26 research outputs found
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Preparation of Bimetallic Nanoparticles Using a Facile Green Synthesis Method and Their Application
A straightforward,
economically viable, and green approach for
the synthesis of well-stabilized Au/Ag bimetallic nanoparticles is
described; this method uses nontoxic and renewable degraded pueraria
starch (DPS) as a matrix and mild reaction conditions. The DPS acted
as both a reducing agent and a capping agent for the bimetallic nanoparticles.
Au/Ag bimetallic nanoparticles were successfully grown within the
DPS matrixes, and the bimetallic structures were characterized using
various methods, including high-resolution transmission electron microscopy,
energy-dispersive X-ray, and X-ray diffraction. Moreover, it was shown
that these DPS-capped Au/Ag bimetallic nanoparticles could function
as catalysts for the reduction of 4-nitrophenol in the presence of
NaBH<sub>4</sub> and were more effective than Au or Ag monometallic
nanoparticles
Preparation of Hybrid Hydrogel Containing Ag Nanoparticles by a Green in Situ Reduction Method
In this Article, large and uniform Ag nanoparticle-containing
hybrid
hydrogels were prepared by in situ reduction of Ag ions in cross-linked
tapioca dialdehyde starch (DAS)–chitosan hydrogels. In the
hybrid hydrogels, chitosan was chosen as a macromolecular cross-linker
because of its abundant source and good biocompatibility. The hybrid
hydrogel showed good water-swelling properties, which could be controlled
by varying the ratio of chitosan to tapioca DAS in the hydrogel. The
reductive aldehyde groups in the cross-linked hydrogels could be used
to reduce Ag ions to Ag nanoparticles without any additional chemical
reductants. Interestingly, by controlling the reduction conditions
such as the tapioca DAS concentration, aqueous AgNO<sub>3</sub> concentration,
reaction time, and aqueous ammonium concentration, Ag nanoparticles
with different sizes and morphologies were obtained. Because of their
biocompatibility, degradable constituents, mild reaction conditions,
and controlled preparation of Ag nanoparticles, these tapioca DAS–chitosan/Ag
nanoparticle hybrid hydrogels show promise as functional hydrogels
Synthesis of Cu-Nanoparticle Hydrogel with Self-Healing and Photothermal Properties
Copper
(Cu) nanoparticles possess unusual electrical, thermal, and optical
properties. However, applications of these materials are often limited
by their tendency to oxidize. We prepared Cu nanoparticles by a simple
polyol method, with a good control over the particle size. The reaction
required no inert atmosphere or surfactant agents. The as-prepared
Cu nanoparticles showed good resistance to oxidation in solution.
These Cu nanoparticles were then incorporated into a biocompatible
polysaccharide hydrogel, which further stabilized the nanoparticles.
The hybrid hydrogel exhibited a rapid self-healing ability. Because
of the excellent photothermal conversion properties of the embedded
Cu nanoparticles, the hybrid hydrogel showed rapid temperature elevation
under laser irradiation. The hybrid hydrogel showed limited cytotoxicity;
however, under laser irradiation the hydrogel displayed antibacterial
properties owing to the heating effects. This study demonstrates that
our hybrid hydrogel may have applications in biomedical fields and
photothermal therapy
Flexible Antibacterial Film Based on Conjugated Polyelectrolyte/Silver Nanocomposites
In
this work, we report a flexible film based on conjugated polyelectrolyte/silver
nanocomposites with efficient antibacterial activity. A flexible polyÂ(dimethylsiloxane)
film served as a substrate for deposition of nanostructured silver.
A light-activated antibacterial agent, based on the cationic conjugated
polyelectrolyte polyÂ({9,9-bisÂ[6′-(<i>N,N</i>-trimethylamino)Âhexyl]-2,7-fluorenyleneethynylene}-<i>alt</i>-<i>co</i>-1,4-(2,5-dimethoxy)Âphenylene)Âdibromide
(PFEMO) was self-assembled on the negatively charged substrate. By
changing the thickness of the polyÂ(l-lysine)/polyÂ(acrylic
acid) multilayers between the metal substrate and PFEMO, we obtained
concomitant enhancement of PFEMO fluorescence, phosphorescence, and
reactive oxygen species generation. These enhancements were induced
by surface plasmon resonance effects of the Ag nanoparticles, which
overlapped the PFEMO absorption band. Owing to the combination of
enhanced bactericidal effects and good flexibility, these films have
great potential for use as novel biomaterials for preventing bacterial
infections
Facile Synthesis of Biocompatible Fluorescent Nanoparticles for Cellular Imaging and Targeted Detection of Cancer Cells
In this work, we report the facile
synthesis of functional core–shell structured nanoparticles
with fluorescence enhancement, which show specific targeting of cancer
cells. Biopolymer poly-l-lysine was used to coat the silver
core with various shell thicknesses. Then, the nanoparticles were
functionalized with folic acid as a targeting agent for folic acid
receptor. The metal-enhanced fluorescence effect was observed when
the fluorophore (5-(and-6)-carboxyfluorescein-succinimidyl ester)
was conjugated to the modified nanoparticle surface. Cellular imaging
assay of the nanoparticles in folic acid receptor-positive cancer
cells showed their excellent biocompatibility and selectivity. The
as-prepared functional nanoparticles demonstrate the efficiency of
the metal-enhanced fluorescence effect and provide an alternative
approach for the cellular imaging and targeting of cancer cells
Flexible Free-Standing Graphene/SnO<sub>2</sub> Nanocomposites Paper for Li-Ion Battery
A flexible free-standing graphene/SnO<sub>2</sub> nanocomposites
paper (GSP) was prepared by coupling a simple filtration method and
a thermal reduction together for the first time. Compared with the
pure SnO<sub>2</sub> nanoparticles, the GSP exhibited a better cycling
stability, because the graphene with high mechanical strength and
elasticity can work as a buffer to prevent the volume expansion and
contraction of SnO<sub>2</sub> nanoparticles during the Li<sup>+</sup> insertion/extraction process. Meanwhile, compared with single graphene
paper, the GSP showed a higher capacity because of the hybridizing
with higher capacity SnO<sub>2</sub> nanoparticles. The excellent
electrochemical performance of the GSP as an anode material in Li-ion
battery was obtained. The as-prepared GSP shows a great potential
for flexible Li-ion batteries
Fluorescence Resonance Energy Transfer in a Binary Organic Nanoparticle System and Its Application
Fluorescent organic nanoparticles
have a much better photostability
than molecule-based probes. Here, we report a simple strategy to detect
chemicals and biomolecules by a binary nanoparticle system based on
fluorescence resonance energy transfer (FRET). PolyÂ(9,9-di-<i>n</i>-octylfluorenyl-2,7-diyl) (PFO, energy donor) and poly
[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV, energy
acceptor) are utilized to prepare the binary nanoparticle system through
a reprecipitation method. Since the FRET process is strongly distance-dependent,
a change in the interparticle distance between the two kinds of nanoparticles
after introduction of analytes will alter the FRET efficiency. The
response of the binary nanoparticle system to cationic polyelectrolytes
was investigated by monitoring the FRET efficiency from PFO to MEH-PPV
nanoparticles and the fluorescence color of the nanoparticle solutions.
Furthermore, the cationic polyelectrolyte pretreated binary nanoparticle
system can be used to detect DNA by desorption of nanoparticles from
the polyelectrolyte’s chains and the detection concentration
can go down to 10<sup>–14</sup> M. Thus, the binary nanoparticle
system shows great promise for applications in chemical sensing or
biosensing
Fluorescent Organic Nanoparticles Based on Branched Small Molecule: Preparation and Ion Detection in Lithium-Ion Battery
Fluorescent organic nanoparticles
(FONs) as a new class of nanomaterials
can provide more advantages than molecule based probes. However, their
applications in specific metal ion detection have rarely been exploited.
We design and synthesize a branched small-molecule compound with triazole
as a core and benzothiadiazole derivative as branches. By a facile
reprecipitation method, nanoparticles (NPs) of this compound can be
prepared in aqueous solutions, which can show high selectivity and
sensitivity to FeÂ(III) ions based on fluorescence quenching. In addition,
the fluorescence intensity of these NPs is resistant to pH changes
in solutions. Such characters of this kind of NPs can be utilized
in Fe<sup>3+</sup> impurity detection in a promising cathode material
(LiFePO<sub>4</sub>) for lithium ion batteries. When exposed to Fe<sup>3+</sup>, both the triazole and benzothiadiazole groups contribute
to the fluorescence quenching of NPs, but the former one plays a more
important role in Fe<sup>3+</sup> impurity detection. The sensing
mechanism has also been investigated which indicates that a Fe-organic
complex formation may be responsible for such sensing behavior. Our
findings demonstrate that specific metal ion detection can be realized
by FONs and have extended the application field of FONs for chemical
sensing in aqueous solutions
Self-Assembly of Conjugated Polymer on Hybrid Nanospheres for Cellular Imaging Applications
A new kind of hybrid core–shell nanosphere was
fabricated
by combining the in situ formation of Au nanoparticles and covalent
cross-linking of biocompatible carboxymethyl starch dialdehyde (CMSD)
and chitosan (CTS). When the fluorescent dye polyÂ[9,9′-bisÂ(6″-(<i>N</i>,<i>N</i>,<i>N</i>-trimethylammonium)-hexyl)Âfluorene-2,7-ylenevinylene-<i>co</i>-alt-1,4-phenylene dibromide] (PFV) was assembled on the
surface of the hybrid nanospheres through electrostatic attraction,
these biocompatible hybrid nanospheres exhibited metal-enhanced fluorescence
effects. The fluorescence intensity of (CTS–Au)@CMSD/PFV hybrid
nanosphere is 1.43 times that of CTS–CMSD/PFV hybrid nanospheres
lacking Au nanoparticle. In addition, the (CTS–Au)@CMSD/PFV
hybrid nanospheres exhibit excellent biodegradability upon exposure
to enzymatic aqueous solution and good biocompatibility when cocultured
with HeLa cervical carcinoma cells; these advantages make them attractive
for cellular imaging and biological analysis and detection