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Ultrasensitive Detection (ultrasensitive + detection)

Distribution by Scientific Domains
Chemistry66%

Selected Abstracts

Ultrasensitive Detection of microRNAs by Exponential Isothermal Amplification,

ANGEWANDTE CHEMIE, Issue 32 2010
Hongxia Jia
Klitzekleine miRNA-Mengen (bis hinab zu 0.1,zmol) lassen sich exakt und in Echtzeit quantitativ bestimmen. Die hierfür eingesetzte Methode beruht auf einer exponentiellen Vervielfältigungsreaktion (siehe Bild) mit einem dynamischen Bereich über 10 Größenordnungen. Die Reaktion dauert nur 30,min, benötigt weder Temperaturwechsel noch modifizierte DNA-Sonden und erkennt miRNA-Sequenzen, die sich in nur einer Base unterscheiden. [source]

Ultrasensitive Detection of Bacteria Using Core,Shell Nanoparticles and an NMR-Filter System,

ANGEWANDTE CHEMIE, Issue 31 2009
Hakho Lee Dr.
Tröpfcheninfektion: Ein hoch empfindliches und schnelles Analysesystem für Erreger wurde entwickelt. Dabei werden die Bakterien mit magnetischen Nanopartikeln (MNPs) inkubiert, in einer Mikrofluidikkammer konzentriert und durch ein miniaturisiertes NMR-Verfahren auf einem Chip detektiert. Die Methode war in der Lage, schon 20 Bakterien in 1,mL einer Auswurfprobe binnen 30,min nachzuweisen. [source]

Inlaid Multi-Walled Carbon Nanotube Nanoelectrode Arrays for Electroanalysis

ELECTROANALYSIS, Issue 1 2005
Jun Li
Abstract The rapid development in nanomaterials and nanotechnologies has provided many new opportunities for electroanalysis. We review our recent results on the fabrication and electroanalytical applications of nanoelectrode arrays based on vertically aligned multi-walled carbon nanotubes (MWCNTs). A bottom-up approach is demonstrated, which is compatible with Si microfabrication processes. MWCNTs are encapsulated in SiO2 matrix leaving only the very end exposed to form inlaid nanoelectrode arrays. The electrical and electrochemical properties have been characterized, showing well-defined quasireversible nanoelectrode behavior. Ultrasensitive detection of small redox molecules in bulk solutions as well as immobilized at the MWCNT ends is demonstrated. A label-free affinity-based DNA sensor has shown extremely high sensitivity approaching that of fluorescence techniques. This platform can be integrated with microelectronics and microfluidics for fully automated microchips. [source]

Hyperefficient PrPSc amplification of mouse-adapted BSE and scrapie strain by protein misfolding cyclic amplification technique

FEBS JOURNAL, Issue 10 2009
Aiko Fujihara
Abnormal forms of prion protein (PrPSc) accumulate via structural conversion of normal PrP (PrPC) in the progression of transmissible spongiform encephalopathy. Under cell-free conditions, the process can be efficiently replicated using in vitro PrPSc amplification methods, including protein misfolding cyclic amplification. These methods enable ultrasensitive detection of PrPSc; however, there remain difficulties in utilizing them in practice. For example, to date, several rounds of protein misfolding cyclic amplification have been necessary to reach maximal sensitivity, which not only take several weeks, but also result in an increased risk of contamination. In this study, we sought to further promote the rate of PrPSc amplification in the protein misfolding cyclic amplification technique using mouse transmissible spongiform encephalopathy models infected with either mouse-adapted bovine spongiform encephalopathy or mouse-adapted scrapie, Chandler strain. Here, we demonstrate that appropriate regulation of sonication dramatically accelerates PrPSc amplification in both strains. In fact, we reached maximum sensitivity, allowing the ultrasensitive detection of < 1 LD50 of PrPSc in the diluted brain homogenates, after only one or two reaction rounds, and in addition, we detected PrPSc in the plasma of mouse-adapted bovine spongiform encephalopathy-infected mice. We believe that these results will advance the establishment of a fast, ultrasensitive diagnostic test for transmissible spongiform encephalopathies. [source]

Quantum-Dot-Functionalized Poly(styrene- co -acrylic acid) Microbeads: Step-Wise Self-Assembly, Characterization, and Applications for Sub-femtomolar Electrochemical Detection of DNA Hybridization

ADVANCED FUNCTIONAL MATERIALS, Issue 7 2010
Haifeng Dong
Abstract A novel nanoparticle label capable of amplifying the electrochemical signal of DNA hybridization is fabricated by functionalizing poly(styrene- co -acrylic acid) microbeads with CdTe quantum dots. CdTe-tagged polybeads are prepared by a layer-by-layer self-assembly of the CdTe quantum dots (diameter,=,3.07,nm) and polyelectrolyte on the polybeads (diameter,=,323,nm). The self-assembly procedure is characterized using scanning and transmission electron microscopy, and X-ray photoelectron, infrared and photoluminescence spectroscopy. The mean quantum-dot coverage is (9.54,±,1.2),×,103 per polybead. The enormous coverage and the unique properties of the quantum dots make the polybeads an effective candidate as a functionalized amplification platform for labelling of DNA or protein. Herein, as an example, the CdTe-tagged polybeads are attached to DNA probes specific to breast cancer by streptavidin,biotin binding to construct a DNA biosensor. The detection of the DNA hybridization process is achieved by the square-wave voltammetry of Cd2+ after the dissolution of the CdTe tags with HNO3. The efficient carrier-bead amplification platform, coupled with the highly sensitive stripping voltammetric measurement, gives rise to a detection limit of 0.52 fmol L,1 and a dynamic range spanning 5 orders of magnitude. This proposed nanoparticle label is promising, exhibits an efficient amplification performance, and opens new opportunities for ultrasensitive detection of other biorecognition events. [source]

Triplex Au,Ag,C Core,Shell Nanoparticles as a Novel Raman Label

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2010
Aiguo Shen
Abstract Monodispersed, readily-grafted, and biocompatible surface-enhanced Raman spectroscopic (SERS) tagging materials are developed; they are composed of bimetallic Au@Ag nanoparticles (NPs) for optical enhancement, a reporter molecule for spectroscopic signature, and a carbon shell for protection and bioconjugation. A controllable and convenient hydrothermal synthetic route is presented to synthesize the layer-by-layer triplex Au,Ag,C core,shell NPs, which can incorporate the Raman-active label 4-mercapto benzoic acid (4-MBA). The obtained gold seed,silver coated particles can be coated further with a thickness-controlled carbon shell to form colloidal carbon-encapsulated Aucore/Agshell spheres with a monodisperse size distribution. Furthermore, these SERS-active spheres demonstrated interesting properties as a novel Raman tag for quantitative immunoassays. The results suggest such SERS tags can be used for multiplex and ultrasensitive detection of biomolecules as well as nontoxic, in vivo molecular imaging of animal or plant tissues. [source]