Layer‐by‐layer Assembled Multilayers of Graphene/Mono‐(6‐amino‐6‐deoxy)‐β‐cyclodextrin for Detection of Dopamine

Graphene/mono‐(6‐amino‐6‐deoxy)‐β‐cyclodextrin multilayer films composed of graphene sheet (GS) and mono‐(6‐amino‐6‐deoxy)‐β‐cyclodextrin (NH₂‐β‐CD) were fabricated easily by two steps. First, negatively charged graphene oxide (GO) and positively charged mono‐(6‐amino‐6‐deoxy)‐β‐cyclodextrin (NH₂‐β‐CD) were layer‐by‐layer (LBL) self‐assembled on glassy carbon electrode (GCE) modified with a layer of poly(diallyldimethylammonium chloride) (PDDA). Then graphene/mono‐(6‐amino‐6‐deoxy)‐β‐cyclodextrin (GS/NH₂‐β‐CD) multilayer films were built up by electrochemical reduction of graphene oxide/mono‐(6‐amino‐6‐deoxy)‐β‐cyclodextrin (GO/NH₂‐β‐CD). Combining the high surface area of GS and the active recognition sites on β‐cyclodextrin (β‐CD), the GS/NH₂‐β‐CD multilayer films show excellent electrochemical sensing performance for the detection of DA with an extraordinary broad linear range from 2.53 to 980.05 µmol·L^?1. This study offers a simple route to the controllable formation of graphene‐based electrochemical sensor for the detection of DA.     

Facile fabrication of porous oil‐absorbent microspheres with high oil absorbency and fast oil absorption speed

A novel type of porous oil‐absorbent microspheres based on poly(stearyl methacrylate‐co‐butyl acrylate) was prepared via suspension polymerization. By investigating the effects of the cross‐linking agent, monomer ratio, initiator, stabilizer, water/oil ratio, and porogen agent on the oil absorbency of the prepared oil‐absorbents, an optimized oil‐absorbent microsphere OAM‐T was obtained, and characterized by FT‐IR and SEM. The oil absorbencies of OAM‐T toward chloroform, toluene, gasoline, and diesel were measured to be 61.9, 32.6, 28.8, and 28.2 g/g respectively, with oil absorption saturation time being 1.0, 1.5, 2.0, and 3.0 hr. The oil retention of OAM‐T toward the four oils is all above 95%. Besides in pure oils, OAM‐T also has high oil absorbencies in oil–water mixture. It can be reused at least 12 times with little change in oil absorbency. Owing to its excellent oil absorption performance, OAM‐T might find applications for removing oil spills and organic pollutants from water. Copyright © 2015 John Wiley & Sons, Ltd.     

A novel composite microsphere as a highly efficient absorbent for oils and organic solvents

A novel composite oil‐absorbent microsphere poly(stearyl methacrylate‐co‐butyl acrylate) (PSB)‐SiO₂ was prepared by introducing hydrophobic nano‐silica Aerosil R812 into the suspension polymerization system of stearyl methacrylate and butyl acrylate and was characterized by Fourier transform infrared and scanning electron microscopy energy‐dispersive spectrometer. PSB‐SiO₂ has a loose network structure and exhibits remarkably fast oil absorption speed in relatively high saturated oil absorbency. Besides, PSB‐SiO₂ has good oil retention and reusability. Moreover, the saturated oil absorbencies of PSB‐SiO₂ toward toluene, gasoline, and diesel over water are roughly equivalent to that in pure oil. Owing to its excellent oil absorption performances, PSB‐SiO₂ will find applications in removing oil spills and organic pollutants over water. Copyright © 2016 John Wiley & Sons, Ltd.     

Preparation and evaluation of a polymeric gel containing ionic liquid‐functionalized MWCNTs as a novel class of organic solvent absorbent

Multiwalled carbon nanotubes grafted with vinyl immidazolium‐based ionic liquid (MWCNT‐IL) were synthesized and utilized as a crosslinking agent for the preparation and evaluation of a polymeric gel as a new class of organic solvent absorbent. Based on our earlier organic solvent‐absorbents, the present polymeric gel exhibited high organic solvent absorbency, fast organic solvent absorption rate, and good reusability. To prepare such polymeric gel, radical polymerization was carried out with dodecyl methacrylate and butyl acrylate as comonomers, MWCNT‐ILs as crosslinking agent, and azoisobutyronitrile as initiator, providing polymeric gel in a quantitative yield. The polymeric gel synthesized under the optimized polymerization conditions absorbed 79 times the dry weight in CCl₄, 57 times in toluene, 96 in CHCl₃, and 100 times in CH₂Cl₂. The reusability of the prepared‐polymeric gel was also checked which established that the gels could be recycled and reused for at least 10 times. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3166–3172     

Synthesis and application of a chiral ionic liquid functionalized β‐cyclodextrin as a chiral selector in capillary electrophoresis

A novel chiral ionic liquid functionalized β‐cyclodextrin, 6‐O‐2‐hydroxpropyltrimethylammonium‐β‐cyclodextrin tetrafluoroborate ([HPTMA‐β‐CD][BF₄]), was synthesized and used as a chiral selector in capillary electrophoresis. [HPTMA‐β‐CD][BF₄] not only increased the solubility in aqueous buffer in comparison with the parent compound, but also provided a stable reversal electroosmotic flow, and the enantioseparation of eight chiral drugs was examined in phosphate buffer containing [HPTMA‐β‐CD][BF₄] as the chiral selector. The effects of the [HPTMA‐β‐CD][BF₄] concentration and the background electrolyte pH were studied. Moreover, the chiral separation abilities of β‐CD and [HPTMA‐β‐CD][BF₄] were compared and possible mechanisms for the chiral recognition of [HPTMA‐β‐CD][BF₄] are discussed. Copyright © 2013 John Wiley & Sons, Ltd.     

Preparation and characterization of poly(ethylene oxide)‐loaded hydroxypropyl‐β‐cyclodextrin nanofibers

Hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) is a modified β‐cyclodextrin (β‐CD) derivative, which is toxicologically harmless to mammals and other animals. HP‐β‐CD is electrospun from an aqueous solution by blending with a non‐toxic, biocompatible, synthetic polymer poly(ethylene oxide) (PEO). Aqueous solutions containing different HP‐β‐CD/PEO blends (50:50–80:20) with variable concentrations (4 wt%–12 wt%) were used. Scanning electron microscope was used to investigate the morphology of the fibers, and Fourier transform infrared spectroscopy analysis confirmed the presence of HP‐β‐CD in the fiber. Uniform nanofibers with an average diameter of 264, 244, and 236 nm were obtained from 8 wt% solution of 50:50, 60:40, and 70:30 HP‐β‐CD/PEO, respectively. The average diameter of the fiber was decreased with increasing of HP‐β‐CD/PEO ratio. However, a higher proportion of HP‐β‐CD in the spinning solution increased beads in the fibers. The polymer concentration had no significant effect on the fiber diameter. The most uniform fibers with the narrowest diameter distribution were obtained from the 8 wt% of 50:50 solution. Copyright © 2015 John Wiley & Sons, Ltd.     

Cyclodextrins in Polymer Synthesis: Photoinitiated Free‐Radical Polymerization of N‐Isopropylacrylamide in Water Initiated by a Methylated β‐Cyclodextrin/2‐Hydroxy‐2‐methyl‐1‐phenylpropan‐1‐one Host/Guest Complex

Methylated β‐cyclodextrin (Me‐β‐CD) was used to complex a free‐radical photoinitiator, 2‐hydroxy‐2‐methyl‐1‐phenylpropan‐1‐one ( 1 ), yielding the water‐soluble 1 : 1 host/guest complex 1 a . The structure of complex 1 a was verified by means of IR, UV/vis and ¹H NMR spectroscopy. The influence of Me‐β‐CD as the host on the photopolymerization kinetics of N‐isopropylacrylamide was studied. Compared to the photopolymerization carried out under nearly identical conditions but without cyclodextrin, an increase in the polymerization rate was registered in the presence of complex 1 a .     

Synthesis,characterization and release profiles of nanoparticles self‐assembled from poly (PEGMA‐co‐MMA‐co‐acryloyl‐β‐CD) copolymers

A novel amphiphilic copolymer was synthesized from poly (ethylene glycol) methyl ether methacrylate (PEGMA950), methyl methacrylate (MMA) and acryloyl‐β‐cyclodextrin (acryloyl‐β‐CD) using the composites of (NH₄)₂S₂O₈/NaHSO₃ as the oxidation–reduction initiators. The successful fabrication of poly(PEGMA‐co‐MMA‐co‐acryloyl‐β‐CD) copolymers was confirmed by Fourier transform infrared spectrometer (FTIR), ¹H‐nuclear magnetic resonance (¹H NMR) spectra. The amphiphilic copolymer could self‐assemble into nanoparticles (NPs), and their morphology and particle size distribution were characterized with transmission electron microscopy (TEM), atomic force microscope (AFM) and dynamic light scattering (DLS) methods. Ibuprofen (IBU) was encapsulated in the novel NPs, and the release profiles of IBU were investigated. FTIR and ¹H NMR spectra illustrated that the poly(PEGMA‐co‐MMA‐co‐acryloyl‐β‐CD) copolymers were synthesized without any residual monomers and initiators. TEM and AFM photographs suggested that the obtained NPs were spherical, and the DLS results indicated that the diameter of blank NPs was 157.3 ± 32.7 nm. The IBU release profile showed that the IBU‐loaded NPs had certain pH responsibility. Copyright © 2014 John Wiley & Sons, Ltd.     

Preparation of Imprinted PVB/β‐CD Nanofiber by Electrospinning Technique and Its Selective Binding Abilities for Naringin

A novel molecularly imprinted composite nanofiber was prepared by a simple electrospinning technique, in which polyvinylbutyral (PVB) was chosen as matrix, β‐cyclodextrin (β‐CD) was used as a functional monomer and naringin (NG) as template molecules. After cross‐linked by hexamethylene diisocyanate (HMDI), the composite nanofiber exhibited a high specific binding capacity. The morphological structure of the nanofibers was studied by means of infrared spectrum (IR), X‐ray diffraction (XRD), and scanning electron microscopy (SEM). The β‐CD molecules were mostly homogeneously distributed within the PVB nanofiber without forming phase separated crystalline aggregates. Compared with traditional imprinted β‐CD polymer, the binding experiments demonstrated that the molecularly imprinted composite nanofiber shows the specific binding sites and the selective binding ability for NG. The molecularly imprinted nanofiber could be used at least six times without any loss in binding capacity.     

1H NMR studies of binary and ternary dapsone supramolecular complexes with different drug carriers: EPC liposome,SBE‐β‐CD and β‐CD

Binary and ternary systems composed of dapsone, sulfobutylether‐β‐cyclodextrin (SBE‐β‐CD), β‐CD and egg phosphatidylcholine (EPC) were evaluated using 1D ROESY, saturation transfer difference NMR and diffusion experiments (DOSY) revealing the binary complexes Dap/β‐CD (K_a 1396 l mol^?1), Dap/SBE‐β‐CD (K_a 246 l mol^?1), Dap/EPC (K_a 84 l mol^?1) and the ternary complex Dap/β‐CD/EPC (K_a 18 l mol^?1) in which dapsone is more soluble. Copyright © 2014 John Wiley & Sons, Ltd.     

Modular β‐cyclodextrin and polyoxyethylene ether modified water‐soluble polyacrylamide for shale hydration inhibition

A novel water‐soluble copolymer was prepared from acrylamide (AM), acrylic acid (AA), mono‐2‐O‐(allyloxy‐2‐hydroxyl‐propyl)‐β‐cyclodextrin (O‐β‐CD) and allyl alcohol polyoxyethylene ether (APEG), which was characterized with infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, ¹³C‐nuclear magnetic resonance spectrometry and static light scattering. This new copolymer combining polyglycols and the massive hydroxyl groups and cavity structure of β‐CD was investigated for inhibiting shale hydration. Based on the salt‐tolerance test, thermogravimetric‐differential scanning calorimetry‐mass spectrometer analyses, copolymer AM/AA/APEG/O‐β‐CD has made progress in the salt and temperature resistances. Moreover, the remarkable inhibiting‐hydration performance of copolymer was found as evidenced by the reduction of interlayer spacing of sodium montmorillonite and the high retention rates of indentation hardness of shale cores. Copyright © 2015 John Wiley & Sons, Ltd.     

Fluorescence Sensing and Selective Binding of a Novel 4,4′‐Sulfonyldianiline‐Bridged Bis(β‐cyclodextrin) for Bile Salts

A novel 4,4′‐sulfonyldianiline‐bridged bis(β‐cyclodextrin (CD)) 2 was synthesized, and its complex stability constants (K_s) for the 1 : 1 inclusion complexation with bile salts, i.e., cholate (CA), deoxycholate (DCA), glycocholate (GCA), and taurocholate (TCA) have been determined in phosphate buffer (pH 7.2) at 25° by fluorescence spectroscopy. The result indicated that 2 can act as efficient fluorescent sensor and display remarkable fluorescence enhancement upon addition of optically inert bile salts. Structures of the inclusion complexes between bile salts and 2 were elucidated by 2D‐NMR experiments, indicating that the anionic tail group and the D ring of bile salts penetrate into one CD cavity of 2 from the wide opening deeply, while the phenyl moiety of the CD linker is partially self‐included in the other CD cavity to form a host–linker–guest binding mode. As compared with native β‐CD 1 upon complexation with bile salts, bis(β‐CD) 2 enhances the binding ability and molecular selectivity. Typically, 2 gives the highest K_s value of 26200 M ^?1 for the complexation with CA, which may be ascribed to the simultaneous contributions of hydrophobic, H‐bond, and electrostatic interactions. These phenomena are discussed from the viewpoints of multiple recognition and induce‐fit interactions between host and guest.     

Enantiomeric Separations in Capillary Electrochromatography with Crown Ether‐Capped β‐Cyclodextrin‐Bonded Silica Particles as Chiral Stationary Phase

Two novel types of crown ether capped β‐cyclodextrin (β‐CD) bonded silica, namely, 4′‐aminobenzo‐X‐crown‐Y (X=15, 18 and Y=5, 6, resp.) capped [3‐(2‐O‐β‐cyclodextrin)‐2‐hydroxypropoxy] propylsilyl‐appended silica, have been prepared and used as stationary phases in capillary electrochromatography (CEC) to separate chiral compounds. The two stationary phases have a chiral selector with two recognition sites: crown ether and β‐CD. They exhibit excellent enantioselectivity in CEC for a wide range of compounds. After inclusion of metal ions (Na⁺ or K⁺) from the running buffer into the crown ether units, the stationary phases become positively charged and can provide extra electrostatic interaction with ionizable solutes and enhance the dipolar interaction with polar neutral solutes. This enhances the host‐guest interaction with the solute and improves chiral recognition and enantioselectivity. Due to the cooperation of the anchored β‐CD and the crown ether, this kind of crown ether capped β‐CD bonded phase shows better enantioselectivity than either β‐CD‐ or crown ether bonded phases only. These new types of stationary phases have good potential for fast chiral separation with CEC.     

Discriminating Influence of α‐ and Methylated β‐Cyclodextrins on Complexation and Polymerization of Diacrylate and Dimethacrylate Monomers

Summary: Host‐guest complexes of α‐cyclodextrin (α‐CD) and methylated β‐cyclodextrin (Me‐β‐CD) with diacrylates and dimethacrylates of butan‐1,4‐diol and hexan‐1,6‐diol at varying stoichiometries were studied. The complexes were analyzed by means of ¹H NMR, two‐dimensional ROESY spectroscopy and Job's curves, which clearly revealed the discriminating influence of the two hosts towards complex formation. The corresponding polymers were obtained using a redox initiator system in water. Thermal analysis and IR measurements of the polymers provided evidence for the existence of a polyrotaxane architecture.

Proposed structure of the cross‐linked polymers obtained by the redox polymerization of the Me‐β‐CD complexed monomers.     

Ultrasound‐assisted green synthesis of Cu‐based complexes of β‐cyclodextrin and their SOD‐like activity

A novel Cu–Zn β‐cyclodextrin (CuZn/β‐CD) model compound was synthesized under ultrasound irradiation to mimic the functionality of copper zinc superoxide dismutase (CuZnSOD). For comparison, Cu/β‐CD and Zn/β‐CD complexes were also synthesized via a sonochemical approach. The obtained complexes were characterized by FTIR, ICP‐OES, UV–vis and Scanning electron microscopy‐Energy dispersive X‐ray (SEM‐EDX) techniques. The SOD activity of the complexes was evaluated by a pyrogallol autoxidation method. These enzyme‐mimetic materials scavenge ambient free radicals, with the potential to provide significant antioxidant protection (scavenging ability > 70%).     

Effect of permodified β‐cyclodextrin on the photophysical properties of poly[2,7‐(9,9‐dioctylfluorene)‐alt‐(5,5′‐bithiophene)] main chain polyrotaxanes

The photophysical properties of two polyrotaxanes ( PFBTh?PSβCD and PFBTh?PMeβCD ) composed of fluorene and bithiophene encapsulated into permodified β‐cyclodextrin cavities have been investigated and compared with those of the reference PFBTh . Rotaxane formation results in improvements of the thermal stability, solubility in common organic solvents, as well as better film forming ability combined with a high transparency. As expected PFBTh and its encapsulated forms absorb at wavelengths beyond 510 nm, and time‐resolved photoluminescence (PL) in solution shows a well‐define vibronic structures with a predominance of the 0‐0 transitions and an energy difference of 0.16 eV. The fluorescence lifetimes follow a monoexponential decay with a value τ = 630 ± 30 ps. Atomic force microscopy, AFM, indicated a tendency of polyrotaxanes to organize into fibers. The advancing contact angles indicated higher surface hydrophobicity and lower surface free‐energy values for polyrotaxanes compared with their unthreaded analogues. The device based on PFBTh?PSβCD: PCBM in a 1/1 w/w ratio under simulated AM 1.5G illumination at 100 mW cm^?2 exhibited improved photovoltaic parameters of cells, resulted in high V_oc (0.68 V), J_sc (1.65 mA cm^?2), FF (31.6%), and PCE (0.35) values, compared with PFBTh or PFBTh?PMeβCD , respectively. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 460–471     

Structure and Photochemical Behavior of the Cyclodextrin Inclusion Complexes of the Benzoylthiophene‐Derived Drugs Tiaprofenic Acid (=5‐Benzoyl‐α‐methylthiophene‐2‐acetic Acid) and Suprofen (=α‐Methyl‐4‐(2‐thienylcarbonyl)benzeneacetic Acid)

The effect of β‐cyclodextrin (β‐CD) on the excited‐state reactivity of the two benzoylthiophene derivatives, tiaprofenic acid (TPA; 2 ) and suprofen (SPF; 3 ) in their carboxylate forms is studied. The presence of β‐cyclodextrin does not affect the nature of the photoproduced transients and the photoproducts, but increases the photodegradation quantum yields of both drugs. The efficiency of the photodecarboxylation process is enhanced. This effect is rationalized in the light of the inclusion of 2 and 3 in the β‐CD cavity, affecting the energy of the lowest excited states of the drugs. The structure of the complexes is determined by induced circular dichroism, and molecular‐mechanics and dynamic Monte Carlo calculations. The photoreactivity of the decarboxylated photoproduct 7 of tiaprofenic acid ( 2 ) in presence of β‐CD is also examined.     

Cationic ring‐opening polymerization of 1,6‐anhydro‐2,3,4‐tri‐O‐allyl‐β‐D‐glucopyranose as a convenient synthesis of dextran

For the convenient synthesis of (1→6)‐α‐D ‐glucopyranan, i. e., dextran ( 4 ), ring‐opening polymerization of 1,6‐anhydro‐2,3,4‐tri‐O‐allyl‐β‐D ‐glucopyranose ( 1 ) has been carried out using BF₃·OEt₂. With a ratio of [BF₃·OEt₂]/[ 1 ] = 0.5 at 0 °C for 140 h, the yield and M_n of the obtained polymer are 84.0% and 21 700, respectively. The polymer consists of (1→6)‐α‐linked 2,3,4‐tri‐O‐allyl‐D ‐glucopyranose ( 2 ) which is similar to the results for the cationic ring‐opening polymerization of 1,6‐anhydro‐2,3,4‐tri‐O‐methyl‐β‐D ‐glucopyranose and 1,6‐anhydro‐2,3,4‐tri‐O‐ethyl‐β‐D ‐glucopyranose. Polymer 2 was isomerized using tris(triphenylphosphine)‐chlororhodium as the catalyst in toluene/ethanol/water to yield polymeric 2,3,4‐tri‐O‐propenyl‐(1→6)‐α‐D ‐glucopyranan ( 3 ). Deprotection of the propenyl ether linkage of 3 was then performed using hydrochloric acid in acetone to give 4 .     

Enantiomeric separation of 2‐arylpropionic acid nonsteroidal anti‐inflammatory drugs by HPLC with hydroxypropyl‐β‐cyclodextrin as chiral mobile phase additive

The enantio‐separations of eight 2‐arylpropionic acid nonsteroidal anti‐inflammatory drugs (2‐APA NSAIDs) were established using reversed‐phase high‐performance liquid chromatography with hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) as chiral mobile phase additive for studying the stereoselective skin permeation of suprofen, ketoprofen, naproxen, indoprofen, fenoprofen, furbiprofen, ibuprofen and carprofen. The effects of the mobile phase composition, concentration of HP‐β‐CD and column temperature on retention and enantioselective separation were investigated. With 2‐APA NSAIDs as acidic analytes, the retention times and resolutions of the enantiomers were strongly related to the pH of the mobile phase. In addition, both the concentration of HP‐β‐CD and temperature had a great effect on retention time, but only a slight or almost no effect on resolutions of the analytes. Enantioseparations were achieved on a Shimpack CLC‐ODS (150 × 4.6 mm i.d., 5 μm) column. The mobile phase was a mixture of methanol and phosphate buffer (pH 4.0–5.5, 20 mM) containing 25 mM HP‐β‐CD. This method was flexible, simple and economically advantageous over the use of chiral stationary phase, and was successfully applied to the enantioselective determination of the racemic 2‐APA NSAIDs in an enantioselective skin permeation study. Copyright © 2009 John Wiley & Sons, Ltd.     

Preparation and adsorption of novel cellulosic fibers modified by β‐cyclodextrin

Novel cellulosic fibers modified by β‐cyclodextrin (CFEC) were prepared for adsorption for heavy metal ions like copper (II) and organic dye like neutral red from their aqueous solutions. The modified cellulosic fibers gave higher copper ion adsorption, and showed copper ion uptake values of 6.24 mg/g at 293°C, as against no adsorption for unmodified cellulosic fibers. Adsorption isotherm model indicated the adsorption of the novel modified fibers for heavy metal ions best fitted for Langmiur model. The adsorption was an exothermic reaction, and the reaction caloric was 6.295 kJ/mol. Copper ions could form a 7:4 complex with β‐cyclodextrin (β‐CD). The novel modified cellulosic fibers could also form inclusion complexes with neutral red via β‐CD molecules. In addition, it was found that the novel modified cellulosic fibers had nearly the same mechanical and thermal properties as the unmodified cellulosic fibers because the modification did not destroy the main chain of cellulose molecules. Copyright © 2008 John Wiley & Sons, Ltd.