Surface plasmon resonance biosensor for genetically modified organisms detection

The development of a surface plasmon resonance (SPR) affinity biosensor based on DNA hybridisation is described. This biosensor has been applied to genetically modified organisms (GMOs) detection. Single stranded DNA (ssDNA) probes were immobilised on the sensor chip of an SPR device and the hybridisation between the immobilised probe and the complementary sequence (target) was monitored. The probe sequences were internal to the sequence of 35S promoter and NOS terminator which are inserted sequences in the genome of GMO regulating the transgene expression. The system has been optimised using synthetic oligonucleotides, then applied to real samples analysis. Samples, containing the transgenic target sequences, were amplified by polymerase chain reaction (PCR) and then detected with the SPR biosensor.     

Tuning the Adsorption Properties of Isoreticular Pyrazolate-Based Metal-Organic Frameworks through Ligand Modification

Two isoreticular series of pyrazolate-based 3D open metal-organic frameworks, MBDP_X, adopting the NiBDP and ZnBDP structure types [H(2)BDP = 1,4-bis(1H-pyrazol-4-yl)benzene], were synthesized with the new tagged organic linkers H(2)BDP_X (X = -NO(2), -NH(2), -OH). All of the MBDP_X materials have been characterized through a combination of techniques. IR spectroscopy proved the effective presence of tags, while X-ray powder diffraction (XRPD) witnessed their isoreticular nature. Simultaneous TG/DSC analyses (STA) demonstrated their remarkable thermal stability, while variable-temperature XRPD experiments highlighted their high degree of flexibility related to guest-induced fit processes of the solvent molecules included in the channels. A structural isomer of the parent NiBDP was obtained with a sulfonate tagged ligand, H(2)BDP_SO(3)H. Structure solution from powder diffraction data collected at three different temperatures (room temperature, 90, and 250 °C) allowed the determination of its structure and the comprehension of its solvent-related flexible behavior. Finally, the potential application of the tagged MOFs in selective adsorption processes for gas separation and purification purposes was investigated by conventional single component adsorption isotherms, as well as by advanced experiments of pulse gas chromatography and breakthrough curve measurements. Noteworthy, the results show that functionalization does not improve the adsorption selectivity (partition coefficients) for the resolution of gas mixtures characterized by similar high quadrupole moments (e.g., CO(2)/C(2)H(2)); however, the resolution of gas mixtures containing molecules with highly differentiated polarities (i.e., N(2)/CO(2) or CH(4)/CO(2)) is highly improved.     

Synthesis and Characterization of the Monomer 2,2′ diallylbisphenol-A (ABFA) for obtaining Proton Exchange Membranes based on Crosslinked Sulphonated Poly(Arylene ether sulphone)s

Summary: In the present work, a methodology of synthesis and characterization of the monomer 2,2′ diallylbisphenol-A (ABFA) was developed, aiming at getting a precursor, with adequate purity, for obtaining cross-linked membranes based on sulphonated poly(arylene ether sulphone)s. The monomer synthesis involved the synthesis of 2,2′ bis(4-allyloxiphenyl)propane (Bisphenol-A, diallyl ether - BFAAE), from Bisphenol-A (BFA), followed by Claisen rearrangement of BFAAE, for the production of the target compound 2,2′ diallylbisphenol-A (ABFA). All the compounds, reagent BFA and obtained products, intermediate product BFAAE and final product ABFA, were characterized by FTIR (Fourier Transform infrared spectroscopy), TGA (Thermo-gravimetric analysis) and HPLC (High-performance liquid chromatography). The compound BFAAE was obtained with a yield of 94.5% and a purity of 97.3%, the latter characterized by TGA and by HPLC. The structure of the product was confirmed by FTIR. The thermal Claisen rearrangement process was conducted by using Differential Scanning Calorimetry (DSC) technique, from a factorial experiment planning, with two factors and three levels, with temperature and time being the variables. The above cited techniques were used for monitoring the Claisen rearrangement and for the characterization of the final product. The best results yield ABFA purity between 85 and 90%, approximately, for 220 °C/60min, 230 °C/30min and 210 °C/90min conditions. The obtained results suggest that, in the studied range, polymerization and degradation of the monomer ABFA occur, simultaneously to its formation.     

Formation and compatibilizing effect of the grafted copolymer in the reactive blending of 2-diethylsuccinate containing polyolefins with poly-ϵ-caprolactam (nylon-6)

The intermolecular reaction and its role in determining the partial compatibility between diethylsuccinate containing linear low-density polyethylene or ethylene propylene copolymer and poly-ϵ-caprolactam (PA6) has been investigated in the melt using a Brabender mixer. The reaction product has been submitted to selective solvent extraction with formic acid and n-heptane; the characterization of the two extracted fractions and the insoluble residue has demonstrated the formation of a polyolefin–nylon (PO–PA6) grafted copolymer. The formation of grafted copolymer has an evident effect on the compatibilization of the two original polymers, indeed the differential scanning calorimetry analysis shows a remarkable decrease of temperature and enthalpy of PA6 crystallization. Moreover scanning electron microscopy micrographs show clear evidence of size reduction of PA6 domains associated with improved interface interactions. © 1998 John Wiley & Sons, Ltd.     

Synthetic peptides in the diagnosis of HIV infection

Peptide-based enzyme-linked immunosorbent assays have been found to be enough sensitive and specific for the diagnosis of human immunodeficiency virus specific antibodies in acquired immunodeficiency syndrome patients. This review provides an overview of the most important peptides developed for use as synthetic antigens in immunodiagnosis of HIV-infected patients. In particular, many studies have been devoted to discriminate between the two retroviruses HIV-1 and HIV-2, as well as different subtypes.     

A new approach to the statistical treatment of 2D-maps in proteomics using fuzzy logic

A new approach to the statistical treatment of 2D-maps has been developed. This method is based on the use of fuzzy logic and allows to take into consideration the typical low reproducibility of 2D-maps. In this approach the signal corresponding to the presence of proteins on the 2D-maps is substituted with probability functions, centred on the signal itself. The standard deviation of the bidimensional gaussian probability function employed to blur the signal allows to assign different uncertainties to the two electrophoretic dimensions. The effect of changing the standard deviation and the digitalisation resolution are investigated.     

A New Cells‐Compatible Microfluidic Device for Single Channel Recordings

We report the fabrication of a microfluidic apparatus and the realization of a sensors based on PEDOT : PSS, a biocompatible semiconductor polymer used in substitution of standard electrodes for electrophysiological studies and for detection of nanopores in membrane. This gives the possibility to study the mechanisms of ions balance and molecular transport though cell membranes. In particular the apparatus is based on two chambers connected through an aperture in a PTFE sheet where lipid bilayer are formed using Montal‐Mueller method, and the pore‐forming proteins activity is detected by polymeric electrodes. This methodology could be applied to examine different membrane proteins for the purpose of biosensing, drug screening and nanopore technologies.     

Zundel-Type H-Bonding in Biomolecular Ions

Using quantum chemical calculations and infrared multiphoton dissociation (IRMPD) spectroscopy in the fingerprint and X-H stretching regions, we demonstrate here that the all-Ala b ₆ fragment ion features a macrocyclic structure with C₂ symmetry. For this structure, the ionizing proton is equally shared by the Ala(1) and Ala(4) amide oxygens in a Zundel-type symmetric (X…H⁺…X) H-bond. Figure

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