The Inclusion Complex of Ferrocene with a Dithiolene Functionalized β-Cyclodextrin

A new cyclodextrin derivative with the anion side-arm, mono[6-deoxy-6-(2-sodium thio-1,2-dicyane ethylenylthio)]-cyclodextrin (6-mnt-CD), and its inclusion complex with ferrocene (6-mnt-CD/Fc), have been prepared and characterized by elemental analysis, IR spectroscopy, UV spectroscopy, mass spectrometry, ¹³C-NMR spectroscopy, thermogravimetry, and cyclic voltammetry (CV). Thermogravimetry analysis of the compound shows that the thermal stabilities of both the host and the guest in the inclusion complex have been greatly improved due to an additional interaction between the side-arm of the host and the guest. The interplay between the guest and the host with side-arm in the complex resulted in smaller positive potential shifts in CV compared to that in the inclusion complex CD/Fc.     

Glucose Biosensor Based on Carbon/PVC-COOH/Ferrocene Composite with Covalently Immobilized Enzyme

A carbon/PVC-COOH/ferrocene composite electrode used for the determination of glucose has been prepared. The ferrocene acted as mediator was incorporated into the PVC-COOH polymer and the leakage could be prevented. The presence of carboxyl groups on the electrode surface allowed immobilizing enzyme via EDC and NHS. The ratio of PVC-COOH to graphite powder （w/w） has been studied. Amperometric determination of glucose has been performed at potential of 0.30 V vs SCE. The response time was 〈 15 s. The linear response range was of 0.1-20 mmol/L with a detection limit of 48μmol/L.     

Biosensor Based on TTF@ SiO2 Nanoparticles as Electron Transfer Mediator for the Determination of Glucose

IntroductionBecause of the high demand for blood glucose mo-nitoring, significant research and development effortshave been devoted to produce reliable glucose sensorsforin vitroorin vivoapplications[1,2]. With the appli-cations of this device, many relev…     

Spectroscopic Study on Interaction of β-Cyclodextrin with Triprolidine Hydrochloride

The complexation of triprolidine hydrochloride （TRP） and β-cyclodextrin （β-CD） in deuterium oxide was investigated by 400 MHz 1^H NMR spectroscopy. The 800 MHz 2D ROESY data revealed that two 1 ：1 and one 2 ： 1 β-CD-TRP inclusion complexes were formed. Both aromatic moieties （p-tolyl and pyridyl ring） has entered into the β-CD cavity, confirming the existence of two different equilibria for 1 ： 1 inclusion complexes in which p-tolyl ring of the guest is more tightly held by the host cavity. The ROE intermolecular interactions provided the plausible structures of these 1 ： 1 and 2 ： 1 stoichiometric inclusion complexes of β-CD-triprolidine hydrochloride in solu- tion.     

A New Amperometric Glucose Biosensor with Naphthol Green B as Mediator

Naphthol green B was used, for the first time, as a new mediator in an amperometric glucose biosensor. It is a good mediator, promoting electron transfer from glucose oxidase to graphite electrode. The biosensor shows high sensitivity to glucose at low potential with response time of 30 seconds. The linear range is from 1.5 to 18μmol/L glucose with detection limit of 0.5μmol/L glucose.     

А Potentiometric Sensor for Ketoprofen Based on a β-Cyclodextrin Derivative

Journal of Analytical Chemistry - The preparation of Ag/AgCl inner electrode in the polymer layer (coated wire electrode) and glassy carbon electrodes for ketoprofen...     

A Novel Cholesterol Oxidase Biosensor Based on Pt-nanoparticle /Carbon Nanotube Modified Electrode

A variety of electrochemical biosensors for cholesterol detection have been proposed because of its importance in clinic and food analysis 1-2. Classical devices for the detection were based on monitoring either the consumption of oxygen or the production of H2O2. The amperometric determination of H2O2 oxidation is sensitive and stable, but it requires a high anodic potential (over 0.6 V vs Ag/AgCl) and is affected by co-oxidable substances such as ascorbic acid and uric acid usually presen…     

Development of Lactose Biosensor Based on β‐Galactosidase and Glucose Oxidase Immobilized into Gelatin

In this article, we describe the preparation of a new lactose biosensor based on electrode coating with β‐galactosidase and glucose oxidase immobilized gelatin. For this purpose, β‐galactosidase and glucose oxidase enzymes were immobilized onto gelatin by crosslinking with glutaraldehyde. Properties of the immobilized β‐galactosidase and glucose oxidase enzymes electrode have been studied. The effects of glutaraldehyde concentration, temperature and pH variations and reusability were among the subjects analyzed. Lactose biosensors were subjected to continuous repeated use in order to observe reusability and shelf life; where standard lactose and milk samples were used as substrate solutions. Continuous reuse experiments showed that most of the lactose biosensors activities were retained even after the 10th use in a period of 30 days.     

Inclusion of Polyphenol Oxidase Substrates in β-Cyclodextrin: A 1 H-NMR Study

A ¹H-NMR study of the interactionsbetween -cyclodextrin (-CD) and included phenolic molecules (chloragenic acid and caffeic acid ) in aqueous medium is reported. The results confirm that inclusion occurs. Data analysis by the continuous variation method shows that all the complexes have 1 : 1 stoichiometries. Values for the apparent association constants of the inclusion compounds are estimated and compared with previously reported values.     

Study on the Structure of Supramolecular Inclusion Complex of β-Cyclodextrin with Retinoic Acid

The importance of Vitamin A for human health has been stressed in resent studies1, meanwhile its derivative so-called retinoic acid (RA) has been widely used as pharmaceutical to treat several types of skin disease and cancer2,3. However the application of retinoic acid is restrained for its poor water solubility, unstability and side effect on the human body.Cyclodextrins (CDs) are macrocyclic oligosaccharides built up from 6, 7, or 8 glucopyranose units called (, (, and (-CD, respectively…     

Study of the Supramolecular Inclusion of β-Cyclodextrin with Andrographolide

An inclusion complex of -cyclodextrin with andrographolide (Andro) was prepared by using a convenient new method of microwave irradiation. The structure of the inclusion complex was determined by UV and IR analyses as well as ¹H NMR, ¹³C NMR and two dimensional NOE spectroscopic measurements. The results indicated that the possible stoichiometry of complex formation is 1:1 (guest:host ratio) and the two isomeric 1:1 inclusion complexes are present simultaneously in solution. Thermal studies proved the thermal stability of the inclusion complex.     

A High Sensitivity Fluorescent Chemo-sensory System Based on β-Cyclodextrin Dimer Modified with Dansyl Moieties

-Cyclodextrin dimer linked with ethylenediamine at the upper rim of the cyclodextrin has been synthesized and then modified with two dansyl moieties inthe presence of N,N'-dicyclohexylcarbodiimide. The sensing ability and bindingproperty of the title compound were investigated for steroids and terpenoids. Thefluorescence intensity of this dimer was decreased when a host–guest complex was formed. The value I/I⁰, where I⁰ and I are fluorescence intensitiesin the absence and presence of a guest and I is I⁰- I, was used as a parameter of sensitivity. This host exhibited a much higher sensitivity and selective molecular recognition ability for bile acids such as ursodeoxycholic acid andchenodeoxycholic acid and terpenoids such as (-)-borneol than the dansyl-modifiedcyclodextrins reported previously including -cyclodextrin dimer. The behaviors of the appended moieties of the host during the formation of host–guest complexes were studied using induced circular dichroism (ICD) and fluorescence spectra. The ICD intensityof this dimer was decreased on accommodation of a guest and this spectral pattern of the title dimer was opposite to that of bis dansyl-modified -cyclodextrin monomer. Theguest-induced variations in the fluorescence and ICD intensities suggest that this dimer formed a 1 : 1 host–guest complex and the appended moieties act as a hydrophobic cap.     

Studies on Inclusion Complexes of Felodipine with β-Cyclodextrin

The inclusion behaviour of -cyclodextrin(-CD) with felodipine (FL) as a guest moleculewas studied. Inclusion complexes were obtained by thekneading method in a binary or ternary system with anaddition of polyethylene glycol 6000. Formation ofinclusion complexes was studied by IR spectroscopy,differential scanning calorimetry (DSC), and¹³C-NMR. It has been shown that an aromaticphenyl ring was involved in the process ofcomplexation, and that in the solid clathrates thesolubility of FL increased two fold when compared tothe physical mixture, while it increased 10 fold inliquid three-component complexes. Moreover, thephotochemical stability of felodipine was studied inits crystalline form and in the inclusion complexeswith -CD. Quantitative assessment of thefelodipine photochemical decomposition was made on thebasis of the rate constants of decomposition (k) inthe first order kinetic reaction, half life time(t_0.5) and the time of decomposition of 10% of thecompound (t_0.1). It was shown that complexationof FL with -CD causes a two fold increase ofthe rate of the photodegradation process.     

Studies on Interactions of β-Cyclodextrin with a Nonionic Surfactant Triton N-101

The complexation ofβ-CD with a nonionic surfactant Triton N-101 (TN) has been studied by surface tension measurement and UV-visible spectroscopy. The surface tension curves and apparent critical micelle concentrationsof TN in the presenceofβ-CDare higher than that in the absenceofβ-CD, which indicates that surface activity of TN decrease and formation of micelle is delayed because of the complexation ofβ-CD with TN. To clearly explicate the influences ofβ-CD-TN complexation on changes of surface tension and formation of micelle, the surface tension of fixed concentrations of TN mixed withβ-CD is measured and the influences ofβ-CD on fixed concentrations of TN are discussed. When the concentration of TN is below its CMC, itssurface tension increases withβ-CD concentrations, and then remainsat amaximum. But when the concentrationof TN isabove itsCMC, itssurface tension remains the same asγCMC(surface tensionswhen TN concentrations are above its CMC) firstly, and then it increases withβ-CD concentration, finally remains at a maximum. The association constantsKaofβ-CD-TN system at 298 K are determined by the numerical method based on surface tension measurements that we developed. By measuring surface tensionsofβ-CD-TN systems, the plotsof calculatedS0-S value as a function ofS0/SorS0/S-1 give good straight line, which verified that, as assumed above, the supramolecularsystemstoichiometry is 1∶1 for the inclusion complexation.Kaofβ-CD-TN system at 298 K is calculated from the slope of the straight line and Gibbs free energy change -ΔG0values ofβ-CD-TN systems have also been obtained. The resultsshow thatKadependsonβ-CD concentration, the higher ofβ-CD concentration, the larger ofKavalues. Spectrophotometric titrations have been performed to show the interaction of this supramolecular system. As can be seen from the experiment results, whenβ-CD concentration is lower, the UV absorbance strength at 200, 222, 275 nm decreases with increasingβ-CDconcentration. But when the concentrationofβ-CDreachesat 8.0mmol/L,the absorbance at 275 nm shift to shorter wavelength. On the basis of this observation, we deduce that the hydrophobic chain of TN enterβ-CD cavity mainly whenβ-CD concentration is lower; But whenβ-CD concentration is increased, the phenyl moietyof TN islocated in amore hydrophobic environment, i.e., within the cyclodextrin cavity, rather than in the bulk aqueous solution. The models of the inclusion complexes are also designed based on experimental results.     

Theoretical Study on the Inclusion Complex of β-Cyclodextrin and Nitrobenzene

Quantum chemical calculations were carried out to investigate the structures and properties for the inclusion complexes of nitrobenzene (NB) into β-cyclodextrin. Two low-energy conformations of β-cyclodextrin (A and B) in the gas phase were initially investigated by the PM3 and B3LYP/6-31+G(d,p) calculations, respectively. Three different orientations were considered in the inclusion process of A and B with NB to form 1:1 complexes. Potential energy scan by PM3 calculations indicated that the phenyl orientation Ab for conformation A and the equator orientation Bc for conformation B are more favorable in energy, respectively. We also considered the 2:1 inclusion complexes of host A or B with guest NB in the gas phase. PM3 calculation indicated that the host-guest interaction energies to form 1:1 complexes are more negative than those to form 2:1 NB/B complexes. Finally, we studied the solvent effect of NB/CD complex, and PM3 results show that the influence of water molecules on the inclusion process is very important. The driving forces for the inclusion process and the geometries of complexes were discussed in detail.     

Study on the Supramolecular Inclusion Complex of β-Cyclodextrin/Lappaconitine

Lappaconitine (Lap) is a diterpenoid akaliamide, naturally occurring in roots and rhizomes of Aconitum and delphinium. Lap reveals bradycardic, hypotensive, antinocieptive activity. However, its application is restrained owing to its poor water solubility, toxicity and side effects on humans. In a number of pharmaceutical studies,CDs have been reported to interact with many drug molecules to form inclusion complexes. These inclusion complexes have been extensively used to improve water solubility of poorly soluble drugs, to reduce their toxicity, and to increase the dissolution rate [1]. In the present work, the β-CD/Lap complex was prepared by kneading method. The products have been characterized by the solubility measurement as well as UV, FTIR, NMR spectroscopy and X-ray powder diffractometry.     

Study on Molecular Recognition of Pinocembrin with Methylated-β-Cyclodextrin

The inclusion behavior, inclusion capacity and inclusion mode of pinocembrin (PIN) with dimethyl-β-cyclodextrin (DM-β-CD) and trimethyl-β-cyclodextrin (TM-β-CD) were characterized by X-ray diffraction (XRD), thermal analysis, scanning electron microscopy (SEM), UV-visible spectral titration and molecular docking. The results showed that the packing ratio of PIN/DM-β-CD complex and PIN/TM-β-CD complex was 1:1. The water solubility of PIN increased by 817 times and 575 times in the inclusion complex with DM-β-CD and TM-β-CD, respectively. Molecular docking showed the PIN entered from the large end of the DM-β-CD molecule and penetrated through the cavity. The A and B rings of the PIN were respectively located at the big and small ends of the CD molecule. For the TM-β-CD, only A and C rings of the PIN entered the cavity of CD.     

Polymerization and Copolymerization of Some Monomers as Adducts with β-Cyclodextrin

The feasibility of chemical bond formation, especially in the chain-transfer reaction between polymer and β-cyclodextrin (β-CD) molecules in the products of the radiation polymerization of β-CD with vinylidene chloride (VDC) its adducts has been considered. The lack of these bonds in the polymerization products of similar β-CD adducts with methyl methacrylate (MM), styrene (St), a mixture of VDC and allyl chloride (AC) and a mixture of VDC and MM (10:90 molar ratio) has been established. On the basis of the results obtained the lack of chemical bonds in the polymerization product of β-CD· VDC adduct is suggested.