Investigating
catalytic behavior of heterogeneous catalysts, especially
at the crystal facets level, is crucial for rational catalyst design
in the energy and environmental fields. Here we demonstrate an efficient
approach to in situ visualize and analyze the heterogeneity
of electrocatalytic activity on different facets at the subparticle
level via electrochemiluminescence (ECL) microscopy. ZnO crystals
with various exposed facet proportions were synthesized, and the correlation
between their electrocatalytic performance toward luminol analogue
degradation and the exposed facets is established. It is clearly imaged
that the ZnO (002) facet has superior catalytic performance compared
to the ZnO (100) facet, which is supported by theoretical computation
and electrochemical experiments as the facet-induced heterogeneity
of the catalytic effect on oxygen reduction into the key reactant
for ECL. Accordingly, the spatial heterogeneity of electrocatalytic
activity at different facets on one particle is visualized for the
first time. The realization of subparticle ECL imaging and kinetic
analysis could provide a special approach to visualize facet-induced
spatial heterogeneity of catalytic behavior and valuable information
for the catalysis study and analysis.
Developing
an electrochemiluminescence (ECL) coreactant to minimize
the biotoxicity and to maximize the enhancement factor is critical
to single-cell ECL microscopy. Here, we reported a guanine-rich single-stranded
DNA (G-ssDNA)-loaded high-index faceted gold nanoflower (Hi-AuNF)
as a synergistic coreactant of Ru(bpy)3
2+ for
single-cell ECL imaging. Because of the excellent catalytic performance
and huge specific surface area, Hi-AuNF serves as not only an ECL
enhancer but also a carrier for G-ssDNA. Guanine in G-ssDNA specifically
reacts with Ru(bpy)3
2+ through a so-called “catalytic
route” and thus significantly enhances the ECL signal of Ru(bpy)3
2+. To endow targeting ability to the synergistic
coreactant, an aptamer of carcinoembryonic antigen (CEA) is incorporated
into the G-ssDNA to form G-ssDNA-Apt for the recognition of human
breast adenocarcinoma cells, which overexpress CEA on the cytomembrane.
Accordingly, the ECL imaging of CEA on the cytomembrane was realized
by using the highly selective Hi-AuNF@G-ssDNA-Apt as the probe as
well as the luminophore of Ru(bpy)3
2+. Compared
with the common coreactant tripropylamine with high toxicity and volatility,
the Hi-AuNF@G-ssDNA-Apt is considered as a high-performance and biocompatible
coreactant, providing exciting opportunities in single-cell imaging
and detection.
Bioinspired smart superwetting surfaces with special wettability have aroused great attention from fundamental research to technological applications including self‐cleaning, oil–water separation, anti‐icing/corrosion/fogging, drag reduction, cell engineering, liquid manipulation, and so on. However, most of the reported smart superwetting surfaces switch their wettability by reversibly changing surface chemistry rather than surface microstructure. Compared with surface chemistry, the regulation of surface microstructure is more difficult and can bring novel functions to the surfaces. As a kind of stimulus‐responsive material, shape‐memory polymer (SMP) has become an excellent candidate for preparing smart superwetting surfaces owing to its unique shape transformation property. This review systematically summarizes the recent progress of smart superwetting SMP surfaces including fabrication methods, smart superwetting phenomena, and related application fields. The smart superwettabilities, such as superhydrophobicity/superomniphobicity with tunable adhesion, reversible switching between superhydrophobicity and superhydrophilicity, switchable isotropic/anisotropic wetting, slippery surface with tunable wettability, and underwater superaerophobicity/superoleophobicity with tunable adhesion, can be obtained on SMP micro/nanostructures by regulating the surface morphology. Finally, the challenges and future prospects of smart superwetting SMP surfaces are discussed.
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