Self-assembling triazolophanes: from croissants through donuts to spherical vesicles

2015 ◽  
Vol 51 (32) ◽  
pp. 6905-6908 ◽  
Author(s):  
V. Haridas ◽  
Appa Rao Sapala ◽  
Jerry P. Jasinski
Keyword(s):  
Crystal Structure ◽  
Self Assembly ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
X Ray ◽  
Self Assembling ◽  
Assembly Mechanism ◽  
Spherical Vesicles

A detailed ultramicroscopic analysis of three novel triazolophanes demonstrated a hierarchical self-assembly mechanism. These macrocycles self-assemble in a concentration dependent manner to hemi-toroids, toroids and finally to vesicles. The finding was supported by ultramicroscopy and X-ray crystal structure studies.

scholarly journals Inulin nanostructures: The sweet-spot of carbohydrate self-assembly

2021 ◽  
Author(s):  
Zohar A. Arnon ◽  
Márkó Grabarics ◽  
Topaz Kreiser ◽  
Avi Raveh ◽  
Kevin Pagel ◽  
...  
Keyword(s):  
Nucleic Acids ◽  
Self Assembly ◽  
The Self ◽  
Dependent Manner ◽  
Supramolecular Architecture ◽  
Sweet Spot ◽  
Concentration Dependent Manner ◽  
Self Assembling ◽  
Spontaneous Organization

Supramolecular architecture formation by the self-assembly of proteins and nucleic acids is well studied. Yet, the spontaneous organization of oligosaccharides, the most common polymers in nature, is less explored. Here, using inulin as a model, we identify the "sweet spot" length for oligosaccharide assembly. Inulin forms discrete spheres in a concentration-dependent manner. Size-based fractionation displayed markedly different aggregation morphologies. Based on these findings, we believe that carbohydrates could become an important source for novel self-assembling materials.

scholarly journals Terminal short arm domains of basement membrane laminin are critical for its self-assembly.

1990 ◽  
Vol 110 (3) ◽  
pp. 825-832 ◽  
Author(s):  
J C Schittny ◽  
P D Yurchenco
Keyword(s):  
Self Assembly ◽  
Affinity Column ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Calcium Dependent ◽  
Domain Specific ◽  
Binding Domains ◽  
Individual Domain ◽  
The Individual

Laminin self-assembles into large polymers by a cooperative two-step calcium-dependent mechanism (Yurchenco, P. D., E. C. Tsilibary, A. S. Charonis, and H. Furthmayr. 1985. J. Biol. Chem. 260:7636-7644). The domain specificity of this process was investigated using defined proteolytically generated fragments corresponding to the NH2-terminal globule and adjacent stem of the short arm of the B1 chain (E4), a complex of the two short arms of the A and B2 chains attached to the proximal stem of a third short arm (E1'), a similar complex lacking the globular domains (P1'), and the distal half of the long arm attached to the adjacent portion of the large globule (E8). Polymerization, followed by an increase of turbidity at 360 nm in neutral isotonic TBS containing CaCl2 at 35 degrees C, was quantitatively inhibited in a concentration-dependent manner with laminin fragments E4 and E1' but not with fragments E8 and P1'. Affinity retardation chromatography was used for further characterization of the binding of laminin domains. The migration of fragment E4, but not of fragments E8 and P1', was retarded in a temperature- and calcium-dependent fashion on a laminin affinity column but not on a similar BSA column. These data are evidence that laminin fragments E4 and E1' possess essential terminal binding domains for the self-aggregation of laminin, while fragments E8 and P1' do not. Furthermore, the individual domain-specific interactions that contribute to assembly are calcium dependent and of low affinity.

scholarly journals Fluorescein-Labeled Starch Maleate Nanoparticles as Sensitive Fluorescent Sensing Probes for Metal Ions

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Suk Fun Chin ◽  
Aressa Azman ◽  
Suh Cem Pang ◽  
Sing Muk Ng
Keyword(s):  
Particle Size ◽  
Metal Ions ◽  
Self Assembly ◽  
Detection Limits ◽  
Emission Wavelength ◽  
Dependent Manner ◽  
Ethanolic Solution ◽  
Concentration Dependent Manner ◽  
Maximum Emission ◽  
Fluorescent Sensing

Fluorescein 5(6)-isothiocyanate starch maleate (FISM) nanoparticles were prepared by covalently attached fluorescein 5(6)-isothiocyanate (FITC) with starch maleate. FISM nanoparticles with a mean particle size of 87 nm were formed via self-assembly upon precipitation in ethanolic solution. FISM nanoparticles were strongly fluorescent with maximum emission wavelength of 518 nm. The fluorescence of FISM nanoparticles can be quenched by silver (Ag+) and lead (Pb2+) ions in a concentration dependent manner. We have demonstrated the first use of FISM nanoparticles as cheap and effective fluorescent sensing probes for Ag+and Pb2+ions with detection limits as low as 2.55×10−5 M and 3.64×10−5 M, respectively.

scholarly journals Heat induces end to end repetitive association in P. furiosus l-asparaginase which enables its thermophilic property

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Pankaj Sharma ◽  
Rachana Tomar ◽  
Shivpratap Singh Yadav ◽  
Maulik D. Badmalia ◽  
Samir Kumar Nath ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Self Assembly ◽  
Elevated Temperatures ◽  
Contact Point ◽  
Saxs Data ◽  
X Ray ◽  
X Ray Scattering ◽  
Crystallographic Structures ◽  
End To End ◽  
Enhanced Stability

AbstractIt remains undeciphered how thermophilic enzymes display enhanced stability at elevated temperatures. Taking l-asparaginase from P. furiosus (PfA) as an example, we combined scattering shapes deduced from small-angle X-ray scattering (SAXS) data at increased temperatures with symmetry mates from crystallographic structures to find that heating caused end-to-end association. The small contact point of self-binding appeared to be enabled by a terminal short β-strand in N-terminal domain, Leu179-Val-Val-Asn182 (LVVN). Interestingly, deletion of this strand led to a defunct enzyme, whereas suplementation of the peptide LVVN to the defunct enzyme restored structural frameworkwith mesophile-type functionality. Crystal structure of the peptide-bound defunct enzyme showed that one peptide ispresent in the same coordinates as in original enzyme, explaining gain-of lost function. A second peptide was seen bound to the protein at a different location suggesting its possible role in substrate-free molecular-association. Overall, we show that the heating induced self-assembly of native shapes of PfA led to an apparent super-stable assembly.

scholarly journals Synthesis, X-ray Crystal Structure and Antimicrobial Activity of Unexpected Trinuclear Cu(II) Complex from s-Triazine-Based Di-Compartmental Ligand via Self-Assembly

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 661
Author(s):  
Saied M. Soliman ◽  
Jamal Lasri ◽  
Matti Haukka ◽  
Essam N. Sholkamy ◽  
Hessa H. Al-Rasheed ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Antimicrobial Activity ◽  
Self Assembly ◽  
Wide Spectrum ◽  
Free Ligand ◽  
Salmonella Typhi ◽  
Positive Control ◽  
Distorted Octahedral Geometry ◽  
X Ray ◽  
Π Stacking

The synthesis and X-ray crystal structure of the trinuclear [Cu3(HL)(Cl)2(NO3)(H2O)5](NO3)2 complex of the s-triazine-based di-compartmental ligand, 2-methoxy-4,6-bis(2-(pyridin-2-ylmsethylene)hydrazinyl)-1,3,5-triazine (H2L), are presented. The Cu1 and Cu2 are penta-coordinated with CuN3ClO coordination environment, distorted square pyramidal coordination geometry while Cu3 is hexa-coordinated with CuN2O4 coordination sphere, and distorted octahedral geometry. The complex crystallized in the primitive P-1 triclinic crystal system with two molecular units per unit cell. Its packing is dominated by the O–H (35.5%) and Cl–H (8.8%) hydrogen bonding interactions as well as the π–π stacking (2.3%) and anion–π-stacking interactions (3.7%). The different coordination interactions were analyzed using atoms in molecules (AIM) theory, and the number of charge transferences from the ligand group to Cu(II) were determined using natural bond orbital calculations. The effect of the free ligand and its Cu(II) complex on the tested pathogenic microbes (Staphylococcus aureus, S. epidermidis, Enterococcus faecalis, Escherichia coli, Salmonella typhi and Pseudomonas aeruginosa) and one fungal isolate (Candida albicans) is presented. Both have wide spectrum antimicrobial activity against the selected microorganism. It is observed that the free ligand at 180 µg/mL was more effective than its Cu(II) complex and showed close results compared to the positive control gentamicin. At higher concentrations (1 mg/mL), the Cu(II) complex was found to be more active against S. epidermidis, E. coli and C. albicans than the lower concentration. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values are also lower for the Cu(II) complex than the free ligand.

scholarly journals The Role of Physisorption and Chemisorption in the Oscillatory Adsorption of Organosilanes on Aluminium Oxide

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 410 ◽  
Author(s):  
Ruby Sims ◽  
Sarah Harmer ◽  
Jamie Quinton
Keyword(s):  
Photoelectron Spectroscopy ◽  
Self Assembly ◽  
Film Growth ◽  
Aluminium Oxide ◽  
Time Dependent ◽  
Chemical Binding ◽  
X Ray ◽  
Assembly Mechanism ◽  
Film Substrate

The effect of physisorbed and chemisorbed species on the time-dependent self-assembly mechanism of organosilane films has been investigated on aluminium oxide using X-ray Photoelectron Spectroscopy. The role of physisorbed species was determined through their removal using a simple rinsing procedure while monitoring film substrate coverage. Removing physisorbed species from Propyldimethylmethoxysilane films, shown to follow a Langmuir-type adsorption profile, reduces the substrate coverage initially but quickly results in coverages equivalent to films that did not undergo a rinsing procedure. This indicates that all Propyldimethylmethoxysilane molecules are covalently bound to the substrate following 15 s of film growth. Removing physisorbed species from films, which have been shown to follow an oscillatory adsorption profile, Propyltrimethoxysilane and Propylmethyldimethoxysilane, reveal the persistence of these oscillations despite a reduction in silane substrate coverage. These results not only confirm the presence of two thermodynamically favourable phases in the condensation equilibrium reaction as physisorbed and chemisorbed species, but also indicate that the desorption of species during film growth involves both states of chemical binding.

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