A bacterial ratchet motor

Self-propelling bacteria are a dream of nano-technology. These unicellular organisms are not just capable of living and reproducing, but they can swim very efficiently, sense the environment and look for food, all packaged in a body measuring a few microns. Before such perfect machines could be artificially assembled, researchers are beginning to explore new ways to harness bacteria as propelling units for micro-devices. Proposed strategies require the careful task of aligning and binding bacterial cells on synthetic surfaces in order to have them work cooperatively. Here we show that asymmetric micro-gears can spontaneously rotate when immersed in an active bacterial bath. The propulsion mechanism is provided by the self assembly of motile Escherichia coli cells along the saw-toothed boundaries of a nano-fabricated rotor. Our results highlight the technological implications of active matter's ability to overcome the restrictions imposed by the second law of thermodynamics on equilibrium passive fluids.Comment: 4 pages, 3 figure

Chapter Photonic Crystals for Plasmonics: From Fundamentals to Superhydrophobic Devices

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Breaking the diffusion limit with super-hydrophobic delivery of molecules to plasmonic nanofocusing SERS structures

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Genital anomalies in newborns

Examination of genitalia should be an essential part of newborn assessment. Early detection of congenital disorders is essential to begin appropriate medical or surgical therapy and to prevent complications that could profoundly affect a child’s life. The present review aims to describe the main genital anomalies in infants and provide images in order to help the physician in current clinical practice

Attomole (amol) myoglobin Raman detection from plasmonic nanostructures

We have demonstrated the fabrication of nano-structures using electro-plating and electron beam lithography techniques to obtain a pattern of gold nanograin aggregate structures of diameter in the range between 80 and 100 nm with interstitial gap of 10–30 nm. The nanostructure based SERS substrate enables one to have better control and reproducibility on generation of plasmon polaritons. Using calculation, we have shown that Raman spectra are derived for the myoglobin concentration down up to attomole. These results are obtained using drop coating deposition Raman (DCDR) method in which solution of interest is microdeposited (2 μL) on SERS substrate

Novel plasmonic nanodevices for few/single molecule detection

This paper reports the fabrication of two reproducible surface enhanced Raman scattering devices using; a) nanoPillar coupled with PC cavity by means of FIB milling and electron beam induced deposition techniques (Device 1), and b) plasmonic gold nanoaggregate structures using electro-plating and e-beam lithography techniques (Device 2). Device 1 consists of photonic crystal cavity as an optical source to couple the incident laser with a metallic tapered nanolens. Exploiting such approach it is possible to overcome the difficulties related to scattering and diffraction phenomena when visible laser (514 nm) illuminates nanostructures. The nanostructure is covered with HMDS and is selectively removed leaving HMDS polymer on nanoPillar only. A clear Raman scattering enhancement has been demonstrated for label-free detection of molecule in sub-wavelength regime. On the other hand, myoglobin protein is deposited on Device 2 using drop coating deposition method and is estimated that the substrate is able to detect the myoglobin concentration down to attomole

Principal component analysis based methodology to distinguish protein SERS spectra

Surface-enhanced Raman scattering (SERS) substrates were fabricated using electro-plating and e-beam lithography techniques. Nano-structures were obtained comprising regular arrays of gold nanoaggregates with a diameter of 80 nm and a mutual distance between the aggregates (gap) ranging from 10 to 30 nm. The nanopatterned SERS substrate enabled to have better control and reproducibility on the generation of plasmon polaritons (PPs). SERS measurements were performed for various proteins, namely bovine serum albumin (BSA), myoglobin, ferritin, lysozyme, RNase-B, α-casein, α-lactalbumin and trypsin. Principal component analysis (PCA) was used to organize and classify the proteins on the basis of their secondary structure. Cluster analysis proved that the error committed in the classification was of about 14%. In the paper, it was clearly shown that the combined use of SERS measurements and PCA analysis is effective in categorizing the proteins on the basis of secondary structure

Nanoporous- micropatterned- superhydrophobic surfaces as harvesting agents for few low molecular weight molecules

Superhydrophobic surfaces were fabricated comprising cylindrical micro-pillars arranged in a regular hexagonal lattice. These structures are hierarchical in that the pillars incorporate, on the top, nanoporous silicon films. In sight of the superhydrophobicity of the system, the devices retain the ability of manipulating and concentrating diluted biological solutions, while, on account of the nanoporous films, they would efficiently filter the biological content of such solutions. The major advance, here, is the simultaneous use of the properties above, and thus important applications are envisioned where extremely small quantities of bio-markers are efficiently extracted from serum and analyzed employing conventional and well assessed spectroscopy techniques. Ultra low concentrated small Rhodamine molecules were here efficiently analyzed using FTIR spectroscopy techniques, thus demonstrating that these devices are effective

Ultra low concentrated molecular detection using super hydrophobic surface based biophotonic devices

Micro and nano-patterned devices were fabricated which disclose the possibility of concentrating, localizing, detecting and thus analyzing with unprecedented accuracy few molecules (at the limit a single molecule) of biological and medical interest. Important applications are envisioned where proteins poorly concentrated in blood are detected thus (early) revealing the appearance of diseases. The major advance of the paper is that it combines micro/nano-fabrication and spectroscopical nano-optics based techniques to study and individualize the biomolecules at study. Super hydrophobic surface would concentrate the diluted solution into a small area whereas spectroscopical nano-optics techniques would gather the molecular/chemical information of the residual solute. Fluorescence and SERS techniques were used to analyze Rhodamine molecules initially highly diluted (10−18 M)