The possibility to fully exploit the diagnostic capabilities of SR-IRMS for studying single living cells under physiological conditions is limited by several constrains. First of all, the technology ...for manufacturing materials transparent to both IR and visible light is quite immature, limiting the design of fluidic devices to simple demountable liquid cells. In addition, the water spectral features become prominent in the Mid IR, hiding several cellular bands and therefore limiting the diagnostic capabilities of SR-IRMS. The overcoming of the so called "water absorption barrier" requires the improvement of the protocols for the compensation of buffer spectral contributions, a goal that can be achieved also advancing the quality of IR-suitable fluidic devices. In this paper, the technical solutions employed for microfabricating completely sealed IR-visible transparent fluidic devices for living cell analysis will be presented. Several examples of the results obtained in the study of living U937 monocytes subjected to different stimuli will be selected for highlighting both the advantages and the disadvantages offered by our approach for cellular biology.
We report on structural and electrical properties of GaAs nanowires (NWs) grown by molecular beam epitaxy (MBE) on GaAs and SiO
2 substrates using Au as growth catalyst. Au–Ga particles are observed ...on the top of the NWs by transmission electron microscopy (TEM). In most of the observed cases, individual particles contain two Au–Ga compositions, in particular orthorhombic AuGa and
β′ hexagonal Au
7Ga
2. The wires grown on GaAs are regularly shaped and tidily oriented on both (1
0
0) and (1
1
1)B substrates. TEM also reveals that the NWs have a wurtzite lattice structure. Electrical transport measurements indicate that nominally undoped NWs are weakly n-type while both Be- and Si-doped wires show p-type behaviour. The effect of the lattice structure on impurity incorporation is briefly discussed.
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► A superhydrophobic structure has been realized for wet sample handling in X-ray measurements. ► First measuring tests has been carried on for X-ray fluorescence, phase contrast ...imaging, and X-ray diffraction. ► Test measurements on ferritin protein sample has been done.
In this work we propose a wet sample handling technique which enables the simultaneous collection of X-ray fluorescence (XRF) spectra and X-ray phase contrast imaging (XPCI) using a few microliters drop confined on a superhydrophobic surface. To this purpose, we fabricated and tested a superhydrophobic patterned surface entailing an hydrophilic region which leads to pinning of the drop, enabling X-ray beam effortless alignment and measuring in liquid phase. Our technique allows to acquire capillary-free XRF spectra, resulting in a significant fluorescence detection gain, which is particularly interesting for light elements. Simultaneous XPCI provides sample geometry assuring a fine control of the experimental conditions and allowing real time monitoring of the drop during measurements. As an additional advantage – after solvent evaporation – the solute is deposited on a precise spot, greatly increasing its concentration allowing further measurements, such as X-ray microanalysis and X-ray diffraction.
These results could have potential applications in the study of blood proteins, such as ferritin and low density lipoprotein, which are usually available in very limited quantity.
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► MIR nanoantennas fabrication on Silicon demonstrated. ► Plasmonic nanoantennas with several different geometries. ► MIR nanoantennas fabrication on CaF2. ► MIR nanoantennas ...characterization by FTIR (Si and CaF2).
We report on the fabrication and systematic characterization of nanoantenna arrays with several different geometries realized both on standard silicon (Si) substrates and Calcium Fluoride (CaF2) substrates aimed at the realization of a mid-Infrared protein detector. In particular, we present a novel nanofabrication procedure which allows the adoption of CaF2 in a standard lithographic process with results comparable to the ones obtained on silicon wafers. The transmittance and reflectance spectra of the nanoantennas, were acquired by means of an Infrared microscope coupled to a Michelson Interferometer. In all the nanoantenna devices, the plasmonic resonance follows a linear scaling relation: a lattice parameter change of a ±(5–10)%, indeed, results in a shift of the Si (1,0) plasmonic resonance frequency which is proportional to 1/a. This scaling behavior offers a useful tool for device frequency tuning, which can be used to obtain a fine spectral overlap with the protein amide-I and amide-II bands. A Lorentzian analysis of the resonance peaks reveals that our nanostructures have an high Q factor (Q=ν0/Δν), demonstrating the effectiveness of our fabrication procedures.
Antitumor immunity driven by intratumoral dendritic cells contributes to the efficacy of anthracycline-based chemotherapy in cancer. We identified a loss-of-function allele of the gene coding for ...formyl peptide receptor 1 (FPR1) that was associated with poor metastasis-free and overall survival in breast and colorectal cancer patients receiving adjuvant chemotherapy. The therapeutic effects of anthracyclines were abrogated in tumor-bearing Fpr1-/- mice due to impaired antitumor immunity. Fpr1-deficient dendritic cells failed to approach dying cancer cells and, as a result, could not elicit antitumor T cell immunity. Experiments performed in a microfluidic device confirmed that FPR1 and its ligand, annexin-1, promoted stable interactions between dying cancer cells and human or murine leukocytes. Altogether, these results highlight the importance of FPR1 in chemotherapy-induced anticancer immune responses.
Two dimensional photonic band gap structures on GaAs/AlGaAs, Si
3N
4 and Si/SiO
2 has been fabricated using a 30
keV gallium ion beam. This process is being developed as a viable alternative for fast ...prototyping of high quality 2D photonic crystal devices. The feasibility of high-resolution (down to 80
nm) unit cell fabrication has been demonstrated as well as the longitudinal depth of the holes (more than 600
nm) over a pattern area of 100
×
100
μm and smaller, using FIB milling as well as FIB gas assisted etching. During milling fluorine gas was added in the sample chamber to control the interior shape of the holes and also to reduce the formation of Ga spherical calotte shaped dots. The in-plane photoluminescence emission of some fabricated devices has been optically characterized by exciting the in plane cavities from the top surface of the device by picosecond laser pulses. As expected, by virtue of its higher back mirror reflectivity leading to lower cavity losses, the 2D photonic crystal cavity showed the occurrence of amplified spontaneous emission.
The unique properties of single-wall carbon nanotubes (SWNTs) and the application of nanotechnology to the nervous system may have a tremendous impact in the future developments of microsystems for ...neural prosthetics as well as immediate benefits for basic research. Despite increasing interest in neuroscience nanotechnologies, little is known about the electrical interactions between nanomaterials and neurons. We developed an integrated SWNT-neuron system to test whether electrical stimulation delivered via SWNT can induce neuronal signaling. To that aim, hippocampal cells were grown on pure SWNT substrates and patch clamped. We compared neuronal responses to voltage steps delivered either via conductive SWNT substrates or via the patch pipette. Our experimental results, supported by mathematical models to describe the electrical interactions occurring in SWNT-neuron hybrid systems, clearly indicate that SWNTs can directly stimulate brain circuit activity.
Aflatoxins are fungal metabolites extensively produced by many different fungal species that may contaminate a wide range of agricultural food products. They have been studied extensively because of ...being associated with various chronic and acute diseases, especially immunosuppression and cancer, and their presence in food is strictly monitored and regulated worldwide.
Aflatoxin detection and measurement rely mainly on chemical methods usually based on chromatography approaches, and recently developed immunochemical based assays that have advantages but also limitations, since these are expensive and destructive techniques. Nondestructive, optical approaches are recently being developed to assess presence of contamination in a cost and time effective way, maintaining acceptable accuracy and reproducibility. In this paper are presented the results obtained with a simple portable device for nondestructive detection of aflatoxins in almonds. The presented approach is based on the analysis of fluorescence spectra of slurried almonds under 375 nm wavelength excitation. Experiments were conducted with almonds contaminated in the range of 2.7–320.2 ng/g total aflatoxins B (AFB1 + AFB2) as determined by High Performance Liquid Chromatography with Fluorescence Detection (HPLC/FLD). After applying pre-processing steps, spectral analysis was carried out using a binary classification model based on Support Vector Machine (SVM) algorithm. A majority vote procedure was then performed on the classification results. In this way we could achieve, as best result, a classification accuracy of 94% (and false negative rate 5%) with a threshold set at 6.4 ng/g. These results illustrate the feasibility of such approach in the great challenge of aflatoxin detection for food and feed safety.
•Fluorescence spectroscopy proves effective as a rapid and low cost approach to detect aflatoxin B.•Results are obtained using machine learning algorithms and a consensus strategy on single results.•Results have proved robust using data from different locations and instruments.
Two lithographic techniques suitable for fabricating complex 3D structures with high spatial resolution are presented and discussed. The first one is based on the combined use of nanoimprint and ...X-ray lithography. Its technological potential has been demonstrated by patterning several types of structures with X-ray lithography on hexagonal array of hemispheres obtained previously by nanoimprinting. These consecutive steps give rise to an intersection-structure where the overall profile of high aspect ratio structures is enveloped by the original 3D imprinted profile. The second technique, two-photon lithography, is an intrinsic 3D lithography and has the highest potential for structuring 3D in the widest sense. The principle of this technology and experimental results in the field of nanomechanics and photonics will be presented.
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