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Gas-phase fragmentation pathways of host-guest complexes of cyclodextrins (CDs) and polyoxometalates (POMs) were examined using collision-induced dissociation (CID). The host-guest complexes studied here were composed of two different classes of POMs—Keggin (PW12O403−) and Lindqvist (M6O192−, M = Mo, W)—and three types of CDs (α-, β-, and γ-CD) differing in the diameter of the inner cavity. The CD-POM complexes were generated either by mixing methanol solutions of POM and CD or through a one-step acidic condensation of tetraoxometalates MO42− (M = Mo, W) with CDs for complexes with Keggin and Lindqvist anions, respectively, and introduced into the gas phase using electrospray ionization (ESI). We observe distinct differences in fragmentation pathways of the complexes of Keggin and Lindqvist POMs under high- and low-energy CID conditions. Specifically, direct dissociation and proton transfer from CD to POM accompanied by the separation of fragments is observed in CID of Keggin CD-POM complexes. In contrast, dissociation of CD complexes with Lindqvist POMs is dominated by the simultaneous loss of multiple water molecules. This unusual fragmentation channel is attributed to dissociation of the POM cluster inside the CD cavity accompanied by covalent bond formation between the fragments and CD and elimination of multiple water molecules. The observed covalent coupling of metal oxide clusters opens up opportunities for derivatization of macrocyclic host molecules using collisional excitation of gaseous non-covalent complexes. [ABSTRACT FROM AUTHOR]

In prior research it has been demonstrated that methylated β-cyclodextrins-threaded acid-labile polyrotaxanes (Me-PRXs) exhibit a lower critical solution temperature (LCST) and form coacervate droplets above their LCST. In this study, the encapsulation of proteins in coacervate droplets and the pH-responsive release of proteins, through the acid-induced dissociation of the Me-PRX, were investigated. The coacervate droplets encapsulate various proteins, such as bovine serum albumin (BSA), lysozyme, and β-galactosidase, at pH 7.4, into their hydrophobic inner phase. Concomitant with the pH-dependent dissociation of the Me-PRXs, the coacervates degraded below pH 6.5 and released encapsulated proteins, with the intrinsic activity of proteins maintained. Additionally, the subcutaneous injection of coacervate droplets encapsulating BSA in mice revealed that the retention time of the BSA at the injection site was prolonged compared to that of free BSA. Altogether, the coacervate droplets of the Me-PRX would be utilized as a new class of pH-responsive and injectable carrier for the controlled release of therapeutic proteins. [ABSTRACT FROM AUTHOR]

Cyclodextrins (CDs) are a family of oligosaccharides with a toroid shape, which exhibit a remarkable ability to include guest molecules in their internal cavity, providing a hydrophobic environment for poorly soluble molecules. Recently, new types of inclusions of α CDs with alkyl grafted polysaccharide chains (pullulan, chitosan, dextran, amylopectin, chondroitin sulfate...) have been prepared which are autoassembled into micro- and nanoplatelets. We report in this paper an extensive investigation of platelets with different compositions, including their reversible hydration (thermogravimetric analysis), crystalline structure (powder X-ray diffraction), dimensions and shapes (scanning electron microscopy-field emission gun), thermal properties, solubility, and melting (micro-differential scanning calorimetry). The crystalline platelets exhibit layered structures intercalating the polysaccharide backbones and CD complexes hosting the grafted alkyl chains. The monoclinic symmetry of columnar-type crystals suggests a head-to-tail arrangement of the CDs. The platelets have a preferentially hexagonal shape with sharp edges, variable sizes, and thicknesses and sometimes show incomplete layers (terraces). The crystal parameters change upon dehydration. Melting temperatures of platelets in aqueous solutions exceed 100 °C. Finally, we discuss the potential relation between the platelet structure and applications for mucoadhesive devices. [ABSTRACT FROM AUTHOR]

It has been found that a cyclodextrin derivative, 2-hydroxypropyl-β-cyclodextrin (HPβCD), has reasonable therapeutic effect on Niemann-Pick disease type C, which is caused by abnormal accumulation of unesterified cholesterol and glycolipids in the lysosomes and shortage of esterified cholesterol in other cellular compartments. We study the binding affinity and mode of HPβCD with cholesterol to elucidate the possible mechanism of HPβCD for removing cholesterol from the lysosomes. The dominant binding mode of HPβCD with cholesterol is found based on the molecular dynamics simulation and a statistical mechanics theory of liquids, or the three-dimensional reference interaction site model theory with Kovalenko-Hirata closure relation. We examine the two types of complexes between HPβCD and cholesterol, namely, one-to-one (1:1) and two-to-one (2:1). It is predicted that the 1:1 complex makes two or three types of stable binding mode in solution, in which the βCD ring tends to be located at the edge of the steroid skeleton. For the 2:1 complex, there are four different types of the complex conceivable, depending on the orientation between the two HPβCDs: head-to-head (HH), head-to-tail (HT), tail-to-head (TH), and tail-to-tail (TT). The HT and HH cyclodextrin dimers show higher affinity to cholesterol compared to the other dimers and to all the binding modes of 1:1 complexes. The physical reason why the HT and HH dimers have higher affinity compared to the other complexes is discussed based on the consistency with the 1:1 complex. On the one hand, in case of the HT and HH dimers, the position of each CD in the dimer along the cholesterol chain comes right on or close to one of the positions where a single CD makes a stable complex. On the other hand, one of the CD molecules is located on unstable region along the cholesterol chain, for the case of TH and TT dimers. [ABSTRACT FROM AUTHOR]

γ-Cyclodextrin metal-organic framework (γ-CD-MOF) is a new type of highly porous carrier for potential loading of therapeutic or diagnostic gas like sulfur hexafluoride (SF6). Here, loading of SF6 into γ-CD-MOF was investigated for its mechanism by molecular simulation and quantitative determination of SF6 using quantitative nuclear magnetic resonance (qNMR). For the SF6 loading, γ-CD-MOF was first degassed to remove the air without thermal decomposition or loss of framework crystallinity, then placed in the copper tube, and sealed to adsorb SF6 under 1.2 MPa and 25 °C for 12 h. The qNMR was employed for the determination of SF6 loaded in γ-CD-MOF using Span 80 as suspending agent and trifluoroacetic acid as internal standard. Then, the thermodynamic parameters had been estimated. Finally, molecular modeling combining with 19F NMR spectra was conducted to reveal the status of SF6 molecules in γ-CD-MOF. The results demonstrated that the content of SF6 loaded in γ-CD-MOF was 2.67 ± 0.46 wt %. After exposing to the environment of free SF6 at 0.1 MPa for 10 days, the relative content was 74.7%. It was confirmed that SF6 preferred to stay in the cavity of γ-CD-MOF cubes rather than in the γ-CD molecular pairs, which was a nonchemical adsorptive process. In conclusion, this research has established qNMR method and molecular simulation to demonstrate SF6 molecules in γ-CD-MOF and its loading mechanism. [ABSTRACT FROM AUTHOR]

Cyclodextrin (CD) complexation is a convenient method to sequester surfactants in a controllable way, for example, during membrane-protein reconstitution. Interestingly, the equilibrium stability of CD/surfactant inclusion complexes increases with the length of the nonpolar surfactant chain even beyond the point where all hydrophobic contacts within the canonical CD cavity are saturated. To rationalize this observation, we have dissected the inclusion complexation equilibria of a structurally well-defined CD, that is, heptakis(2,6-di-O-methyl)-β-CD (DIMEB), and a homologous series of surfactants, namely, n-alkyl-N,N-dimethyl-3-ammonio-1-propanesulfonates (SB3-x) with chain lengths ranging from x = 8 to 14. Thermodynamic parameters obtained by isothermal titration calorimetry and structural insights derived from nuclear magnetic resonance spectroscopy and molecular dynamics simulations revealed that, upon inclusion, long-chain surfactants with x = =10 extend beyond the canonical CD cavity. This enables the formation of hydrophobic contacts between long surfactant chains and the extracavity parts of DIMEB, which make additional favorable contributions to the stability of the inclusion complex. These results explain the finding that the stability of CD/surfactant inclusion complexes monotonously increases with the surfactant chain length even for long chains that completely fill the canonical CD cavity. [ABSTRACT FROM AUTHOR]

In the present work, a noncovalent and eco-friendly approach was proposed to prepare a carbon-black/β-cyclodextrin (CB/β-CD) nanocomposite. CB/β-CD-nanocomposite-modified screen-printed carbon electrodes were applied for the simultaneous determination of the anticancer drug flutamide (Flut) and the environmental pollutant 4- nitrophenol (4-NP). The electrochemical performance of the proposed sensor relied on the conductivity of CB, the different binding strengths of the guests (Flut and 4-NP) to the host (β-CD), and the different reduction potentials of the nitroaromatic compounds. Fascinatingly, the proposed sensor exhibited an excellent electrochemical performance with high sensitivity, selectivity, and reproducibility. The obtained wide linear ranges were 0.05-158.3 and 0.125-225.8 μM for Flut and 4-NP. The low detection limits of 0.016 and 0.040 μM with the higher sensitivities of 5.476 and 9.168 μA µM-1 cm-2 were achieved for the determination of Flut and 4-NP, respectively. The practical feasibility of the proposed sensor was studied in tap-water and human-serum samples. [ABSTRACT FROM AUTHOR]

Templated (T) and nontemplated (NT) cross-linked materials containing β-cyclodextrin (β-CD) and epichlorohydrin (EPH) were prepared at variable β-CD-EPH ratios (1:15, 1:20, and 1:25) in the presence and absence of a molecular template (toluene). The structural characterization of the materials was carried out using spectroscopy (Fourier transform infrared, solids 13C NMR, and scanning electron microscopy) and thermogravimetric analysis. The adsorption properties were studied with phenol-based adsorbates (2,4,6-trinitrophenol (TNP) and p-nitrophenol (PNP)) at equilibrium and dynamic conditions. The monolayer adsorption capacity (Qm) varied for the T-polymer/TNP systems (Qm = 0.10-0.95 mmol/g) and NT-polymer/TNP systems (Qm = 0.23-0.83 mmol/g). The range of Qm values for the T-polymer/PNP systems (0.26-0.62 mmol/g) exceeded that of the NT-polymer/PNP systems (0.23-0.40 mmol/g). The kinetic uptake profiles for the polymers and phenolphthalein were reliably described by the pseudo-first-order model. The β-CD inclusion site accessibility for the polymers varied from 15 to 20%, according to the level of cross-linking, where the accessibility of the T-polymers exceeded that of the NT-polymers. The structural characterization and phenol adsorption properties provide complementary support for the role of tunable polymer morphology in adsorption processes. The role of two-site binding was demonstrated for linear and globular polymer materials according to their unique adsorption properties with phenols of variable size and hydrophile-lipophile character. [ABSTRACT FROM AUTHOR]

Use of environmentally friendly additives to promote methane hydrate formation is an active area of research for gas storage via solidified natural gas (SNG) technology. The key advantages of SNG technology include a high degree of safety and a compact mode of natural gas storage in comparison to conventional methods of NG storage. In this paper, we evaluate the effect of β-cyclodextrin as a kinetic promoter for mixed methane-tetrahydrofuran hydrate formation. β-Cyclodextrin is an eco-friendly cyclic oligosaccharide containing seven glucose monomers that form a ring structure. The concentration of β-cyclodextrin was varied under different hydrate forming conditions (temperature and pressure), and the formation kinetics along with the morphology of mixed hydrate formation were observed. It is found that β-cyclodextrin served as an effective kinetic promoter for mixed methane-tetrahydrofuran hydrate formation at moderate pressure and temperatures in a simple unstirred reactor configuration. Further, no foam formation was observed during the hydrate dissociation that envisages an enhanced gas recovery and suitability of SNG technology for methane storage. [ABSTRACT FROM AUTHOR]

Perfluorooctanoic acid (PFOA), a persistent organic pollutant known to cause adverse health effects, strongly binds to human serum albumin (HSA). β-Cyclodextrin (β-CD), a nontoxic cyclic sugar, strongly complexes PFOA in a host-guest complex and has been proposed for environmental remediation of PFOA. The interactions between HSA, PFOA, and β-CD were investigated in order to determine if β-CD can reverse the binding of PFOA to HSA, with potential therapeutic applications toward exposure to PFOA. 19F Nuclear magnetic resonance (NMR), circular dichroism, and fluorescence spectroscopies were used to study these interactions. Multiple PFOA binding sites to HSA, one with strong affinity and others with low affinity, are evident from changes in the fluorescence emission spectra of HSA and the fluorescence lifetimes of the single Trp residue in HSA with increasing PFOA concentration. Structural changes in the protein are also evident from changes in the circular dichroism spectra of HSA upon titration of PFOA. Addition of β-CD to PFOA and HSA reversed these changes, indicating that formation of the β-CD:PFOA host-guest complex is favored even in the presence of HSA. Equimolar β-CD to PFOA (1:1 β-CD:PFOA ratio) causes dissociation of the weakly bound PFOA from HSA, whereas excess β-CD relative to PFOA (5:1 β-CD:PFOA ratio) leads to the complete disassociation of the strongly bound PFOA molecule from HSA. The 19F NMR studies further suggest that the 2:1 β-CD:PFOA complex inhibits PFOA binding to HSA. These data demonstrate that β-CD has potential to be used in therapeutic applications for PFOA in human blood. [ABSTRACT FROM AUTHOR]

The dynamics of solvation of an excited chromophore, 5-(4"-dimethylaminophenyl)-2-(4'-sulfophenyl)oxazole, sodium salt (DMO), has been explored in confined nanoscopic environments of β-cyclodextrin (βCD) and heptakis(2,6-di-O-methyl)-β-cyclodextrin (DIMEB). Solvation occurs on a distinctly slower time scale (τS3 ~ 47 ps, τS4 ~ 517 ps) in the host cavity of DIMEB than in that of βCD (τS3 ~ 20 ps, τS4 ~ 174 ps). The calculated equilibrium solvation response of DMO was characterized by four relaxation components (τS1 ~ 0.46-0.48 ps, τS² ~ 3.2-3.4 ps, τS³ ~ 32.3-37.7 ps, and τS4 ~ 232-485 ps), of which the longer ones (τS3, τS4) are well-consistent with experiments, whereas the ultrafast components (τS1, τS²) are unresolved. The observed time constant (τS³) within the ~20-47 ps range arises from slow water molecules in the primary hydration layers of the host CDs and is slower for DIMEB than for βCD presumably due to longer-lived and stronger hydrogen bonds that water forms with the former host relative to the latter. Decomposition of the calculated solvation response of DMO has revealed that conformational fluctuations of the macrocyclic hosts give rise to the observed long-time relaxation component (τS4), which is much slower for the inclusion complexes with DIMEB than for those with βCD because of slower conformational dynamics of the former host than that of the latter. [ABSTRACT FROM AUTHOR]

A [1]rotaxane with two threaded α-cyclodextrin (α-CD) wheels was synthesized in 92% yield using a one-pot process at room temperature that employed spontaneous α-CD threading onto a 12-carbon alkyl chain in water followed by an oxime condensation reaction that attached two boronic acid-containing stopper groups. Rapid pirouetting of the threaded α-CD wheels around the encapsulated dumbbell was switched “ON” or “OFF” by the presence of chemical additives that controlled boronate ester bond formation between the interlocked components. [ABSTRACT FROM AUTHOR]

Chiral slipped 5,8:9',10'-cyclodimers were preferentially produced over classical 9,10:9',10'-cyclodimers upon supramolecular photocyclodimerization of 2-anthracenecarboxylate (AC) mediated by β-cyclodextrin (β-CD). This photochirogenic route to the slipped cyclodimers, exclusively head-to-tail (HT) and highly enantioselective, has long been overlooked in foregoing studies but is dominant in reality and is absolutely supramolecularly activated by 2:2 complexation of AC with β-CD. The intricate structural and photophysical aspects of this higher-order complexation-triggered process have been comprehensively elucidated, while the absolute configurations of the slipped cyclodimers have been unambiguously assigned by comparing the experimental and theoretical circular dichroism spectra. In the 2:2 complex, two ACs packed in a dual β-CD capsule are not fully overlapped with each other but are only partially stacked in a slipped anti- or syn-HT manner. Hence, they do not spontaneously cyclodimerize upon photoexcitation but instead emit long-lived excimer fluorescence at wavelengths slightly longer than the monomer fluorescence, indicating that the slipped excimer is neither extremely reactive nor completely relaxed in conformation and energy. Because of the slipped conformation of the AC pair in the soft capsule, the subsequent photocyclodimerization becomes manipulable by various internal or external factors, such as temperature, pressure, added salt, and host modification, enabling us to exclusively obtain the slipped cyclodimers with high regio- and enantioselectivities. In this supramolecularly driven photochirogenesis, the dual β-CD capsule functions as a chiral organophotocatalyst to trigger and accelerate the nonclassical photochirogenic route to slipped cyclodimers by preorganizing the conformation of the encapsulated AC pair, formally mimicking a catalytic antibody. [ABSTRACT FROM AUTHOR]

Naproxen is one of the most consumed nonsteroidal antiinflammatory drugs and marketed as S-naproxen since R-naproxen is hepatotoxic. In this study, chiral recognition of naproxen has been investigated by tandem mass spectrometry (MS/MS). Among all diastereomeric complexes formed between naproxen and the examined chiral selectors, including cyclodextrins (α/β/γ-CD), modified phenylalanines (Nacetyl- phenylalanine, N-t-butoxycarbonyl-phenylalanine, N-9-fluorenylmethyloxycarbonyl- phenylalanine), amino acids (Trp, Phe, Tyr, His), glucose, tartaric acid, and vancomycin, a novel binuclear metal bound diastereomeric complexes [(M(II))2(S/R-naproxen)(L-His)2-3H]+: (M = Cu, Ni, or Co with Cu being the best) could allow effective identification of the absolute configuration of naproxen and determination of its enantiomeric excess (ee) through MS/MS analysis. The key candidate structure of [(Cu(II))2(S/Rnaproxen)( L-His)2-3H] + has been revealed by means of collision-induced dissociation, ion mobility mass spectrometry and density functional theory calculations, indicating an interesting and unusual self-assembled compact geometry with the two Cu(II) ions bridged closely together (Cu-Cu distance is 3.04 Å) by the carboxylate groups of the two histidines. It was shown that the difference in dissociation efficiency between the two diastereomers was attributed to the interaction between the NH2 bond of the amino group of one histidine and the naphthyl ring of naproxen. The present report is the first to observe and characterize the complex of (Cu(II))2(His)2 with aromatic acid, which could contribute to the chiral recognition of other chiral aromatic acids, design of catalysts based on binuclear copper bound complex, as well as the better understanding of metal ion complexation by His or His-containing ligands. [ABSTRACT FROM AUTHOR]

Lanthanum impregnated chitosan/β-cyclodextrin (CS-La-βCD) composite was prepared using a facile in situ fabrication method and successfully evaluated for the adsorption of CrO42- and F-. The pristine and treated CS-La-βCD was characterized using Fourier transform infrared, scanning electron microscopy, energy dispersive X-ray spectroscopy with mapping, X-ray diffraction, and thermal gravametric analytical techniques. The optimum conditions for the uptake of CrO42- and F- were investigated as a function of shaking time, dosage, initial ion concentration, pH, and predatory ions in batch experiments. The equilibrium data were fitted using Langmuir, Freundlich, and Dubinin-Radushkevich models for the defluoridation and sorption of chromium onto CS-La-βCD. The adsorption kinetics of CrO42- and F- followed the pseudo-second order model. The maximum Langmuir adsorption capacity was found to be 91.58 mg/g and 8.14 mg/g for CrO42- and F-, respectively at 303 K. Sequential adsorption and desorption studies were carried out up to five cycles using 0.1 M of NaOH as an eluent to check the reusability of the adsorbents. [ABSTRACT FROM AUTHOR]

A reasonable and efficient strategy for the construction of hyper-cross-linked porous MoS2-CD-polymer frameworks (MoS2CDPFs) was demonstrated. Here, MoS2 nanosheets (NSs) can be decorated with amino functionalized β-cyclodextrin, producing a nanoscale structural motif (MoS2CD) for the synthesis of MoS2CDPFs. We demonstrated that CD polymer (CDP) as linker can be uniformly incorporated into the frameworks. Except for the pores created between MoS2 NSs, polymer doping generates extra interspace between MoS2 NSs and CD monomer. Interestingly, the resultant MoS2CDPFs can rapidly sequester aromatic phenolic micropollutant bisphenol A (0.1 mM) from water with 93.2% adsorption capacity, which is higher than that of MoS2, MoS2CD, and CDP. The intercalation between MoS2 sheets with CDP imparts the frameworks durability in adsorption/ desorption of aromatic phenolic micropollutants. Remarkably, the removal efficiency reduced only 3% after 10 regeneration- reuse cycles. These findings demonstrated that the porous MoS2-CD-polymer-based frameworks are promising adsorbents for rapid, flow-through water remediation. [ABSTRACT FROM AUTHOR]

1H and 13C dynamic nuclear polarizations have been studied in 13C-enriched β-cyclodextrins doped with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl free radical. 1H and 13C polarizations raised above 7.5 and 7%, respectively and for both nuclear species, the transfer of polarization from the electron spins appears to be consistent with a thermal mixing scenario for a concentration of 9 13C nuclei per molecule. When the concentration is increased to 21 13C nuclei per molecule, a decrease in the spin-lattice relaxation and polarization buildup rates is observed. This reduction is associated with the bottleneck effect induced by the decrease in the number of electron spins per nucleus when both the nuclear spin-lattice relaxation and the polarization occur through the electron non-Zeeman reservoir. 13C nuclear spin-lattice relaxation has been studied in the 1.8-340 K range, and the effects of internal molecular motions and of the free radicals on the relaxation are discussed. 13C hyperpolarization performances and room-temperature spin-lattice relaxation times show that these are promising materials for future biomedical applications. [ABSTRACT FROM AUTHOR]

A family of mPEG-b-polycarbonate (mPEG-PC) diblock pendant polymers were synthesized from trimethylene carbonate and other cyclic carbonate monomers bearing hydrophobic guest ligands via organocatalytic ring-opening polymerization using 1,4,5-triazabicyclo[4.4.0]dec-5-ene catalyst or 1,8-diazabicyclo[5.4.0]undec-7-ene/thiourea cocatalyst. Diblock copolymers composed of a methoxypoly(ethylene oxide) (mPEG) block and a polycarbonate block containing either homopolymer or mixed polycarbonates (PC) were prepared by homopolymerization or copolymerization of the cyclic carbonate monomers in the presence of mPEG2000 or mPEG5000 initiator to give materials having a tunable pendant group density along the polycarbonate backbone. Polycarbonate blocks targeting the 2.4-10 kDa range were prepared with good molecular weight control and modest polydispersities (averaging ~1.3). Complexation of plasmid DNA with β-cyclodextrin-polyethylenimine2.5 kDa produced nanoparticle cores that were then coated with the mPEG-PC diblock copolymers to produce transfection complexes in the 100-250 nm size range. Stable transfection complexes prepared at N/P ratios >10 had slightly positive ζ potentials and showed comparable or modestly better transfection efficiencies in HeLa cells than the commercial transfection agent, Lipofectamine2000. Transfection efficiencies were not dependent on polycarbonate block molecular weights. The mPEG-PC constructs displayed similar efficacy for adamantyl and cholesteryl pendants that strongly bind to β-cyclodextrin; however, slightly better performance was observed for the weakly bound pendant, benzyl. These findings suggest that pDNA release is largely mediated by hydrolysis of the ester-bound pendant ligand within the endolysosomal compartment of the cell, with desorption of the mPEG-PC layer also contributing to plasmid release and activation in the case of weak binding pendant groups. We infer from these results that mPEG-PC may be an effective degradable transfection agent for in vivo applications. [ABSTRACT FROM AUTHOR]

A wood based yarn platform for capturing pharmaceutical molecules from water was developed. Cellulose fiber yarns were modified with cyclodextrins, and the capture of 17α-ethinyl estradiol (EE2), a synthetic estrogen hormone used as contraceptive, from water was tested. The yarns were prepared by spinning a deep eutectic solution (DES) of cellulose in choline chloride-urea. Despite their high porosity and water sorption capacity (5 g/g), the spun fiber yarns displayed high wet strength, up to 60% of that recorded in dry condition (128 MPa with 17% strain at break). Cyclodextrin irreversible attachment on the yarns was achieved with adsorbed chitosan and the conjugation reactions and capture of EE2 by the cyclodextrin-modified cellulose were confirmed via online detection with Surface Plasmon Resonance (SPR). The facile synthesis of the bioactive yarns and EE2 binding capacity from aqueous matrices (as high as 2.5 mg/g) indicate excellent prospects for inexpensive platforms in disposable affinity filtration. The study presents a strategy to produce a wood fiber based yarn to be used as a platform for human and veterinary pharmaceutical hormone capture. [ABSTRACT FROM AUTHOR]

Poly(vinyl alcohol) (PVA) is a cytocompatible synthetic polymer and has been commonly used to prepare hydrogels. Bile acids and β-cyclodextrin are both natural compounds and they form stable host-guest inclusion complexes. They are attached covalently onto a low molecular weight PVA separately. Self-healing hydrogels can be easily formed by mixing the aqueous solutions of these PVA based polymers. The mechanical properties of the hydrogels can be tuned by varying the molar fractions of bile acid units on PVA. The dynamic inclusion complexation of the host-guest pair of the hydrogel allows the self-healing rapidly under ambient atmosphere and their mechanical properties could recover their original values in 1 min after incision. These PVA based polymers exhibited the good cytocompatibility and high hemocompatibility as shown by their biological evaluations. The use of natural compounds for host-guest interaction make such gels especially convenient to use as biomaterials, an advantage over conventional hydrogels prepared through freeze-thaw method. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations of native α-, β- and γ-cyclodextrin in aqueous solution have been conducted with the goal to investigate the performance of the CHARMM36 force field, the AMBER-compatible q4md-CD force field and five variants of the GROMOS force field. The properties analyzed are structural parameters derived from X-ray diffraction and NMR experiments as well as hydrogen bonds and hydration patterns, including hydration free enthalpies. Recent revisions of the torsional-angle parameters for carbohydrate systems within the GROMOS family of force fields lead to a significant improvement of the agreement between simulated and experimental NMR data. Therefore, we recommend using the variant 53A6GLYC instead of 53A6 and 56A6CARBO_R or 2016H66 instead of 56A6CARBO to simulate cyclodextrins in solution. The CHARMM36 and q4md-CD force fields show a similar performance as the three recommended GROMOS parameter sets. A significant difference is the more flexible nature of the cyclodextrins modeled with the CHARMM36 and q4md-CD force fields compared to the three recommended GROMOS parameter sets. [ABSTRACT FROM AUTHOR]

Metal-free room-temperature phosphorescence (RTP) materials offer unprecedented potentials for photoelectric and biochemical materials due to their unique advantages of long lifetime and low toxicity. However, the achievements of phosphorescence at ambient condition so far have been mainly focused on ordered crystal lattice or on embedding into rigid matrices, where the preparation process might bring out poor repeatability and limited application. In this research, a series of amorphous organic small molecular compounds were developed with efficient RTP emission through conveniently modifying phosphor moieties to ß-cyclodextrin (ß-CD). The hydrogen bonding between the cyclodextrin derivatives immobilizes the phosphors to suppress the nonradiative relaxation and shields phosphors from quenchers, which enables such molecules to emit efficient RTP emission with decent quantum yields. Furthermore, one such cyclodextrin derivative was utilized to construct a host-guest system incorporating a fluorescent guest molecule, exhibiting excellent RTP-fluorescence dual-emission properties and multicolor emission with a wide range from yellow to purple including white-light emission. This innovative and universal strategy opens up new research paths to construct amorphous metal-free small molecular RTP materials and to design organic white-light-emitting materials using a single supramolecular platform. [ABSTRACT FROM AUTHOR]

Novel biocompatible and biodegradable pH/reduction dual-responsive oxidized alginate-doxorubicin (mPEG-OAL-DOX/Cys) prodrug nanohydrogels were designed for tumor-specific intracellular triggered release of anticancer drug DOX by conjugating DOX via acid-labile Schiff base linkage into the PEGylated oxidized alginate (mPEG-OAL) cross-linked with bioreducible disulfide bond. The effect of the complexation with cyclodextrins (α-CD and β-CD) before or after the cross-linking of the mPEG-OAL on the DOX content and controlled release performance was investigated. It was found that the cyclodextrin inclusion complex prodrug nanohydrogels mPEG(CD)-OAL-DOX/Cys, prepared by cross-linking of the mPEG-OAL after complexation with cyclodextrins, exhibited better pH/reduction dual-responsive controlled release performance than the mPEG-OAL-DOX/Cys(CD) ones prepared by cross-linking of the mPEG-OAL before complexation with cyclodextrins, owing to the supramolecular cross-linking of the adjacent pseudopolyrotaxanes. Especially for the cyclodextrin inclusion complex prodrug nanohydrogels mPEG(α-CD)-OAL-DOX/Cys, DOX was released rapidly under lower pH media mimicking the tumor microenvironment and completely released within 48 h, while the premature leakage under the simulated physiological condition was ~40%, without burst release in both cases. The cellular toxicity and uptake results demonstrated that the mPEG(α-CD)-OAL-DOX/Cys prodrug nanohydrogels possessed similar inhibition against cancer cell growth in comparison with the free DOX and enhanced drug intracellular accumulation. [ABSTRACT FROM AUTHOR]

The use of natural compounds to construct reversible networks is an attractive strategy in biomaterials design. Our design is based on a host-guest pair of natural compounds β-cyclodextrin and cholic acid through the use of a cholic acid dimer tethered with a poly(ethylene glycol) spacer, which subsequently served as a guest cross-linker to afford a hydrogel with copolymers bearing β-cyclodextrin pendants. The hydrogel after incision self-heals rapidly under ambient atmosphere as observed and confirmed by rheological measurements. To endow the hydrogels with reversibility and responsiveness, the addition of a CO2-switchable guest of benzimidazole followed by alternating treatments with CO2 and N2 leads to a reversible sol-gel transition due to the dynamic complexation between the cholic acid and β-cyclodextrin units. The CO2 responsiveness and the natural origin of the constituents make these self-healing hydrogels attractive as smart biomaterials. [ABSTRACT FROM AUTHOR]

A stacking approach in capillary electrophoresis based on the reversal of the analytes' effective electrophoretic velocities at a dynamic stacking boundary formed between charged micelles (i.e., from long chain ionic surfactants) and neutral cyclodextrins (i.e., native α-, β-, or γ-cyclodextrin) is presented. The approach was demonstrated by the long injection of samples in a micellar solution followed by injection of a cyclodextrin solution zone, and then separation by co-electro-osmotic flow capillary zone electrophoresis. The reversal is caused by the formation of stable cyclodextrin-surfactant complexes at the boundary that significantly decreased the retention factor of the analytes in the presence of a micellar pseudostationary phase. The dynamic boundary was formed at the cyclodextrin zone as the micelles penetrated this zone. Under optimum conditions, the boundary disappears, and the stacking ends when all the micelles have electrophoretically migrated to the boundary. Cationic and anionic small molecules were enriched using oppositely charged micelles from sodium dodecyl sulfate and cetyltrimethylammonium bromide, respectively. There were 1-2 orders of concentration magnitude improvement in analyte detection, which is expected in stacking with hydrodynamic injection. The improvements in the peak signals (height/corrected area) were up to 236/445 and 101/76 for the cationic and anionic analytes tested, respectively. Linearity (r[sup 2]) and repeatability (%RSD of migration time, peak height, and corrected peak area) under the chosen stacking conditions (cations/anions) were ≥0.998/≥0.995 and ≤3.8%/≤5.7%, respectively. The stacking approach was also implemented in the direct analysis of peptides from trypsin digested bovine serum albumin. [ABSTRACT FROM AUTHOR]

The use of natural compounds to construct reversible networks is an attractive strategy in biomaterials design. Our design is based on a host-guest pair of natural compounds β-cyclodextrin and cholic acid through the use of a cholic acid dimer tethered with a poly(ethylene glycol) spacer, which subsequently served as a guest cross-linker to afford a hydrogel with copolymers bearing β-cyclodextrin pendants. The hydrogel after incision self-heals rapidly under ambient atmosphere as observed and confirmed by rheological measurements. To endow the hydrogels with reversibility and responsiveness, the addition of a CO2-switchable guest of benzimidazole followed by alternating treatments with CO2 and N2 leads to a reversible sol-gel transition due to the dynamic complexation between the cholic acid and β-cyclodextrin units. The CO2 responsiveness and the natural origin of the constituents make these self-healing hydrogels attractive as smart biomaterials. [ABSTRACT FROM AUTHOR]

Biological-material-functionalized porous monoliths were prepared with lactoferrin and ß-cyclodextrin via a click reaction. With the monolith as an extraction medium, a method combined with ICP-MS was developed for the determination of total gallium originating from metabolic residues of orally bioavailable gallium complexes with tris(8-quinolinolato)gallium (GaQ3) as a representative. The method exhibited favorable adsorption behaviors for gallium with high selectivity, low detection limit (2 ng L-1), and an enrichment factor of 29-fold with the sample throughput of 30 min-1. The developed approach was validated by the analysis of gallium from GaQ3 metabolic residues in a human cell line. Additionally, the practical applicability of this method was evaluated by the determination of gallium in human blood and urine samples from cancer patients. Results illustrated that the prepared monolith had potential in Ga-based anticancer drug analysis in complex biological samples. [ABSTRACT FROM AUTHOR]

Finding new nucleants to promote protein crystallization is an important task, especially for purposes other than structural determination. Here, we investigated cyclodextrins and its derivative particles, as potential nucleants for protein crystallization. β-Cyclodextrin (β-CD) and its derivatives (including p-toluenesulfonyl-β-cyclodextrin (PTCD), polymer-β-cyclodextrin (PCD), mono-(6-(1,6-hexamethylenediamine)-6-deoxy)-β-cyclodextrin (MHCD) and mercapto-β-cyclodextrin (MCD)) were used as nucleants. The experimental results confirmed that β-CD and its derivatives showed significantly positive effects, promoting protein crystallization and improving crystal quality. A larger number of protein molecules (including lysozyme, catalase, subtilisin A VIII, concanavalin A VI, α-chymotrypsinogen, proteinase K, cellulase, papain, glucose isomerase, hemoglobin, and ribonuclease A XII) attached to the particles usually corresponded to a higher crystallization success rate. More detailed analysis showed that cyclodextrins exhibited the best performance when the overall charge of protein in solution was the opposite to zeta potential of the cyclodextrins particle. Our results showed that cyclodextrins can be useful as nucleants due to the ease of modifying them to suit the crystallization of different proteins, and they can be explored for use in the mass purification of proteins for the biopharmaceutical industry. Furthermore, the phenomenon discovered in this study pointed toward a way to find new nucleants based on the overall charge of proteins in a solution: the nucleants should preferably be the opposite between the overall charge of target protein and the zeta potential of the cyclodextrin particle. [ABSTRACT FROM AUTHOR]

The low aqueous solubility of phospholipids makes necessary the use of lipid carriers in studies ranging from lipid traffic and metabolism to the engineering of model membranes bearing lipid transverse asymmetry. One particular lipid carrier that has proven to be particularly useful is methyl-β-cyclodextrin (MβCD). To assess the interaction of MβCD with structurally different phospholipids, the present work reports the results of isothermal titration calorimetry in conjunction with dynamic light scattering measurements. The results showed that the interaction of MβCD with large unilamellar vesicles composed of a single type of lipid led to the solubilization of the lipid vesicle and, consequently, the complexation of MβCD with the lipids. This interaction is dependent on the nature of the lipid headgroup, with a preferable interaction with phosphatidylglycerol in comparison to phosphatidylcholine. It was also possible to show a role played by the phospholipid backbone in this interaction. In many cases, the differences in the transfer energy between one lipid and another in going from a bilayer to a cyclodextrin-bound state can be qualitatively explained by the energy required to extract the lipid from a bilayer. In all cases, the data showed that the solubilization of the vesicles is entropically driven with a large negative ΔCp, suggesting a mechanism dependent on the hydrophobic effect. [ABSTRACT FROM AUTHOR]

Readily available cyclodextrins (CDs) with an inherent hydrophobic internal cavity and hydrophilic external surface are macrocyclic entities that display a combination of molecular recognition and complexation properties with vital implications for host -- guest supramolecular chemistry. While the host -- guest chemistry of CDs has been widely recognized and led to their exploitation in a variety of important functions over the last five decades, these naturally occurring macrocyclic systems have emerged only recently as promising macrocyclic molecules to fabricate environmentally benign functional nanomaterials. This review surveys the development in the field paying special attention to the synthesis and emerging uses of various unmodified CD-metal complexes and CD-inorganic nanoparticle systems and identifies possible future directions. The association of a hydrophobic cavity of CDs with metal ions or various inorganic nanoparticles is a very appealing strategy for controlling the inorganic subunits properties in the very competitive water environment. In this review we provide the most prominent examples of unmodified CDs' inclusion complexes with organometallic guests and update the research in this field from the past decade. We discuss also the coordination flexibility of native CDs to metal ions in CD-based metal complexes and summarize the progress in the synthesis and characterization of CD -- metal complexes and their use in catalysis and sensing as well as construction of molecular magnets. Then we provide a comprehensive overview of emerging applications of native CDs in materials science and nanotechnology. Remarkably, in the past few years CDs have appeared as attractive building units for the synthesis of carbohydrate metal -- organic frameworks (CD-MOFs) in a combination of alkali-metal cations. The preparation of this new class of highly porous materials and their applications in the separation of small molecules, the loading of drug molecules, as well as efficient host templates in the construction of nanomaterials with the desired functionality, including the first-in-class devices including sensors and memristors, are highlighted. Finally, CDs as well-known "green" molecular hosts have also been used as ideal functional molecules to improve the solubility, stability, and bioavailability of inorganic nanoparticles. In this regard, we demonstrate various strategies for the preparation of native CDs-modified inorganic nanomaterials such as metal, metal oxide, and semiconductor and magnetic nanoparticles, aiming to take advantage of both the controlled properties of the inorganic core and the controlled properties of the coating molecules. The functionalization of a CD hydrophobic cavity with an inorganic nanoparticle is very prospective for the development of novel catalytic systems and new tools for highly selective and sensitive sensing platforms for various targets. [ABSTRACT FROM AUTHOR]

Molecular encapsulation is extremely important in pharmaceutical and drug delivery science. In this article, one of the most important sulfa drugs, namely, sulfacetamide sodium, has been probed in the solution and solid phases for encapsulation within the cavities of α- and β-cyclodextrins. Various physicochemical techniques were employed to establish the outcome of the work. The isothermal titration calorimetric method was used to evaluate the stoichiometry, association constant, and thermodynamic parameters with high accuracy. The solid inclusion complexes were analyzed by spectroscopic techniques to ascertain the encapsulation of the investigated drug within the cavities of α- and β-cyclodextrins. This phenomenon of drug inclusion is exceedingly significant for its stabilization against external hazards, such as oxidation, sensitization, and photolytic cleavage, for the proficient and accurate regulatory release of an essential amount of drug at the targeted site for a period of time and for the prevention of overdose when applied as an ophthalmic solution and ointment. [ABSTRACT FROM AUTHOR]

In this communication, we report on a noteworthy hybrid supramolecular assembly built from three functional components hierarchically organized through noncovalent interactions. The one-pot synthesis procedure leads to the formation of large Mo-blue ring-shaped anion {Mo154}, which contains the supramolecular adduct based on the symmetric encapsulation of the Dawson-type [P2W18O62]6-anion by two γ-cyclodextrin units. Such a nanoscopic onion-like structure, noted [P2W18O62]@2γ-CD@{Mo154} has been characterized by single-crystal X-ray diffraction, thus demonstrating the capability of the giant inorganic torus to develop relevant supramolecular chemistry, probing the strong affinity of the inner and outer faces of the γ-CD for the polyoxometalate surfaces. Furthermore, interactions and behavior in solution have been studied by multinuclear NMR spectroscopy, which supports specific interactions between γ-CD and POM units. Finally, the formation of this three-component hybrid assembly from one-pot procedure, in water and using nearly stoichiometric conditions, is discussed in terms of the driving forces orchestrating this highly efficient multilevel recognition process. [ABSTRACT FROM AUTHOR]

To develop reactive oxygen species (ROS)-responsive anti-inflammatory materials and establish their structure-property correlations, a series of H2O2-eliminating materials (OxbCDs) were designed and synthesized by conjugating different phenylboronic acid pinacol ester (PBAP) groups onto a biocompatible scaffold compound ß-cyclodextrin via varied linker groups. Both the H2O2-triggered hydrolysis profiles and H2O2-eliminating capacities of these materials were dependent on the chemical structure of the PBAP moieties. Together with the elucidation of hydrolysis mechanisms, we established structure-property correlations of these OxbCD materials. Extensive in vitro experiments revealed nanoparticles (NPs) based on OxbCDs showed no adverse biological effects on normal cells. OxbCD NPs could effectively inhibit inflammatory responses and oxidative stress in stimulated macrophages. Consistently, OxbCD NPs efficaciously alleviated the symptoms of peritonitis in mice, with respect to reducing the counts of neutrophils and macrophages as well as inhibiting the secretion of pro-inflammatory cytokines, chemokines, and oxidative mediators. Similarly, OxbCD NPs loaded with anti-inflammatory drugs displayed superior efficacy in an acute inflammation model of peritonitis in mice. More importantly, OxbCD NPs showed good biocompatibility after administration via different routes. Consequently, besides serving as anti-inflammatory materials, the newly developed H2O2-eliminating materials may be utilized as pharmacologically functional carriers for targeted therapy of many diseases associated with inflammation and oxidative stress. [ABSTRACT FROM AUTHOR]

Cyclodextrins (CDs) are among the most widely used native host systems with ability to form inclusion complexes with various molecular objects. This ability is so strong that the "hydrophobic" CD cavity never remains empty, even in the guest-free state it is filled with water molecules. However, no consensus has been reached concerning both the total number of hydrating water molecules and their preferred binding location in the CDs. Several outstanding questions regarding the CD hydration still wait to be answered: (1) Which spots of the CD cavity ("hot spots") have the highest affinity for the guest water molecules? (2) How stable are water clusters inside the cavity? (3) Which mode of water binding, sequential or bulk, is thermodynamically more favored? (4) What is the upper limit of the number of water molecules bound inside the host cavity? (5) What factors do control the CD hydration process? Here, using αCD as a typical representative of the cyclodextrin family, we endeavor to answer these questions by combining experimental measurements (differential scanning calorimetry and thermogravimetry) with theoretical (DFT) calculations. Enthalpies of the αCD hydrate formation are evaluated and the role of different factors, such as the number and mode of binding (sequential vs bulk) of water molecules, type of hydrogen bonds established (water-water vs water-αCD), and the dielectric properties of the medium, on the complexation process is assessed. The results obtained shed light on the intimate mechanism of water binding to αCD and disclose the key factors governing the process. [ABSTRACT FROM AUTHOR]

The interaction of a painkiller Isoxicam, belonging to the oxicam group of nonsteroidal anti-inflammatory drugs (NSAIDs) and its copper complex with different cyclodextrins (β-CD, γ-CD, HPβCD, and HPγCD), has been investigated in both solution and the solid state. Steady state and time-resolved fluorescence spectroscopy, fluorescence anisotropy, ¹H NMR, and FTIR spectroscopy are used. Both the drug and its copper complex form a host-guest inclusion complex with all CDs. Fluorescence spectroscopy is used to determine binding constants and stoichiometries of the host-guest complex. The strongest binding is seen for γ-CD. 1H NMR study showed that Isoxicam penetrates into the CD cavity from the more accessible wider side. For β- and γ-CD, Isoxicam showed one type of binding, i.e., formation of an inclusion complex, whereas, for HPβCD and HPγCD, it showed two types of binding, i.e., inclusion in the CD cavities and interaction with the outer surface of the CD molecules mainly near the hydroxy propyl group. Deeper penetration occurred into the larger diameter cavity of γ-CD and HPγCD compared to β-CD and HPβCD. From FTIR and 1H NMR study, it is seen that predominantly the π-electron-rich benzene part of the drug and its complex penetrate into the host cavity. [ABSTRACT FROM AUTHOR]

Legacy perfluoroalkyl substances (PFASs) are known environmental pollutants with serious adverse health effects. Perfluoroethercarboxylic acids (PFECAs), emerging PFASs now being substituted for legacy PFASs, have recently been detected in the environment. Cyclodextrins (CDs) have been proposed as agents for the remediation of problematic pollutants, including legacy PFASs. The current study uses 19F NMR spectroscopy to measure the complexation of mono-, di-, and triether PFECAs by CDs for eventual environmental applications. Eight PFECAs were characterized by 19F and 13C NMR. The change in chemical shift of individual fluorines upon complexation of CDs at various stoichiometric ratios was used to determine the host-guest association constants. All studied PFECAs were most strongly encapsulated by β-CD, with association constants from 10²-105 M-1 depending on chain length and number of ether functionalities. 19F-¹H heteronuclear Overhauser effect spectroscopy (HOESY) NMR experiments were performed for the β-CD complexes of two branched monoethers, PFPrOPrA ("GenX") and PFDMMOBA, to elucidate the structural details of the complexes, determine the specific orientation, and position of β-CD along the PFAS chain, and assess the roles of hydrogen-bonding and PFECA branching on the host-guest interactions. The results give new understanding into the fundamental nature of the host-guest complex between cyclodextrins and perfluorinated surfactants. [ABSTRACT FROM AUTHOR]

The effect of the distance between a β-cyclodextrin (βCD) host core and a conductive substrate on the electron-transfer rate of complexed guests as well as of free-diffusing electrochemically active probes has been studied. First we have evaluated a set of short-tethered βCD adsorbates bearing different anchoring groups in order to get a reliable platform for the study of short-distance electron transfer. An electrochemically active trivalent guest was immobilized on these host monolayers in a selective and reversible manner, providing information about the packing density. Iodine- and nitrile-functionalized βCD monolayers gave coverages close to maximum packing. Electron transfer in the presence of Fe(CN)63-/4- studied by impedance spectroscopy revealed that the electron transfer of the diffusing probe was 3 orders of magnitude faster than when the βCD cores were separated from the surface by undecyl chains. When an electrochemically active guest was immobilized on the surface, electron-transfer rate measurements by cyclic voltammetry and capacitance spectroscopy showed differences of up to a factor of 8 for different βCD monolayers. These results suggest that increasing the distance between the βCD core and the underlying conductive substrate leads to a diminishing of the electron-transfer rate. [ABSTRACT FROM AUTHOR]

A series of β-cyclodextrin (βCD) amphiphilic derivatives with varying degrees of substitution were prepared by acylating βCDs on their secondary face using thermolysin to catalyze the transesterification. After dissolution in acetone, the βCD-Cn derivatives (n = 8, 10, 12, 14) were nanoprecipitated in water, where they self-organized into structured particles that were characterized using cryo-transmission electron microscopy (cryo-TEM) images and small-angle X-ray scattering (SAXS) data. Two types of morphologies and ultrastructures were observed depending on the total degree of substitution (TDS) of the parent derivative. The molecules with TDS < 5 formed nanospheres with a multilamellar organization, whereas those with TDS > 5 self-assembled into barrel-like (n = 8, 10, 12) or more tortuous (n = 14) particles with a columnar inverse hexagonal structure. In particular, faceted βCD-C14 particles (TDS = 7) appeared to be composed of several domains with different orientations that were separated by sharp interfaces. Ultrastructural models were proposed on the basis of cryo-TEM images and the analysis of the contrast distribution in different projections of the lattice. Complementary compression isotherm experiments carried out at the air-water interface also suggested that differences in the molecular conformation of the series of derivatives existed depending on whether TDS was lower or higher than 5. [ABSTRACT FROM AUTHOR]

Co-crystallization of K[+] and Li[+] ions with γ-cyclodextrin (γ-CD) has been shown to substitute the K[+] ion sites partially by Li[+] ions, while retaining the structural integrity and accessible porosity of CD-MOF-1 (MOF, metal -- organic framework). A series of experiments, in which the K[+]/Li[+] ratio was varied with respect to that of γ-CD, have been conducted in order to achieve the highest possible proportion of Li[+] ions in the framework. Attempts to obtain a CD-MOF containing only Li[+] ions resulted in nonporous materials. The structural occupancy on the part of the Li[+] ions in the new CD-MOF has been confirmed by single-crystal X-ray analysis by determining the vacancies of K[+]-ion sites and accounting for the cation/γ-CD ratio in CD-MOF-1. The proportion of Li[+] ions has also been confirmed by elemental analysis, whereas powder X-ray diffraction has established the stability of the extended framework. This noninvasive synthetic approach to generating mixed-metal CD-MOFs is a promising method for obtaining porous framework unattainable de novo. Furthermore, the CO[sub 2] and H[sub 2] capture capacities of the Li[+]-ion-substituted CD-MOF have been shown to exceed the highest sorption capacities reported so far for CD-MOFs. [ABSTRACT FROM AUTHOR]

Acrylamide derivatives of bile acids are chosen as a hydrophobic comonomer to copolymerize with acrylamide via reversible addition and fragmentation chain transfer (RAFT) polymerization to afford a series of copolymers of P(AAm-co-CAA). These copolymers exhibit a sharp and reversible insoluble-soluble transition in water upon heating to a mixing temperature (T mix) related to the upper critical solution temperature (UCST). T mix of these copolymers can be conveniently tuned to a practical temperature range, around 37 °C for biomedical applications. T mix rises with increasing molar fraction of the bile acid-based acrylamide and increasing concentration of the aqueous solution of the copolymers. The addition of a natural host molecule β-cyclodextrin lowered the T mix. The insoluble-soluble transition of the copolymers was also evidenced by dynamic light scattering and transmission electron microscopy. The biocompatible nature of the bile acids and β-cyclodextrins may make these copolymers potentially useful for biomedical applications. [ABSTRACT FROM AUTHOR]

The superbasic proton sponge 1,8-bis(tripyrrolidinylphosphazenyl)naphthalene (TPPN) has been successfully employed for the structural characterization of neutral saccharides, cyclodextrins, and saccharide alditols by matrix assisted laser desorption/ionization tandem mass spectrometry (MALDI-MS/MS). Owing to its inherently high basicity, TPPN is capable of deprotonating neutral carbohydrates (M) providing an efficient and simple way to produce gas-phase [M - H] ions. Highly informative negative ions MS/MS spectra showing several diagnostic fragment ions were obtained, mainly A-type cross-ring and C-type glycosidic cleavages. Indeed, cross-ring cleavages of monosaccharides with formation of A, A, A, A, A, and X product ions dominate the MS/MS spectra. A significant difference between reducing (e.g., lactose, maltose) and non-reducing disaccharides (e.g., sucrose, trehalose) was observed. Though disaccharides with the anomeric positions blocked give rise to deprotonated molecules, [M - H], at m/ z 341.1, reducing ones exhibited a peak at m/ z 340.1, most likely as radical anion, [M - H- H]. The superiority of TPPN was clearly demonstrated by comparison with well recognized matrices, such as 2,5-dihydroxybenzoic acid and 2',4',6'-trihydroxyacetophenone (positive ion mode) and nor-harman (negative ion mode). MALDI MS/MS experiments on isotopically labeled sugars have greatly supported the interpretation of plausible fragmentation pathways. [ABSTRACT FROM AUTHOR]

In this study, we report a versatile method to assemble tunable poly(ethylene glycol) (PEG)-based polyrotaxane (PRX) particles and capsules. By threading a-cyclodextrins (aCDs) onto PEG chains physically adsorbed onto template particles and subsequently dissolving the templates, PRX replica particles and hollow capsules are formed. This approach overcomes issues related to CD steric hindrance, and also reduces the multiple processing steps often associated with PRX-based particle formation. By simple variation of the molecular weight and end-group functionality of the PEG, we show that the rate of particle degradation as well as the stability of the particles can be tuned. We also demonstrate the loading and release of model (drug) compounds, achieving burst and controlled release of the compounds. It is envisaged that this approach will provide a flexible platform for the engineering of a diverse range of PRX-based particles, enabling PRX materials to be further explored in various applications. [ABSTRACT FROM AUTHOR]

The cost-effective and energy-efficient removal of organic micropollutants (MPs) from water and wastewater is challenging. The objective of this research was to evaluate the performance of porous β-cyclodextrin polymers (P-CDP) as adsorbents of MPs in aquatic matrixes. Adsorption kinetics and MP removal were measured in batch and flow-through experiments for a mixture of 83 MPs at environmentally relevant concentrations (1 µg L-1) and across gradients of pH, ionic strength, and natural organic matter (NOM) concentrations. Performance was benchmarked against a coconut-shell activated carbon (CCAC). Data reveal pseudo-second-order rate constants for most MPs ranging between 1.5 and 40 g mg-1 min-1 for CCAC and 30 and 40000 g mg-1 min-1 for P-CDP. The extent of MP removal demonstrates slower but more uniform uptake on CCAC and faster but more selective uptake on P-CDP. Increasing ionic strength and the presence of NOM had a negative effect on the adsorption of MPs to CCAC but had almost no effect on adsorption of MPs to P-CDP. P-CDP performed particularly well for positively charged MPs and neutral or negatively charged MPs with McGowan volumes greater than 1.7 (cm³ mol-1)/100. These data highlight advantages of P-CDP adsorbents relevant to MP removal during water and wastewater treatment. [ABSTRACT FROM AUTHOR]

Self-aggregation of organic molecules is rarely seen with macrocyclic hosts like β-cyclodextrin, as they preferentially involve the formation of inclusion complexes with the guest molecule. In this contribution, we report the self-aggregation of a guest molecule induced by negatively charged sulfated β-cyclodextrin (SCD) to yield highly emissive aggregates of a recently projected amyloid marker dye, Auramine O (AuO). The SCD templated AuO aggregates display very different photophysics when compared to its reported behavior in a wide range of various chemical and biological environment but show a remarkable similarity with the recently reported photophysical behavior of AuO in human insulin fibrillar media, thus providing important insights into the molecular form of AuO responsible for its amyloid sensing ability. The self-assembled AuO aggregates formed in the presence of SCD display a significantly long excited-state lifetime, suggesting the retardation of the torsional relaxation of dye in the aggregated state, which otherwise leads to a very short excited-state lifetime for the monomeric form of the dye in the isolated form. Detailed time-resolved emission spectra (TRES) measurements show a dynamic Stokes shift suggesting excitonic migration within the AuO aggregates. The supramolecular aggregate assembly displays remarkable sensitivity to important external stimuli like temperature or ionic strength of the medium, pitching for its possible application in designing stimuli-responsive sensing schemes for important analytes. [ABSTRACT FROM AUTHOR]

Cyclodextrins (CD), produced from enzymatic degradation of starch, are a form of biorenewable cyclic oligosaccharide which has an outstanding capability to form inclusion complexes with a variety of molecules including pollutants due to their toroid-shaped molecular structure. In this study, by a simple reprecipitation method, we obtained "channel-type" packing from γ-CD where CD molecules are stacked on top of each other to form long cylindrical channels. The γ-CD "channel-type" crystals have shown very effective removal of organic volatile compounds (VOCs; aniline and toluene) from the surroundings, whereas cage-type γ-CD could not entrap VOCs from the same environment. Encapsulation capability of channel-type γ-CD is at a ~2:1 and ~1:1 molar ratio for aniline/CD and toluene/CD, respectively. Thus, channel-type γ-CD crystals have shown higher removal efficiency for aniline compared to toluene. Channel-type γ-CD is also able to remove aniline selectively from surroundings. Additionally, computational modeling studies suggested that single γ-CD cavity can host two molecules of aniline or toluene for the complexation, yet, aniline is more insistent to make a complex with the γ-CD cavity when compared to toluene. We show that channel-type γ-CD can remove VOCs molecules (aniline and toluene) as efficiently as activated carbon. Hence, being a starch-based biorenewable cyclic oligosaccharide in the form of white powder, the use of "channel-type" γ-CD crystals could be a competitive alternative to activated carbon as an adsorbent for the VOC removal/filtering. [ABSTRACT FROM AUTHOR]

The visualization of changes in the stress and bonding state inside polymeric materials is an attractive function in materials science. In this study, phenolphthalein (PP) was selected to prepare stimuli-responsive coloring materials. PP becomes purple under basic conditions in aqueous solutions; however, PP becomes colorless under basic conditions when it forms a complex with β-cyclodextrin (βCD). To exploit this property of PP, we prepared a color-changing hydrogel (βCD-PP AAm hydrogel) based on acrylamide (AAm) as the main chain and βCD and PP moieties as the side chains. The βCD-PP AAm hydrogel exhibits a color change when heat or a competing molecule is applied at a pH less than 8. This color change was confirmed by ultraviolet–visible (UV–vis) spectroscopy, and the mechanical properties were determined via compression and tensile measurements. The βCD-PP AAm hydrogel also exhibits a rapid, reversible color change upon Joule heating produced by an electric current passing through the gel. [ABSTRACT FROM AUTHOR]

Highly tunable metal–organic framework (MOF) materials, including, for example, UiO-66-NH2, are known to be effective catalysts to degrade chemical warfare agents (CWAs) with half-lives near 1 min. Therefore, many researchers have been actively working on producing supported MOF materials to improve application effectiveness by using relatively slow solvothermal synthesis or repetitious stepwise layer-by-layer methods. Herein, we demonstrate a facile route to rapidly assemble presynthesized UiO-66-NH2 crystals onto nonwoven polypropylene (PP) fibrous mats at ambient temperature. Crystal assembly is chemically directed using β-cyclodextrin (β-CD) and cetyltrimethylammonium bromide (CTAB) as surfactant assembly agents, where the agents quickly (within 5 min) self-assemble on the crystal surface and promote physically robust chemical surface attachment while simultaneously impeding solution-phase crystal agglomeration. Furthermore, we find that when the PP is preconditioned using conformal metal oxide thin films, including Al2O3, TiO2, or ZnO formed via atomic layer deposition (ALD), the hydrophilic metal oxide surface further helps improve assembly uniformity and MOF mass loading, producing MOF crystal loading as high as 40 wt % and an overall BET surface area exceeding 200 m2/g(MOF+Fiber). Using these surface-assembled MOFs, we observe catalytic degradation of dimethyl 4-nitrophenyl phosphate (DMNP), a CWA simulant, with a half-life of less than 5 min. [ABSTRACT FROM AUTHOR]

The aggregation and structure of d-α-tocopheryl polyethylene glycol succinate micelles, TPGS-1000, an amphiphilic derivative of vitamin E, were characterized using scattering and spectroscopic methods, and the impact of different cyclodextrins (CDs) on the self-assembly was investigated, with the view of combining these two versatile pharmaceutical excipients in drug formulations. Combined small-angle neutron scattering (SANS), dynamic light scattering, and time-resolved and steady-state fluorescence emission experiments revealed a core-shell architecture with a high aggregation number (N agg ≈ 100) and a highly hydrated poly(ethylene oxide) corona (~11 molecules of solvent per ethylene oxide unit). Micelles form gradually, with no sharp onset. Structural parameters and hydration of the aggregates were surprisingly stable with both temperature and concentration, which is a critical advantage for their use in pharmaceutical formulations. CDs were shown to affect the self-assembly of TPGS in different ways. Whereas native CDs induced the precipitation of a solid complex (pseudopolyrotaxane), methylated β-CDs led to different outcomes: constructive (micellar expansion), destructive (micellar rupture), or no effect, depending on the number of substituents and whether the substitution pattern was regular or random on the rims of the macrocycle. Time-resolved SANS studies on mixtures of TPGS with regularly dimethylated β-CD (DIMEB), which ruptures the micelles, revealed an almost instantaneous demicellization (<100 ms) and showed that the process involved the formation of large aggregates whose size evolved over time. Micellar rupture is caused by the formation of a TPGS-DIMEB inclusion complex, involving the incorporation of up to three macrocycles on the tocopherol, as shown by proton nuclear magnetic resonance (NMR) and ROESY NMR. Analysis of NMR data using Hill's equation revealed that the binding is rather cooperative, with the threading of the CD favoring the subsequent inclusion of additional CDs on the aliphatic moiety. [ABSTRACT FROM AUTHOR]

Artificial supramolecular-hierarchical structures that emulate nature represent an overcoming alternative for the design of new drug delivery systems. Thermodynamic and topographic properties of films formed by a monoacylated amphiphilic β-cyclodextrin (βCD-C16) with the phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) at the air/water interface were studied. βCD-C16 formed stable mixed films with POPC at several proportions when spread together at the air/water interface. The orientation of βCD-C16 cavity at the interface depends on its mole fraction in the film as reveled by the analysis of partial mean molecular areas as a function of composition. Furthermore, βCD-C16 was able to penetrate POPC preformed films in a broad range of initial surface pressures, including that near the collapse pressure of the phospholipid. These results demonstrated the strong tendency of βCD-C16 to be inserted into this lipid matrix commonly used in liposome formulations. Topography studies show that βCD-C16 segregate from POPC forming clusters enriched in βCD-C16. Segregation of βCD-C16 was especially noticeable when βCD-C16 were incorporated by themselves into a preformed POPC matrix leading to ordered and highly birefringent structures that suggest the formation of hierarchical stacked βCD-C16 arrangement at the interface. [ABSTRACT FROM AUTHOR]

Carbon monoxide (CO) is produced in mammalian cells during heme metabolism and serves as an important signaling messenger. Here we report the bioactive properties of selective CO scavengers, hemoCD1 and its derivative R8-hemoCD1, which have the ability to detect and remove endogenous CO in cells. HemoCD1 is a supramolecular hemoprotein-model complex composed of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphinatoiron(II) and a per-O-methylated β-cyclodextrin dimer having an pyridine linker. We demonstrate that hemoCD1 can be used effectively to quantify endogenous CO in cell lysates by a simple spectrophotometric method. The hemoCD1 assay detected ca. 260 pmol of CO in 106 hepatocytes, which was well-correlated with the amount of intracellular bilirubin, the final breakdown product of heme metabolism. We then covalently attached an octaarginine peptide to a maleimide-appended hemoCD1 to synthesize R8-hemoCD1, a cell-permeable CO scavenger. Indeed, R8-hemoCD1 was taken up by intact cells and captured intracellular CO with high efficiency. Moreover, we revealed that removal of endogenous CO by R8-hemoCD1 in cultured macrophages led to a significant increase (ca. 2.5-fold) in reactive oxygen species production and exacerbation of inflammation after challenge with lipopolysaccharide. Thus, R8-hemoCD1 represents a powerful expedient for exploring specific and still unidentified biological functions of CO in cells. [ABSTRACT FROM AUTHOR]