A Short and Highly Stereoselective Synthesis of Cerebrosterol

Ｃｅｒｅｂｒｏｓｔｅｒｏｌ (2 4Ｓ ｈｙｄｒｏｘｙｃｈｏｌｅｓｔｅｒｏｌ,1)ｆｏｒｍｅｄｉｎｓｍａｌｌａｍｏｕｎｔｓｉｎｈｕｍａｎａｎｄａｎｉｍａｌｂｒａｉｎ1ｆｒｏｍｃｈｏｌｅｓ ｔｅｒｏｌｉｓｉｍｐｏｒｔａｎｔｆｏｒｃｈｏｌｅｓｔｅｒｏｌｈｏｍｅｏｓｔａｓｉｓｉｎｔｈｉｓｏｒｇａｎ .Ｔｈｅｅｘｃｅｓｓｃｈｏｌｅｓｔｅｒｏｌｉｓｃｏｎｖｅｒｔｅｄｉｎｔｏ 2 4Ｓ ｈｙｄｒｏｘｙ ｃｈｏｌｅｓｔｅｒｏｌｂｙａｕｎｉｑｕｅｂｒａｉｎ ｓｐｅｃｉｆｉｃ 2 4Ｓ ｈｙｄｒｏｘｙｌａｓｅ ,ｗｈｉｃｈｃｏｕｌｄｂｅｒ…     

Gas-phase cluster cations generated by direct laser ablation on AgBr/S mixture

Ｔｈｅｓｅｎｓｉｔｉｖｉｔｙｏｆｓｉｌｖｅｒｈａｌｉｄｅｅｍｕｌｓｉｏｎｓｃｏｕｌｄｂｅｉｍｐｒｏｖｅｄｇｒｅａｔｌｙａｆｔｅｒｂｅｉｎｇｃｈｅｍｉｃａｌｌｙｓｅｎｓｉｔｉｚｅｄ.Ｔｈｅｍａｔｔｅｒｗｈｉｃｈｐｌａｙｓａｎｉｍｐｏｒｔａｎｔｒｏｌｅｉｓｔｈｅｓｏｃａｌｌｅｄｓｅｎｓｉｔｉｚａｔｉｏｎｃｅｎｔｅｒｓｆｏｒｍｅｄｄｕｒｉｎｇｔｈｅｃｈｅｍｉｃａｌｓｅｎｓｉｔｉｚａｔｉｏｎｐｒｏｃｅｓｓ.Ｔｈｅｓｔｕｄｙｏｎｔｈｅｆｏｒｍａｔｉｎ,ｎａｔｕｒｅａｎｄｆｕｎｃｔｉｏｎｏｆｔｈｅｓｅｃｅｎｔ…     

A Convenient Synthesis of 2-Aryl-3-per(poly)fluoroacylindoles

ＩｎｔｒｏｄｕｃｔｉｏｎＤｕｅｔｏｔｈｅｓｐｅｃｉｆｉｃｐｒｏｐｅｒｔｉｅｓｉｍｐａｒｔｅｄｂｙｆｌｕｏｒｉｎｅ ,ｔｈｅｉｎｔｒｏｄｕｃｔｉｏｎｏｆａｆｌｕｏｒｉｎｅａｔｏｍｏｒａｆｌｕｏｒｏａｌｋｙｌｇｒｏｕｐｉｎｔｏｌｅａｄｍｏｌｅｃｕｌｅｓｈａｓｂｅｅｎｗｉｄｅｌｙｕｓｅｄａｓｏｎｅｏｆｔｈｅｍｅｔｈｏｄｓｆｏｒｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｎｏｖｅｌｂｉｏｌｏｇｉｃａｌｌｙａｃｔｉｖｅｃｏｍｐｏｕｎｄｓ.1Ｉｎｄｏｌｅｓａｒｅａｔｔｒａｃｔｉｖｅｃｏｍｐｏｕｎｄｓｆｒｏｍｔｈｅｖｉｅｗｐ…     

An Electropolymerized Membrane Biosensor for Specific DNA Recognition

ＩｎｔｒｏｄｕｃｔｉｏｎＷｈｅｎａｓｓＤＮＡｅｎｃｏｕｎｔｅｒｓａｃｏｍｐｌｅｍｅｎｔａｒｙｐａｒｔｎｅｒｉｎａｓａｍｐｌｅｓｏｌｕｔｉｏｎ ,ｉｔｗｉｌｌｈｙｂｒｉｄｉｚｅ .Ｔｈｉｓｈｙｂｒｉｄｉｚａｔｉｏｎｃａｎｂｅｄｅｔｅｃｔｅｄｂｙｃｈａｎｇｅｓｉｎａｎｅｌｅｃｔｒｏｃｈｅｍｉｃａｌｓｉｇｎａｌｖｏｌｔａｇｅｏｒｃｕｒｒｅｎｔ.Ａｎｅｌｅｃｔｒｏｃｈｅｍｉｃａｌｂｉｏｓｅｎｓｏｒｗｉｔｈｔｈｅｓｅｌｅｃｔｉｖｉｔｙｏｆｂｉｏｃｈｅｍｉｃａｌｒｅａｃｔｉｏｎａｎｄｔｈｅｓｅｎｓｉｔｉｖｉｔｙ…     

Intramolecular reaction of polymer coordinated cationic rhodium complex

Ｓｑｕａｒｅｐｌａｎａｒｃｉｓｄｉｃａｒｂｏｎｙｌｒｈｏｄｉｕｍｃｏｍｐｌｅｘ,ａｐｒｅｃｕｒｓｏｒｏｆｃａｔａｌｙｔｉｃａｌｌｙａｃｔｉｖｅｃｏｍｐｏｕｎｄｉｎｃａｔａｌｙｔｉｃｒｅａｃｔｉｏｎ,ｉｓａｔｙｐｉｃａｌｋｉｎｄｏｆｃａｔａｌｙｓｔ[1].Ｉｔｉｓｕｓｕａｌｌｙｕｎｓｔａｂｌｅ.Ｆｏｒｅｘａｍｐｌｅ,ｗｉｔｈｏｕｔｅｆｆｉｃｉｅｎｔｐｒｏｔｅｃｔｉｏｎｏｆＣＯａｎｄｈｉｇｈｔｅｍｐｅｒａｔｕｒｅ,ｄｉｉｏｄｏｄｉｃａｒｂｏｎｙｌｒｈｏｄｉｕｍ,ａｎｅｆｆｅｃｔｉｖｅｃａｔａｌｙｓｔｆｏｒｔｈ…     

Branched-Polyethylene Produced by Asymmetric Metallocene Catalyst Using Ethylene as Monomer

Ｃｏｎｔｉｎｕｏｕｓｆｕｎｄａｍｅｎｔａｌｉｎｖｅｓｔｉｇａｔｉｏｎｓｏｎｍｅｔａｌｏｃｅｎｅｈａｖｅｌｅｄｔｏｔｈｅｂａｓｉｃｕｎｄｅｒ－ｓｔａｎｄｉｎｇａｎｄｔｈｅｃｏｎｔｒｏｌｏｆｐｏｌｙｍｅｒｉｚａｔｉｏｎａｃｔｉｖｅｓｉｔｅｓ,ｔｈｕｓｃａ...     

Oxidative biomacromolecular damage from novel phthalocyanine

Ｉｎｒｅｃｅｎｔｙｅａｒｓ,ｐｈｔｈａｌｏｃｙａｎｉｎｅｓａｒｅｗｉｄｅｌｙｕｓｅｄｉｎｐｈｏｔｏｄｙｎａｍｉｃｔｈｅｒａｐｙ(ＰＤＴ)ａｎｄｌｉｇｈｔｉｎｄｕｃｅｄｅｌｅｃｔｒｏｎｉｃｄｅｖｉｃｅｓ.Ｔｈｅｙｃａｎｂｅｐｏｔｅｎｔｉａｌｌｙｕｓｅｄｉｎｔｈｅｔｈｅｒａｐｙｏｆｃａｎｃｅｒａｎｄｉｎｔｈｅｒｅｓｔｒａｉｎｔｏｆｈｕｍａｎｉｍｍｕｎｏｌｏｇｙｖｉｒｕｓ(ＨＩＶ),ｅｔｃ.[1,2].Ｐｈｏｔｏｓｅｎｓｉｔｉｚｅｄｏｘｉｄａｔｉｏｎｉｓａｐｒｏｃｅｓｓｉｎｗｈｉｃｈｐｈｏｔｏｓｅｎｓｉｔｉｚｅｒｏ…     

Enantioselective Transfer Hydrogenation of Aromatic Ketones Catalyzed by New Diaminodiphosphine Ru(Ⅱ) Complexes

Ｃｈｉｒａｌｂｉｐｈｏｓｐｈｉｎｅｌｉｇａｎｄｓｐｒｏｖｉｄｅａｕｓｅｆｕｌｔｏｏｌｆｏｒｐｒｅｐａｒｉｎｇｏｐｔｉｃａｌｙａｃｔｉｖｅｓｅｃｏｎｄａｒｙａｌｃｏｈｏｌｓａｎｄｈａｖｅｂｅｅｎｔｈｅｉｎｔｅｒｅｓｔｉｎｇｓｕｂｊｅｃｔｏｆｎｕｍｅｒｏ...     

A New Furanolactam from the Chinese Sponge Phacellis Fusca

Ｉｎｔｈｅｃｏｕｒｓｅｏｆｏｕｒｃｏｎｔｉｎｕｉｎｇｓｅａｒｃｈｆｏｒｂｉｏａｃｔｉｖｅｓｕｂｓｔａｎｃｅｓｆｒｏｍｍａｒｉｎｅｏｒｇａｎｉｓｍｓ,ｗｅｈａｖｅｓｔｕｄｉｅｄｔｈｅｓｅｃｏｎｄａｒｙｍｅｔａｂｏｌｉｔｅｓｏｆｍａｒｉｎｅｓｐｏｎｇｅＰ...     

A New Fluorescence Method for the Measurement of Intracellular Free Rare Earth Ions： Fura－2 as an Indicator

ＡＮｅｗＦｌｕｏｒｅｓｃｅｎｃｅＭｅｔｈｏｄｆｏｒｔｈｅＭｅａｓｕｒｅｍｅｎｔｏｆＩｎｔｒａｃｅｌｌｕｌａｒＦｒｅｅＲａｒｅＥａｒｔｈＩｏｎｓ,Ｆｕｒａ－２ａｓａｎＩｎｄｉｃａｔｏｒＡＮｅｗＦｌｕｏｒｅｓｃｅｎｃｅＭｅｔｈｏｄｆｏｒｔｈｅＭｅａｓｕｒ?..     

An Electrochemical Biosensor with Cholesterol Oxidase/ Sol‐Gel Film on a Nanoplatinum/Carbon Nanotube Electrode

The carbon nanotubes decorated nanoplatinum (CNT‐Pt) were prepared using a chemical reduction method and a novel base electrode was constructed by intercalating CNT‐Pt on the surface of a waxed graphite electrode. The results showed that the nano‐particles of platinum at a waxed graphite electrode exhibits high catalytic activity for the reduction of hydrogen peroxide. The cholesterol oxidase (ChOx), chosen as a model enzyme, was immobilized with sol‐gel on the CNT‐Pt base electrode to construct a biosensor. The current response of the biosensor for cholesterol was very rapid (<20 s). The linear range for cholesterol measurement was 4.0×10^?6 mol/L ?1.0×10^?4 mol/L with a detection limit of 1.4×10^?6 mol/L. The experiments also showed that the ChOx/sol‐gel/CNT‐Pt biosensor was sensitive and stable in detecting cholesterol in serum samples.     

A Cholesterol Biosensor Based on Entrapment of Cholesterol Oxidase in a Silicic Sol‐Gel Matrix at a Prussian Blue Modified Electrode

A cholesterol biosensors fabricated by immobilization of cholesterol oxidase (ChOx) in a layer of silicic sol‐gel matrix on the top of a Prussian Blue‐modified glassy carbon electrode was prepared. It is based on the detection of hydrogen peroxide produced by ChOx at ?0.05 V. The half‐lifetime of the biosensor is about 35 days. Cholesterol can be determined in the concentration range of 1×10^?6?8×10^?5 mol/L with a detection limit of 1.2×10^?7 mol/L. Normal interfering compounds, such as ascorbic acid and uric acid do not affect the determination. The high sensitivity and outstanding selectivity are attributed to the Prussian Blue film modified on the sensor.     

A Selective Cholesterol Biosensor Based on Composite Film Modified Electrode for Amperometric Detection

An amperometric cholesterol biosensor based on immobilization of cholesterol oxidase in a Prussian blue (PB)/polypyrrole (PPy) composite film on the surface of a glassy carbon electrode was fabricated. Hydrogen peroxide produced by the enzymatic reaction was catalytically reduced on the PB film electrode at 0 V with a sensitivity of 39 μA (mol/L)^?1. Cholesterol in the concentration range of 10^?5 ? 10^?4 mol/L was determined with a detection limit of 6 × 10^?7 mol/L by amperometric method. Normal coexisting compounds in the bio‐samples such as ascorbic acid and uric acid do not interfere with the determination. The excellent properties of the sensor in sensitivity and selectivity are attributed to the PB/PPy layer modified on the sensor.     

A Uric Acid Biosensor Based on Langmuir-Blodgett Film as an Enzyme-Immobilizing Matrix

A uric acid biosensor was fabricated by the Langmuir–Blodgett (LB) technique to immobilize the uricase on chitosan/Prussian blue (CS/PB) prefunctionalized indium-tin oxide (ITO) electrode. The effects of ionic strengths, acidity of subphase, and uricase amount on the film were studied. The electrochemical properties of the uricase/n-nonadecanoic acid (UOx/NA) LB film proved that CS/PB was a good electro-catalyst for the reduction of hydrogen peroxide produced by enzymatic reaction of UOx, and protein molecules retained their natural electro-catalytic activity. The linear range of uric acid detection was from 5 × 10^?6 mol/L to 1.15 × 10^?3 mol/L with a detection limit of 1.8 × 10^?7 mol/L.     

A Nitric Oxide Biosensor Based on Myoglobin Adsorbed on Multi‐Walled Carbon Nanotubes

Myoglobin (Myb) of horse heart is incorporated on multi‐walled carbon nanotubes (MWNTs) and immobilized at a glassy carbon (GC) electrode surface. Its electrochemical behavior and enzyme activity are characterized by employing electrochemical methods. The results indicate that MWNTs can obviously promote the direct electron transfer between Myb and electrode, and that the Myb on MWNTs behaves as an enzyme‐like activity towards the electrochemical reduction of nitric oxide (NO). Accordingly, an unmediated NO biosensor is constructed. Experimental results reveal that the peak current related to NO is linearly proportional to its concentration in the range of 2.0×10^?7–4.0×10^?5 mol/L. The detection limit is estimated to be 8.0×10^?8 mol/L. Considering a relative standard deviation of 2.1% in seven independent determinations of 1.0×10^?5 mol/L NO, this biosensor shows a good reproducibility. The biosensor based on Myb/MWNTs modified electrode can be used for the rapid determination of trace NO in aqueous solution with a good stability, nice selectivity and easy construction.     

Carbon Nanotubes‐Based Amperometric Cholesterol Biosensor Fabricated Through Layer‐by‐Layer Technique

A carbon nanotubes‐based amperometric cholesterol biosensor has been fabricated through layer‐by‐layer (LBL) deposition of a cationic polyelectrolyte (PDDA, poly(diallyldimethylammonium chloride)) and cholesterol oxidase (ChOx) on multi‐walled carbon nanotubes (MWNTs)‐modified gold electrode, followed by electrochemical generation of a nonconducting poly(o‐phenylenediamine) (PPD) film as the protective coating. Electrochemical impedance measurements have shown that PDDA/ChOx multilayer film could be formed uniformly on MWNTs‐modified gold electrode. Due to the strong electrocatalytic properties of MWNTs toward H₂O₂ and the low permeability of PPD film for electroacitve species, such as ascorbic acid, uric acid and acetaminophen, the biosensor has shown high sensitivity and good anti‐interferent ability in the detection of cholesterol. The effect of the pH value of the detection solution on the response of the biosensor was also investigated. A linear range up to 6.0 mM has been observed for the biosensor with a detection limit of 0.2 mM. The apparent Michaelis‐Menten constant and the maximum response current density were calculated to be 7.17 mM and 7.32 μA cm^?2, respectively.     

Cholesterol oxidase biosensor based on a glassy carbon electrode modified with Nafion and methyl viologen

Cholesterol oxidase biosensor has been constructed by using bovine serum albumin and glutaraldehyde as cross linker to immobilize cholesterol oxidase and cholesterol esterase on a glassy carbon electrode modified with Nafion and methyl viologen. The biosensor has been used to determine total cholesterol in blood. The linear range of the determination is 2.5×10~7 to 1.0×10-4 mol/L. The detection limit is about 5.0×10~8 mol/L. The response time is 12 s. This biosensor has the advantage of high selectivity, sensitivity and short response time.     

Amperometric Hydrogen Peroxide Biosensor Based on the Immobilization of Horseradish Peroxidase (HRP) on the Layer‐by‐Layer Assembly Films of Gold Colloidal Nanoparticles and Toluidine Blue

The precursor film was first formed on the Au electrode surface based on the self‐assembly of L ‐cysteine and the adsorption of gold colloidal nanoparticles (nano‐Au). Layer‐by‐layer (LBL) assembly films of toluidine blue (TB) and nano‐Au were fabricated by alternately immersing the electrode with precursor film into the solution of toluidine blue and gold colloid. Cyclic voltammetry (CV) and quartz crystal microbalance (QCM) were adopted to monitor the regular growth of {TB/Au} bilayer films. The successful assembly of {TB/Au}_n films brings a new strategy for electrochemical devices to construct layer‐by‐layer assembly films of nanomaterials and low molecular weight materials. In this article, {TB/Au}_n films were used as model films to fabricate a mediated H₂O₂ biosensor based on horseradish peroxidase, which responded rapidly to H₂O₂ in the linear range from 1.5×10^?7 mol/L to 8.6×10^?3 mol/L with a detection limit of 7.0×10^?8 mol/L. Morphologies of the final assembly films were characterized with scanning probe microscopy (SPM).     

Electrochemical DNA Biosensor Based on Graphene and TiO2 Nanorods Composite Film for the Detection of Transgenic Soybean Gene Sequence of MON89788

Based on graphene (GR), TiO₂ nanorods, and chitosan (CTS) nanocomposite modified carbon ionic liquid electrode (CILE) as substrate electrode, a new electrochemical DNA biosensor was effectively fabricated for the detection of the transgenic soybean sequence of MON89788. By using methylene blue (MB) as hybridization indicator for monitoring the hybridization with different ssDNA sequences, the differential pulse voltammetric response of MB on DNA modified electrodes were recorded and compared. Due to the synergistic effects of TiO₂ nanorods and GR on the electrode surface, the electrochemical responses of MB were greatly increased. Under optimal conditions the differential pulse voltammetric response of the target ssDNA sequence could be detected in the range from 1.0×10^?12 to 1.0×10^?6 mol/L with a detection limit of 7.21×10^?13 mol/L (3σ). This electrochemical DNA biosensor was further applied to the polymerase chain reaction (PCR) product of transgenic soybeans with satisfactory results.     

Xanthine Biosensor Based on Didodecyldimethylammonium Bromide Modified Pyrolytic Graphite Electrode

ＩｎｔｒｏｄｕｃｔｉｏｎＯｒｄｅｒｅｄｆｉｌｍｓｏｆｗａｔｅｒ ｉｎｓｏｌｕｂｌｅｓｕｒｆａｃｔａｎｔｓｃａｎｂｅｐｒｅｐａｒｅｄｂｙｃａｓｔｉｎｇｔｈｅｉｒｓｏｌｕｔｉｏｎｓｏｒｄｉｓｐｅｒｓｉｏｎｓｏｎｔｏａｓｏｌｉｄｓｕｐｐｏｒｔ .1Ｅｖａｐｏｒａｔｉｏｎｏｆｔｈｅｓｏｌｖｅｎｔａｆｔｅｒｃａｓｔｉｎｇｌｅａｖｅｓｔｈｉｎｆｉｌｍｓｅｌｆ ａｓｓｅｍｂｌｅｄｉｎｔｏｏｒｄｅｒｅｄｓｔａｃｋｏｆｂｉ ｌａｙｅｒ ,ｗｈｉｃｈｉｓｓｉｍｉｌａｒｔｏｂｉｏｌｏｇｉｃａｌｍｅｍｂｒａｎｅｆｏｒｍｅｄｂｙ…