共查询到20条相似文献,搜索用时 15 毫秒
1.
Hong JS Vreeland WN Lacerda SH Locascio LE Gaitan M Raghavan SR 《Langmuir : the ACS journal of surfaces and colloids》2008,24(8):4092-4096
Nanosized gel particles (nanogels) are of interest for a variety of applications, including drug delivery and single-molecule encapsulation. Here, we employ the cores of nanoscale liposomes as reaction vessels to template the assembly of calcium alginate nanogels. For our experiments, a liposome formulation with a high bilayer melting temperature (Tm) is selected, and sodium alginate is encapsulated in the liposomal core. The liposomes are then placed in an aqueous buffer containing calcium chloride, and the temperature is raised up to Tm. This allows permeation of Ca2+ ions through the bilayer and into the core, whereupon these ions gel the encapsulated alginate. Subsequently, the lipid bilayer covering the gelled core is removed by the addition of a detergent. The resulting alginate nanogels have a size distribution consistent with that of the template liposomes (ca. 120-200 nm), as confirmed by transmission electron microscopy and light scattering. Nanogels of different average sizes can be synthesized by varying the template dimensions, and the gel size can be further tuned after synthesis by the addition of monovalent salt to the solution. 相似文献
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Kevin D. Belfield Mykhailo V. Bondar Florencio E. Hernandez Olga V. Przhonska Sheng Yao 《Chemical physics》2006,320(2-3):118-124
Linear spectral properties, including excitation anisotropy, of pseudoisocyanine or 1,1′-diethyl-2,2′-cyanine iodide (PIC) J-aggregates in aqueous solutions with J-band position at 573 nm were investigated. Two-photon absorption of PIC J-aggregates and monomer molecules was studied using an open aperture Z-scan technique. A strong enhancement of the two-photon absorption cross-section of PIC in the supramolecular J-aggregate assembly was observed in aqueous solution. This enhancement is attributed to a strong coupling of the molecular transition dipoles. No two-photon absorption at the peak of the J-band was detected. 相似文献
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Tang H de Oliveira CS Sonntag G Gibb CL Gibb BC Bohne C 《Journal of the American Chemical Society》2012,134(12):5544-5547
Water-soluble octaacid cavitands (OAs) form dimeric capsules suitable for guest incorporation. Our studies reveal that the mechanism of pyrene (Py) binding involves the rapid (<1 ms) formation of the Py·OA complex followed by slower binding with the second OA. The dissociation of the capsular OA·Py·OA complex occurs with a lifetime of 2.7 s, which is 5 orders of magnitude slower than the microsecond opening/closing ("breathing") previously observed to provide access of small molecules to the encapsulated guest. These different dynamics of the capsules have a potential impact on how the chemistry of included guests could be altered. 相似文献
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Tooru Ooya Hideharu Mori Minoru Terano Nobuhiko Yui 《Macromolecular rapid communications》1995,16(4):259-263
A novel design of a biodegradable carrier for drug delivery was established by constructing a supramolecular assembly of drugs and polymer backbones without any covalent bonds. A biodegradable polyrotaxane was synthesized in which α-cyclodextrins (α-CDs) as drug carriers were threaded onto poly(ethylene glycol) chains which then were capped at each chain end by L -phenylalanine via peptide linkages. The release of α-CDs was observed only when the terminal peptide linkages were degraded. 相似文献
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A novel trimeric resorcinarene molecular box is induced during hydrothermal synthesis by use of the 3-fold symmetric tripyridyl triazine linker molecule. 相似文献
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Miyawaki A Miyauchi M Takashima Y Yamaguchi H Harada A 《Chemical communications (Cambridge, England)》2008,(4):456-458
Poly[2]rotaxane and supramolecular assembly have been prepared by modified cyclodextrins bearing an adamantyl group in an aqueous medium. 相似文献
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Self-complementary monomer 1, which combines a macrotricyclic polyether and two dibenzylammonium ions together, was synthesized, and its self-assembly into supramolecular polymer networks by host-guest interactions was studied. For the purpose of comparative study, two model molecules 2 and 3 were also prepared. It was found that model molecule 2 and dibenzylammonium ion 4 form a 1:2 complex in solution and in the solid state, which afforded a model system for the investigation of the assembly behavior of monomer 1. Consequently, the (1)H NMR spectrum of 1 in CD(3)CN showed characteristic proton signals similar to the model system, which suggested that 1 self-assembles into a supramolecular polymer network. Formation of the supramolecular polymer was further evidenced by the MALDI-TOF MS spectrum, viscometry, and dynamic light-scattering (DLS) experiments. Moreover, it was found that the decomposition and re-formation of the supramolecular polymer could be chemically controlled by the use of triethylamine and trifluoroacetic acid. Interestingly, the supramolecular polymer forms an organogel both in CD(3)CN and in 1:1 (v/v) CDCl(3)/CD(3)CN, and reversible thermo- and pH-induced gel-sol transitions were also found. The presented work will provide a new strategy for the construction of supramolecular polymers with specific structures and properties. 相似文献
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Kodama H Matsumura S Yamashita T Mihara H 《Chemical communications (Cambridge, England)》2004,(24):2876-2877
Amyloid-like fibrils formed from de novo designed short peptides, made up a nanoscale scaffold on which streptavidin was arranged in a regular spacing, potentially allowing the development into an array technology utilizing bio-nanoconstructs. 相似文献
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Tao Liu Ling-Li Han Chun-Mei Du Zhang-Yu Yu 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(7):1085-1090
Dopamine (DA) can be oxidized to dopamine quinone (DAquinone) through a one-step, two-electron redox reaction. The electron transfer property of DA and its supramolecular complex with aspartic acid (Asp) has been investigated by the theoretical calculations. We calculated the standard redox potentials (E o) of DA/DAquinone at the MP2/6-31G(d,p)//B3LYP/6-31G(d,p), MP2/6-31+G(d,p)//B3LYP/6-31+G(d,p), MP2/6-31G(d,p)//B3LYP/6-311G(d,p), and MP2/6-311+G(d,p)//B3LYP/6-311+G(d,p) levels. Comparing the experimental value, the redox potentials of DA/DAquinone obtained at MP2//B3LYP/6-311G(d,p) and MP2//B3LYP/6-311+G(d,p) levels can be considered as the upper and lower estimates. DA can form supramolecular complex (DA-Asp) with Asp through hydrogen bond (H-bond). Therefore, the values of 0.631 and 0.628 V obtained at MP2//B3LYP/6-311G(d,p) and MP2//B3LYP/6-311+G(d,p) levels for DA-Asp/DAquinone-Asp can be proposed as the upper and lower estimates of a probable (about 0.630 V) value of the corresponding redox potential. The calculated E o values of DA-Asp/DAquinone-Asp at the four theoretical levels are upper than those of DA/DAquinone, which indicates that the formation of H-bonds weaken the electron-donating ability of DA. 相似文献
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Aakeröy CB Rajbanshi A Desper J 《Chemical communications (Cambridge, England)》2011,47(41):11411-11413
Resorcinarene-based cavitands functionalized with acetamido groups capable of self-complementary hydrogen-bond interactions, were synthesized in order to construct supramolecular capsules. The 1,3-bifunctionalized cavitand produced a polymeric assembly, whereas the tetra-functionalized analogue yielded a discrete capsule held together via N-H···O hydrogen bonds. The ethynyl species attached to the rim of these host molecules deepen each cavitand and expands the volume of the resulting capsule. 相似文献
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G Mukherjee P Singh C Ganguri S Sharma HB Singh N Goel UP Singh RJ Butcher 《Inorganic chemistry》2012,51(15):8128-8140
The synthesis and characterization of the complexes of Cu(I), Ag(I), Cu(II), and Co(II) ions with 1,2,5-selenadiazolopyridine (psd) is reported. The following complexes have been prepared: [Cu(2)(psd)(3)(CH(3)CN)(2)](2+)2(PF(6)(-)); [(CuCl)(2)(psd)(3)]; [Cu(2)(psd)(6)](2+)2(ClO(4))(-); [Ag(2)(psd)(2)](2+)2(NO(3))(-); [Ag(2)(psd)(2)](2+)2(CF(3)COO)(-); [Cu(psd)(2)(H(2)O)(3)](2+)2(ClO(4))(-)·(psd)(2); [Cu(psd)(4)(H(2)O)](2+)2(ClO(4))(-)·(CHCl(3)); [Cu(psd)(2)(H(2)O)(3)](2+)2(NO(3))(-)·(H(2)O)·(psd)(2), and [Co(psd)(2)(H(2)O)(4)](2+)2(ClO(4))(-)·(psd)(2). The electronic structure of ligand psd, in particular the bond order of Se-N bonds, has been probed by X-ray diffraction, (77)Se NMR, and computational studies. A detailed analysis of the crystal structures of the ligand and the complexes revealed interesting supramolecular assembly. The assembly was further facilitated by the presence of neutral ligands for some complexes (Cu(II) and Co(II)). The molecular structure of the ligand showed that it was present as a dimer in the solid state where the monomers were linked by strong secondary bonding Se···N interactions. The crystal structures of Cu(I) and Ag(I) complexes revealed the dinuclear nature with characteristic metallophilic interactions [M···M] (M = Cu, Ag), while the Cu(II) and Co(II) complexes were mononuclear. The presence of M···M interactions has been further probed by Atoms in Molecules (AIM) calculations. The paramagnetic Cu(II) and Co(II) complexes have been characterized by UV-vis, ESI spectroscopy, and room temperature magnetic measurements. 相似文献
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Ghosh S Dey S Mandal U Adhikari A Mondal SK Bhattacharyya K 《The journal of physical chemistry. B》2007,111(48):13504-13510
Excited-state proton transfer (ESPT) of pyranine (8-hydroxypyrene-1,3,6-trisulfonate, HPTS) is studied in a polymer-surfactant aggregate using femtosecond emission spectroscopy. The polymer-surfactant aggregate is a supramolecular assembly consisting of a triblock copolymer (PEO)(20)-(PPO)(70)-(PEO)(20) (P123) and a cationic surfactant, cetyltrimethylammonium chloride (CTAC). ESPT of the protonated species (HA) in HPTS leads to the formation of A(-). The dynamics of ESPT may be followed from the decay of the HA emission (at approximately 440 nm) and rise of the A(-) emission (at approximately 550 nm). Both steady-state and time-resolved studies suggest that ESPT of HPTS in P123-CTAC aggregate is much slower than that in bulk water, in P123 micelle, or in CTAC micelle. The ratio of the steady-state emission intensities (HA/A(-)) in P123-CTAC aggregate is 2.2. This ratio is approximately 50, 12, and 2 times higher than that respectively in water, in P123 micelle, and in CTAC micelle. Retardation of ESPT causes an increase in the rise time of the A(-) emission of HPTS. In P123-CTAC aggregate, A(-) displays three rise times: 30, 250, and 2400 ps. These rise times are longer than those in CTAC micelle (23, 250, and 1800 ps), in bulk water (0.3, 3, and 90 ps), and in P123 micelle (15 and 750 ps). The rate constants for initial proton transfer, recombination, and dissociation of the ion pair are estimated using a simple kinetic scheme. The slow fluorescence anisotropy decay of HPTS in P123-CTAC aggregate is analyzed in terms of the wobbling-in-cone model. 相似文献
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Shao-Ping Zheng Yao-Wei Xu Pei-Yang Su Chen-Hui Liu Yin-Hui Huang Yu-Lin Lu Zhang-Wen Wei Zhiwei Jiao Hai-Sen Xu Cheng-Yong Su 《中国化学快报》2024,(3):297-301
The intimate host-anion interactions will regulate thermodynamics and kinetics in the self-assembly of cationic cages mimicking biological counterparts. Herein, we report construction and transformation of three Pd(Ⅱ)-based metal-organic cages(MOCs) depending on different anions. Stoichiometric conversions of the lantern-shaped MOC-34 into either octahedral MOC-35 or tricapped trigonal prism MOC-36 are induced by BF4~– or NO3~– , respectively. MOC-36 is kinetically favored ... 相似文献
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Xia C Fan X Locklin J Advincula RC Gies A Nonidez W 《Journal of the American Chemical Society》2004,126(28):8735-8743
We report the synthesis and characterization of dendritic thiophene derivatives with their unique supramolecular assembly into 2-D crystals, nanowires, and nanoparticle aggregates. The structure and size of the dendrons and dendrimers have been confirmed with various techniques, such as NMR, SEC, and MALDI-TOF-MS. The mass values were consistent with the mass observed by MALDI-TOF-MS, whereas SEC measurements also gave useful information on the hydrodynamic volume of the individual dendrimers. The interesting electrooptical properties were highlighted by very broad absorption spectra and narrower fluorescence consistent with their electrochemical behavior. The self-organization of the dendrimers on the solid substrate is dependent on the nature of the substrate, preparation methods, and the molecule-molecule and molecule-substrate interactions. Thus, 14T-1 and 30T both formed globular aggregates on mica surface, while 14T-1 also formed nanowires on graphite surface. On the other hand, the larger 30T was observed to form 2-D crystalline structures. By varying the alkyl chain length attached to 14T-1, we were also able to obtain 2-D crystals on graphite. This showed that the different symmetry of packing for 30T and 14T-1 is also dependent on several factors, such as the molecular shape, size, and the presence of noncovalent intermolecular interactions. The results demonstrated the unique ability of thiophene dendrimers to form nanostructures on surfaces. 相似文献
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[reaction: see text] A new method for the bioassay of concanavalin A is based on the interaction of saccharide-substituted oligopyrrolic macrocycles with lectins. A general sensing mechanism involves the interaction of aggregated and primarily nonfluorescent labels with the target protein, label deaggregation, site-specific binding, and fluorescence signaling. Addition of saccharides to the fluorescent lectin-macrocycle complex leads to the release of the label and partial quenching of fluorescence due to reaggregation. Specificity of the protein-probe binding is discussed. 相似文献
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In the new inclusion compound [(C2H5)4N+]2 x CO3(2-) x 7(NH2)2CS, the carbonate ion is surrounded by twelve convergent NH donor groups from six thiourea molecules to form a hydrogen-bonded aggregate shaped like two concave three-leaved propellers sharing a common core, whereas in [(n-C3H7)4N+]2 x C2O4(2-) x 4(NH2)2CS the oxalate ion serves as a hub for binding four thiourea molecules to generate a cross-shaped structural motif. 相似文献