Página 1 dos resultados de 15 itens digitais encontrados em 0.009 segundos

Developing nucleic acid-based electrical detection systems

Gabig-Ciminska, Magdalena
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Publicado em 02/03/2006 EN
Relevância na Pesquisa
25.88%
Development of nucleic acid-based detection systems is the main focus of many research groups and high technology companies. The enormous work done in this field is particularly due to the broad versatility and variety of these sensing devices. From optical to electrical systems, from label-dependent to label-free approaches, from single to multi-analyte and array formats, this wide range of possibilities makes the research field very diversified and competitive. New challenges and requirements for an ideal detector suitable for nucleic acid analysis include high sensitivity and high specificity protocol that can be completed in a relatively short time offering at the same time low detection limit. Moreover, systems that can be miniaturized and automated present a significant advantage over conventional technology, especially if detection is needed in the field. Electrical system technology for nucleic acid-based detection is an enabling mode for making miniaturized to micro- and nanometer scale bio-monitoring devices via the fusion of modern micro- and nanofabrication technology and molecular biotechnology. The electrical biosensors that rely on the conversion of the Watson-Crick base-pair recognition event into a useful electrical signal are advancing rapidly...

Label-free detection with the liquid core optical ring resonator sensing platform

White, Ian M.; Zhu, Hongying; Suter, Jonathan D.; Fan, Xudong; Zourob, Mohammed
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
Relevância na Pesquisa
46%
Optical label-free detection avoids the cost and complexity of fluorescence and radio labeling while providing accurate quantitative and kinetic results. We have developed a new optical label-free sensor called the liquid core optical ring resonator (LCORR). The LCORR integrates optical ring resonator sensors into the microfluidic delivery system by using glass capillaries with a thin wall. The LCORR is capable of performing refractive index detection on liquid samples, as well as bio/chemical analyte detection down to detection limits on the scale of pg/mm2.

A reflection-based localized surface plasmon resonance fiber-optic probe for biochemical sensing

Lin, Yongbin; Zou, Yang; Lindquist, Robert G.
Fonte: Optical Society of America Publicador: Optical Society of America
Tipo: Artigo de Revista Científica
Publicado em 01/02/2011 EN
Relevância na Pesquisa
35.91%
We report the fabrication and characterization of an optical fiber biochemical sensing probe based on localized surface plasmon resonance (LSPR) and spectra reflection. Ordered array of gold nanodots was fabricated on the optical fiber end facet using electron-beam lithography (EBL). We experimentally demonstrated for the first time the blue shift of the LSPR scattering spectrum with respected to the LSPR extinction spectrum, which had been predicted theoretically. High sensitivity [195.72 nm/refractive index unit (RIU)] of this sensor for detecting changes in the bulk refractive indices has been demonstrated. The label-free affinity bio-molecules sensing capability has also been demonstrated using biotin and streptavidin as the receptor and the analyte.

Study on a Luminol-based Electrochemiluminescent Sensor for Label-Free DNA Sensing

Chu, Hai-Hong; Yan, Ji-Lin; Tu, Yi-Feng
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 21/10/2010 EN
Relevância na Pesquisa
56.07%
Automatic, inexpensive, simple and sensitive methods for DNA sensing and quantification are highly desirable for biomedical research. The rapid development of both the fundamentals and applications of electrochemiluminescence (ECL) over the past years has demonstrated its potential for analytical and bio-analytical chemistry. This paper reports the quenching effect of DNA on the ECL of luminol and the further development of a DNA sensing device. With the pre-functionalization by a composite of carbon nano-tubes (CNTs) and Au nanoparticles (AuNPs), the sensor provides a novel and valuable label-free approach for DNA sensing. Here the ECL intensity was remarkably decreased when more than 1.0 × 10−12 molar of DNA were adsorbed on the sensor. Linearity of the DNA amount with the reciprocal of ECL intensity was observed. A saturated sensor caused a 92.8% quenching effect. The research also proposes the mechanism for the quenching effect which could be attributed to the interaction between luminol and DNA and the elimination of reactive oxygen species (ROSs) by DNA.

Real-Time Sensing of Cell Morphology by Infrared Waveguide Spectroscopy

Yashunsky, Victor; Marciano, Tal; Lirtsman, Vladislav; Golosovsky, Michael; Davidov, Dan; Aroeti, Benjamin
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 31/10/2012 EN
Relevância na Pesquisa
35.87%
We demonstrate that a live epithelial cell monolayer can act as a planar waveguide. Our infrared reflectivity measurements show that highly differentiated simple epithelial cells, which maintain tight intercellular connectivity, support efficient waveguiding of the infrared light in the spectral region of 1.4–2.5 µm and 3.5–4 µm. The wavelength and the magnitude of the waveguide mode resonances disclose quantitative dynamic information on cell height and cell-cell connectivity. To demonstrate this we show two experiments. In the first one we trace in real-time the kinetics of the disruption of cell-cell contacts induced by calcium depletion. In the second one we show that cell treatment with the PI3-kinase inhibitor LY294002 results in a progressive decrease in cell height without affecting intercellular connectivity. Our data suggest that infrared waveguide spectroscopy can be used as a novel bio-sensing approach for studying the morphology of epithelial cell sheets in real-time, label-free manner and with high spatial-temporal resolution.

Real-time and Label-free Bio-sensing of Molecular Interactions by Surface Plasmon Resonance: A Laboratory Medicine Perspective

Helmerhorst, Erik; Chandler, David J; Nussio, Matt; Mamotte, Cyril D
Fonte: The Australian Association of Clinical Biochemists Publicador: The Australian Association of Clinical Biochemists
Tipo: Artigo de Revista Científica
Publicado em /11/2012 EN
Relevância na Pesquisa
66%
Radioactive, chromogenic, fluorescent and other labels have long provided the basis of detection systems for biomolecular interactions including immunoassays and receptor binding studies. However there has been unprecedented growth in a number of powerful label free biosensor technologies over the last decade. While largely at the proof-of-concept stage in terms of clinical applications, the development of more accessible platforms may see surface plasmon resonance (SPR) emerge as one of the most powerful optical detection platforms for the real-time monitoring of biomolecular interactions in a label-free environment.

Non-toxic dry-coated nanosilver for plasmonic biosensors

Sotiriou, Georgios A.; Sannomiya, Takumi; Teleki, Alexandra; Krumeich, Frank; Vörös, Janos; Pratsinis, Sotiris E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 21/12/2010 EN
Relevância na Pesquisa
25.93%
The plasmonic properties of noble metals facilitate their use for in-vivo bio-applications such as targeted drug delivery and cancer cell therapy. Nanosilver is best suited for such applications as it has the lowest plasmonic losses among all such materials in the UV-visible spectrum. Its toxicity, however, can destroy surrounding healthy tissues and thus, hinders its safe use. Here, that toxicity against a model biological system (Escherichia coli) is “cured” or blocked by coating nanosilver hermetically with a about 2 nm thin SiO2 layer in one-step by a scalable flame aerosol method followed by swirl injection of a silica precursor vapor (hexamethyldisiloxane) without reducing the plasmonic performance of the enclosed or encapsulated silver nanoparticles (20 – 40 nm in diameter as determined by X-ray diffraction and microscopy). This creates the opportunity to safely use powerful nanosilver for intracellular bio-applications. The label-free biosensing and surface bio-functionalization of these ready-to-use, non-toxic (benign) Ag nanoparticles is presented by measuring the adsorption of bovine serum albumin (BSA) in a model sensing experiment. Furthermore, the silica coating around nanosilver prevents its agglomeration or flocculation (as determined by thermal annealing...

Kinase detection with gallium nitride based high electron mobility transistors

Makowski, Matthew S.; Bryan, Isaac; Sitar, Zlatko; Arellano, Consuelo; Xie, Jinqiao; Collazo, Ramon; Ivanisevic, Albena
Fonte: AIP Publishing LLC Publicador: AIP Publishing LLC
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
35.79%
A label-free kinase detection system was fabricated by the adsorption of gold nanoparticles functionalized with kinase inhibitor onto AlGaN/GaN high electron mobility transistors (HEMTs). The HEMTs were operated near threshold voltage due to the greatest sensitivity in this operational region. The Au NP/HEMT biosensor system electrically detected 1 pM SRC kinase in ionic solutions. These results are pertinent to drug development applications associated with kinase sensing.

A droplet-based novel approach for viable and low volume consumption surface plasmon resonance bio-sensing inside a polydimethylsiloxane microchip

Ghosh, T.; Xie, Y.; Mastrangelo, C.
Fonte: AIP Publishing LLC Publicador: AIP Publishing LLC
Tipo: Artigo de Revista Científica
Publicado em 21/08/2013 EN
Relevância na Pesquisa
46.05%
Over the course of last two decades, surface plasmon resonance (SPR) has emerged as a viable candidate for label-free detection and characterization for a large pool of biological interactions, ranging from hybridization of oligonucleotides to high throughput drug-screening. Conventional SPR bio-sensing involves a step-response method where the SPR sensorgram in response to a switched sequential flow of analyte and buffer is plotted in real-time and fitted to an exponential curve to extract the associative and dissociative reaction rates. Such measurement schemes involve continuous flow conditions where a substantial reagent volume is consumed and is subject to dispersive mixing at flow switching zones. In this paper, we demonstrate a new plug-train SPR technique in a microfluidic chip that separates and singulates solvent plugs in analyte and buffer by an immiscible air phase. Bio-samples are first discretized within plug droplets with volumes in order of few hundred nanoliters or less followed by pressure-driven transport onto SPR sensing sites of this hydrophobically modified SPR microdevise. The kinetic constants ka and kd for a model protein-small molecule interaction pair are extracted from a plug-train signal and are shown to be in reasonable agreement with our previous reports.

Nanotextured Superhydrophobic Electrodes enable Detection of attomolar-scale DNA concentration within a Droplet by non-Faradaic Impedance Spectroscopy

Ebrahimi, Aida; Dak, Piyush; Salm, Eric; Dash, Susmita; Garimella, Suresh V.; Bashir, Rashid; Alam, Muhammad A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 07/11/2013 EN
Relevância na Pesquisa
25.87%
Label-free, rapid detection of biomolecules in microliter volumes of highly diluted solutions (sub-femtomolar) is of essential importance for numerous applications in medical diagnostics, food safety, and chem-bio sensing for homeland security. At ultra-low concentrations, regardless of the sensitivity of the detection approach, the sensor response time is limited by physical diffusion of molecules towards the sensor surface. We have developed a fast, low cost, non-faradaic impedance sensing method for detection of synthetic DNA molecules in DI water at attomolar levels by beating the diffusion limit through evaporation of a micro-liter droplet of DNA on a nanotextured superhydrophobic electrode array. Continuous monitoring of the impedance of individual droplets as a function of evaporation time is exploited to dramatically improve the sensitivity and robustness of detection. Formation of the nanostructures on the electrode surface not only increases the surface hydrophobicity, but also allows robust pinning of the droplet contact area to the sensor surface. These two features are critical for performing highly stable impedance measurements as the droplet evaporates. Using this scheme, the detection limit of conventional non-faradaic methods is improved by five orders of magnitude. The proposed platform represents a step-forward towards realization of ultra-sensitive lab-on-chip biomolecule detectors for real time point-of-care application. Further works are however needed to ultimately realize the full potential of the proposed approach to appraise biological samples in complex buffer solutions rather than DI water.

Photonic Crystal Nanobeam Cavities for Biomedical Sensing

Quan, Qimin
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
EN_US
Relevância na Pesquisa
76.19%
Manipulation of light at the nanoscale has the promise to enable numerous technological advances in biomedical sensing, optical communications, nano-mechanics and quantum optics. As photons have vanishingly small interaction cross sections, their interactions have to be mitigated by matters (i.e. quantum emitters, molecules, electrons etc.). Waveguides and cavities are the fundamental building blocks of the optical circuits, which control or confine light to specific matters of interest. The first half of the thesis (Chapters 2 & 3) focuses on how to design various photonic nanostructures to manipulate light on nano- to micro- scale, especially to modify the light-matter interaction properties. Chapter 2 discusses how nano-slot waveguides and photonic crystal nanobeam waveguides are able to modify the emission of quantum emitters, in a different way that normal ridge waveguides are not able to. Chapter 3 focuses on a more complicated and powerful structure: the photonic crystal nanobeam cavity. The design, fabrication and characterization of the photonic crystal nanobeam cavities are described and demonstrated in detail, which lays out the foundation of the biomedical sensing applications in the second half of the thesis. The second half of the thesis (Chapters 4 & 5) focuses on the application of photonic crystal nanobeam cavities in the label-free sensing of biomedical substances. Chapter 4 demonstrates detection of solutions with different refractive index (aceton...

When nano meets bio : biological molecule detection based on silicon two-dimensional photonic crystals

Lee, Mindy Ren (1981 - ); Fauchet, Philippe Max
Fonte: University of Rochester. Publicador: University of Rochester.
Tipo: Tese de Doutorado Formato: Number of Pages:xv, 118 leaves
ENG
Relevância na Pesquisa
35.91%
Thesis (Ph. D.)--University of Rochester. Institute of Optics, 2008.; Over the past few years, techniques for early detection and identification of biological substances have been pursued with great interest in wide-ranging fields. One of the fast growing areas in biosensing research involves developing label-free optical biosensors. Theses biosensors do not use radioactive or fluorescent labels, hence not only reduce the complexity in sample preparation and possible contamination to biological materials in vivo but allow measurement in real-time. Recently photonic crystals (PhCs) have shown great promise as a novel sensing platform because of their strong light confinement. By introducing a localized defect (e.g. point-like defect, line-like defect) inside a PhC, an electromagnetic microcavity can be created which gives rise to defect states inside photonic bandgaps. The transmission spectrum of the microcavity shows resonance peaks. The capture of material inside the microcavity is monitored by observing resonance peak shifts. Such cavities can be designed to have ultra-high quality factor (Q > 106) and hence are extremely sensitive to the refractive index change due to biological molecule capture. Our device has a small sensing area (1 μm2~ 40 μm2) which requires only a very small amount of sample analyte (~ fg). Moreover...

Core-shell of FePt@SiO2-Au magnetic nanoparticles for rapid SERS detection

Hardiansyah, Andri; Chen, An-Yu; Liao, Hung-Liang; Yang, Ming-Chien; Liu, Ting-Yu; Chan, Tzu-Yi; Tsou, Hui-Ming; Kuo, Chih-Yu; Wang, Juen-Kai; Wang, Yuh-Lin
Fonte: Springer US Publicador: Springer US
Tipo: Artigo de Revista Científica
Publicado em 22/10/2015 EN
Relevância na Pesquisa
25.79%
In this study, multifunctional hybrid nanoparticles composed of iron platinum (FePt), silica (SiO2), and gold nanoparticles (AuNPs) had been developed for surface-enhanced Raman scattering (SERS) application. Core-shell structure of SiO2 and FePt nanoparticles (FePt@SiO2) was fabricated through sol-gel process and then immobilized gold nanoparticles onto the surface of FePt@SiO2, which displays huge Raman enhancement effect and magnetic separation capability. The resulting core-shell nanoparticles were subject to evaluation by transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX), zeta potential measurement, and X-ray photoelectron spectroscopy (XPS). TEM observation revealed that the particle size of resultant nanoparticles displayed spherical structure with the size ~30 nm and further proved the successful immobilization of Au onto the surface of FePt@SiO2. Zeta potential measurement exhibited the successful reaction between FePt@SiO2 and AuNPs. The rapid SERS detection and identification of small biomolecules (adenine) and microorganisms (gram-positive bacteria, Staphylococcus aureus) was conducted through Raman spectroscopy. In summary, the novel core-shell magnetic nanoparticles could be anticipated to apply in the rapid magnetic separation under the external magnetic field due to the core of the FePt superparamagnetic nanoparticles and label-free SERS bio-sensing of biomolecules and bacteria.

Vertical One-Dimensional Photonic Crystal Platforms for Label-Free (Bio)Sensing: Towards Drop-And- Measure Applications

Barillaro, Giuseppe
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 19/10/2015
Relevância na Pesquisa
66%
In this work, all-silicon, integrated optofluidic platforms, fabricated by electrochemical micromachining technology, making use of vertical, one-dimensional high-aspect- ratio photonic crystals for flow-through (bio)sensing applications are reviewed. The potential of such platforms for point-of-care applications is discussed for both pressure-driven and capillarity- driven operations with reference to refractometry and biochemical sensing.

Nanomechanical Resonators and Their Applications in Biological/Chemical Detection: Nanomechanics Principles

Eom, Kilho; Park, Harold S.; Yoon, Dae Sung; Kwon, Taeyun
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 09/05/2011
Relevância na Pesquisa
25.79%
Recent advances in nanotechnology have led to the development of nano-electro-mechanical systems (NEMS) such as nanomechanical resonators, which have recently received significant attention from the scientific community. This has not only been for their capability for the label-free detection of bio/chemical-molecules at single-molecule (or atomic) resolution for future applications such as the early diagnostics of diseases such as cancer, but also for their unprecedented ability to detect physical quantities such as molecular weight, elastic stiffness, surface stress, and surface elastic stiffness for adsorbed molecules on the surface. Most experimental works on resonator-based molecular detection have been based on the principle that molecular adsorption onto a resonator surface increases the effective mass, and consequently decreases the resonant frequencies of the nanomechanical resonator. However, this principle is insufficient to provide fundamental insights into resonator-based molecular detection at the nanoscale; this is due to recently proposed novel nanoscale detection principles including various effects such as surface effects, nonlinear oscillations, coupled resonance, and stiffness effects. Therefore, our objective in this review is to overview the current attempts to understand the underlying mechanisms in nanoresonator-based detection using physical models coupled to computational simulations and/or experiments. Specifically...