Microgravimetric immunosensor for direct detection of aerosolized influenza A virus particles.

The development and characterization of a quartz crystal microbalance (QCM) sensor for the direct detection of aerosolized influenza A virions is reported. Self-assembled monolayers (SAMs) of mercaptoundecanoic acid (MUA) are formed on QCM gold electrodes to provide a surface amenable for the immobilization of anti-influenza A antibodies using NHS/EDC coupling chemistry. The surface-bound antibody provides a selective and specific sensing interface for the capture of influenza virions. A nebulizer is used to create aerosolized samples and is directly connected to a chamber housing the antibody-modified crystal ("immunochip"). Upon exposure to the aerosolized virus, the interaction between the antibody and virus leads to a dampening of the oscillation frequency of the quartz crystal. The magnitude of frequency change is directly related to virus concentration. Control experiments using aerosols from chicken egg allantoic fluid and an anti-murine antibody based immunosensor confirm that the observed signal originates from specific viral binding on the chip surface. Step-by-step surface modification of MUA assembly, antibody attachment, and antibody-virus interaction are characterized by atomic force microscopy (AFM) imaging analysis. Using the S/N = 3 principle, the limit of detection is estimated to be 4 virus particles/mL. The high sensitivity and real-time sensing scheme presented here can play an important role in the public health arena by offering a new analytical tool for identifying bio-contaminated areas and assisting in timely patient diagnosis

Fabrication of one-dimensional organic nanostructures using anodic aluminum oxide templates

Organic nanostructures are new comers to the fields of nanoscience and nanotechnology. In recent years novel methods for controlling the growth and uniformity of one-dimensional (1D) organic nanostructures (nanowires and nanotubes) have been developing. The use of hard templates as molds for the formation of organic nanowires or nanotubes seems to be a reliable and convenient method. In this review we will discuss the use of anodic aluminum oxide (AAO) templates as the inorganic hard template of choice. We will briefly survey advances in the fabrication of 1D polymer nanostructures using AAO templates, while the bulk of the review will focus on the synthesis of small molecule nanowires, nanotubes, and nanorods. We will also discuss unique properties of some highly crystalline small molecule nanorods fabricated using AAO templates

New smart functional fluorophores based on stable spirocyclic zwitterionic Meisenheimer compounds

Altres ajuts: Universitat Autònoma de Barcelona predoctoral PIF fellowshipMolecules and materials showing stimulus-induced modulation of their optical properties are of interest in a large variety of areas. In this paper, we focus on fluorescent switches based on stable spirocyclic zwitterionic Meisenheimer compounds (SZMC), which are composed of a 2,4,6-trisubstituted cyclohexadienyl anion chromophore fused with a triazene ring via a spiro carbon atom. By exploiting a facile one-pot synthetic strategy, new SZMC switches have been prepared with halo-, electro- and thermochromic properties. These properties can be controlled by modifying the substituents on their two constituting units. In particular, the optical properties, the sensitivity to different chemical stimuli, and the range of thermal response of these systems can be tailored by varying (a) the nature of the electron-withdrawing groups in their 2,4,6-trisubstituted cyclohexadienyl anion chromophore, and (b) the bulkiness of the pending chains in their triazene ring. In combination with their versatile optical switching behavior, this synthetic tunability makes SZMC switches very promising functional molecules for applications in chemistry, materials science, and biosciences

Fluorescent "turn-Off" detection of fluoride and cyanide ions using zwitterionic spirocyclic meisenheimer compounds

Stable zwitterionic spirocyclic Meisenheimer compounds were synthesized using a one-step reaction between picric acid and diisopropyl (ZW1) or dicyclohexyl (ZW3) carbodiimide. A solution of these compounds displays intense orange fluorescence upon UV or visible light excitation, which can be quenched or "turned-off" by adding a mole equivalent amount of F⁻ or CN⁻ ions in acetonitrile.Fluorescence is not quenched in the presence of other ions such as Cl⁻, Br⁻, I⁻, NO₂⁻ , NO₃⁻ , or H₂PO₄⁻ These compounds can therefore be utilized as practical colorimetric and fluorescent probes for monitoring the presence of F⁻ or CN⁻ anions

Photoresponsive Organic Molecular Crystals

The Special Issue on “Photoresponsive Molecular Crystals” is a collection of four original research articles dedicated to theoretical and experimental research works providing new insights and experimental findings in the field of photoresponsive crystals [...

Meisenheimer Complex from Picric Acid and Diisopropylcarbodiimide

Reaction of picric acid with diisopropylcarbodiimide produces a pale yellow 1:1 adduct N-(2′,4′,6′-trinitrophenyl)-N,N′-di(isopropyl)urea (5) and a 1:2 adduct fluorescent red zwitterionic Meisenheimer complex (6) as approximately N′,N”,N′”-tri(isopropyl)-4-oxo-6-(isopropyliminio)-2-s-(2H)triazinespiro-1′-2′,4′,6′-trinitro cyclohexadienylide. Crystals of (5) are triclinic, P-1 (#2), with a = 10.444(13) Å, b = 15.47(2) Å, c = 17.74(2) Å, α = 110.43(9)°, β = 99.85(10)°, γ = 92.78(10)°, V = 2629(6) Å3 for Z = 6 (three molecules per asymmetric unit). Crystals of (6) are orthorhombic, Pna21 (#33), with a = 24.12(4), b = 9.011(19) Å, c = 10.87(2) Å, V = 2362(8) Å3 for Z = 4. Nitro groups in the Meisenheimer complex are twisted 2–8° from the mean formerly aryl ring plane; in (5), nitro groups are twisted out of the aryl plane by 11–62°. In the Meisenheimer complex, cationic charge is distributed over an iminium/guanidinium group; anion charge is distributed over the cyclohexadienide ring and attached nitro groups

Fabrication of one-dimensional organic nanostructures using anodic aluminum oxide templates

Organic nanostructures are new comers to the fields of nanoscience and nanotechnology. In recent years novel methods for controlling the growth and uniformity of one-dimensional (1D) organic nanostructures (nanowires and nanotubes) have been developing. The use of hard templates as molds for the formation of organic nanowires or nanotubes seems to be a reliable and convenient method. In this review we will discuss the use of anodic aluminum oxide (AAO) templates as the inorganic hard template of choice. We will briefly survey advances in the fabrication of 1D polymer nanostructures using AAO templates, while the bulk of the review will focus on the synthesis of small molecule nanowires, nanotubes, and nanorods. We will also discuss unique properties of some highly crystalline small molecule nanorods fabricated using AAO templates