Carbon nanotube-templated assembly of protein.

This paper describes a novel general strategy for fabricating protein-polyion multilayers by electrostatic layer-by-layer (LBL) self-assembly on carbon nanotube templates. Such a noncovalent functionalization method is important for preserving the activity of biomolecular, the mechanical, and electrical properties of carbon nanotubes. Glucose oxidase and poly(diallyldimethylammonium) chloride polymer (PDDA) were used as models to investigate the LBL process on CNT templates.

Templated one-step synthesis of compositionally encoded nanowire tags.

Multimetal nanowire tags, with distinct encoding patterns, have been prepared using a one-step templated electrodeposition from solutions containing different concentrations of various metal ions. Such synthesis of compositionally encoded nanowire tags is substantially faster and simpler than the preparation of striped nanowires based on sequential plating steps from different metal solutions and leads to high identification accuracy. The alloy nanowire preparation route leads to a high coding capacity with a large number of distinguishable voltammetric signatures, reflecting the predetermined composition of the metal mixture plating solution (and hence the nanowire composition).

Amperometric choline biosensor fabricated through electrostatic assembly of bienzyme/polyelectrolyte hybrid layers on carbon nanotubes.

We report a flow injection amperometric choline biosensor based on the electrostatic assembly of the choline oxidase (ChO) enzyme and a bienzyme of ChO and horseradish peroxidase (HRP) onto multi-wall carbon nanotubes (MWCNT) modified glassy carbon (GC) electrodes. These choline biosensors were fabricated by immobilization of enzymes on the negatively charged MWCNT surface through alternately assembling a cationic poly(diallydimethylammonium chloride) (PDDA) layer and an enzyme layer. Using this layer-by-layer assembling approach, a bioactive nanocomposite film of PDDA/ChO/PDDA/HRP/PDDA/CNT (ChO/HRP/CNT) and PDDA/ChO/PDDA/CNT (ChO/CNT) was fabricated on the GC surface.

Biosensor based on self-assembling acetylcholinesterase on carbon nanotubes for flow injection/amperometric detection of organophosphate pesticides and nerve agents.

A highly sensitive flow injection amperometric biosensor for organophosphate pesticides and nerve agents based on self-assembled acetylcholinesterase (AChE) on a carbon nanotube (CNT)-modified glassy carbon (GC) electrode is described. AChE is immobilized on the negatively charged CNT surface by alternatively assembling a cationic poly(diallyldimethylammonium chloride) (PDDA) layer and an AChE layer. Transmission electron microscopy images confirm the formation of layer-by-layer nanostructures on carboxyl-functionalized CNTs.

Electrochemical sensor for organophosphate pesticides and nerve agents using zirconia nanoparticles as selective sorbents.

An electrochemical sensor for detection of organophosphate (OP) pesticides and nerve agents using zirconia (ZrO2) nanoparticles as selective sorbents is presented. Zirconia nanoparticles were electrodynamically deposited onto the polycrystalline gold electrode by cyclic voltammetry. Because of the strong affinity of zirconia for the phosphoric group, nitroaromatic OPs strongly bind to the ZrO2 nanoparticle surface.

A renewable electrochemical magnetic immunosensor based on gold nanoparticle labels.

A particle-based renewable electrochemical magnetic immunosensor was developed by using magnetic beads and gold nanoparticle labels. Anti-IgG antibody-modified magnetic beads were attached to a renewable carbon paste transducer surface by magnet that was fixed inside the sensor. Gold nanoparticle labels were capsulated to the surface of magnetic beads by sandwich immunoassay.

Multiple enzyme layers on carbon nanotubes for electrochemical detection down to 80 DNA copies.

Signal amplification using enzyme multilayers on carbon nanotube (CNT) templates is shown to yield a remarkably sensitive electrochemical detection of proteins and nucleic acids. The electrostatic layer-by-layer (LBL) self-assembly onto CNT carriers maximizes the ratio of enzyme tags per binding event to offer the greatest amplification factor reported to date. Absorption spectroscopy, TEM, and electrochemical characterization confirm the formation of LBL enzyme nanostructures on individual CNT carriers.

Enzyme nanoparticles-based electronic biosensor.

A simple and effective method to prepare an enzyme electronic biosensor by immobilizing enzyme nanoparticles directly onto the gold electrode surface is described; prepared horseradish peroxidase nanoparticles have been successfully used to develop reagentless electronic biosensors for H2O2 detection without promoters and mediators and offer great potential to develop enzyme-based electronic biosensors.

Ultrasensitive voltammetric detection of trace heavy metal ions using carbon nanotube nanoelectrode array.

We describe an ultrasensitive voltammetric detection of trace heavy metal ions using nanoelectrode arrays (NEAs) that are based on low-site density carbon nanotubes (CNTs). The NEAs were prepared by sealing the side-walls of CNTs with an epoxy passive layer that reduces the current leakage and eliminates the electrode capacitance, leading to a low background current. This provides a high signal-to-noise ratio.

Photochromic diarylethene for rewritable holographic data storage.

A new diarylethene doped with poly(methyl methacrylate) film is developed and its characteristics of volume holographic recording are investigated. The maximum diffraction efficiency of the 10microm thick film is 1.2%, and the rewritable hologram recording exhibits its high resolution, fatigue resistance, negligible shrinkage, and long lifetime, which are critical to apply this material to high-density rewritable holographic data storage.

Alpha-trialkylsilyl amino acid stability.

Alpha-trialkylsilyl amino acids have been evaluated for their stability toward methanolysis as a model for physiological conditions. The juxtaposition of amine and carbonyl groups significantly destabilizes the silicon-carbon bond, but changing a single methyl on silicon to an ethyl led to a dramatic stability enhancement. Converting the ester to an amide gave an additional jump in stability, suggesting broad potential for these novel amino acids in bioactive peptides and pharmaceuticals.

Nanocrystal-based bioelectronic coding of single nucleotide polymorphisms.

A bioelectronic method for coding unknown single nucleotide polymorphisms (SNPs) based on the use of different encoding nanocrystals is described. Four such nanocrystals, ZnS, CdS, PbS, and CuS, linked to the adenosine, cytidine, guanosine and thymidine mononucleotides, respectively, are sequentially introduced to the DNA hybrid-coated magnetic-bead solution. Each mutation captures via base pairing different nanocrystal-mononucleotide conjugates, and yields a characteristic multipotential voltammogram, whose peak potentials reflect the identity of the mismatch.

Electrochemical coding for multiplexed immunoassays of proteins.

An electrochemical immunoassay protocol for the simultaneous measurements of proteins, based on the use of different inorganic nanocrystal tracers is described. The multiprotein electrical detection capability is coupled to the amplification feature of electrochemical stripping transduction (to yield fmol detection limits) and with an efficient magnetic separation (to minimize nonspecific adsorption effects). The multianalyte electrical sandwich immunoassay involves a dual binding event, based on antibodies linked to the nanocrystal tags and magnetic beads.

Improvement of photorefractive properties and holographic applications of lithium niobate crystal.

Based on analyzing and synthesizing the effects of In doping, Fe doping and oxidation state, we propose an efficient way to improve photorefractive properties of LiNbO3 crystal. According to the proposed way, a sample of In:Fe:LiNbO3 crystal is grown and achieves larger dynamic range, higher sensitivity and better signal-to-noise ratio thanFe:LiNbO3 crystal (Fe:0.03wt.

[Apoptosis and hemodynamic changes of the penile tissue in diabetic rats].

Objective: To compare the apoptosis and hemodynamic changes of the penile tissue in diabetic and healthy rats.

Methods: Sixteen chronic diabetic and 10 matched normal control rats were injected with a single dose of streptozotocin (STZ) 65 mg/kg and the diabetic model established. Eight weeks later the rats were killed, their haemoglobin Alc( HbAlc) measured, and their penises harvested.

Effects of hemoperfusion adsorption and/or plasma exchange in treatment of severe viral hepatitis: a comparative study.

Aim: Non-bioartificial liver has been applied to clinic for quite a long time, but the reported efficacy has been very different. The aim of this study was to compare the efficacy and safety of hemoperfusion adsorption, plasma exchange and plasma exchange plus hemoperfusion adsorption in treatment of severe viral hepatitis.

Methods: Seventy-five patients with severe viral hepatitis were treated with hemoperfusion adsorption therapy (24 cases), plasma exchange therapy (17 cases) and plasma exchange plus hemoperfusion adsorption therapy (34 cases).

Silica sol-gel amperometric immunosensor for Schistosoma japonicum antibody assay.

An amperometric immunosensor was constructed by dispersing graphite, schistosoma-japonicum antigen (SjAg) and silica sol-gel at low temperature. The performance characteristics of the prepared immunosensor were examined in the buffered solution of o-aminophenol (o-AP) used as a substrate. It exhibited excellent physical and electrochemical stability with a renewable external surface.

[The primary comparative analysis between the host genetic factors and their relationships with clinical phenotype of HBV infected twins].

Objective: The primary comparative analysis between the host genetic factors and their relationships with clinical phenotype of 20 pairs of HBV infected and high risk twins.

Methods: Zygosity of twins was diagnosed by STR microsatellite polymorphism analysis. To identify the serological model and exclude the evidence of coinfection with other virus, we detected HAV, HBV, HCV, HDV, HEV serological markers by electrochemiluminescence method.

Ultrasensitive electrical biosensing of proteins and DNA: carbon-nanotube derived amplification of the recognition and transduction events.

A new strategy for dramatically amplifying enzyme-linked electrical detection of proteins and DNA using carbon nanotubes (CNTs) for carrying numerous enzyme tracers and accumulating the enzymatically liberated product on CNT-modified transducer is described. Such a CNT-derived double-step amplification pathway (of both the recognition and transduction events) allows the detection of DNA and proteins down to 1.3 and 160 zmol, respectively, in 25-50 muL samples and indicates great promise for PCR-free DNA analysis.

[Effects evaluation of middle mode artificial liver in treatment of severe hepatitis].

Objective: To evaluate the clinical efficacy and safety of middle mode artificial liver-plasma pheresis in treatment of severe hepatitis.

Methods: Seventeen patients with severe hepatitis were treated with plasma pheresis. The results of liver function, renal function, blood routine, prothrombin time (PT), prothrombin time activity (PTa) before and after the treatment were analyzed.

Encoded beads for electrochemical identification.

Encoded redox beads, based on the encapsulation of different quantum dots (QD) within polystyrene microspheres, have been developed for electrochemical identification. Encoded redox rods, prepared by sequential plating of different metal tracers into the pores of a host membrane, have also been designed. By incorporating different predetermined levels of multiple metal markers, such redox-encoded particles lead to a large number of recognizable voltammetric signatures and, hence, offer great promise for covert tagging of commercial products.

Enantioselective alpha-silyl amino acid synthesis by reverse-aza-Brook rearrangement.

[reaction: see text] Asymmetric reverse-aza-Brook rearrangement of N-Boc-N-trialkylsilyl allylamine yields an enantiomerically enriched alpha-amino allylsilane. Oxidative cleavage of the alkene leads to a Boc-protected amino acid with the configuration of naturally occurring amino acids (L). Standard coupling protocols, including the use of trifluoroacetic acid for removal of the Boc group, yield a tripeptide with a central silane amino acid.

Indium microrod tags for electrochemical detection of DNA hybridization.

The preparation and advantages of indium microrod tracers for solid-state electrochemical detection of DNA hybridization are described. The cylindrical metal particles were prepared by a template-directed electrochemical synthetic route involving plating of indium into the pores of a host membrane. The linear relationship between the charge passed during the preparation and the resulting particle size allows tailoring of the sensitivity of the electrical DNA assay.