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Some natural structures show three-dimensional morphologies on the micro- and nano- scale, characterized by levels of symmetry and complexity well far beyond those fabricated by best technologies available. This is the case of diatoms, unicellular microalgae, whose protoplasm is enclosed in a nanoporous microshell, made of hydrogenated amorphous silica, called frustule. We have studied the optical properties of Arachnoidiscus sp. single valves both in visible and ultraviolet range. We found photonic effects due to diffraction by ordered pattern of pores and slits, accordingly to an elaborated theoretical model. For the first time, we experimentally revealed spatial separation of focused light in different spots, which could be the basis of a micro-bio-spectrometer. Characterization of such intricate structures can be of great inspiration for photonic devices of next generation.

Inspired by the concept of complementary media, we experimentally demonstrate that an engineered metamaterial made of alternating, stripe layers of negatively refracting (photonic crystals) and positively refracting (air) materials strongly collimates a beam of near-infrared light. This quasi-zero-average-index metamaterial fully preserves the beam spot size throughout the sample for a light beam traveling through the metamaterial a distance of 2 mm-more than 1000 times the input wavelength lambda=1.55 microm. These results demonstrate the first explicit experimental verification of optical antimatter as proposed by Pendry and Ramakrishna [J. Pendry and S. Ramakrishna, J. Phys. Condens. Matter 15, 6345 (2003)10.1088/0953-8984/15/37/004], using two complementary media in which each n(eff)=-1 layer appears to annihilate an equal thickness layer of air.

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In this work, two procedures for fabrication of polymeric microneedles based on direct photolithography, without any etching or molding process, are reported. Polyethylene glycol (average molecular weight 250 Da), casted into a silicone vessel and exposed to ultraviolet light (365 nm) through a mask, cross-links when added by a commercial photocatalyzer. By changing the position of the microneedles support with respect to the vessel, different shapes and lengths can be achieved. Microneedles from a hundred microns up to two millimeters have been obtained just tuning the radiation dose, by changing the exposure time (5–15 s) and/or the power density (9–18 mW/cm2) during photolithography. Different microneedle shapes, such as cylindrical, conic or lancet-like, for specific applications such as micro-indentation or drug delivery, are demonstrated.

Human α-thrombin (TB) is a serine protease with a crucial role in coagulation and hemostasis. The monitoring of the TB level in blood serum could be of great importance in order to prevent serious damage to human health. In this work, an aptasensor is realized by in situ synthesis of a 17-mer Thrombin Binding Aptamer analogue (TBATT) on silanized macroporous silica (PSi). The interaction between TBATT and TB at different concentrations is monitored by a label-free optical method, spectroscopic reflectometry, and quantified by fast Fourier transform (FFT) analysis. A TBATT-TB affinity constant of 14 ± 8 nM and limit of detection of 1.5 ± 0.3 nM are demonstrated. The selectivity and reversibility of the aptasensor are also proved

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