Single and multilayer metamaterials fabricated by nanoimprint lithography.

We demonstrate for the first time a fast and easy nanoimprint lithography (NIL) based stacking process of negative index structures like fishnet and Swiss-cross metamaterials. The process takes a few seconds, is cheap and produces three-dimensional (3D) negative index materials (NIMs) on a large area which is suitable for mass production. It can be performed on all common substrates even on flexible plastic foils. This work is therefore an important step toward novel and breakthrough applications of NIMs such as cloaking devices, perfect lenses and magnification of objects using NIM prisms. The optical properties of the fabricated samples were measured by means of transmission and reflection spectroscopy. From the measured data we retrieved the effective refractive index which is shown to be negative for a wavelength around 1.8 µm for the fishnet metamaterial while the Swiss-cross metamaterial samples show a distinct resonance at wavelength around 1.4 µm.

Analysis of myeloperoxidase activity in wound fluids as a marker of infection.

BACKGROUND: Neutrophilic polymorphonuclear leukocytes play a crucial role in the host defence against bacterial and fungal infections. They participate in the inflammatory response through the liberation of peptides and enzymes like myeloperoxidase (MPO). Therefore, MPO has a potential as a marker enzyme for the diagnosis of wound infection. METHODS: Substrate specificities and reaction pathways of MPO were investigated for new MPO substrates: crystal violet, leuco crystal violet, fast blue RR (4-benzoylamino-2,5-dimethoxybenzenediazonium chloride hemi(zinc chloride) salt) and various systematically substituted model substrates based on 2,7-dihydroxy-1-(4-hydroxyphenylazo)naphtalene-3,6-disulphonic acid. In addition, fast blue RR was covalently bound to siloxanes allowing immobilization of the substrate, while cellobiosedehydrogenase was integrated for generation of hydrogen peroxide required by MPO. RESULTS: Elevated concentrations of MPO were found in infected wounds compared with non-infected wounds (92.2 ± 45.0 versus 1.9 ± 1.8 U/mL). Various soluble and immobilized substrates were oxidized by MPO in wound samples and the influence of substrate structure and reaction pathways were elucidated for selected compounds. CONCLUSIONS: Incubation of different MPO substrates with infected wound fluid samples resulted in a clear colour change in the case of elevated MPO concentrations, thus allowing early diagnosis of wound infection.