Synthesis and Application of Carbon Nanotubes

Owing to the unique structure, the superior physical and chemical properties, the super strong mechanical performances, and so on, carbon nanotubes have attracted the attention of researchers all over the world. In this article, the basic properties and the main production processes of carbon nanotubes are introduced in brief, and the progress of applied research for carbon nanotubes is reviewed.     

Synthesis of Hydroxypropyl-β-cyclodextrin Bonded Silica-gel and its Application to Resolution

Many chiral separation methods have been set up for efficient, precise and dependable determination of optical purity and/or separation of optical isomers in preparative scale. However, most of the methods could only be used to analyze chiral substances, …     

Inclusion Complex of Paclitaxel in Hydroxypropyl-β-cyclodextrin

Introduction Paclitaxel （as Taxol） is a kind of diterpenoid natural product extracted from Chinese yew. It has been reported to have high anti-tumor effects, such as the activity against oophorama, mammary cancer, encephaloma, cervical carcinoma, and non- small-cell lung carcinoma. One of the major problems of paclitaxel applied to therapy is its extremely low solubility in water. In addition, paclitaxel is administered as a slow infusion in a vehicle consisting of Cremophor EL （ polyoxyethylated castor oil ）. However, Cremophor has been observed to cause severe, occasionally fatal hypersensitivity reactions in animals and humans. Therefore, paclitaxel therapy includes a prophylactic regimen of antihistamines and corticosteroids , along with a prolonged infusion time to reduce the severity and incidence of hypersensitivity reactions. Because of the reasons mentioned above, currently its preparation needs to be improved further.     

Inclusion Complex of Paclitaxel in Hydroxypropyl-β-cyclodextrin

Introduction Paclitaxel (as Taxol) is a kind of diterpenoid natural product[1] extracted from Chinese yew. It has been reported to have high anti-tumor effects, such as the activity against oophorama, mammary cancer, encephaloma, cervical carcinoma, and non- small-cell lung carcinoma[2-5]. One of the major problems of paclitaxel applied to therapy is its extremely low solubility in water[6]. In addition, paclitaxel is administered as a slow infusion in a vehicle consisting of Cremophor EL (polyoxyethylated castor oil ). However, Cremophor has been observed to cause severe, occasionally fatal hypersensitivity reactions in animals and humans[7].Therefore, paclitaxel therapy includes a prophylactic regimen of antihistamines and corticosteroids[8] , along with a prolonged infusion time to reduce the severity and incidence of hypersensitivity reactions. Because of the reasons mentioned above, currently its preparation needs to be improved further[9].     

Electrochemical Reduction of Oxygen on Multi-walled Carbon Nanotubes Electrode in Alkaline Solution

The multi-walled carbon nanotubes (MWNTs) electrode was constructed using polytetrafluoroethylene as binder, and the electrochemical reductive behavior of oxygen in alkaline solution was first examined on this electrode. Compared with other carbon materials, MWNTs show higher electrocatalytic activity, and the reversibility of O2 reduction reaction is greatly improved. The experiments reveal that the electrochemical reduction of O2 to HO2 is controlled by adsorption. The preliminary results illustrate the potential application of MWNTs in fuel cells.     

Direct Electron Transfer between Glucose Oxidase and Multi-walled Carbon Nanotubes

The direct dedrochemical behavior between the glucose oxfdase ( GOD ) and the multi-wailed carbon nauotubes (MWNTs) has been studied. Two pairs of cyclic voltammetric peaks corresponding to the two different processes, i. e. mass-transportand surface reaction of GOD are observed on this MWNTs. The formal potentials with E^o‘=-0.45Vand E^o‘=-0.55V were obtained respectively.The GOD film was observed on the carbon nanotube by the TEM.     

Flow Field Induced Steady Alignment of Oxidized Multi-walled Carbon Nanotubes

The steady ordered micro-ribbons of oxidized multi-walled carbon nanotubes (MWNTs) were obtained through micro-aperture PTFE membrane by vacuum filtration. After treatment by mixture of concentrated nitric acid and sulfuric acid, the surface functional groups modified MWNTs can be easily dispersed to form a homogeneous suspension. It is found that the steady micro-ribbons existed in the films obtained by vacuum filtration of the suspension. The filtration formed steady flow field and induced steady alignment of oxidized MWNTs. The chemical treatment of MWNTs forming strong interaction between MWNTs is necessity to keep steady of the micro-ribbons microstructure.     

Preparation of Ionic Liquids and Their Application in Hydrogenation of Aromatic Nitriles

On the basis of their characteristic polar nature, phase behavior and lack of vapour pressure, ionic liquids are considered as green solvents and have attracted significant attention as an alternative reaction medium for homogeneous catalysis.[1] However, the "greenness" of typical ionic liquids used in the literature consisted of halogen-containing anions (such as [AlCl4]-, [BF4]- and [PF6]-) was limited in some sense, due to the serious environment concerns if the hydrolysis stability of the anion is poor (e.g. for [AlCl4]-and [PF6]-) or thermal stability of used ionic liquid is undesired. In both cases, the additional effort is needed to avoid the liberation of toxic and corrosive HF or HCl into the environment.     

A New Application of Carbon Nanotubes Constructing Biosensor

Carbon nanotubes used for constructing biosensor was described for the first time. Single-wall carbon nanotubes (SWNTs) functionalized with carboxylic acid groups were used to immobilize glucose oxidase forming a glucose biosensor. The biosensor response can be determined by amperometric method at a low applied potential (0.40V).     

Inclusion Complex of Carprofen with Hydroxypropyl-β-cyclodextrin

The aim of this study was to investigate the characteristics ofhydroxypropyl--cyclodextrin (HPCD) on the solubility,photostability and dissolution of carprofen (CP). It was found that the solubility of carprofen increased 52-fold when16% HPCD was added to H₂O (w/v). The phase-solubility diagram revealed the formation of a 1 : 1 inclusion complex of CP-HPCD with a stability constant (k_s) of 487 M^-1. Formation of the inclusion complex of CP-HPCD was analyzed using differential scanning calorimetry (DSC). Changes in chemical shifts of the ¹H-nuclear magnetic resonance spectra of CP-HPCD demonstrated that the inclusion site of CP by HPCD was carbazolyl aromatic ring skeleton rather thanthe side chain of propanoic acid. The photostability study revealed that theCP-HPCD complex could not significantly decrease the rate of photodegradation of CP, implying that the rate-determining step of CP mainly occurredat the side chain. The dissolution rates of CP were significantly enhanced as the proportions of HPCD increasedin the prepared discs. The dissolution of the physical mixture (in a 1 : 3 molarratio) increased by about 6-fold in comparison with the parent drug. The improvement of wettability and solubility of CP by complexing to HPCD was reflected in theenhanced dissolution rate.     

Synthesis of Ni／Mg／Al Layered Double Hydroxides and Their Use as Catalyst Precursors in the Preparation of Carbon Nanotubes

Ni/Mg/Al layered double hydroxides(LDHs) with different n(Ni) : n(Mg) : n(Al) ratio values were prepared via a coprecipitation reaction. Then Ni/Mg/Al mixed oxides were obtained by calcination of these LDHs precursors. Carbon nanotubes were produced in the catalytic decomposition of propane over the Ni/Mg/Al mixed oxide catalysts. The quality of as-made nanotubes was investigated by SEM and TEM. The nanotubes were multiwall with a high length-diameter ratio and appeared to be flexible. The catalytic activities of these mixed oxides increased with increasing the Ni content. The Ni/Mg/Al mixed oxide with the highest Ni content [ n( Ni)/n( Mg)/n(Al) = 1/1/1 ] showed the highest activity and the carbon nanotubes grown on its surface had the best quality.     

Synthesis of Iso-condensed Heteroaromatic Pyrroles and Their Application in the Preparation of Conducting Polymers

Iso-condensed heteroaromatic pyrroles 1 are 10π-electron aromatic compounds. They are of interest from both theoretical and synthetic points of view. They are the cyclic analogues of heteroaromatic ortho-quinodimethanes 2, and can react with dienophiles in a Diels-Alder reaction to give the synthetically useful cycloadducts 3. Many of them are also of potential pharmaceutical importance because they are isosteric with indoles. Iso-condensed heteroaromatic pyrroles 1 can be used also as the m…     

Preparation of a Cyclomaltoheptaose(β-cyclodextrin) Cross-linked Chitosan Derivative via Glyoxal or Glutaraldehyde

Chitosan has been regarded as a multifunctional polymer applicable to various purpos-es1. The potential of the material in medical applications, particularly in drug-delivery formu-lations has been demonstrated2, 3. Recently, a crosslinked chitosan with various crosslink-ing agents was prepared as adsorbents4-7. A -cyclodextrin (?CD) has been subjected to numerous studies, particular in terms of its complexing ability with a variety of components8, 9. The complexing ability of -CD has b…     

Preparation of 6,6′—Bisperfluoroalkylated BINOLs and Their Application in Asymmetric Alkylation of Benzaldehyde

6，6′-Bis(1H,1H,2H,2H-perfluorooctyl)-BINOL and 6,6′-bis(1H,1H,2H,2H-perfluorodecyl)-BINOL were synthesized through Suzuki coupling reaction and used in fluorous biphase asymmetric alkylation of benzldehyde,Good enantioselectivity was obtained and the catalysts could be recovered by liquid-liq-uid extraction.     

Preparation and characterization of inclusion complexes of carvedilol with methyl-β-cyclodextrin

Aim of the present work was to investigate the effect of methyl-β-cyclodextrin (MβCD) on the solubility and dissolution rate of carvedilol (CAR), a drug used orally for the treatment of hypertension. Phase solubility studies showed an A_L-type diagram indicating the formation of inclusion complex in 1:1 molar ratio. Solid binary systems of the drug with MβCD were prepared by various methods. Physicochemical characterizations were performed using Fourier Transformation Infrared Spectroscopy, Differential Scanning Calorimetry and powder X-Ray Diffractometry. It could be concluded that CAR can form inclusion complex with MβCD. The dissolution profiles of inclusion complexes were determined and compared with those of CAR alone and the physical mixture. The dissolution rate of CAR was increased by MβCD inclusion complexation remarkably.     

Immobilization and Characterization of Glucose Oxidase on Single-Walled Carbon Nanotubes and Its Application to Sensing Glucose

The negatively charged （at pH 8.2） glucose oxidase （GOx, pI ca. 4.2） was assembled onto the surface of single-walled carbon nanotubes （SWNT）, which was covered （or wrapped） by a layer of positively charged polyelectrolyte poly（dimethyldiallylammonium chloride） （PDDA）, via the electrostatic interaction forming GOx-PDDASWNT nanocomposites. Fourier transform infrared （FTIR）, UV-Vis and electrochemical impedance spectroscopy （EIS） were used to characterize the growth processes of the nanocomposites. The results indicated that GOx retained its native secondary conformational structure after it was immobilized on the surface of PDDA-SWNT. A biosensor （Nafion-GOx-PDDA-SWNT/GC） was developed by immobilization of GOx-PDDA-SWNT nanocomposites on the surface of glassy carbon （GC） electrode using Nafion （5%） as a binder. The biosensor showed the electrocatalytic activity toward the oxidation of glucose under the presence of ferrocene monocarboxylic acid （FcM） as an electroactive mediator with a good stability, reproducibility and higher biological affinity. Under an optimal condition, the biosensor could be used to detection of glucose, presenting a typical characteristic of Michaelis-Menten kinetics with the apparent Michaelis-Menten constant of KM^app ca. 4.5 mmol/L, with a linear range of the concentration of glucose from 0.5 to 5.5 mmol/L （with correlation coefficient of 0.999） and the detection limit of ca. 83 μmol/L （at a signal-to-noise ratio of 3）. Thus the biosensor was useful in sensing the glucose concentration in serum since the normal glucose concentration in blood serum was around 4.6 mmol/L. The facile procedure of immobilizing GOx used in present work would promote the developments of electrochemical research for enzymes （proteins）, biosensors, biofuel cells and other bioelectrochemical devices.     

Preparation and characterization of theβ-cyclodextrin inclusion complex with sulfafurazole

The 1 : 1 inclusion complex involving sulfafurazole (SF) and-cyclodextrin (-CD) is prepared by the freeze-drying method and characterized on the basis of its chemical analysis, thermal behavior, infrared spectrum, X-ray powder pattern and¹³C NMR spectrum in DMSO-d₆ solution. The stability constant of the inclusion complex was determined by the solubility method. The effect of cyclodextrin on the UV absorption spectrum of sulfafurazole was also observed.     

Preparation of Monolithic Column and Its Application in p-CEC

A novel monolithic stationary phase having long alkyl chain ligands was introduced and evaluated in pressurized-capillary electrochromatography of small neutral and charged compounds.The monolithic column was prepared by the in situ copolymerization of ethylene dimethacrylate,1-hexadecene,allyl alcohol and 2-acrylamido-2-methyl-l-propanesulfonic acid in a quaternary porogenic solvent mixture consisting of 1,4-butanediol,cyclohexanol,dodecanol and water.     

Preparation and characteristics of hydroxypropyl-β-cyclodextrin polymeric nanocapsules loading nimodipine

Nimodipine loaded hydroxypropyl-β-cyclodextrin polymeric nanocapsules were prepared by interfacial polyaddition of hydroxypropyl-β-cyclodextrin and isophorone diisocyante in a miniemulsion system. The effects of ultrasonicate times on the preparation of miniemulsion, the total amount of hydroxypropyl-β-cyclodextrin and isophorone diisocyante, and the molar ratio of isophorone diisocyante to hydroxypropyl-β-cyclodextrin on the capsule size and drug release behavior from capsule were investigated. The chitosan based polymeric nanocapsules were prepared as a control to study the effect of hydroxypropyl-β-cyclodextrin molecules in capsule matrix on the drug release. The results indicated that the droplet size of miniemulsion and capsule size decreased with increasing sonicate times. When the total amount of hydroxypropyl-β-cyclodextrin and isophorone diisocyante, and the molar ratio of isophorone diisocyante to hydroxypropyl-β-cyclodextrin were increased, the capsule as well, but the drug release rates from capsules became slower. The drug release behaviors from hydroxypropyl-β-cyclodextrin polymeric nanocapsules were affected by the drug diffusion through the polymer matrix and the formation of inclusion complex between drug and hydroxypropyl-β-cyclodextrin.     

Preparation of a novel cyclodextrin derivative of benzimido-β-cyclodextrin and its enantioseparation performance in HPLC

A novel cyclodextrin (CD) derivative, mono-6-deoxy-benzimide-β-CD (MB-β-CD), in which a rigid substituent was linked to the narrow edge of the CD with a flexible H(2)C-N group, was successfully synthesized through the condensation of mono-6-deoxy-6-amino-β-cyclodextrin and benzaldehyde. To evaluate its enantioseparation abilities and investigate the role of the CD substituents and linkage in chiral recognition, MB-β-CD and mono-6-deoxyphenylimine-β-CD (MP-β-CD) with a rigid linkage were compared in the separation of 36 chiral compounds in a methanol/water mobile phase. The separation results showed that most of the analytes with rigid structures afforded better enantioresolutions on the MP-β-CD (with a rigid linkage) chiral stationary phase (CSP), while better enantioseparations for analytes with flexible structures and big steric hindrance were obtained on the MB-β-CD (with a flexible linkage) CSP. The former exhibited a specificity for the analyte structures, while the latter was more adaptable. Molecular dynamics simulations were performed to further understand the discrimination process and the function of the CD side arm.