3 research outputs found
Self-Catalytic Growth of Unmodified Gold Nanoparticles as Conductive Bridges Mediated Gap-Electrical Signal Transduction for DNA Hybridization Detection
A simple and sensitive gap-electrical
biosensor based on self-catalytic
growth of unmodified gold nanoparticles (AuNPs) as conductive bridges
has been developed for amplifying DNA hybridization events. In this
strategy, the signal amplification degree of such conductive bridges
is closely related to the variation of the glucose oxidase (GOx)-like
catalytic activity of AuNPs upon interaction with single- and double-stranded
DNA (ssDNA and dsDNA), respectively. In the presence of target DNA,
the obtained dsDNA product cannot adsorb onto the surface of AuNPs
due to electrostatic interaction, which makes the unmodified AuNPs
exhibit excellent GOx-like catalytic activity. Such catalytic activity
can enlarge the diameters of AuNPs in the glucose and HAuCl<sub>4</sub> solution and result in a connection between most of the AuNPs and
a conductive gold film formation with a dramatically increased conductance.
For the control sample, the catalytic activity sites of AuNPs are
fully blocked by ssDNA due to the noncovalent interaction between
nucleotide bases and AuNPs. Thus, the growth of the assembled AuNPs
will not happen and the conductance between microelectrodes will be
not changed. Under the optimal experimental conditions, the developed
strategy exhibited a sensitive response to target DNA with a high
signal-to-noise ratio. Moreover, this strategy was also demonstrated
to provide excellent differentiation ability for single-nucleotide
polymorphism. Such performances indicated the great potential of this
label-free electrical strategy for clinical diagnostics and genetic
analysis under real biological sample separation
Sulfur-Doped Graphene as an Efficient Metal-free Cathode Catalyst for Oxygen Reduction
Tailoring the electronic arrangement of graphene by doping is a practical strategy for producing significantly improved materials for the oxygen-reduction reaction (ORR) in fuel cells (FCs). Recent studies have proven that the carbon materials doped with the elements, which have the larger (N) or smaller (P, B) electronegative atoms than carbon such as N-doped carbon nanotubes (CNTs), P-doped graphite layers and B-doped CNTs, have also shown pronounced catalytic activity. Herein, we find that the graphenes doped with the elements, which have the similar electronegativity with carbon such as sulfur and selenium, can also exhibit better catalytic activity than the commercial Pt/C in alkaline media, indicating that these doped graphenes hold great potential for a substitute for Pt-based catalysts in FCs. The experimental results are believed to be significant because they not only give further insight into the ORR mechanism of these metal-free doped carbon materials, but also open a way to fabricate other new low-cost NPMCs with high electrocatalytic activity by a simple, economical, and scalable approach for real FC applications
Size-Selective Suzuki–Miyaura Coupling Reaction over Ultrafine Pd Nanocatalysts in a Water-Stable Indium–Organic Framework
Metal
nanoparticles stabilized by crystalline metal–organic
frameworks (MOFs) are highly promising for green heterogeneous catalysis.
In this work, in situ formed ultrafine Pd nanocatalysts
with an average size of 3.14 nm have been successfully immobilized
into the mesopores or defects of a water-stable indium-based MOF by
the double-solvent method and subsequent reduction. Significantly,
the obtained Pd@InOF-1 displays an obvious and satisfactory size-selective
effect in the Suzuki–Miyaura coupling reaction between arylboronic
acids and aryl bromides. On the basis of the synergistic effect, microporous
InOF-1 nanorods afford a confined space for improving the selectivity
of target products while Pd nanoparticles endow abundant active sites
for catalysis. Herein, choosing the smallest size reactant with only
one benzene ring gives the highest isolated yield of 90%, and if the
size is larger, the yield is obviously reduced or even the target
product could not be collected. Looking forward, this demonstrated
study not only assembles a well-designed Pd@MOF composite with unique
micro-nanostructures but also delivers an impressive option for cross-coupling
reaction, which has implications for the further development of MOF
hybrids for sustainable applications