We report an ultrasensitive wireless electrochemiluminescence (ECL) protocol for the detection of a nucleic acid target in tumor cells on an indium tin oxide bipolar electrode (BPE) in a poly(dimethylsiloxane) microchannel. The approach is based on the modification of the anodic pole of the BPE with antisense DNA as the recognition element, Ru(bpy)(3)(2+)-conjugated silica nanoparticles (RuSi@Ru(bpy)(3)(2+)) as the signal amplification tag, and reporter DNA as a reference standard. It employs the hybridization-induced changes of RuSi@Ru(bpy)(3)(2+) ECL efficiency for the specific detection of reporter DNA released from tumor cells. Prior to ECL detection, tumor cells are transfected with CdSe@ZnS quantum dot (QD)-antisense DNA/reporter DNA conjugates. Upon the selective binding of antisense DNA probes to intracellular target mRNA, reporter DNA will be released from the QDs, which indicates the amount of the target mRNA. The proof of concept is demonstrated using a proto-oncogene c-Myc mRNA in MCF-7 cells (breast cancer cell line) as a model target. The wireless ECL biosensor exhibited excellent ECL signals which showed a good linear range over 2 × 10(-16) to 1 × 10(-11) M toward the reporter DNA detection and could accurately quantify c-Myc mRNA copy numbers in living cells. C-Myc mRNA in each MCF-7 cell and LO2 cell was estimated to be 2203 and 13 copies, respectively. This wireless ECL strategy provides great promise in a miniaturized device and may facilitate the achievement of point of care testing.
DNA/RNA strand displacement is one of the most fundamental reactions in DNA and RNA circuits and nanomachines. In this work, we reported an exploration of the dynamic process of the toehold-mediated strand displacement via core-satellite plasmon rulers at the single-molecule level. Applying plasmon rulers with unlimited lifetime, single-strand displacement triggered by the invader that resulted in stepwise leaving of satellite from the core was continuously monitored by changes of scattering signal for hours. The kinetics of strand displacement in vitro with three different toehold lengths have been investigated. Also, the study revealed the difference in the kinetics of strand displacement between DNA/RNA and DNA/DNA duplexes. For the kinetics study in vivo, influence from the surrounding medium has been evaluated using both phosphate buffer and cell lysate. Applying core-satellite plasmon rulers with high signal/noise ratio, kinetics study in living cells proceeded for the first time, which was not possible by conventional methods with a fluorescent reporter. The plasmon rulers, which are flexible, easily constructed, and robust, have proven to be effective tools in exploring the dynamical behaviors of biochemical reactions in vivo.
Various processed types of FUZI (the daughter roots of the highly toxic plant Aconitum carmichaeli Debx, FZ) decoction pieces (the herbal materials processed according to the specifications of Chinese medicine manuals; " YINPIAN" in Chinese transliteration) are widely used in traditional medicine to treat various diseases, but their toxicities are not known. Nine types of FZ decoction pieces, including one raw slice and eight processed forms, were therefore prepared, each in 7 to 10 batches, to assess for their toxicity. Altogether 84 FZ samples were quantified on the amount of highly toxic diester diterpenoid alkaloids, i.e., aconitine, mesaconitine and hypaconitine by a newly developed HPLC method with HPLC-DAD and LC-MS techniques. The comparison of the processed FZ to raw slices of the root showed that the amount of each analyte in the processed FZ was drastically decreased. The sum of the three toxic compounds in the 8 types of processed FZ was only 3.91-34.80 % of this value in the FZ raw slice. This implies that the toxicity of processed FZ was decreased significantly. The amounts of toxic components in the 8 types of processed FZ varied significantly, often by a power of ten, indicating that the dosage of these herbs, when prescribed for clinical uses, should be cautiously set in order to avoid poisoning incidents.
Gold nanoparticle dimers assembled on the surface of CdS QD thin films served as nano-antennas to mediate the distance-dependent plasmon enhanced electrochemiluminescence of QDs.
Asymmetric supercapacitors (ASCs) are emerging as a new class of energy storage devices that could potentially meet the increasing power and energy demand for next‐generation portable and flexible electronics. Yet, the energy density of ASC is severely limited by the low capacitance of the anode side, which commonly uses the carbon‐based nanomaterials. Here, the demonstration of sulfur‐doped MoO3−x nanobelts (denoted as S‐MoO3−x) as the anode for high‐performance fiber‐shaped ASC are reported. The Mo sites in MoO3 are intentionally modulated at the atomic level through sulfur doping, where sulfur could be introduced into the MoO6 octahedron to intrinsically tune the covalency character of bonds around Mo sites and thus boost the charge storage kinetics of S‐MoO3−x. Moreover, the oxygen defects are occurring along with sulfur‐doping in MoO3, enabling efficient electron transport. As expected, the fiber‐shaped S‐MoO3−x achieves outstanding capacitance with good rate capability and long cycling life. More impressively, the fiber‐shaped ASC based on S‐MoO3−x anode delivers extremely high volumetric capacitance of 6.19 F cm−3 at 0.5 mA cm−1, which makes it promising as one of the most attractive candidates of anode materials for high‐performance fiber‐shaped ASCs.
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