Protein microarrays represent an emerging class of proteomic tools to investigate multiple protein-protein interactions in
parallel. A sufficient proportion of immobilized proteins must maintain an active conformation and an orientation that allows
for the sensitive and specific detection of antibody and ligand binding. In order to establish protein array technology for
the characterization of the weak interactions between leukocyte membrane proteins, we selected the human leukocyte membrane
protein CD200 (OX2) and its cell surface receptor (hCD200R) as a model system. As antibody-antigen reactions are generally
of higher affinity than receptor-ligand binding, we first analyzed the reactivity of monoclonal antibodies (mAb) to normal
and mutant forms of immobilized CD200R. 相似文献
Amplicons corresponding to the GC-rich p53 exon 5 and its analogues, synthesized by substituting 60% of cytosine by 5-methyl-cytosine, or 60% of guanosine by inosine
and GC-poor p53 exon 6 were synthesized and investigated electrochemically, in the presence and absence of proflavine, by differential pulse
voltammetry (DPV). Incorporation of base analogues and the thermal stability of the resulting amplicons were tested in the
presence of a fluorescent probe (Sybr–Green). Peak current at 1.0 V was lower for methylated than for unmethylated PCR amplicons
and was similarly affected by proflavine intercalation. In contrast, considerable peak current differences were observed in
the presence of proflavine for unmodified exon 5 v.s. exon 6 or inosine-containing amplicons. Thermal analysis verified the
expected shifts in melting temperature (Tm) due to the base analogue incorporation and GC-content variations. In conclusion, methylated and unmethylated PCR amplicons
could be distinguished in model DNA systems using differential pulse voltammetry (DPV) and use of proflavine could serve as
an electrochemical probe for identifying different DNA conformations. 相似文献
A fluorometric lateral flow assay has been developed for the detection of nucleic acids. The fluorophores phycoerythrin (PE) and fluorescein isothiocyanate (FITC) were used as labels, while a common digital camera and a colored vinyl-sheet, acting as a cut-off optical filter, are used for fluorescence imaging. After DNA amplification by polymerase chain reaction (PCR), the biotinylated PCR product is hybridized to its complementary probe that carries a poly(dA) tail at 3? edge and then applied to the lateral flow strip. The hybrids are captured to the test zone of the strip by immobilized poly(dT) sequences and detected by streptavidin-fluorescein and streptavidin-phycoerythrin conjugates, through streptavidin-biotin interaction. The assay is widely applicable, simple, cost-effective, and offers a large multiplexing potential. Its performance is comparable to assays based on the use of streptavidin-gold nanoparticles conjugates. As low as 7.8 fmol of a ssDNA and 12.5 fmol of an amplified dsDNA target were detectable.
Graphical abstract Schematic presentation of a fluorometric lateral flow assay based on fluorescein and phycoerythrin fluorescent labels for the detection of single-stranded (ssDNA) and double-stranded DNA (dsDNA) sequences and using a digital camera readout. SA: streptavidin, BSA: Bovine Serum Albumin, B: biotin, FITC: fluorescein isothiocyanate, PE: phycoerythrin, TZ: test zone, CZ: control zone.
Nafion®–polyaniline (PAn) composite films deposited by a two-step process on a stainless steel (SS) substrate were characterized in this study using Fourier transform infrared (FTIR) spectroscopy under various conditions employed to evaluate their anticorrosion properties. The SS|Nafion® electrode was first prepared by placing a certain amount of Nafion® on the SS substrate, and then polymerization of aniline was carried out potentiodynamically on the SS|Nafion® electrode. The SS|Nafion®–PAn electrodes subjected to both potentiodynamic polarization and open-circuit conditions in sulfuric acid solutions without and with chlorides appeared to have distinct differences in their FTIR spectra. It is proposed that under the electrochemical conditions used in this study, the PAn is mostly formed inside the Nafion® membrane with a high proportion of oligomers influencing the ionic transport through the membrane. The inhibition of pitting corrosion arises primarily from the enhanced permselectivity of the composite film due to the Nafion® membrane that prevents chloride transport. An essential beneficial effect comes also from the PAn redox properties on the growth of the passive oxide film. Even under severe corrosion conditions, Nafion®–PAn films retain their redox activity and chemical stability, whereas the membrane crystallinity seems to be enhanced.
In this paper we deal with oriented rectilinear congruences in a three-dimensional Euclidean space E3 establishing a conformal mapping between their middle surface and their middle envelope. We give some properties and determine
a special class of them, which have a minimal middle envelope. 相似文献
The present study reports a simple method to control the mechanical and surface properties of cellulose fiber networks and to protect them from humidity, without altering their initial morphology. This is achieved by dip coating the fiber networks in solutions containing different amounts of ethyl cyanoacrylate monomer (ECA). Under ambient humidity and due to the presence of the -OH groups of the cellulose, the ECA polymerizes around each individual cellulosic fiber forming a thin poly(ethyl cyanoacrylate) (PECA) shell. PECA was found to interact with the cellulose surface via hydrogen bonding as evidenced by Fourier transform infrared spectroscopy and thermogravimetric analysis measurements. The detailed surface characterization reveals that only 3.5 wt% of ECA in solution is sufficient to form compact PECA cladding around every cellulose fiber. After the proposed treatment the cellulose sheets become hydrophobic, well protected from the environmental humidity and with increased Young’s modulus. 相似文献
Nafion?–polyaniline (PAn) composite films deposited by a two-step process on a stainless steel (SS) substrate were characterized in this study using Fourier transform infrared (FTIR) spectroscopy under various conditions employed to evaluate their anticorrosion properties. The SS|Nafion? electrode was first prepared by placing a certain amount of Nafion? on the SS substrate, and then polymerization of aniline was carried out potentiodynamically on the SS|Nafion? electrode. The SS|Nafion?–PAn electrodes subjected to both potentiodynamic polarization and open-circuit conditions in sulfuric acid solutions without and with chlorides appeared to have distinct differences in their FTIR spectra. It is proposed that under the electrochemical conditions used in this study, the PAn is mostly formed inside the Nafion? membrane with a high proportion of oligomers influencing the ionic transport through the membrane. The inhibition of pitting corrosion arises primarily from the enhanced permselectivity of the composite film due to the Nafion? membrane that prevents chloride transport. An essential beneficial effect comes also from the PAn redox properties on the growth of the passive oxide film. Even under severe corrosion conditions, Nafion???/em>PAn films retain their redox activity and chemical stability, whereas the membrane crystallinity seems to be enhanced. 相似文献
The perovskite LaCoO3 evolves from a nonmagnetic Mott insulator to a spin cluster ferromagnet (FM) with the substitution of Sr2+ for La3+ in La1-xSrxCoO3. The clusters increase in size and number with x and the charge percolation through the clusters leads to a metallic state. Using elastic neutron scattering on La1-xSrxCoO3 single crystals, we show that an incommensurate spin superstructure coexists with the FM spin clusters. The incommensurability increases continuously with x, with the intensity rising in the insulating phase and dropping in the metallic phase as it directly competes with the commensurate FM, itinerant clusters. The spin incommensurability arises from local order of Co3+-Co4+ clusters but no long-range static or dynamic spin stripes develop. The coexistence and competition of the two magnetic phases explain the residual resistivity at low temperatures in samples with metalliclike transport. 相似文献