Transmittance measurements were performed in the 300-850 nm wavelengths on samples of six photoprotective products applied to polymethyl methacrylate plates. Porphyrin protection factor was calculated in the 300-700 nm region to provide a measurement for the efficacy of each product based on the action spectrum of protoporphyrin IX. Results: Product A showed the highest porphyrin protection factor among tested products with a median value of 4.22. Product A is a sunscreen containing organic filters, titanium dioxide and synthetic iron oxides, pigmentary grade active ingredients that absorb visible radiation. Other products showed inefficient protection in the visible, with transmittance between 75 and 95% at 500 nm. The low porphyrin protection factor of inorganic filter product B was attributed to particle micronization, as declared by the manufacturer. Conclusion: Adding porphyrin protection factor to sunscreen labeling could help patients with erythropoietic protoporphyria and other photosensitivity disorders identify products tailored on their specific needs. The development of sunscreens providing protection from visible radiation and excellent cosmetical tolerability could improve the lifestyle of patients with erythropoietic protoporphyria.

A hybrid metal-dielectric zero mode waveguide for enhanced single molecule detection.

We fabricated hybrid metal-dielectric nanoslots and measured their optical response at three different wavelengths. The nanostructure is fabricated on a bilayer film formed by the sequential deposition of silicon and gold on a transparent substrate. The optical characterization is done via fluorescence spectroscopy measurements. We characterized the fluorescence enhancement, as well as the lifetime and the detection volume reduction for each wavelength. We observe that the hybrid metal-dielectric nanoslots behave as enhanced zero mode waveguides in the near-infrared spectral region. Their detection volume is such that they can perform enhanced single-molecule detection at tens of µM. We compared their behavior with that of a golden ZMW, and we demonstrated that the dielectric silicon layer improves both the optical performance and the stability of the device.

Rad-hard properties of the optical glass adopted for the PLATO space telescope refractive components.

PLAnetary Transits and Oscillations of stars (PLATO) is a medium sized mission (M3) selected by the European Space Agency (ESA) for launch in 2026. The PLATO payload includes 26 telescopes all based on a six-element refractive optical scheme. Some components will be eventually manufactured by S-FPL51, N-KZFS11 and S-FTM16 glass whose radiation resistance is partially or totally unknown. The radiation-resistance properties of such materials have been investigated by using a 60Co γ-rays source as probe. Each optical component has been characterized by a depth profile curve which describes the transmission loss as a function of the thickness in dependence of the impinging dose. A model to simulate the throughput of the whole instrument has been developed and used to verify the instrument performance considering different stellar spectra.