Presepsin for the detection of early-onset sepsis in preterm newborns

n/

Protein clustering in chemically stressed HeLa cells studied by infrared nanospectroscopy

Photo-Thermal Induced Resonance (PTIR) nanospectroscopy, tuned towards amide-I absorption, was used to study the distribution of proteic material in 34 different HeLa cells, of which 18 were chemically stressed by oxidative stress with Na3AsO3. The cell nucleus was found to provide a weaker amide-I signal than the surrounding cytoplasm, while the strongest PTIR signal comes from the perinuclear region. AFM topography shows that the cells exposed to oxidative stress undergo a volume reduction with respect to the control cells, through an accumulation of the proteic material around and above the nucleus. This is confirmed by the PTIR maps of the cytoplasm, where the pixels providing a high amide-I signal were identified with a space resolution of ∼300 × 300 nm. By analyzing their distribution with two different statistical procedures we found that the probability to find protein clusters smaller than 0.6 μm in the cytoplasm of stressed HeLa cells is higher by 35% than in the control cells. These results indicate that it is possible to study proteic clustering within single cells by label-free optical nanospectroscopy

Benchmarking the Use of Heavily-Doped Ge Against Noble Metals for Plasmonics and Sensing in the Mid-Infrared

Despite the recent introduction of heavily-doped semiconductors for mid-infrared plasmonics, it still remains an open point whether such materials can compete with noble metals. We employ a whole set of figures of merit to thoroughly assess the use of heavily-doped Ge on Si as a mid-infrared plasmonic material and benchmark it against standard noble metals such as Au. In doing this, we design and model high-performance, CMOS compatible mid-infrared plasmonic sensors based on experimental material data reaching plasma frequencies up to about 1950 cm−1. We demonstrate that plasmonic Ge sensors can provide signal enhancements for vibrational spectroscopy above 3 orders of magnitude, thus representing a viable alternative to noble metals

Integrated Germanium-on-silicon Waveguides for Mid-infrared Photonic Sensing Chips

Germanium-on-silicon waveguides are designed, fabricated and characterized with a novel near-field infrared spectroscopy technique that allows on-chip investigation of the in-coupling efficiency. On-chip propagation along bends and straight sections up to 0.8 mm is demonstrated around λ = 6 μm

Point Mutation I261M Affects the Dynamics of BVDV and its Interaction with Benzimidazole Antiviral 227G

Bovine viral diarrhea virus (BVDV) is a Pestivirus of the Flaviviridae family and represents a major viral pathogen in cattle and other ruminants. Infection with BVDV can result in a wide assortment of disease manifestations including resorption, mummification, or abortion of the dead fetus. Recently the point mutation I261M on the thumb domain was shown to confer resistance to BDVD against 227G and other benzimidazole compounds. Here we investigated the role of this mutation by using a multidisciplinary protocol, not involving free energy calculations on structures of the mutated complex which are taken a priori similar to those of the wild one. Namely, we firstly performed MD simulations on the wild and mutated BVDV RdRp proteins in aqueous solution. Then, we selected representative equilibrium conformations by performing a cluster analysis, and ran docking calculations of 277G on representative of the 5 most populated clusters of each protein. Finally, we performed MD simulation on selected complexes as to assess structural and dynamical differences between wild and mutated 227G-protein adducts. Interestingly, the mutation affects the structure and the dynamics of the protein, particularly in the region of binding of the ligand, and this results in a different binding site of 227G with respect to the wild protein. Moreover, while 227G closes the entrance to the RNA strand in the case of the wild protein, a gate and a channel leading to the catalytic site are still present in the mutated complex. These results could offer a possible molecular explanation of the resistance mechanism by mutation I261M

Germanium-on-silicon Waveguides for Mid-infrared Photonic Sensing Chips

Germanium-on-silicon rib waveguides are modelled, fabricated and characterized with a novel near-field infrared spectroscopy technique that allows on-chip investigation of the waveguide losses at 5.8 μm wavelength

Group-IV midinfrared plasmonics

The use of heavily doped semiconductors to achieve plasma frequencies in the mid-IR has been recently proposed as a promising way to obtain high-quality and tunable plasmonic materials. We introduce a plasmonic platform based on epitaxial n-type Ge grown on standard Si wafers by means of low-energy plasma-enhanced chemical vapor deposition. Due to the large carrier concentration achieved with P dopants and to the compatibility with the existing CMOS technology, SiGe plasmonics hold promises for mid-IR applications in optoelectronics, IR detection, sensing, and light harvesting. As a representative example, we show simulations of mid-IR plasmonic waveguides based on the experimentally retrieved dielectric constants of the grown materials

Heavily-doped Germanium on Silicon with Activated Doping Exceeding 1020 cm−3 as an Alternative to Gold for Mid-infrared Plasmonics

Ge-on-Si has been demonstrated as a platform for Si foundry compatible plasmonics. We use laser thermal annealing to demonstrate activated doping levels >1020 cm-3 which allows most of the 3 to 20 μm mid-infrared sensing window to be covered with enhancements comparable to gold plasmonics

Mid-infrared n-Ge on Si Plasmonic Based Microbolometer Sensors

The detection and amplification of molecular absorption lines from a chemical weapons simulant is demonstrated using plasmonic antennas fabricated from n-Ge epitaxially grown on Si. A free-standing Si0.25Ge0.75 microbolometer detector with n-Ge plasmonic antenna is demonstrated as an integrated mid-infrared plasmonic sensor