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Joao Paulo Coelho, José Osío Barcina, Elena Junquera, Emilio Aicart, Gloria Tardajos, Sergio Gómez-Graña, Pablo Cruz-Gil, Cástor Salgado, Pablo Díaz-Núñez, Ovidio Peña-Rodríguez, Andrés Guerrero-Martínez
Amphiphilic nonionic ligands, synthesized with a fixed hydrophobic moiety formed by a thiolated alkyl chain and an aromatic ring, and with a hydrophilic tail composed of a variable number of oxyethylene units, were used to functionalize spherical gold nanoparticles (AuNPs) in water. Steady-state and time-resolved fluorescence measurements of the AuNPs in the presence of α-cyclodextrin (α-CD) revealed the formation of supramolecular complexes between the ligand and macrocycle at the surface of the nanocrystals...
March 16, 2018: Nanomaterials
Hao Chen, Yueyue Chen, Han Wu, Jiang-Fei Xu, Zhiwei Sun, Xi Zhang
We develop a strategy of supramolecular polymeric chemotherapy based on a new kind of water-soluble polymer that bears cucurbit[7]uril (CB[7]) in the main-chain. To this end, we synthesized a bis-alkynyl functionalized CB[7] and polymerized it with α,ω-diazide-PEG through click reaction to form the desired CB[7] based main-chain polymer (poly-CB[7]). Anticancer drug, oxaliplatin, could be encapsulated into the cavity of poly-CB[7] to form a supramolecular polymeric complex, which displayed low cytotoxicity to normal cells...
February 28, 2018: Biomaterials
A V Efimov
In proteins, the polypeptide chain forms a number of right- and left-handed helices and superhelices, right- and left-turned hairpins, and some other structures that are nonsuperimposable, although they are not mirror images of each other as the L-amino acids are not converted to the D-amino acids. This property of protein structures will be referred to here as pseudo-chirality - or handedness. It has been shown that there are two kinds of handedness in proteins - helical handedness and handedness of arrangement...
January 2018: Biochemistry. Biokhimii︠a︡
Serguei V Feskov, Anatoly I Ivanov
An approach to the construction of diabatic free energy surfaces (FESs) for ultrafast electron transfer (ET) in a supramolecule with an arbitrary number of electron localization centers (redox sites) is developed, supposing that the reorganization energies for the charge transfers and shifts between all these centers are known. Dimensionality of the coordinate space required for the description of multistage ET in this supramolecular system is shown to be equal to N - 1, where N is the number of the molecular centers involved in the reaction...
March 14, 2018: Journal of Chemical Physics
Sreetama Pal, Nirnay Samanta, Debasish Das Mahanta, Rajib Kumar Mitra, Amitabha Chattopadhyay
Biological membranes are highly organized supramolecular assemblies of lipids and proteins. The membrane interface separates the outer (bulk) aqueous phase from the hydrophobic membrane interior. In this work, we have explored the microstructure and collective dynamics of the membrane interfacial hydration shell in zwitterionic and negatively charged phospholipid membrane bilayers using terahertz time-domain spectroscopy. We show here that the relaxation time constants of water hydrogen bond network exhibit a unique "rise and dip" pattern with increasing lipid concentration...
March 15, 2018: Journal of Physical Chemistry. B
Andrea Torchi, Davide Bochicchio, Giovanni M Pavan
The rational design of supramolecular polymers that can adapt or respond in time to specific stimuli in controlled way is interesting for many applications, but this requires understanding the molecular factors that make the material faster or slower in responding to the stimulus. To this end, it is necessary to study the dynamic adaptive properties at submolecular resolution, which is difficult at experimental level. Here we show coarse-grained molecular dynamics simulations (<5Å resolution) demonstrating how the dynamic adaptivity and stimuli responsiveness of a supramolecular polymer is controlled by the intrinsic dynamics of the assembly, which is in turn determined by the structure of the monomers...
March 15, 2018: Journal of Physical Chemistry. B
Qing Li, Biao Yang, Jonas Björk, Qigang Zhong, Huanxin Ju, Junjie Zhang, Nan Cao, Ziliang Shi, Haiming Zhang, Daniel Ebeling, Andre Schirmeisen, Junfa Zhu, Lifeng Chi
Hierarchical control of chemical reactions is being considered as one of the most ambitious and challenging topics in modern organic chemistry. In this study, we have realized the one-by-one scission of the X-H bonds (X=N and C) of aromatic amines in a controlled fashion on the Cu(111) surface. Each dehydrogenation reaction leads to certain metal-organic supramolecular structures, which were monitored in single-bond resolution via scanning tunneling microscopy and non-contact atomic force microscopy. Moreover, the reaction pathways were elucidated from X-ray photoelectron spectroscopy measurements and density functional theory calculations...
March 15, 2018: Journal of the American Chemical Society
Giacomo Reina, Ngoc Do Quyen Chau, Yuta Nishina, Alberto Bianco
Several studies have demonstrated the ability of graphene oxide (GO) to efficiently adsorb small-interfering RNA (siRNA) on its surface and to transport it into cells. However, studies on whether and how siRNA interacts with GO are still inconclusive. In this context, understanding the interaction between GO and siRNA is fundamental to design new efficient gene silencing tools. In this work, the interactions between GO and siRNA molecules were systematically investigated. We focused on how the GO size, oxygenated groups present on the surface and chemical functionalization affect the double helix siRNA structure, using gel electrophoresis, UV-Vis spectroscopy, fluorescence resonance energy transfer (FRET) and circular dichroism (CD)...
March 15, 2018: Nanoscale
Beatriz Bernardo-Maestro, Elisa Garrido-Martín, Fernando López-Arbeloa, Joaquín Pérez-Pariente, Luis Gómez-Hortigüela
In an attempt to promote the crystallization of chiral inorganic frameworks, we explore the ability of chiral (1R,2S)-ephedrine and its diastereoisomer (1S,2S)-pseudoephedrine to act as organic building blocks for the crystallization of hybrid organo-inorganic aluminophosphate frameworks in the presence of fluoride. These molecules were selected because of their particular molecular asymmetric structure, which enables a rich supramolecular chemistry and a potential chiral recognition phenomenon during crystallization...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
Héctor Miranda-Astudillo, Lilia Colina-Tenorio, Alejandra Jiménez-Suárez, Miriam Vázquez-Acevedo, Bénédicte Salin, Marie-France Giraud, Claire Remacle, Pierre Cardol, Diego González-Halphen
The proposal that the respiratory complexes can associate with each other in larger structures named supercomplexes (SC) is generally accepted. In the last decade's most of the data about this association came from studies in yeasts, mammals and plants, and information is scarce in other lineages. Here we studied the supramolecular association of the F1 FO -ATP synthase (complex V) and the respiratory complexes I, III and IV of the colorless alga Polytomella sp. with an approach that involves solubilization using mild detergents, n-dodecyl-β-D-maltoside (DDM) or digitonin, followed by separation of native protein complexes by electrophoresis (BN-PAGE), after which we identified oligomeric forms of complex V (mainly V2 and V4 ) and different respiratory supercomplexes (I/IV6 , I/III4 , I/IV)...
March 11, 2018: Biochimica et Biophysica Acta
Nicole L Ing, Ryan K Spencer, Son H Luong, Hung D Nguyen, Allon I Hochbaum
Examples of long-range electronic conductivity are rare in biological systems. The observation of micrometer-scale electronic transport through protein wires produced by bacteria is therefore notable, providing an opportunity to study fundamental aspects of conduction through protein-based materials and natural inspiration for bioelectronics materials. Borrowing sequence and structural motifs from these conductive protein fibers, we designed self-assembling peptides that form electronically conductive nanofibers under aqueous conditions...
March 14, 2018: ACS Nano
Nazario Martin, Alicia López-Andarias, Javier López-Andarias, Carmen Atienza, Francisco J Chichón, José L Carrascosa
Supramolecular chemistry has evolved from the traditional focus on thermodynamic on-pathways to the complex study of kinetic off-pathways, which are strongly dependent of the environmental conditions. Moreover, the control over pathway complexity allows obtaining nanostructures that are inaccessible through spontaneous thermodynamic processes. Here, we present a family of peptide-based π-extended tetrathiafulvalene (exTTF) molecules which show two self-assembly pathways leading to two distinct J-aggregates, namely metastable (M) and thermodynamic (T), with different spectroscopic, chiroptical and electrochemical behavior...
March 14, 2018: Chemistry: a European Journal
Sushovan Paladhi, In-Soo Hwang, Eun Jeong Yoo, Do Hyun Ryu, Choong Eui Song
A practical and highly enantioselective nonenzymatic kinetic resolution of racemic β-hydroxy carbonyl (aldol) compounds through enantioselective dehydration process was developed using a cation-binding Song's oligoethylene glycol (oligoEG) catalyst with potassium fluoride (KF) as base. A wide range of racemic aldols was resolved with extremely high selectivity factors ( s = up to 2393) under mild reaction conditions. This protocol is easily scalable. It provides an alternative approach for the syntheses of diverse biologically and pharmaceutically relevant chiral aldols in enantiomerically pure form...
March 14, 2018: Organic Letters
Federica Scaletti, Joseph Hardie, Yi-Wei Lee, David C Luther, Moumita Ray, Vincent M Rotello
The delivery of proteins into cells is a potential game changer for a wide array of therapeutic purposes, including cancer therapy, immunomodulation and treatment of inherited diseases. In this review, we present recently developed nanoassemblies for protein delivery that utilize strategies that range from direct assembly, encapsulation and composite formation. We will discuss factors that affect the efficacy of nanoassemblies for delivery from the perspective of both nanoparticles and proteins. Challenges in the field, particularly achieving effective cytosolar protein delivery through endosomal escape or evasion are discussed...
March 14, 2018: Chemical Society Reviews
Xin-Da Huang, Mohamedally Kurmoo, Song-Song Bao, Kun Fan, Yan Xu, Zhao-Bo Hu, Li-Min Zheng
DyIII (depma)3 (NO3 )3 (1) and DyIII (depma)4 (NO3 )2 (CF3 SO3 ) (2) differ structurally by the number of depma ligands and the supramolecular interactions (π-π and C-Hπ, respectively) between anthracene moieties. They exhibit single-ion-magnetism which is coupled to photo- and mechanochromism that are partially reversible by thermal annealing. The changes are associated with the formation and destruction of excimers.
March 14, 2018: Chemical Communications: Chem Comm
Guangwei Geng, Zhongju Wang, Penglei Chen, Bo Guan, Changchun Yang, Minghua Liu
Porphyrin-based supramolecular nanoassemblies of a spherical morphology have been attracting broad interest owing to their wide application possibilities in numerous fields of paramount significance. Most of the existing assembly protocols, however, either suffer from the requirement of elaborately-designed yet tediously-synthesized ad hoc porphyrins, the use of surfactant templates, or accurate consideration of the experimental parameters etc. The initiation of a facile surfactant-free fabrication protocol performable under ambient conditions using commercial porphyrins as building blocks is strongly desired...
March 14, 2018: Physical Chemistry Chemical Physics: PCCP
Li-Xuan Cai, Shao-Chuan Li, Dan-Ni Yan, Li-Peng Zhou, Fang Guo, Qing-Fu Sun
Transformations within container-molecules provide a good alternative between traditional homogeneous and heter-ogeneous catalysis, as the containers themselves can be regarded as single molecular nanomicelles. We report here the designed-synthesis of a water-soluble redox-active supramolecular Pd4L2 cage and its application in the encapsulation of aromatic molecules and polyoxometalates (POMs) catalysts. Compared to the previous known Pd6L4 cage, our results show that replacement of two cis-blocked palladium corners with p-xylene bridges through pyridinium bonds formation between the 2,4,6-tri-4-pyridyl-1,3,5-triazine (TPT) ligands not only provides reversible redox-activities for the new Pd4L2 cage, but also realizes the expansion and subdivision of its internal cavity...
March 13, 2018: Journal of the American Chemical Society
Tatsuru Yamada, Shoji Fujiwara, Kyohhei Fujita, Yuji Tsuchido, Takeshi Hashimoto, Takashi Hayashita
The construction of supramolecular recognition systems based on specific host-guest interactions has been studied in order to design selective chemical sensors. In this study, guest-responsive receptors for ATP have been designed with cyclodextrins (CyDs) as a basic prototype of the turn-on type fluorescent indicator. We synthesized dipicolylamine (DPA)-modified CyD-Cu2+ complexes ( Cu·1 α , Cu·1 β , and Cu·1 γ ), and evaluated their recognition capabilities toward phosphoric acid derivatives in water...
March 12, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Carmine Gaeta, Pellegrino La Manna, Carmen Talotta, Giuseppe Floresta, Margherita De Rosa, Annunziata Soriente, Antonio Rescifina, Placido Neri
A novel catalytical feature of the hexameric resorcinarene capsule (C) is here highlighted. The self-assembled cage C has been exploited to promote a mild Friedel-Crafts benzylation of several arenes and heteroarenes. In silico studies show the existence of a catalytically relevant H-bonding interaction between the bridged water molecules of the capsule and benzyl chloride, which is fundamental for the activation of the C-Cl bond. A supramolecular control of the capsule on the reaction outcome is evidenced...
March 13, 2018: Angewandte Chemie
Naohiro Kameta, Jiuchao Dong, Hiroharu Yui
A series of nanotubes with a dense layer of short poly(ethylene glycol) (PEG) chains on the inner surface are prepared by means of a coassembly process using glycolipids and PEG derivatives. Dehydration of the PEG chains by heating increases the hydrophobicity of the nanotube channel and fluorescent-dye-labeled amino acids are extracted from bulk solution. Rehydration of the PEG chains by cooling results in back-extraction of the amino acids into the bulk solution. Because of the supramolecular chirality of the nanotubes, amino acid enantiomers can be separated in the back-extraction procedure, which is detectable with the naked eye as a change in fluorescence as the amino acids are released from the nanotubes...
March 13, 2018: Small
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