Herein,
a single biomolecule is imaged by electrochemiluminescence
(ECL) using Ru(bpy)3
2+-doped silica/Au nanoparticles
(RuDSNs/AuNPs) as the ECL nanoemitters. The ECL emission is confined
to the local surface of RuDSNs leading to a significant enhancement
in the intensity. To prove the concept, a single protein molecule
at the electrode is initially visualized using the as-prepared RuDSN/AuNPs
nanoemitters. Furthermore, the nanoemitter-labeled antibody is linked
at the cellular membrane to image a single membrane protein at one
cell, without the interference of current and optical background.
The success in single-biomolecule ECL imaging solves the long-lasting
task in the ultrasensitive ECL analysis, which should be able to provide
more elegant information about the protein in cellular biology.
The in vitro detection of low abundance biomolecules via nonenzymatic signal amplification is an attractive strategy. However, it remains a challenge to monitor targets of interest in situ in living cells by low-background interference and visualized enzyme-free signal amplification strategies. Taking advantage of the single-molecule imaging and dynamic DNA nanotechnologies, we have achieved the target-triggered self-assembly of nanostructure-based dual-color fluorescent probes (NDFPs) by an enzyme-free toehold-mediated strand displacement cascade. NDFPs will facilitate the simple and visualized monitoring of microRNA (miRNA) at the femtomolar level. The recycled miRNA can be considered as the catalyst for the assembly of multiple H1/H2 duplexes. This generated the fluorescence signal of the enhanced target expression, indicating both in vitro and in vivo signal-amplified imaging. Moreover, the NDFPs improved the measurement accuracy by dual-color colocalization imaging to greatly avoid false-positive signals and enabled the successful in situ imaging of miRNA in living cells in real time. This work provides a strategy to visually monitor and study the integration of signal amplification detection and single-molecule imaging. NDFPs may be an important step toward the enzyme-free amplified monitoring and imaging of various biomolecules in living cells at the single-molecule level.
Artificial aquaporins are synthetic
molecules that mimic the structure
and function of natural aquaporins (AQPs) in cell membranes. The development
of artificial aquaporins would provide an alternative strategy for
treatment of AQP-related diseases. In this report, an artificial aquaporin
has been constructed from an amino-terminated tubular molecule, which
operates in a unimolecular mechanism. The artificial channel can work
in cell membranes with high water permeability and selectivity rivaling
those of AQPs. Importantly, the channel can restore wound healing
of the cells that contain function-lost AQPs.
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