16 research outputs found
A facile preparation method for nanosized MOFs as a multifunctional material for cellular imaging and drug delivery
<p>Tb-based metal-organic framework nanoparticles (Tb-MOF NPs) with good colloidal stability and stable fluorescence properties in an aqueous solution were prepared by a simple mechanical grinding of Tb-MOF with a biocompatible polymer surfactant (F127). The characteristic fluorescence property of Tb-MOF NPs allowed us to use this nanomaterial as a cell imaging probe. Efficient cellular uptake of Tb-MOF NPs apparently via an energy-dependent endocytosis was observed by confocal laser scanning microscopy. By taking advantage of the porous nature of the Tb-MOF NPs an anticancer drug (doxorubicin) was successfully loaded and delivered to kill cancer cells to demonstrate their usage as a drug delivery vehicle. This simple grinding method afforded a nanosized, multifunctional biomaterial that was used for cell imaging and drug delivery, and it can be extended to other MOFs to widen their applications.</p
Semicrystalline Dihydroxyacetone Copolymers Derived from Glycerol
The
ring-opening polymerization of glycerol-derived six-membered
cyclic dimethylacetal dihydroxyacetone carbonate (MeO<sub>2</sub>DHAC)
have been studied both in solution and bulk conditions with organic
catalysts. The guanidine 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD)
was the most active catalyst in solution, whereas the thiourea/sparteine
catalytic system displayed the most predictable kinetics. Ring-opening
polymerization of MeO<sub>2</sub>DHAC or copolymerization with ε-caprolactone
(CL) in the melt occurred readily with TBD as catalyst to afford random
copolymers. Acetal deprotection afforded the polycarbonate poly(dihydroxyactone
carbonate) (p(DHAC)) or poly(carbonate ester) copolymers p(DHAC-<i>r</i>-CL). The polycarbonate p(DHAC) is a high-melting thermoplastic
with a melting point of 246 °C. The p(DHAC-<i>r</i>-CL) copolymers all displayed semicrystalline behavior as evidenced
by DSC and WAXS analysis with <i>T</i><sub>g</sub> and <i>T</i><sub>m</sub> changing as a function of comonomer composition.
These new materials could have potential use in biomedical applications
or as biomass-derived thermoplastics
Selective Synthesis of Molecular Borromean Rings: Engineering of Supramolecular Topology via Coordination-Driven Self-Assembly
Molecular Borromean
rings (BRs) is one of the rare topology among
interlocked molecules. Template-free synthesis of BRs via coordination-driven
self-assembly of tetracene-based Ru(II) acceptor and ditopic pyridyl
donors is reported. NMR and single-crystal XRD analysis observed sequential
transformation of a fully characterized monomeric rectangle to molecular
BRs and vice versa. Crystal structure of BRs revealed that the particular
topology was enforced by the appropriate geometry of the metallacycle
and multiple parallel-displaced π–π interactions
between the donor and tetracene moiety of the acceptor. Computational
studies based on density functional theory also supported the formation
of BRs through dispersive intermolecular interactions in solution
Selective Synthesis of Ruthenium(II) Metalla[2]Catenane via Solvent and Guest-Dependent Self-Assembly
The coordination-driven
self-assembly of an anthracene-functionalized
ditopic pyridyl donor and a tetracene-based dinuclear Ru(II) acceptor
resulted in an interlocked metalla[2]catenane, [M<sub>2</sub>L<sub>2</sub>]<sub>2</sub>, in methanol and a corresponding monorectangle,
[M<sub>2</sub>L<sub>2</sub>], in nitromethane. Subsequently, guest
template, solvent, and concentration effects allowed the self-assembly
to be reversibly fine-tuned among monorectangle and catenane structures
Coordination-Driven Self-Assembly and Anticancer Potency Studies of Arene–Ruthenium-Based Molecular Metalla-Rectangles
The
two new large molecular metalla-rectangles <b>6</b> and <b>8</b> were obtained by the reaction of the two different arene–ruthenium
acceptors [Ru<sub>2</sub>(<i>p-</i>cymene)<sub>2</sub>(μ-η<sup>4</sup>-C<sub>2</sub>O<sub>4</sub>)Cl<sub>2</sub>] (<b>2</b>) and [Ru<sub>2</sub>(<i>p-</i>cymene)<sub>2</sub>(donq)(Cl)<sub>2</sub>] (donq = 5,8-dioxido-1,4-naphthoquinonato) (<b>4</b>) with a symmetrical <i>N</i>,<i>N</i>′-bis(4-(pyridin-4-ylethynyl)phenyl)terephthalamide
(<b>1</b>) donor ligand. Both metalla-rectangles were isolated
in good yields as triflate salts and were characterized by multinuclear
NMR, ESI–MS, and UV–vis spectroscopy. X-ray crystallography
of <b>6</b> confirmed a molecular metalla-rectangle. The cytotoxicities
of metalla-rectangles <b>6</b>–<b>9</b> were established
in SK-hep-1 (liver cancer), AGS (gastric cancer), and HCT-15 (colorectal
cancer) human cancer cell lines. The cytotoxicity of metalla-rectangle <b>8</b> was found to be considerably stronger against all cancer
cell lines, even much more effective than the well-known anticancer
drugs doxorubicin and cisplatin. In addition, expressions of APC and
p53, colorectal cancer suppressor genes, were significantly increased
following exposure to the metalla-rectangle <b>8</b>
Banking performance’ determinants
У статті розглянуто фактори впливу на ефективність банківського бізнесу. З позиції необхідності управління ефективністю банківського бізнесу запропоновано внутрішні фактори розглядати як сукупність статусних характеристик банку та характеристик його бізнес-моделі.The article deals with banking performance’s determinants. In context of banking performance management its proposed internal factors to consider as a set of status characteristics and the characteristics of the bank's business model
Organocatalytic Synthesis of Quinine-Functionalized Poly(carbonate)s
The ring-opening polymerization of substituted cyclic
carbonates
with 1-(3,5-bis-trifluoromethyl-phenyl)-3-cyclohexyl-thiourea (TU)/1,8-diazabicyclo[5.4.0]undec-7-ene
(DBU) organocatalysts afford highly functionalized oligocarbonates.
The fluorescent alkaloid quinine can be readily incorporated into
the oligocarbonates either by initiation from quinine or by ring-opening
polymerization of a quinine-functionalized cyclic carbonate (MTC-Q).
Copolymerization of MTC-Q with a boc-protected guanidinium cyclic
carbonate affords, after deprotection, highly water-soluble cationic
copolymers functionalized with both quinine and pendant guanidinium
groups. When multiple quinine groups are attached to the oligomers,
they exhibit minimal fluorescence due to self-quenching. Upon hydrolysis,
the fluorescence intensity increases, providing a potential strategy
for monitoring the hydrolysis rates in real time
Formation of [3]Catenanes from 10 Precursors via Multicomponent Coordination-Driven Self-Assembly of Metallarectangles
We describe the formation of a suite of [3]catenanes
via multicomponent
coordination-driven self-assembly and host–guest complexation
of a rectangular scaffold comprising a 90° Pt-based acceptor
building block with a pseudorotaxane bis(pyridinium)ethane/dibenzo-24-crown-8
linear dipyridyl ligand and three dicarboxylate donors. The doubly
threaded [3]catenanes are formed from a total of 10 molecular components
from four unique species. Furthermore, the dynamic catenation process
is reversible and can be switched off and on in a controllable manner
by successive addition of KPF<sub>6</sub> and 18-crown-6, as monitored
by <sup>1</sup>H and <sup>31</sup>P NMR spectroscopy
A Unique Non-catenane Interlocked Self-Assembled Supramolecular Architecture and Its Photophysical Properties
A novel, interlocked, self-assembled (M<sub>2</sub>L<sub>2</sub>)<sub>2</sub> molecular architecture was constructed from an arene-Ru acceptor and a 1,4-di(pyridin-4-yl)buta-1,3-diyne donor. Two M<sub>2</sub>L<sub>2</sub> units, with cavities of ∼7.21 Å, spontaneously interlock, with one unit encapsulating a twin in a non-catenane fashion. The dimeric host–guest complex thus formed is unique among two-dimensional self-assemblies and is stabilized by π–π interactions between the M<sub>2</sub>L<sub>2</sub> units
Coordination-Driven Self-Assembly Using Ditopic Pyridyl–Pyrazolyl Donor and <i>p</i>‑Cymene Ru(II) Acceptors: [2]Catenane Synthesis and Anticancer Activities
Coordination-driven
self-assembly of <i>m</i>-bis[3-(4-pyridyl)pyrazolyl]xylene
(<b>L</b>) and [(<i>p</i>-cymene)<sub>2</sub>Ru<sub>2</sub>(OO∩OO)<sub>2</sub>(OTf)<sub>2</sub>] (<b>A</b><sub><b>1</b></sub>) (OO∩OO = 6,11-dioxido-5,12-naphthacenedione)
in methanol resulted in a mixture of [2]catenane <b>1</b> and
macrocycle <b>2</b>, and self-assembly in nitromethane resulted
in pure macrocycle <b>2</b>, whereas the coordination-driven
self-assembly of <b>L</b> and similar acceptors [(<i>p</i>-cymene)<sub>2</sub>Ru<sub>2</sub>(OO∩OO)<sub>2</sub>(OTf)<sub>2</sub>] [OO∩OO = 5,8-dioxido-1,4-naphthoquinonnato (<b>A</b><sub><b>2</b></sub>); 2,5-dioxido-1,4-benzoquinonato
(<b>A</b><sub><b>3</b></sub>); oxalato (<b>A</b><sub><b>4</b></sub>)] resulted in the formations of monomeric
macrocycles <b>3</b>–<b>5</b>, respectively. All
self-assembled macrocycles were obtained in excellent yields (>90%)
as triflate salts and were fully characterized by multinuclear NMR,
elemental analysis, and electrospray ionization mass spectrometry
(ESI-MS). The structures of [2]catenane <b>1</b> and macrocycles <b>5</b> were confirmed by single-crystal X-ray diffraction analysis.
The X-ray structure of <b>1</b> confirmed an edge-to-face interaction
between the tetracene moiety in parallel-displaced π–π
stacks (3.5 Å), and CH···π (2.5 Å)
stabilizes the [2]catenane topology. Macrocycles <b>2</b>–<b>5</b> were assessed for anticancer activities using human cancer
cell lines of different origins, and the macrocycle <b>3</b> was found to exhibit the best inhibitory effect and to do so in
a dose-dependent manner. Further examination with the Tali apoptosis
assay suggested the growth inhibitory effect of <b>3</b> involved
the induction of the programmed cell death, and this suggestion was
supported by observations of PARP and caspase 3 cleavage after treating
cells with <b>3</b>. In addition, exposure to <b>3</b> increased the expression of Bax and repressed the expression of
Bcl-2, thus indicating the involvement of macrocycle <b>3</b> upstream of Bax and Bcl-2 in the apoptotic signaling pathway. Macrocycle <b>3</b> also tended to repress metastasis as evidenced by changes
in the transcriptional expressions E- and N-cadherin (markers of metastasis).
Furthermore, a stability assay demonstrated macrocycle <b>3</b> remained stable at high concentration