Anti-PSMA antibody-coupled gold nanorods detection by optical and electron microscopies

While cancer is one of the greatest challenges to public health care, prostate cancer was chosen as cancer model to develop a more accurate imaging assessment than those currently available. Indeed, an efficient imaging technique which considerably improves the sensitivity and specificity of the diagnostic and predicting the cancer behavior would be extremely valuable. The concept of optoacoustic imaging using home-made functionalized gold nanoparticles coupled to an antibody targeting PSMA (prostate specific membrane antigen) was evaluated on different cancer cell lines to demonstrate the specificity of the designed platform. Two commonly used microscopy techniques (indirect fluorescence and scanning electron microscopy) showed their straightforwardness and versatility for the nanoparticle binding investigations regardless the composition of the investigated nanoobjects. Moreover most of the research laboratories and centers are equipped with fluorescence microscopes, so indirect fluorescence using Quantum dots can be used for any active targeting nanocarriers (polymers, ceramics, metals, etc.). The second technique based on backscattered electron is not only limited to gold nanoparticles but also suits for any study of metallic nanoparticles as the electronic density difference between the nanoparticles and binding surface stays high enough. Optoacoustic imaging was finally performed on a 3D cellular model to assess and prove the concept of the developed platform.

Fabrication of GaN nanorods by focused ion beam

Ordered arrays of III-Nitride nanocolumns are excellent candidates for the fabrication of nano-optoelectronic devices. Different technologies such as e-beam lithography or colloidal lithography, have been used to obtain ordered arrays. All these technologies have in common several processing steps that can affect the crystalline growth of the nanocolumns. In this work, we present a single lithographic step that permits to grow ordered GaN nanocolumns with different geometries. The patterning is based in the use of a focusedionbeam with different doses. With this method has been possible to create GaN nanopillars and nanocylinders

E-beam nanopatterning for the selective area growth of III-V nitride nanorods

GaN/InGaN nanorods have attracted much scientific interest during the last decade because of their unique optical and electrical properties [1,2]. The high crystal quality and the absence of extended defects make them ideal candidates for the fabrication of high efficiency opto-electronic devices such as nano-photodetectors, light-emitting diodes, and solar cells [1-3]. Nitrides nanorods are commonly grown in the self-assembled mode by plasma-assisted molecular beam epitaxy (MBE) [4]. However, self-assembled nanorods are characterized by inhomogeneous heights and diameters, which render the device processing very difficult and negatively affect the electronic transport properties of the final device. For this reason, the selective area growth (SAG) mode has been proposed, where the nanorods preferentially grow on pre-defined sites on a pre-patterned substrate [5].

Ordered gan/ingan nanorods arrays grown by molecular beam epitaxy for phosphor-free white light emission

The basics of the self-assembled growth of GaN nanorods on Si(111) are reviewed. Morphology differences and optical properties are compared to those of GaN layers grown directly on Si(111). The effects of the growth temperature on the In incorporation in self-assembled InGaN nanorods grown on Si(111) is described. In addition, the inclusion of InGaN quantum disk structures into selfassembled GaN nanorods show clear confinement effects as a function of the quantum disk thickness. In order to overcome the properties dispersion and the intrinsic inhomogeneous nature of the self-assembled growth, the selective area growth of GaN nanorods on both, c-plane and a-plane GaN on sapphire templates, is addressed, with special emphasis on optical quality and morphology differences. The analysis of the optical emission from a single InGaN quantum disk is shown for both polar and non-polar nanorod orientations

E-beam nano-patterning for the ordered growth of GaN/InGaN nanorods

E-beam lithography was used to pattern a titanium mask on a GaN substrate with ordered arrays of nanoholes. This patterned mask served as a template for the subsequent ordered growth of GaN/InGaN nanorods by plasma-assisted molecular beam epitaxy. The mask patterning process was optimized for several holes configurations. The smallest holes were 30 nm in diameter with a pitch (center-to-center distance) of 100 nm only. High quality masks of several geometries were obtained that could be used to grow ordered GaN/InGaN nanorods with full selectivity (growth localized inside the nanoholes only) over areas of hundreds of microns. Although some parasitic InGaN growth occurred between the nanorods during the In incorporation, transmission electron microscopy and photoluminescence measurements demonstrated that these ordered nanorods exhibit high crystal quality and reproducible optical properties.

Fabrication of GaN nanorods by focused ion beam

Ordered arrays of III-Nitride nanocolumns are excellent candidates for the fabrication of nano-optoelectronic devices. Different technologies such as e-beam lithography or colloidal lithography, have been used to obtain ordered arrays. All these technologies have in common several processing steps that can affect the crystalline growth of the nanocolumns. In this work, we present a single lithographic step that permits to grow ordered GaN nanocolumns with different geometries. The patterning is based in the use of a focused ion beam with different doses. With this method has been possible to create GaN nanopillars and nanocylinders.

Photoacoustic effect measurement in aqueous suspensions of gold nanorods caused by low-frequency and low-power near-infrared pulsing laser irradiation

When aqueous suspensions of gold nanorods are irradiated with a pulsing laser (808 nm), pressure waves appear even at low frequencies (pulse repetition rate of 25 kHz). We found that the pressure wave amplitude depends on the dynamics of the phenomenon. For fixed concentration and average laser current intensity, the amplitude of the pressure waves shows a trend of increasing with the pulse slope and the pulse maximum amplitude.We postulate that the detected ultrasonic pressure waves are a sort of shock waves that would be generated at the beginning of each pulse, because the pressure wave amplitude would be the result of the positive interference of all the individual shock waves.

Evaluation of the bioaccumulation kinetics of gold nanorods in vital mammalian organs by mean of TXRF spectrometry

This work presents the first application of total-reflection X-ray fluorescence (TXRF) spectrometry, a new and powerful alternative analytical method, to evaluation of the bioaccumulation kinetics of gold nanorods (GNRs) in various tissues upon intravenous administration in mice. The analytical parameters for developed methodology by TXRF were evaluated by means of the parallel analysis of bovine liver certified reference material samples (BCR-185R) doped with 10 μg/g gold. The average values (n = 5) achieved for gold measurements in lyophilized tissue weight were as follows: recovery 99.7%, expanded uncertainty (k = 2) 7%, repeatability 1.7%, detection limit 112 ng/g, and quantification limit 370 ng/g. The GNR bioaccumulation kinetics was analyzed in several vital mammalian organs such as liver, spleen, brain, and lung at different times. Additionally, urine samples were analyzed to study the kinetics of elimination of the GNRs by this excretion route. The main achievement was clearly differentiating two kinds of behaviors. GNRs were quickly bioaccumulated by highly vascular filtration organs such as liver and spleen, while GNRs do not show a bioaccumulation rates in brain and lung for the period of time investigated. In parallel, urine also shows a lack of GNR accumulation. TXRF has proven to be a powerful, versatile, and precise analytical technique for the evaluation of GNRs content in biological systems and, in a more general way, for any kind of metallic nanoparticles.

Identification of transforming growth factor-β- regulated genes in Caenorhabditis elegans by differential hybridization of arrayed cDNAs

Members of the transforming growth factor-β family play critical roles in body patterning, in both vertebrates and invertebrates. One transforming growth factor-β-related gene, dbl-1, has been shown to regulate body length and male ray patterning in Caenorhabditis elegans. We screened arrayed cDNAs to identify downstream target genes for the DBL-1 signaling by using differential hybridization. C. elegans cDNAs representing 7,584 independent genes were arrayed on a nylon membrane at high density and hybridized with 33P-labeled DNA probes synthesized from the mRNAs of wild-type, dbl-1, sma-2, and lon-2 worms. Signals for all the spots representing hybridized DNA were quantified and compared among strains. The screening identified 22 and 2 clones, which were positively and negatively regulated, respectively, by the DBL-1 signal. Northern hybridization confirmed the expression profiles of most of the clones, indicating good reliability of the differential hybridization using arrayed cDNAs. In situ hybridization analysis revealed the spatial and temporal expression patterns of each clone and showed that at least four genes, including the gene for the type I receptor for DBL-1, sma-6, were transcriptionally regulated by the DBL-1 signal.

Arrayed transposase-binding sequences on the ends of transposon Tn5090/Tn402

The transposon Tn5090/Tn402 encodes a 559 amino acid transposase, TniA, with a DDE motif. Gel mobility shifting and cleavage protection analysis with DNase I and hydroxyl radical probes revealed that TniA binds to multiple repeat sequences on either terminus of Tn5090/Tn402. Four of these TniA-binding 19mers occurred on the left-hand (t) end and two on the right-hand (i) end. Hydroxyl radical cleavage protection demonstrated the presence of 3–6 bp contact sequences on one face of the DNA helix. The binding pattern and organisation of repeats suggested parallels between Tn5090/Tn402 and Mu, which controls its transpositional activity in the assembly step of a higher order transpososome complex. The complex terminal structure and genes of transposase and nucleotide-binding proteins in tandem are hallmarks of the handful of Mu-like elements that are known to date.

Extended range interrogation of wavelength division multiplexed fibre Bragg grating sensors using an arrayed waveguide grating

A technique for interrogating multiplexed fibre Bragg grating (FBG) sensors using an arrayed waveguide grating (AWG) is described. The approach considerably extends the sensing range from that achieved previously, while providing a strain resolution of 17nevHz at 30 Hz.

Interferometric sensor interrogation using an arrayed waveguide grating

We experimentally investigate the use of an arrayed waveguide grating (AWG) to interrogate interferometric sensors. A single broad-band light source is used to illuminate the system. Reflected spectral information is directed to an AWG with integral photodetectors providing 40 electrical outputs. We show that using the dual-wavelength technique we can measure the length of a Fabry-Perot cavity by determining the optical phase changes of the scanned interferometric pattern, which produced a maximum unambiguous range of 1440 mum with an active sensor and a maximum unambiguous range of 300 mum with the introduction of a second processing interferometer, which allows the sensor to be passive.

Interrogation of fibre Bragg grating sensors using an arrayed waveguide grating

We experimentally investigate the use of an arrayed waveguide grating (AWG) to interrogate fibre Bragg grating (FBG) sensors. A broadband light source is used to illuminate the FBG sensors. Reflected spectral information is directed to the AWG containing integral photodetectors providing 40 electrical outputs. Three methods are described to interrogate FBG sensors. The first technique makes use of the wavelength-dependent transmission profile of an AWG channel passband, giving a usable range of 500 µe and a dynamic strain resolution of 96 ne Hz-1/2 at 13 Hz. The second approach utilizes wide gratings larger than the channel spacing of the AWG; by monitoring the intensity present in several neighbouring AWG channels an improved range of 1890 µe was achieved. The third method improves the dynamic range by utilizing a heterodyne approach based on interferometric wavelength shift detection, providing an improved dynamic strain resolution of 17 ne Hz-1/2 at 30 Hz.

Extended range interrogation of wavelength division multiplexed fibre Bragg grating sensors using arrayed waveguide grating

A technique for interrogating multiplexed fibre Bragg grating (FBG) sensors using an arrayed waveguide grating (AWG) is described. The approach considerably extends the sensing range from that achieved previously, while providing a strain resolution of 17nε/√Hz at 30 Hz.