A novel β-cyclodextrin polymer modified by sulfonate groups

Based on the special properties and advantages of β-cyclodextrin (β-CD), β-CD polymers have been widely studied and used in recent years. A lot of researches have focused on the adsorption and separation properties of β-CD polymers. In this paper, β-CD polymer modified by sulfonate groups, which was named S-β-CDP, was prepared using epichlorohydrin as crosslinker and tiron (1,2-dihydroxybenzene-3,5-disulfonic acid disodium salt) as modifier. β-CD polymer without modification, which was named β-CDP, was also prepared for comparison. Infrared spectra, elemental analysis and adsorption tests of S-β-CDP were carried out and compared with β-CDP. The content of sulfonate groups in S-β-CDP was obtained from elemental analysis. The dramatically increased adsorption capability toward methylene blue and basic magenta confirmed the existence and chemical activity of sulfonate groups in S-β-CDP. Due to the convenient preparation process and modified adsorption properties, S-β-CDP will find its applications in various fields such as water purification, drug loading, separation and analysis.     

Effective adsorption of Hg(II) ions by new ethylene imine polymer/β-cyclodextrin crosslinked functionalized magnetic composite

A new effective magnetic composite material was prepared successfully for adsorption Hg(II) ions by introducing β-cyclodextrin/ethylene imine polymer to the mesoporous silica. The morphology and structure of EIP-β-CD magnetic adsorbents were characterized by FT-IR, XR, DTG, XPS and SEM technologies. The effect of many factors were discussed detailedly such as adsorption time, initial concentration, pH, different composition of adsorbent and adsorption temperature. It was found that EIP-β-CD showed excellent adsorption capacity, high selectivity, good reutilization and fast adsorption rate. The maximum adsorption capacity was 248.72 mg/g and the best removal rate was 99.49 % under the optimized experimental conditions. The kinetic and thermodynamic study showed typical characteristic of chemical adsorption, exothermic and spontaneous. The best mass proportion of β-cyclodextrin, ethylene imine polymer and glutaraldehyde was 1.0:0.4:0.2, and proper β-cyclodextrin can develop the adsorption capacity for Hg(II) ions in this adsorbent. The possible adsorption mechanism was investigated in detail. After the fifth cycle experiment, this new adsorbent still showed excellent adsorption capacity which indicated that it has great potential for Hg(II) ions cleanup in water solution.     

Studies on the formation and properties of polypyrrole doped with ionised β-cyclodextrins: influence of the anionic pendants

Journal of Solid State Electrochemistry - Polypyrrole films doped with sulfonated β-cyclodextrin (PPy/sβ-CD) and carboxymethyl β-cyclodextrin (PPy/CMβ-CD) were formed on...     

Effect of coexisting cations on the adsorption of cesium onto poly (β-cyclodextrin)/bentonite composite

A novel poly(β-cyclodextrin)/bentonite composite (β-CD/BNC) was successfully prepared through graft polymerisation by using ammonium persulphate–sodium bisulphate as initiators, and characterized by FT-IR and EDS. The equilibrium data fit Freundlich isotherm satisfactorily. Adsorption kinetic was fitted with pseudo-second-order. The maximum adsorption capacities for Cs⁺ by β-CD/BNC in absence and presence of Na⁺ and Mg²⁺ were 48.83 ± 0.35, 47.30 ± 0.28, and 42.52 ± 0.85 mg g^?1, respectively. Adsorption of Cs⁺ was suppressed by presence of Mg²⁺ more than Na⁺. β-CD/BNC had a higher affinity to Cs⁺ than Na⁺ and Mg²⁺. β-CD/BNC was an effective sorbent for the treatment cesium waste water.     

Diffusions of β-cyclodextrins in mucus studied by <Superscript>19</Superscript>F diffusion NMR

β-Cyclodextrin (β-CD) based materials have been widely used as drug carriers for pharmaceutical applications. To understand the diffusion of β-CDs in mucus is important for selecting β-CD based drug carriers for applications targeting mucosal absorption because the surfaces of many biological membranes are covered with a highly viscous aqueous mucus layer which forms relatively effective diffusion barriers for drugs. In this study, ¹⁹F self-diffusion NMR technique has been applied to study the self-diffusions of β-CDs in mucus. The ¹⁹F NMR signals arose from 1-fluoroadamantane molecules entrapped in the cavities of β-CDs. The diffusive abilities of different β-CDs in mucus were assessed through analyzing the diffusion coefficients using the presented kinetic model, and Ogston’s and Renkin’s diffusion models for hydrogel systems. The kinetic results show that 2-hydroxypropyl-β-CD and 2-Carboxyethyl-β-CD have the smallest binding affinities to bovine submaxillary mucin and human nasal mucin among five tested β-CDs. The mesh sizes of the bovine submaxillary mucus at different concentrations and that of the human nasal mucus were evaluated using the diffusion models. We hope that this ¹⁹F diffusion method will be useful to study the diffusion of β-CD based materials in other biological systems.     

Molecularly imprinted polymer using beta-cyclodextrin as functional monomer for the efficient recognition of bilirubin

Bilirubin (BR) imprinted polymer was successfully prepared using supramolecular host compound β-cyclodextrin (β-CD) as functional monomer. The adsorption equilibrium was attained in about 4 h, which indicated that the adsorption kinetics was comparatively fast. The results of adsorption and selectivity experiments indicated that BR-imprinted β-CD polymer was able to bind BR specifically and reversibly. The specific recognition of BR-imprinted β-CD polymer for BR may be due to the cooperative effects of inclusion interaction and hydrogen bonding. This BR-imprinted β-CD polymer was further applied to eliminate BR in human serum sample. It was verified that the binding specificity of the BR-imprinted polymer for BR was essentially sufficient in the presence of other compounds coexisting in serum sample. Therefore, as a reusable material possessing high affinity and selectivity, BR-imprinted β-CD polymer has a potential application perspective as a clinical hemoperfusion material.     

Action of Humicola lanuginosa lipase on long-chain lipid substrates: 2. Hydrolysis of diolein monolayers

The hydrolysis of 1,2-diolein (DO) monomolecular films by Humicola lanuginosa lipase (HLL) was studied by simultaneous measuring the decrease in the film area and the changes in the surface potential in the “zero-order trough” at constant surface pressure and in the presence of β-cyclodextrin (β-CD). The decrease with time in the film area reflects both the reduction in the area per molecule due to the transformation of substrate DO molecules into the products molecules of monoolein (MO) and oleic acid (OA) and the desorption of the soluble inclusion complexes β-CD–MO and β-CD–OA. The surface potential data were interpreted as an accumulation at the interface of negatively charged products of OA and insoluble β-CD–DO complexes. In the proposed kinetic model, the product solubilization rates in the presence of β-CD and the flux supplied progressively by the moving barrier from the reservoir to the reaction compartment in order to keep the constant surface pressure were taken into account. The surface concentrations of MO and OA transiently present at the interface were determined. The values of the global kinetic constant Q_m′ of hydrolysis of DO to MO were obtained. Comparison with the values of the global kinetic constant of hydrolysis of monoglyceride MO to OA shows that the rates of hydrolysis of diglyceride and monoglyceride by HLL are of the same order of magnitude.     

聚乙烯醇固载β-环糊精线性高聚物的合成及其药物控制释放研究

利用缩醛化反应将醛基化 β 环糊精 (β CD)固载到聚乙烯醇 (PVA)大分子链上 ,合成出了聚乙烯醇固载 β 环糊精 (PVA β CD)的线性环糊精高分子 ,其最佳反应条件是反应时间 2h ,温度 70℃ ,β CD 6 CHO与PVA的质量比小于等于 4∶1.采用红外光谱及核磁共振表征了该聚合物的分子结构 .通过研究PVA β CD与模型药物喜树碱 (CPT)的包合作用 ,对不同环糊精固载量的PVA β CD膜在不同pH值下的药物释放机理进行了探讨 .结果表明 ,PVA β CD因包合增溶作用促进了水难溶性药物的释放 .     

Complexation of tyrosol with cyclodextrins

Tyrosol (TY), 4-(2-hydroxyethyl)phenol, is an olive oil biophenol with antioxidant activity and positive effects on human health. This study has investigated the interactions of TY with cyclodextrins (CD) and a CD polymer. Complexation of TY with β-CD, hydroxypropyl-β-CD (HP-β-CD), and methyl-β-CD (Me-β-CD) has been evaluated both in aqueous solution and in the solid state. The techniques employed in solution to determine the apparent stability constants of the respective complexes were fluorescence and UV–visible spectroscopies. Complexation with β-CD and its derivatives involved an increase of both the UV absorbance and the intrinsic fluorescence of TY; a bathochromic shift of the UV spectrum was detected as well. The apparent stability constants obtained with native β-CD, Me-β-CD and HP-β-CD presented similar values. Complexes in the solid state were obtained by coevaporation and kneading. They were characterised by X-ray diffraction analysis and differential thermal analysis. The interaction of TY with β-CD led to a crystalline complex; the same diffraction pattern was obtained by coevaporation and kneading. The complexes obtained with methyl- and HP-β-CD were amorphous irrespective of the preparation method. In addition, the retention of TY in an insoluble polymer of CD crosslinked with epichlorohydrin has been quantified. In approximately 20 min, 1 mg of TY per gram of polymer was retained.     

Water-insoluble β-cyclodextrin polymer crosslinked by citric acid: synthesis and adsorption properties toward phenol and methylene blue

Water-insoluble β-cyclodextrin polymer (β-CDP) crosslinked by citric acid was obtained with a yield of 65% through an environment friendly synthesis procedure. FT-IR spectra disclosed that the hydroxyl groups of β-CD had reacted and condensated with the carboxyl groups of citric acid, and at the same time the structural characteristics of β-CD were essentially maintained in β-CDP. The β-CDP exhibited notable adsorption capability toward phenol (q _max = 13.8 mg g^?1) and especially large adsorption capability toward methylene blue (q _max = 105 mg g^?1). The concentration of methylene blue in water could be reduced to 0.11 mg L^?1 by the β-CDP, indicating the excellent adsorption sensitivity of β-CDP toward methylene blue. The adsorption results disclosed that the interior cavity and inclusion property of β-CD were maintained in the synthesized β-CDP.     

The role of maltosyl residue of maltosyl-β-cyclodextrin in the inclusion with dehydrocholic acid

Maltose substituted β-cyclodextrin (M-β-CD) is an important drug carrier due to its excellent water solubility and good compatibility. In this work, dehydrocholic acid (DHA) was taken as the model drug; the inclusion of M-β-CD/DHA was studied through molecular dynamics simulations. The effect of the maltosyl residue of M-β-CD on the interactions of M-β-CD with DHA, M-β-CD with water, and DHA with water were analyzed. Based on the results, the difference between the complex of M-β-CD/DHA and that of β-CD/DHA can be explained and understood.     

Layered assemblies composed of sulfonated cyclodextrin and poly(allylamine)

Layered assemblies containing cyclodextrin (CD) have been prepared by layer-by-layer deposition of poly(allylamine) and sulfonated α-CD or β-CD on a solid surface. A quartz crystal microbalance study revealed that α-CD and β-CD form multilayers in the films upon each deposition. The sulfonated-α-CD-containing film bound methyl orange (MO) by forming an inclusion complex, resulting in the isolation of MO as a monomer in the film, whereas MO formed aggregates in the sulfonated-β-CD and CD-free films.     

Development and evaluation of cyclodextrin complexed hydroxyapatite nanoparticles for preferential albumin adsorption

Our study focuses on the incorporation of β-CD into the HA structure, its effects on the phase of HA and the biological responses to proteins and blood cells. Hydroxyapatite (HA) containing levels of β-cyclodextrin (β-CD) of upto 0.9 wt% has been produced by co-precipitation method. The complexes were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, thermal gravimetric analysis (TG) and differential scanning analysis (DSC) methods. The size of the complexes as analyzed using DLS (dynamic light scattering) was between 150 nm and 350 nm. The results show that an increase in concentration of β-CD in the prepared samples that leads to an increase in hydrophobicity seems to promote an affinity for albumin adsorption. The PAGE results were substantiated by Lowry measurements and the results reveal that the H2 (containing 0.7 wt% β-CD) sample shows around 40% increase in albumin adsorption when compared to the H1 (containing 0.5 wt% β-CD) sample. The preferential adsorption of albumin has not been demonstrated in vivo. The ability to design particles that can preferentially interact with particular protein can obtain desired targeting effects. So the results indicate that HA/β-CD complexes have immense potential in targeted delivery of drugs. The in vivo potential of the developed samples was further confirmed in vitro by the results of cell aggregation and haemolytic activity.     

β-Cyclodextrin derivatives hybrid Fe3O4 magnetic nanoparticles as the drug delivery for ketoprofen

β-Cyclodextrin (β-CD) and its derivatives carboxymethyl-β-CD (CM-β-CD) and 2,6-dimethyl-β-CD (DM-β-CD) modified magnetic nanoparticles (CD-MNPs) were synthesized via layer-by-layer method. CDs grafted onto Fe₃O₄ MNPs were demonstrated by transmission electron microscopy, Fourier transform infrared and Zeta potential. Magnetic properties of CM-β-CD-MNPs, DM-β-CD-MNPs and β-CD-MNPs were characterized by vibrating sample magnetometer and the magnetic saturation values were 47, 46 and 44 emu g^?1, respectively. CD-MNPs as drug carriers were investigated by inclusion behavior and in vitro release using ketoprofen (KP) as a model drug. The maximum adsorption quantities of CM-β-CD-MNPs, DM-β-CD-MNPs and β-CD-MNPs for KP were 37.03, 7.63 and 25.12 mg g^?1, respectively, and the loading behaviors followed the Langmuir adsorption isotherm model with monolayer adsorption. The release profiles of KP released from KP-loaded CD-MNPs were rapid in initial 60 min and then gradually tend to level off, the release efficiency order was CM-β-CD-MNPs > β-CD-MNPs > DM-β-CD-MNPs, which was consistent with the order of inclusion capability. Therefore, the CD-MNPs were promising candidates for drug delivery.     

Chiral electrokinetic chromatography-electrospray ionization-mass spectrometry using a double junction interface

A double junction interface was utilized to preserve separation efficiency and alleviate ion suppression from sulfated β-cyclodextrin (S-β-CD) in electrokinetic chromatography-electrospray ionization-mass spectrometry. The utility of the approach was demonstrated by chiral EKC-MS analysis of dihydroxyphenylalanine and methyldihydroxyphenylalanine enantiomers using either low concentration (counter-migration mode; 0.1% S-β-CD) or high concentration (carrier mode; 2% S-β-CD). In the counter-migration mode, S-β-CD anions were supplied continuously from the junction reservoir to the separation column so that the effective separation length was preserved. This interface is especially useful under carrier mode in which high concentration of S-β-CD will migrate toward the ESI source. With the use of the double junction interface, the S-β-CD exited the separation column will remain in the junction reservoir, whereas the analyte will flow toward the ESI source through a connecting column. As a result, no ion suppression was observed and the sensitivity was improved significantly.     

Investigation on Non-covalent Complexes of Cyclodextrins with Li+ in Gas Phase by Mass Spectrometry

To investigate the non-covalent interaction between cyclodextrins (CD) and lithium ion, a stoichiometry of α-CD, β-CD, heptakis(2,6-di-O-methyl)-β-CD (DM-β-CD), or heptakis(2,3,6-tri-O-methyl)-β-CD (TM-β-CD) was mixed with lithium salt, respectively, and then incubated at room temperature for 10 min to reach the equilibrium. In posi-tive mode, the electrospray ionization mass spectrometry (ESI-MS) results demonstrated that lithium ion can conjugate to α-, β-, DM-β- or TM-β-CD and form 1:1 stoichiometric non-covalent complexes. The binding of the complexes was further confirmed by collision-induced dissociation. The dissociation constants K_d1 of four complexes (Li+α-CD, Li+β-CD, Li+DM-β-CD, and Li+TM-β-CD) were determined by mass spectrometric titration. The results showed K_d1 were 18.7, 26.7, 33.6, 30.5 μmol/L for the complexes of Li+ with α-CD, β-CD, DM-β-CD, and TM-β-CD, respectively. K_d1 for the Li⁺ complexes of β-CD is smaller than that of DM-β-CD due to its steric effect of the partial substituted -CH₃. The Kd1 for the Li⁺ complexes of DM-β-CD is nearly in agreement with that of TM-β-CD, indicating Li⁺ is more likely to locate in the small rim of DM-β-CD's hydrophobic cavity. The DFT results showed through electrostatic interaction, one Li+ can strongly conjugate to four neighboring oxygen atoms. For the (α-CD+Li)⁺ complex, one Li⁺ may also situate the small rim of α-CD's hydrophobic cavity to form a non-specific host-guest complex.     

Sol-gel approach for fabrication of coated anodized titanium wire for solid-phase microextraction: highly efficient adsorbents for enrichment of trace polar analytes

Nanotubular titania film was prepared in situ on titanium wire and was used as the fiber substrate for solid-phase microextraction (SPME) because of its high surface-to-volume ratio, easy preparation, and mechanical stability. Three different functional coatings, β-cyclodextrin (β-CD), β-cyclodextrin-co-poly(ethylenepropylene glycol) (β-CD/PEG), and polyethylene glycol (PEG)-based sorbents were chemically bonded to the nanostructured wire surface via sol-gel technology to further enhance the absorbing capability and extraction selectivity. Coupled to gas chromatography-flame ionic detection (GC-FID), the prepared SPME fibers were investigated using diverse compounds. The results indicated that the fibers showed good mechanical strength, excellent thermal stability, and wonderful capacity and selectivity to polar compounds, including polar aromatic compounds, alcohols, and ketones. Combining the superior hydrophilic property of a bonded functional molecule and the highly porous structure of a fiber coating, the prepared PEG-coated SPME fiber showed much higher adsorption affinity to ephedrine and methylephedrine than β-CD and β-CD/PEG fibers. The as-established PEG-coated SPME-GC analytical method provided excellent sensitivity (LODs, 0.004 and 0.001 ng mL^–1 for ephedrine and methylephedrine, respectively) and better linear range (0.01–2 000 μg L^?1). In addition, it has surprising repeatability and reproducibility. Finally, the present approach was used to analyze ephedrine and methylephedrine from real urine samples, and reliable results were obtained.

Configurational stability of 9-hydroxyrisperidone. Kinetics and mechanism of racemization

The configurational stability of 9-hydroxyrisperidone, an atypical antipsychotic, was studied under acidic, basic and physiological conditions. The analysis of 9-hydroxyrisperidone was performed using a recently validated chiral capillary electrophoretic method developed using a dual cyclodextrin mode (hydroxypropylated-β-CD and sulfated-α-CD). The kinetic parameters (rate constants, half-lives, and apparent free energy barriers) of the racemization were calculated through a mathematical model of the first-order reaction. The influences of the pH, the temperature, the nature and the concentration of the buffer, and the presence of an organic co-solvent were investigated. The fastest racemizations were observed under acidic conditions with high phosphate buffer concentrations and high temperatures. Under these conditions, the cyclodextrins (β-CD, methyl- β-CD, or hydroxypropylated-β-CD) added to both enantiomers in various molar ratios were not able to retard the racemization. Finally, the mechanism of racemization was investigated using nuclear magnetic resonance (NMR) and the proton–deuterium exchange of the proton H₉ borne by the chiral carbon has proven the presence of an imine–enamine tautomerism.     

Inclusion of Bisphenols by Cyclodextrin Derivatives

Complexation of various kinds of bisphenols (BPs) with cycloheptaamylose(β-cyclodextrin, β-CD) derivatives (β-CD, hydroxyethyl-β-CD (HE-β-CD), 2,6-di-O-methyl-β-CD (DM-β-CD) and polymerised β-CD (L-Poly-β-CD)) was examined fluorimetrically using2-anilinonaphthalene-6-sulfonic acid (2,6-ANS) as a probe. From the inhibitory effectof BPs on the inclusion of 2,6-ANS by the β-CD derivatives, the associationconstants (K_ass) of BPs with the β-CD derivatives were determined.The K_ass values for bisphenol B (BPB) with β-cyclodextrin derivatives except for L-Poly-β-CD were always larger than those for other BPs including bisphenol A (BPA), due to the interaction between the non-polar cavity and hydrophobic BPB. Thermodynamic parameters indicated that the entropy change was always largely negative (-90～ -120 J/mol...K in the β-CD system, for example), and the inclusion of bisphenols into the CD cavity was completely enthalpy-driven. The very largely negative entropy change might be mainly due to the tight fixation of guest molecules in the CD cavity, resulting in the loss of freedom of both CD and guest molecules. The effect of the structure of guest and host molecules on the association was also examined.     

Theoretical and experimental study of the inclusion complexes of ferulic acid with cyclodextrins

The inclusion complexation behaviour of ferulic acid (FA) with β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) was investigated by UV–vis, fluorescence and ¹H NMR spectroscopy. Since the guest may exist in either anionic or neutral form, the experiments were performed at different pH values. The stoichiometry and association constants of the complexes were determined by nonlinear regression analysis. The phase-solubility studies indicated that the water solubility of FA was improved through complexation with β-CD and HP-β-CD. An increase in the antioxidant reactivity was observed when inclusion complexes that FA formed with CDs were studied. Based on the NMR data, the spatial configurations of FA/β-CD and FA/HP-β-CD complexes were proposed, which suggested that FA entered into the cavity of β-CD from the narrow side, with the lipophilic aromatic ring and ethylenic moieties inside the CD cavity, and the –COOH group was close to the wider rim and exposed outside the cavity. A theoretical study of the complexes using molecular modelling gives the results in good agreement with the NMR data.