Science.gov

Sample records for achieve signal amplification

  1. A Simple Structure for Signal Amplification

    NASA Astrophysics Data System (ADS)

    Ding, Wan-Xiang; Gu, Chang-Gui; Liang, Xiao-Ming

    2016-02-01

    It has been found that a triple-node feed-forward motif has a function of signal amplification, where two input nodes receive the external weak signal and jointly modulate the response of the third output node [Liang et al., Phys. Rev. E 88 (2013) 012910]. We here show that the signal amplification can be further enhanced by adding a link between the two input nodes in the feed-forward motif. We further reveal that the coupling strength of the link regulates the enhancement of signal amplification in the modified feed-forward motif. We finally analyze the mechanism of signal amplification of such simple structure. Supported by the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning under Grant No. QD2015016, the National Natural Science Foundation of China under Grant Nos. 11505114 and 11305078

  2. Signal Amplification of Bioassay Using Zinc Nanomaterials

    NASA Astrophysics Data System (ADS)

    Cowles, Chad L.

    An emerging trend in the analytical detection sciences is the employment of nanomaterials for bioassay signal transduction to identify analytes critical to public health. These nanomaterials have been specifically investigated for applications which require identification of trace levels of cells, proteins, or other molecules that can have broad ranging impacts to human health in fields such as clinical diagnostics, environmental monitoring, food and drink control, and the prevention of bioterrorism. Oftentimes these nanoparticle-based signal transduction or amplification approaches offer distinct advantages over conventional methods such as increased sensitivity, rapidity, or stability. The biological application of nanoparticles however, does suffer from drawbacks that have limited more widespread adoption of these techniques. Some of these drawbacks are, high cost and toxicity, arduous synthesis methods, functionalization and bioconjugation challenges, and laboratory disposal and environmental hazard issues, all of which have impeded the progression of this technology in some way or another. This work aims at developing novel techniques that offer solutions to a number of these hurdles through the development of new nanoparticle-based signal transduction approaches and the description of a previously undescribed nanomaterial. Zinc-based nanomaterials offer the opportunity to overcome some of the limitations that are encountered when other nanomaterials are employed for bioassay signal transduction. On the other hand, the biological application of zinc nanomaterials has been difficult because in general their fluorescence is in the blue range and the reported quantum yields are usually too low for highly sensitive applications. The advantages of using zinc nanomaterials for biological applications, such as reduced toxicity, simple synthesis, low cost, and straightforward functionalization strategies contribute to the research interest in their application as

  3. Enzymatic signal amplification of molecular beacons for sensitive DNA detection

    PubMed Central

    Li, Jianwei Jeffery; Chu, Yizhuo; Lee, Benjamin Yi-Hung; Xie, Xiaoliang Sunney

    2008-01-01

    Molecular beacons represent a new family of fluorescent probes for nucleic acids, and have found broad applications in recent years due to their unique advantages over traditional probes. Detection of nucleic acids using molecular beacons has been based on hybridization between target molecules and molecular beacons in a 1:1 stoichiometric ratio. The stoichiometric hybridization, however, puts an intrinsic limitation on detection sensitivity, because one target molecule converts only one beacon molecule to its fluorescent form. To increase the detection sensitivity, a conventional strategy has been target amplification through polymerase chain reaction. Instead of target amplification, here we introduce a scheme of signal amplification, nicking enzyme signal amplification, to increase the detection sensitivity of molecular beacons. The mechanism of the signal amplification lies in target-dependent cleavage of molecular beacons by a DNA nicking enzyme, through which one target DNA can open many beacon molecules, giving rise to amplification of fluorescent signal. Our results indicate that one target DNA leads to cleavage of hundreds of beacon molecules, increasing detection sensitivity by nearly three orders of magnitude. We designed two versions of signal amplification. The basic version, though simple, requires that nicking enzyme recognition sequence be present in the target DNA. The extended version allows detection of target of any sequence by incorporating rolling circle amplification. Moreover, the extended version provides one additional level of signal amplification, bringing the detection limit down to tens of femtomolar, nearly five orders of magnitude lower than that of conventional hybridization assay. PMID:18304948

  4. Brillouin amplification and processing of the Rayleigh scattered signal.

    PubMed

    Mermelstein, David; Shacham, Eliashiv; Biton, Moran; Sternklar, Shmuel

    2015-07-15

    Brillouin amplification of Rayleigh scattering is demonstrated using two different configurations. In the first technique, the Rayleigh scattering and amplification occurs simultaneously in the same fiber. In the second technique, the amplification takes place in a second fiber. The differences between the two techniques are delineated. Using the second technique, we demonstrate single-sideband off-resonant Brillouin amplification of the Rayleigh signal. This technique is shown to enhance the SNR of a signal that is due to vibration-induced strain on the fiber. PMID:26176464

  5. Method Of Signal Amplification In Multi-Chromophore Luminescence Sensors

    DOEpatents

    Levitsky, Igor A.; Krivoshlykov, Sergei G.

    2004-02-03

    A fluorescence-based method for highly sensitive and selective detection of analyte molecules is proposed. The method employs the energy transfer between two or more fluorescent chromophores in a carefully selected polymer matrix. In one preferred embodiment, signal amplification has been achieved in the fluorescent sensing of dimethyl methylphosphonate (DMMP) using two dyes, 3-aminofluoranthene (AM) and Nile Red (NR), in a hydrogen bond acidic polymer matrix. The selected polymer matrix quenches the fluorescence of both dyes and shifts dye emission and absorption spectra relative to more inert matrices. Upon DMMP sorption, the AM fluorescence shifts to the red at the same time the NR absorption shifts to the blue, resulting in better band overlap and increased energy transfer between chromophores. In another preferred embodiment, the sensitive material is incorporated into an optical fiber system enabling efficient excitation of the dye and collecting the fluorescent signal form the sensitive material on the remote end of the system. The proposed method can be applied to multichromophore luminescence sensor systems incorporating N-chromophores leading to N-fold signal amplification and improved selectivity. The method can be used in all applications where highly sensitive detection of basic gases, such as dimethyl methylphosphonate (DMMP), Sarin, Soman and other chemical warfare agents having basic properties, is required, including environmental monitoring, chemical industry and medicine.

  6. Reversible Gating of Plasmonic Coupling for Optical Signal Amplification.

    PubMed

    Khoury, Christopher G; Fales, Andrew M; Vo-Dinh, Tuan

    2016-07-20

    Amplification of optical signals is useful for a wide variety of applications, ranging from data signal transmission to chemical sensing and biomedical diagnostics. One such application in chemical sensing is surface-enhanced Raman scattering (SERS), an important technique for increasing the Raman signal using the plasmonic effect of enhanced electromagnetic fields associated with metallic nanostructures. One of the most important limitations of SERS-based amplification is the difficulty to reproducibly control the SERS signal. Here, we describe the design and implementation of a unique hybrid system capable of producing reversible gating of plasmonic coupling for Raman signal amplification. The hybrid system is composed of two subsystems: (1) colloidal magneto-plasmonic nanoparticles for SERS enhancement and (2) a micromagnet substrate with an externally applied magnetic field to modulate the colloidal nanoparticles. For this proof of concept demonstration, the nanoparticles were labeled with a Raman-active dye, and it was shown that the detected SERS signal could be reproducibly modulated by controlling the externally applied magnetic field. The developed system provides a simple, robust, inexpensive, and reusable device for SERS signal modulation. These properties will open up new possibilities for optical signal amplification and gating as well for high-throughput, reproducible SERS detection. PMID:27347606

  7. Signal bi-amplification in networks of unidirectionally coupled MEMS

    NASA Astrophysics Data System (ADS)

    Tchakui, Murielle Vanessa; Woafo, Paul; Colet, Pere

    2016-01-01

    The purpose of this paper is to analyze the propagation and the amplification of an input signal in networks of unidirectionally coupled micro-electro-mechanical systems (MEMS). Two types of external excitations are considered: sinusoidal and stochastic signals. We show that sinusoidal signals are amplified up to a saturation level which depends on the transmission rate and despite MEMS being nonlinear the sinusoidal shape is well preserved if the number of MEMS is not too large. However, increasing the number of MEMS, there is an instability that leads to chaotic behavior and which is triggered by the amplification of the harmonics generated by the nonlinearities. We also show that for stochastic input signals, the MEMS array acts as a band-pass filter and after just a few elements the signal has a narrow power spectra.

  8. Cascade signal amplification strategy for subattomolar protein detection by rolling circle amplification and quantum dots tagging.

    PubMed

    Cheng, Wei; Yan, Feng; Ding, Lin; Ju, Huangxian; Yin, Yibing

    2010-04-15

    A cascade signal amplification strategy was proposed for detection of protein target at ultralow concentration by combining the rolling circle amplification (RCA) technique with oligonucleotide functionalized quantum dots (QDs), multiplex binding of the biotin-strepavidin system, and anodic stripping voltammetric detection. The RCA product containing tandem-repeat sequences could serve as excellent template for periodic assembly of QDs, which presented per protein recognition event to numerous quantum dot tags for electrochemical readout. Both the RCA and the multiplex binding system showed remarkable amplification efficiency, very little nonspecific adsorption, and low background signal. Using human vascular endothelial growth factor as a model protein, the designed strategy could quantitatively detect protein down to 16 molecules in a 100 microL sample with a linear calibration range from 1 aM to 1 pM and was amenable to quantification of protein target in complex biological matrixes. The proposed cascade signal amplification strategy would become a powerful tool for proteomics research and clinical diagnostics. PMID:20345087

  9. Preferential amplification of rising versus falling frequency whistler mode signals

    NASA Astrophysics Data System (ADS)

    Li, J. D.; Harid, V.; Spasojevic, M.; Gołkowski, M.; Inan, U. S.

    2015-01-01

    Analysis of ground-based ELF/VLF observations of injected whistler mode waves from the 1986 Siple Station experiment demonstrates the preferential magnetospheric amplification of rising over descending frequency-time ramps. From examining conjugate region receptions of ±1 kHz/s frequency-time ramps, we find that rising ramps generate an average total power 1.9 times higher than that of falling frequency ramps when both are observed during a transmission. And in 17% of receptions, only rising ramps are observed above the noise floor. Furthermore, the amplification ratio inversely correlates with the noise and total signal power. Using a narrowband Vlasov-Maxwell numerical simulation, we explore the preferential amplification due to differences in linear growth rate as a function of frequency, relative to the frequency which maximizes the linear growth rate for a given anisotropy, and in nonlinear phase trapping. These results contribute to the understanding of magnetospheric wave amplification and the preference for structured rising elements in chorus.

  10. Coherent signal amplification in bistable nanomechanical oscillators by stochastic resonance

    NASA Astrophysics Data System (ADS)

    Badzey, Robert L.; Mohanty, Pritiraj

    2005-10-01

    Stochastic resonance is a counterintuitive concept: the addition of noise to a noisy system induces coherent amplification of its response. First suggested as a mechanism for the cyclic recurrence of ice ages, stochastic resonance has been seen in a wide variety of macroscopic physical systems: bistable ring lasers, superconducting quantum interference devices (SQUIDs), magnetoelastic ribbons and neurophysiological systems such as the receptors in crickets and crayfish. Although fundamentally important as a mechanism of coherent signal amplification, stochastic resonance has yet to be observed in nanoscale systems. Here we report the observation of stochastic resonance in bistable nanomechanical silicon oscillators. Our nanomechanical systems consist of beams that are clamped at each end and driven into transverse oscillation with the use of a radiofrequency source. Modulation of the source induces controllable switching of the beams between two stable, distinct states. We observe that the addition of white noise causes a marked amplification of the signal strength. Stochastic resonance in nanomechanical systems could have a function in the realization of controllable high-speed nanomechanical memory cells, and paves the way for exploring macroscopic quantum coherence and tunnelling.

  11. Extended amplification of acoustic signals by amphibian burrows.

    PubMed

    Muñoz, Matías I; Penna, Mario

    2016-07-01

    Animals relying on acoustic signals for communication must cope with the constraints imposed by the environment for sound propagation. A resource to improve signal broadcast is the use of structures that favor the emission or the reception of sounds. We conducted playback experiments to assess the effect of the burrows occupied by the frogs Eupsophus emiliopugini and E. calcaratus on the amplitude of outgoing vocalizations. In addition, we evaluated the influence of these cavities on the reception of externally generated sounds potentially interfering with conspecific communication, namely, the vocalizations emitted by four syntopic species of anurans (E. emiliopugini, E. calcaratus, Batrachyla antartandica, and Pleurodema thaul) and the nocturnal owls Strix rufipes and Glaucidium nanum. Eupsophus advertisement calls emitted from within the burrows experienced average amplitude gains of 3-6 dB at 100 cm from the burrow openings. Likewise, the incoming vocalizations of amphibians and birds were amplified on average above 6 dB inside the cavities. The amplification of internally broadcast Eupsophus vocalizations favors signal detection by nearby conspecifics. Reciprocally, the amplification of incoming conspecific and heterospecific signals facilitates the detection of neighboring males and the monitoring of the levels of potentially interfering biotic noise by resident frogs, respectively. PMID:27209276

  12. Ultrasensitive Detection of Low-Abundance Protein Biomarkers by Mass Spectrometry Signal Amplification Assay.

    PubMed

    Du, Ruijun; Zhu, Lina; Gan, Jinrui; Wang, Yuning; Qiao, Liang; Liu, Baohong

    2016-07-01

    A mass spectrometry signal amplification method is developed for the ultrasensitive and selective detection of low-abundance protein biomarkers by utilizing tag molecules on gold nanoparticles (AuNPs). EpCAM and thrombin as model targets are captured by specific aptamers immobilized on the AuNPs. With laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS), the mass tag molecules are detected to represent the protein biomarkers. Benefiting from the MS signal amplification, the assay can achieve a limit of detection of 100 aM. The method is further applied to detect thrombin in fetal bovine serum and EpCAM in cell lysates to demonstrate its selectivity and feasibility in complex biological samples. With the high sensitivity and specificity, the protocol shows great promise for providing a new route to single-cell analysis and early disease diagnosis. PMID:27253396

  13. Amplification of Stokes signals with phase conjugation by combined laser and SBS amplifiers

    SciTech Connect

    Bel'dyugin, Igor' M; Efimkov, V F; Zubarev, I G; Mikhailov, S I; Sobolev, V B

    2007-01-31

    Various schemes for amplification of Stokes signals are investigated. Some new systems, such as an SBS amplifier in the transient amplification regime and a combined laser amplifier-SBS amplifier, are proposed and realised. Conditions are found under which amplification is accompanied by small distortions of the spatial structure of a signal. A two-pass system for small-signal amplification with phase conjugation is developed by using a PC mirror in the combined amplification system. The gains up to 10{sup 16} were obtained for the phase conjugation quality {approx}80%, the output energy {approx}1 J, and pulse duration {approx}30 ns. (nonlinear optical phenomena)

  14. Dual signal amplification of surface plasmon resonance imaging for sensitive immunoassay of tumor marker.

    PubMed

    Hu, Weihua; Chen, Hongming; Shi, Zhuanzhuan; Yu, Ling

    2014-05-15

    Surface plasmon resonance imaging (SPRi) is an intriguing technique for immunoassay with the inherent advantages of being high throughput, real time, and label free, but its sensitivity needs essential improvement for practical applications. Here, we report a dual signal amplification strategy using functional gold nanoparticles (AuNPs) followed by on-chip atom transfer radical polymerization (ATRP) for sensitive SPRi immunoassay of tumor biomarker in human serum. The AuNPs are grafted with an initiator of ATRP as well as a recognition antibody, where the antibody directs the specific binding of functional AuNPs onto the SPRi sensing surface to form immunocomplexes for first signal amplification and the initiator allows for on-chip ATRP of 2-hydroxyethyl methacrylate (HEMA) from the AuNPs to further enhance the SPRi signal. High sensitivity and broad dynamic range are achieved with this dual signal amplification strategy for detection of a model tumor marker, α-fetoprotein (AFP), in 10% human serum. PMID:24607795

  15. Polydimethylsiloxane microfluidic chemiluminescence immunodevice with the signal amplification strategy for sensitive detection of human immunoglobin G.

    PubMed

    Li, Huifang; Zhao, Mei; Liu, Wei; Chu, Weiru; Guo, Yumei

    2016-01-15

    A polydimethylsiloxane (PDMS) microfluidic chemiluminescence (CL) immunodevice for sensitive detection of human immunoglobin G (IgG) with the signal amplification strategy was developed in this work. The immunodevice was prepared by covalently immobilizing capture antibodies (Abs) on the silanized microchannel of microfluidic chip. Gold nanoparticles (AuNPs) functionalized with a high molar ratio of horseradish peroxidase (HRP) were used as an Ab label for signal amplification. Using a sandwich immunoassay, the multi-HRP conjugated AuNPs can catalyze the luminol-H2O2 CL system to achieve the high sensitivity. In addition, the double spiral flow-channel was adopted here, which can still contribute to the high sensitivity. Based on signal amplification strategy, the performance of human IgG tests revealed a lower detection limit (DL) of 0.03ng/mL and showed an increase of 7.4-fold in detection sensitivity compared to a commercial Ab-HRP conjugation. This microfluidic immunodevice can provide an alternative approach for sensitive detection of human IgG in the field of clinic diagnostic and therapeutic. PMID:26592629

  16. Insertion approach: bolstering the reproducibility of electrochemical signal amplification via DNA superstructures.

    PubMed

    Yang, Li; Zhang, Caihua; Jiang, Hong; Li, Guijuan; Wang, Jiahai; Wang, Erkang

    2014-05-20

    For more than a decade, the backfilling approach for the immobilization of DNA probes has been routinely adopted for the construction of functional interfaces; however, reliably reproducing electrochemical signal amplification by this method is a challenge. In this research, we demonstrate that the insertion approach significantly bolsters the reproducibility of electrochemical signal amplification via DNA superstructures. The combination of the backfilling approach and the DNA superstructure formation poses a big challenge to reliably reproducing electrochemical signal amplification. In order to use the detection of Hg(2+) as a prototype of this new strategy, a thymine-rich DNA probe that is specific to mercury ion was applied in this study. The presence of Hg(2+) induces the folding of the DNA probes and inhibits the formation of DNA superstructures. By using electroactive probes ([Ru(NH3)6](3+)) that are electrostatically adsorbed onto the double strands, differential pulse voltammetry (DPV) could quantitatively confirm the presence of Hg(2+). A limit of detection (LOD) and a limit of quantification (LOQ) (LOQ) as low as 0.3 and 9.5 pM, respectively, were achieved. Furthermore, excellent selectivity and real sample analysis demonstrated the promising potential of this approach in future applications. PMID:24761933

  17. Optomechanical correlations and signal self-amplification in interferometric measurements

    NASA Astrophysics Data System (ADS)

    Cohadon, P.-F.; Verlot, P.; Tavernarakis, A.; Briant, T.; Heidmann, A.

    2010-05-01

    Radiation pressure exerted by light in interferometric measurements is responsible for displacements of mirrors which appear as an additional back-action noise and limit the sensitivity of the measurement. We experimentally study these effects by monitoring in a very high-finesse optical cavity the displacements of a mirror with a sensitivity at the 10-20 m/ level. This very high sensitivity is a step towards the observation of fundamental quantum effects of radiation pressure such as the standard quantum limit in interferometric measurements. We report the observation of optomechanical correlations between two optical beams sent into the same moving mirror cavity. We also observed a self-amplification of a signal, which is a consequence of dynamical back-action of radiation pressure in a detuned cavity, and may improve the interferometric measurement sensitivity beyond the standard quantum limit.

  18. Trichotomous noise controlled signal amplification in a generalized Verhulst model

    NASA Astrophysics Data System (ADS)

    Mankin, Romi; Soika, Erkki; Lumi, Neeme

    2014-10-01

    The long-time limit of the probability distribution and statistical moments for a population size are studied by means of a stochastic growth model with generalized Verhulst self-regulation. The effect of variable environment on the carrying capacity of a population is modeled by a multiplicative three-level Markovian noise and by a time periodic deterministic component. Exact expressions for the moments of the population size have been calculated. It is shown that an interplay of a small periodic forcing and colored noise can cause large oscillations of the mean population size. The conditions for the appearance of such a phenomenon are found and illustrated by graphs. Implications of the results on models of symbiotic metapopulations are also discussed. Particularly, it is demonstrated that the effect of noise-generated amplification of an input signal gets more pronounced as the intensity of symbiotic interaction increases.

  19. Liposomes with High Refractive Index Encapsulants as Tunable Signal Amplification Tools in Surface Plasmon Resonance Spectroscopy.

    PubMed

    Fenzl, Christoph; Hirsch, Thomas; Baeumner, Antje J

    2015-11-01

    One major goal in the surface plasmon resonance (SPR) technique is the reliable detection of small molecules as well as low analyte concentrations. This can be achieved by a viable signal amplification strategy. We therefore investigated optimal liposome characteristics for use as a signal enhancement system for SPR sensors, as liposomes excel not only at versatility but also at colloidal stability and ease of functionalization. These characteristics include the encapsulation of high refractive index markers, lipid composition, liposome size, and surface modifications to best match the requirements of the SPR system. Our studies of the binding of biotinylated liposomes to surface-immobilized streptavidin show that the refractive index of the encapsulant has a major influence on the SPR signal and outweighs the influence of the thin lipid bilayer. Thus, the signal amplification properties of liposomes can be adjusted to the respective needs of any analytical task by simply exchanging the encapsulant solution. In this work, a maximum enhancement factor of 23 was achieved by encapsulating a 500 mM sucrose solution. Dose-response studies with and without liposome enhancement revealed an improvement of the limit of detection from 10 nmol L(-1) to 320 pmol L(-1) streptavidin concentration with a much higher sensitivity of 3 mRIU per logarithmic unit of the concentration between 500 pmol L(-1) and 10 nmol L(-1). PMID:26455696

  20. Dual-signal amplification strategy for ultrasensitive photoelectrochemical immunosensing of α-fetoprotein.

    PubMed

    Li, Yong-Jie; Ma, Meng-Jie; Zhu, Jun-Jie

    2012-12-01

    An ultrasensitive photoelectrochemical immunoassay of cancer biomarker α-fetoprotein (AFP) is proposed that uses titanium dioxide (TiO(2)) coupled with AFP-CdTe-GOx bioconjugate, which featured AFP antigen and glucose oxidase (GOx) labels linked to CdTe quantum dots (QDs) for signal amplification. The synthesized CdTe QDs yielded a homogeneous and narrow size distribution, which allowed the binding of AFP and GOx on CdTe QDs. Greatly enhanced sensitivity for AFP came from a dual signal amplification strategy. First, an effective matching of energy levels between the conduction bands of CdTe QDs and TiO(2) allowed for fast electron injection from excited CdTe QDs to TiO(2) upon irradiation, which reduced the recombination process of electron-hole pairs and prompted photoelectrochemical performance. Second, GOx enzyme could catalyze glucose to produce H(2)O(2), which acted as a sacrificial electron donor to scavenge the photogenerated holes in the valence band of CdTe QDs, further causing an enhanced photocurrent. Thus, on the basis of the dual signal amplification strategy, the competitive immunosensor based on the specific binding of anti-AFP antibodies to AFP and AFP-CdTe-GOx bioconjugates was achieved. This proposed biosensor for AFP possessed largely increased linear detection range from 0.5 pg/mL to 10 μg/mL with a detection limit of 0.13 pg/mL. The proposed amplification strategy shows high sensitivity, stability, and reproducibility and can become a promising platform for other protein detection. PMID:23140135

  1. Amplification and Damping of Environmental Signals in Intensively Managed Landscapes

    NASA Astrophysics Data System (ADS)

    Belmont, P.; Kumarasamy, K.; Kelly, S. A.; Vaughan, A. A.; Call, B.

    2015-12-01

    Landscapes transmit pulses of water, sediment and solutes through the terrestrial environment and network of stream channels. The timing, frequency and magnitude of these pulses depend on inputs of water, energy and rock/soil as well as a multitude of critical zone processes that may modulate the signal. Therefore, the potential for a landscape to generate and transmit these pulses changes over long timescales, primarily as a function of climate and local base level rise or fall. Humans have profoundly altered many critical zone processes that govern these environmental signals, often targeting rate-limiting processes for the purpose of enhancing economic productivity and/or reducing financial risk. These alterations are especially evident in the intensively managed landscapes of the Midwestern US, where vegetation change, soil tillage, and pervasive modifications of the surface and subsurface drainage system have substantially changed water, sediment and nutrient fluxes. Effects, in terms of amplification or damping of environmental signals, are strongly dependent on landscape setting, and often non-linear. Hysteresis and sensitivity may hinder the return to the initial state when perturbations have reached a certain threshold. We draw from multiple examples in the upper Midwestern US to illustrate, at a basic level, the mechanisms by which landscape evolution establishes the template for generation and transmission of environmental signals and furthermore how humans have altered critical zone processes to optimize specific landscape outputs, often at the expense of modifying the rate and/or magnitude of many other landscape outputs. We present a conceptual model and discuss implications for mathematical modeling of water, sediment and nutrient fluxes to guide watershed management and restoration.

  2. A Strategy for Minimizing Background Signal in Autoinductive Signal Amplification Reactions for Point-of-Need Assays

    PubMed Central

    Brooks, Adam D.; Yeung, Kimy; Lewis, Gregory G.

    2015-01-01

    Rapid point-of-need assays are used to detect abundant biomarkers. The development of in situ signal amplification reactions could extend these assays to screening and triaging of patients for trace levels of biomarkers, even in resource-limited settings. We, and others, have developed small molecule-based in situ signal amplification reactions that eventually may be useful in this context. Herein we describe a design strategy for minimizing background signal that may occur in the absence of the target analyte, thus moving this in situ signal amplification approach one step closer to practical applications. Specifically, we describe allylic ethers as privileged connectors for linking detection and propagating functionality in a small molecule signal amplification reagent. Allylic ethers minimize background reactions while still enabling controlled release of a propagating signal in order to continue the signal amplification reaction. This paper characterizes the ability of allylic ethers to provide an amplified response, and offers insight into additional design considerations that are needed before in situ small molecule-based signal amplification becomes a viable strategy for point-of-need diagnostics. PMID:26604988

  3. Enzyme-free signal amplification for electrochemical detection of Mycobacterium lipoarabinomannan antibody on a disposable chip.

    PubMed

    Wang, Lisong; Leng, Chuan; Tang, Sheng; Lei, Jianping; Ju, Huangxian

    2012-01-01

    A simple, rapid, and disposable immunosensor at screen printed carbon electrode (SPCE) was developed by using gold nanoparticles (AuNPs) labeled Staphylococcal protein A (Au-SPA) as the electrochemical tag for detection of lipoarabinomannan antibody (anti-LAM). The immunosensor as the disposable chip was prepared by immobilizing capture antigen on screen printed carbon working electrode by passive adsorption, and characterized with scanning electron microscopy. After binding with the anti-LAM for further capture of Au-SPA, AuNPs were introduced as an electrochemical tag by the eletrooxidation of AuNPs in 0.1M HCl to produce strong electroactive substance for signal amplification. Compared with the enzyme-based immunosensor, AuNPs as enzyme-free tag for signal amplification exhibited many advantages such as no requirement of deoxygenation, and high stability. Under optimal detection conditions and at a preoxidation potential of +1.3 V for 30s, this method achieved the linear concentration of anti-LAM from 15.6 to 1000 ng mL(-1) with a detection limit of 5.3 ng mL(-1). The immunosensor showed a good performance with high selectivity, acceptable stability, and simple operation, providing a promising application as an adjunctive tool in early tuberculosis diagnosis. PMID:22709935

  4. Ultrasensitive detection of uranyl by graphene oxide-based background reduction and RCDzyme-based enzyme strand recycling signal amplification.

    PubMed

    Li, Ming-Hui; Wang, Yong-Sheng; Cao, Jin-Xiu; Chen, Si-Han; Tang, Xian; Wang, Xiao-Feng; Zhu, Yu-Feng; Huang, Yan-Qin

    2015-10-15

    We proposed a novel strategy which combines graphene oxide-based background reduction with RCDzyme-based enzyme strand recycling amplification for ultrahigh sensitive detection of uranyl. The RCDzyme is designed to contain a guanine (G)-rich sequence that replaces the partial sequence in an uranyl-specific DNAzyme. This multifunctional probe can act as the target recognition element, DNAzyme and the primer of signal amplification. The presence of UO2(2+) can induce the cleavage of the substrate strands in RCDzyme. Then, each released enzyme strand can hybridize with another substrate strands to trigger many cycles of the cleavage by binding uranyl, leading to the formation of more G-quadruplexes by split guanine-rich oligonucleotide fragments. The resulting G-quadruplexes could bind to N-methyl-mesoporphyrin IX (NMM), causing an amplified detection signal for the target uranyl. Next, graphene oxide-based background reduction strategy was further employed for adsorbing free ssDNA and NMM, thereby providing a proximalis zero-background signal. The combination of RCDzyme signal amplification and proximalis zero-background signal remarkably improves the sensitivity of this method, achieving a dynamic range of two orders of magnitude and giving a detection limit down to 86 pM, which is much lower than those of related literature reports. These achievements might be helpful in the design of highly sensitive analytical platform for wide applications in environmental and biomedical fields. PMID:26000462

  5. Spin-current signal amplification by a geometrical ratchet

    NASA Astrophysics Data System (ADS)

    Abdullah, Ranjdar M.; Vick, Andrew J.; Murphy, Benedict A.; Hirohata, Atsufumi

    2014-12-01

    We report the demonstration of spin-current amplification in a lateral spin-valve with a non-local configuration. A geometrical ratchet has been implemented in a non-magnetic nanowire bridging two ferromagnetic nanowires. Such geometry induces a difference in resistivity for diffusive electrons travelling in opposite directions by differentiating the scattering coefficients. This difference amplifies the total spin current by a factor of more than 7. Amplification by a geometrical ratchet can be predicted by simple two channel electrical transport calculations and provides a method to increase the efficiency of pure spin current flow in lateral spin valves.

  6. Beyond "turn-on" readout: from zero background to signal amplification by combination of magnetic separation and plasmon enhanced fluorescence.

    PubMed

    Gong, Suqin; Xia, Yunsheng

    2016-08-11

    By magnetic separation and subsequent plasmon enhanced fluorescence, an assay platform with a signal output from completely "zero" background to fluorescence amplification is achieved, using quantum dots as reporters. So, it well breaks through the conventional "turn-on" strategy in both lower and upper limits. The sensitivity for hyaluronidase sensing is enhanced 10(4)-10(6) times as compared with previous fluorescence methods. PMID:27398675

  7. Engineering self-contained DNA circuit for proximity recognition and localized signal amplification of target biomolecules

    PubMed Central

    Ang, Yan Shan; Yung, Lin-Yue Lanry

    2014-01-01

    Biomolecular interactions have important cellular implications, however, a simple method for the sensing of such proximal events is lacking in the current molecular toolbox. We designed a dynamic DNA circuit capable of recognizing targets in close proximity to initiate a pre-programmed signal transduction process resulting in localized signal amplification. The entire circuit was engineered to be self-contained, i.e. it can self-assemble onto individual target molecules autonomously and form localized signal with minimal cross-talk. α-thrombin was used as a model protein to evaluate the performance of the individual modules and the overall circuit for proximity interaction under physiologically relevant buffer condition. The circuit achieved good selectivity in presence of non-specific protein and interfering serum matrix and successfully detected for physiologically relevant α-thrombin concentration (50 nM–5 μM) in a single mixing step without any further washing. The formation of localized signal at the interaction site can be enhanced kinetically through the control of temperature and probe concentration. This work provides a basic general framework from which other circuit modules can be adapted for the sensing of other biomolecular or cellular interaction of interest. PMID:25056307

  8. An ultrasensitive and universal photoelectrochemical immunoassay based on enzyme mimetics enhanced signal amplification.

    PubMed

    Wang, Guang-Li; Shu, Jun-Xian; Dong, Yu-Ming; Wu, Xiu-Ming; Li, Zai-Jun

    2015-04-15

    An ultrasensitive photoelectrochemical (PEC) immunoassay based on signal amplification by enzyme mimetics was fabricated for the detection of mouse IgG (as a model protein). The PEC immunosensor was constructed by a layer-by-layer assembly of poly (diallyldimethylammonium chloride) (PDDA), CdS quantum dots (QDs), primary antibody (Ab1, polyclonal goat antimouse IgG), and the antigen (Ag, mouse IgG) on an indium-tin oxide (ITO) electrode. Then, the secondary antibody (Ab2, polyclonal goat antimouse IgG) combined to a bio-bar-coded Pt nanoparticle(NP)-G-quadruplex/hemin probe was used for signal amplification. The bio-bar-coded Pt NP-G-quadruplex/hemin probe could catalyze the oxidation of hydroquinone (HQ) using H2O2 as an oxidant, demonstrating its intrinsic enzyme-like activity. High sensitivity for the target Ag was achieved by using the bio-bar-coded probe as signal amplifier due to its high catalytic activity, a competitive nonproductive absorption of hemin and the steric hindrance caused by the polymeric oxidation products of HQ. For most important, the oxidation product of HQ acted as an efficient electron acceptor of the illuminated CdS QDs. The target Ag could be detected from 0.01pg/mL to 1.0ng/mL with a low detection limit of 6.0fg/mL. The as-obtained immunosensor exhibited high sensitivity, good stability and acceptable reproducibility. This method might be attractive for clinical and biomedical applications. PMID:25437365

  9. E2F Activators Signal and Maintain Centrosome Amplification in Breast Cancer Cells

    PubMed Central

    Lee, Mi-Young; Moreno, Carlos S.

    2014-01-01

    Centrosomes ensure accurate chromosome segregation by directing spindle bipolarity. Loss of centrosome regulation results in centrosome amplification, multipolar mitosis and aneuploidy. Since centrosome amplification is common in premalignant lesions and breast tumors, it is proposed to play a central role in breast tumorigenesis, a hypothesis that remains to be tested. The coordination between the cell and centrosome cycles is of paramount importance to maintain normal centrosome numbers, and the E2Fs may be responsible for regulating these cycles. However, the role of E2F activators in centrosome amplification is unclear. Because E2Fs are deregulated in Her2+ cells displaying centrosome amplification, we addressed whether they signal this abnormal process. Knockdown of E2F1 or E2F3 in Her2+ cells decreased centrosome amplification without significantly affecting cell cycle progression, whereas the overexpression of E2F1, E2F2, or E2F3 increased centrosome amplification in MCF10A mammary epithelial cells. Our results revealed that E2Fs affect the expression of proteins, including Nek2 and Plk4, known to influence the cell/centrosome cycles and mitosis. Downregulation of E2F3 resulted in cell death and delays/blocks in cytokinesis, which was reversed by Nek2 overexpression. Nek2 overexpression enhanced centrosome amplification in Her2+ breast cancer cells silenced for E2F3, revealing a role for the E2F activators in maintaining centrosome amplification in part through Nek2. PMID:24797070

  10. Drastic disorder-induced reduction of signal amplification in scale-free networks.

    PubMed

    Chacón, Ricardo; Martínez, Pedro J

    2015-07-01

    Understanding information transmission across a network is a fundamental task for controlling and manipulating both biological and manmade information-processing systems. Here we show how topological resonant-like amplification effects in scale-free networks of signaling devices are drastically reduced when phase disorder in the external signals is considered. This is demonstrated theoretically by means of a starlike network of overdamped bistable systems, and confirmed numerically by simulations of scale-free networks of such systems. The taming effect of the phase disorder is found to be sensitive to the amplification's strength, while the topology-induced amplification mechanism is robust against this kind of quenched disorder in the sense that it does not significantly change the values of the coupling strength where amplification is maximum in its absence. PMID:26274239

  11. Tiny Grains Give Huge Gains: Nanocrystal–Based Signal Amplification for Biomolecule Detection

    PubMed Central

    Tong, Sheng; Ren, Binbin; Zheng, Zhilan; Shen, Han; Bao, Gang

    2013-01-01

    Nanocrystals, despite their tiny sizes, contain thousands to millions of atoms. Here we show that the large number of atoms packed in each metallic nanocrystal can provide a huge gain in signal amplification for biomolecule detection. We have devised a highly sensitive, linear amplification scheme by integrating the dissolution of bound nanocrystals and metal-induced stoichiometric chromogenesis, and demonstrated that signal amplification is fully defined by the size and atom density of nanocrystals, which can be optimized through well-controlled nanocrystal synthesis. Further, the rich library of chromogenic reactions allows implementation of this scheme in various assay formats, as demonstrated by the iron oxide nanoparticle linked immunosorbent assay (ILISA) and blotting assay developed in this study. Our results indicate that, owing to the inherent simplicity, high sensitivity and repeatability, the nanocrystal based amplification scheme can significantly improve biomolecule quantification in both laboratory research and clinical diagnostics. This novel method adds a new dimension to current nanoparticle-based bioassays. PMID:23659350

  12. Drastic disorder-induced reduction of signal amplification in scale-free networks

    NASA Astrophysics Data System (ADS)

    Chacón, Ricardo; Martínez, Pedro J.

    2015-07-01

    Understanding information transmission across a network is a fundamental task for controlling and manipulating both biological and manmade information-processing systems. Here we show how topological resonant-like amplification effects in scale-free networks of signaling devices are drastically reduced when phase disorder in the external signals is considered. This is demonstrated theoretically by means of a starlike network of overdamped bistable systems, and confirmed numerically by simulations of scale-free networks of such systems. The taming effect of the phase disorder is found to be sensitive to the amplification's strength, while the topology-induced amplification mechanism is robust against this kind of quenched disorder in the sense that it does not significantly change the values of the coupling strength where amplification is maximum in its absence.

  13. Noiseless intensity amplification of repetitive signals by coherent addition using the temporal Talbot effect

    PubMed Central

    Maram, Reza; Van Howe, James; Li, Ming; Azaña, José

    2014-01-01

    Amplification of signal intensity is essential for initiating physical processes, diagnostics, sensing, communications and measurement. During traditional amplification, the signal is amplified by multiplying the signal carriers through an active gain process, requiring the use of an external power source. In addition, the signal is degraded by noise and distortions that typically accompany active gain processes. We show noiseless intensity amplification of repetitive optical pulse waveforms with gain from 2 to ~20 without using active gain. The proposed method uses a dispersion-induced temporal self-imaging (Talbot) effect to redistribute and coherently accumulate energy of the original repetitive waveforms into fewer replica waveforms. In addition, we show how our passive amplifier performs a real-time average of the wave-train to reduce its original noise fluctuation, as well as enhances the extinction ratio of pulses to stand above the noise floor. Our technique is applicable to repetitive waveforms in any spectral region or wave system. PMID:25319207

  14. Optimization of noise in non-integrated instrumentation amplifier for the amplification of very low electrophysiological [corrected] signals. Case of electro cardio graphic signals (ECG).

    PubMed

    Ngounou, Guy Merlin; Kom, Martin

    2014-12-01

    In this paper we present an instrumentation amplifier with discrete elements and optimized noise for the amplification of very low signals. In amplifying signals of very weak amplitude, the noise can completely absorb these signals if the used amplifier does not present the optimal guarantee to minimize the noise. Based on related research and re-viewing of recent patents Journal of Medical Systems, 30:205-209, 2006, we suggest an approach of noise reduction in amplification much more thoroughly than re-viewing of recent patents and we deduce from it the general criteria necessary and essential to achieve this optimization. The comparison of these criteria with the provisions adopted in practice leads to the inadequacy of conventional amplifiers for effective noise reduction. The amplifier we propose is an instrumentation amplifier with active negative feedback and optimized noise for the amplification of signals with very low amplitude. The application of this method in the case of electro cardio graphic signals (ECG) provides simulation results fully in line with forecasts. PMID:25381049

  15. Highly skin-conformal microhairy sensor for pulse signal amplification.

    PubMed

    Pang, Changhyun; Koo, Ja Hoon; Nguyen, Amanda; Caves, Jeffrey M; Kim, Myung-Gil; Chortos, Alex; Kim, Kwanpyo; Wang, Paul J; Tok, Jeffrey B-H; Bao, Zhenan

    2015-01-27

    A bioinspired microhairy sensor is developed to enable ultraconformability on nonflat surfaces and significant enhancement in the signal-to-noise ratio of the retrieved signals. The device shows ≈12 times increase in the signal-to-noise ratio in the generated capacitive signals, allowing the ultraconformal microhair pressure sensors to be capable of measuring weak pulsations of internal jugular venous pulses stemming from a human neck. PMID:25358966

  16. Sensitive SERS detection of DNA methyltransferase by target triggering primer generation-based multiple signal amplification strategy.

    PubMed

    Li, Ying; Yu, Chuanfeng; Han, Huixia; Zhao, Caisheng; Zhang, Xiaoru

    2016-07-15

    A novel and sensitive surface-enhanced Raman scattering (SERS) method is proposed for the assay of DNA methyltransferase (MTase) activity and evaluation of inhibitors by developing a target triggering primer generation-based multiple signal amplification strategy. By using of a duplex substrate for Dam MTase, two hairpin templates and a Raman probe, multiple signal amplification mode is achieved. Once recognized by Dam MTase, the duplex substrate can be cleaved by Dpn I endonuclease and two primers are released for triggering the multiple signal amplification reaction. Consequently, a wide dynamic range and remarkably high sensitivity are obtained under isothermal conditions. The detection limit is 2.57×10(-4)UmL(-1). This assay exhibits an excellent selectivity and is successfully applied in the screening of inhibitors for Dam MTase. In addition, this novel sensing system is potentially universal as the recognition element can be conveniently designed for other target analytes by changing the substrate of DNA MTase. PMID:26926592

  17. Nonlinear photoacoustic signal amplification from single targets in absorption background☆

    PubMed Central

    Sarimollaoglu, Mustafa; Nedosekin, Dmitry A.; Menyaev, Yulian A.; Juratli, Mazen A.; Zharov, Vladimir P.

    2013-01-01

    Photoacoustic (PA) detection of single absorbing targets such as nanoparticles or cells can be limited by absorption background. We show here that this problem can be overcome by using the nonlinear photoacoustics based on the differences in PA signal dependences on the laser energy from targets and background. Among different nonlinear phenomena, we focused on laser generation of nanobubbles as more efficient PA signal amplifiers from strongly absorbing, highly localized targets in the presence of spatially homogenous absorption background generating linear signals only. This approach was demonstrated by using nonlinear PA flow cytometry platform for label-free detection of circulating melanoma cells in blood background in vitro and in vivo. Nonlinearly amplified PA signals from overheated melanin nanoclusters in melanoma cells became detectable above still linear blood background. Nonlinear nanobubble-based photoacoustics provide new opportunities to significantly (5–20-fold) increase PA contrast of single nanoparticles, cells, viruses and bacteria in complex biological environments. PMID:24921062

  18. Nonlinear photoacoustic signal amplification from single targets in absorption background.

    PubMed

    Sarimollaoglu, Mustafa; Nedosekin, Dmitry A; Menyaev, Yulian A; Juratli, Mazen A; Zharov, Vladimir P

    2014-03-01

    Photoacoustic (PA) detection of single absorbing targets such as nanoparticles or cells can be limited by absorption background. We show here that this problem can be overcome by using the nonlinear photoacoustics based on the differences in PA signal dependences on the laser energy from targets and background. Among different nonlinear phenomena, we focused on laser generation of nanobubbles as more efficient PA signal amplifiers from strongly absorbing, highly localized targets in the presence of spatially homogenous absorption background generating linear signals only. This approach was demonstrated by using nonlinear PA flow cytometry platform for label-free detection of circulating melanoma cells in blood background in vitro and in vivo. Nonlinearly amplified PA signals from overheated melanin nanoclusters in melanoma cells became detectable above still linear blood background. Nonlinear nanobubble-based photoacoustics provide new opportunities to significantly (5-20-fold) increase PA contrast of single nanoparticles, cells, viruses and bacteria in complex biological environments. PMID:24921062

  19. Rolling chain amplification based signal-enhanced electrochemical aptasensor for ultrasensitive detection of ochratoxin A.

    PubMed

    Huang, Lin; Wu, Jingjing; Zheng, Lei; Qian, Haisheng; Xue, Feng; Wu, Yucheng; Pan, Daodong; Adeloju, Samuel B; Chen, Wei

    2013-11-19

    A novel electrochemical aptasensor is described for rapid and ultrasensitive detection of ochratoxin A (OTA) based on signal enhancement with rolling circle amplification (RCA). The primer for RCA was designed to compose of a two-part sequence, one part of the aptamer sequence directed against OTA while the other part was complementary to the capture probe on the electrode surface. In the presence of target OTA, the primer, originally hybridized with the RCA padlock, is replaced to combine with OTA. This induces the inhibition of RCA and decreases the OTA sensing signal obtained with the electrochemical aptasensor. Under the optimized conditions, ultrasensitive detection of OTA was achieved with a limit of detection (LOD) of 0.065 ppt (pg/mL), which is much lower than previously reported. The electrochemical aptasensor was also successfully applied to the determination of OTA in wine samples. This ultrasensitive electrochemical aptasensor is of great practical importance in food safety and could be widely extended to the detection of other toxins by replacing the sequence of the recognition aptamer. PMID:24206525

  20. An immunochromatographic biosensor combined with a water-swellable polymer for automatic signal generation or amplification.

    PubMed

    Kim, Kahee; Joung, Hyou-Arm; Han, Gyeo-Re; Kim, Min-Gon

    2016-11-15

    An immunochromatographic assay (ICA) strip is one of the most widely used platforms in the field of point-of-care biosensors for the detection of various analytes in a simple, fast, and inexpensive manner. Currently, several approaches for sequential reactions in ICA platforms have improved their usability, sensitivity, and versatility. In this study, a new, simple, and low-cost approach using automatic sequential-reaction ICA strip is described. The automatic switching of a reagent pad from separation to attachment to the test membrane was achieved using a water-swellable polymer. The reagent pad was dried with an enzyme substrate for signal generation or with signal-enhancing materials. The strip design and system operation were confirmed by the characterization of the raw materials and flow analysis. We demonstrated the operation of the proposed sensor by using various chemical reaction-based assays, including metal-ion amplification, enzyme-colorimetric reaction, and enzyme-catalyzed chemiluminescence. Furthermore, by employing C-reactive protein as a model, we successfully demonstrated that the new water-swellable polymer-based ICA sensor can be utilized to detect biologically relevant analytes in human serum. PMID:27203463

  1. Impulse-induced optimum signal amplification in scale-free networks.

    PubMed

    Martínez, Pedro J; Chacón, Ricardo

    2016-04-01

    Optimizing information transmission across a network is an essential task for controlling and manipulating generic information-processing systems. Here, we show how topological amplification effects in scale-free networks of signaling devices are optimally enhanced when the impulse transmitted by periodic external signals (time integral over two consecutive zeros) is maximum. This is demonstrated theoretically by means of a star-like network of overdamped bistable systems subjected to generic zero-mean periodic signals and confirmed numerically by simulations of scale-free networks of such systems. Our results show that the enhancer effect of increasing values of the signal's impulse is due to a correlative increase of the energy transmitted by the periodic signals, while it is found to be resonant-like with respect to the topology-induced amplification mechanism. PMID:27176316

  2. Impulse-induced optimum signal amplification in scale-free networks

    NASA Astrophysics Data System (ADS)

    Martínez, Pedro J.; Chacón, Ricardo

    2016-04-01

    Optimizing information transmission across a network is an essential task for controlling and manipulating generic information-processing systems. Here, we show how topological amplification effects in scale-free networks of signaling devices are optimally enhanced when the impulse transmitted by periodic external signals (time integral over two consecutive zeros) is maximum. This is demonstrated theoretically by means of a star-like network of overdamped bistable systems subjected to generic zero-mean periodic signals and confirmed numerically by simulations of scale-free networks of such systems. Our results show that the enhancer effect of increasing values of the signal's impulse is due to a correlative increase of the energy transmitted by the periodic signals, while it is found to be resonant-like with respect to the topology-induced amplification mechanism.

  3. Nonenzymatic catalytic signal amplification for nucleic acid hybridization assays

    NASA Technical Reports Server (NTRS)

    Fan, Wenhong (Inventor); Cassell, Alan M. (Inventor); Han, Jie (Inventor)

    2006-01-01

    Devices, methods, and kits for amplifying the signal from hybridization reactions between nucleic acid probes and their cognate targets are presented. The devices provide partially-duplexed, immobilized probe complexes, spatially separate from and separately addressable from immobilized docking strands. Cognate target acts catalytically to transfer probe from the site of probe complex immobilization to the site of immobilized docking strand, generating a detectable signal. The methods and kits of the present invention may be used to identify the presence of cognate target in a fluid sample.

  4. Sensitive SERS detection of miRNA via enzyme-free DNA machine signal amplification.

    PubMed

    Li, Xiaoxiao; Ye, Sujuan; Luo, Xiliang

    2016-08-11

    In this work, an enzyme-free signal amplified detection platform is described for miRNA detection with a DNA fueled molecular machine. Coupling SERS technology with multiple amplification modes, this flexible biosensing system exhibits high sensitivity and specificity. PMID:27469084

  5. Thousand-fold fluorescent signal amplification for mHealth diagnostics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The low sensitivity of Mobile Health (mHealth) optical detectors, such as those found on mobile phones, is a limiting factor for many mHealth clinical applications. To improve sensitivity, we have combined two approaches for optical signal amplification: (1) a computational approach based on an imag...

  6. Development of a near-infrared fluorescence ELISA method using tyramide signal amplification.

    PubMed

    Gong, Haibiao; Cradduck, Mark; Cheung, Lael; Olive, D Michael

    2012-07-01

    In this study, we applied tyramide signal amplification (TSA) to fluorescence enzyme-linked immunosorbent assay (ELISA) employing horseradish peroxidase (HRP) as the detection enzyme. When used with a human epidermal growth factor ELISA kit, the TSA method led to a >100-fold increase in fluorescence signal intensity in comparison to an unamplified method. It also showed wider dynamic range and better sensitivity compared to a conventional method using tetramethylbenzidine as the HRP substrate. PMID:22490466

  7. Comparison of sensor structures for the signal amplification of surface plasmon resonance immunoassay using enzyme precipitation

    NASA Astrophysics Data System (ADS)

    Yang, Chih-Tsung; Thierry, Benjamin

    2015-12-01

    Surface plasmon resonance (SPR) biosensing has been successfully applied for the label-free detection of a broad range of bioanalytes ranging from bacteria, cell, exosome, protein and nucleic acids. When it comes to the detection of small molecules or analytes found at low concentration, amplification schemes are desirable to enhance binding signals and in turn increase sensitivity. A number of SPR signal amplification schemes have been developed and validated; however, little effort has been devoted to understanding the effect of the SPR sensor structures on the amplification of binding signals and therefore on the overall sensing performance. The physical phenomenon of long-range SPR (LRSPR) relies on the propagation of coupled surface plasmonic waves on the opposite sides of a nanoscale-thick noble metal film suspended between two dielectrics with similar refractive indices. Importantly, as compared with commonly used conventional SPR (cSPR), LRSPR is not only characterized by a longer penetration depth of the plasmonic waves in the analyzed medium but also by a greater sensitivity to bulk refractive index changes. In this work, an immunoassay signal amplification platform based on horseradish peroxidase (HRP) catalyzed precipitation was utilized to investigate the sensing performance with regards to cSPR and LRSPR. The enzymatic precipitation of 3, 3'-diaminobenzidine tetrahydrochloride (DAB)/H2O2 was used to amplify SPR signals. The structure-function relationship of cSPR and LRSPR sensors is presented for both standard refractometric measurements and the enzymatic precipitation scheme. Experimental data shows that despite its inherent higher sensitivity to bulk refractive index changes and higher figure of merit, LRSPR was characterized by a lower angular sensitivity in the model enzymatic amplification scheme used here.

  8. Ultrasensitive electrochemical strategy for trace detection of APE-1 via triple signal amplification strategy.

    PubMed

    Han, Jing; Zhuo, Ying; Chai, Yaqin; Xiang, Yu; Yuan, Ruo; Yuan, Yali; Liao, Ni

    2013-03-15

    A novel ultrasensitive electrochemical immunoassay for the determination of apurinic/apyrimidinic endonuclease (APE-1) using a three-step signal amplification process was reported in this work. The first-step signal amplification process was based on the labeled biotinylated alkaline phosphatase (bio-AP) on the nickel hexacyanoferrates nanoparticle-decorated Au nanochains (Ni-AuNCs) toward the biocatalysis of ascorbic acid 2-phosphate (AA-P) to in-situ produce ascorbic acid (AA). Then the signal was further amplified by electrochemical oxidation of the in-situ-produced AA because of the catalysis of Ni-AuNCs. Finally, with the nanochain-modified streptavidin (SA), the stoichiometry of bio-AP could be increased through the specific and high affinity interaction of streptavidin-biotin. On the other hand, a kind of organic material (PTC-NH(2)), owing the amino-functionalized interface and unique electrochemical properties, as matrix for primary antibodies (Ab(1)) immobilization could lower the background current signal and enhance the amount of immobilized Ab(1). With a sandwich-type immunoreaction, the triple signal amplification greatly enhanced the sensitivity for the detection of APE-1. Under optimal conditions, the electrochemical immunosensor exhibited a linear range of 0.01-100 pg/mL with an extremely low detection limit of 3.9 fg/mL (signal/noise=3). PMID:22981009

  9. Cycling excitation process: An ultra efficient and quiet signal amplification mechanism in semiconductor

    SciTech Connect

    Liu, Yu-Hsin; Yan, Lujiang; Zhang, Alex Ce; Hall, David; Niaz, Iftikhar Ahmad; Zhou, Yuchun; Sham, L. J.; Lo, Yu-Hwa

    2015-08-03

    Signal amplification, performed by transistor amplifiers with its merit rated by the efficiency and noise characteristics, is ubiquitous in all electronic systems. Because of transistor thermal noise, an intrinsic signal amplification mechanism, impact ionization was sought after to complement the limits of transistor amplifiers. However, due to the high operation voltage (30-200 V typically), low power efficiency, limited scalability, and, above all, rapidly increasing excess noise with amplification factor, impact ionization has been out of favor for most electronic systems except for a few applications such as avalanche photodetectors and single-photon Geiger detectors. Here, we report an internal signal amplification mechanism based on the principle of the phonon-assisted cycling excitation process (CEP). Si devices using this concept show ultrahigh gain, low operation voltage, CMOS compatibility, and, above all, quantum limit noise performance that is 30 times lower than devices using impact ionization. Established on a unique physical effect of attractive properties, CEP-based devices can potentially revolutionize the fields of semiconductor electronics.

  10. Cycling excitation process: An ultra efficient and quiet signal amplification mechanism in semiconductor

    NASA Astrophysics Data System (ADS)

    Liu, Yu-Hsin; Yan, Lujiang; Zhang, Alex Ce; Hall, David; Niaz, Iftikhar Ahmad; Zhou, Yuchun; Sham, L. J.; Lo, Yu-Hwa

    2015-08-01

    Signal amplification, performed by transistor amplifiers with its merit rated by the efficiency and noise characteristics, is ubiquitous in all electronic systems. Because of transistor thermal noise, an intrinsic signal amplification mechanism, impact ionization was sought after to complement the limits of transistor amplifiers. However, due to the high operation voltage (30-200 V typically), low power efficiency, limited scalability, and, above all, rapidly increasing excess noise with amplification factor, impact ionization has been out of favor for most electronic systems except for a few applications such as avalanche photodetectors and single-photon Geiger detectors. Here, we report an internal signal amplification mechanism based on the principle of the phonon-assisted cycling excitation process (CEP). Si devices using this concept show ultrahigh gain, low operation voltage, CMOS compatibility, and, above all, quantum limit noise performance that is 30 times lower than devices using impact ionization. Established on a unique physical effect of attractive properties, CEP-based devices can potentially revolutionize the fields of semiconductor electronics.

  11. Increased sensitivity of HIV-1 p24 ELISA using a photochemical signal amplification system

    PubMed Central

    Bystryak, Simon; Santockyte, Rasa

    2016-01-01

    In this study we describe a photochemical signal amplification method (PSAM) for increasing of the sensitivity of enzyme-linked immunosorbent assay (ELISA) for determination of HIV-1 p24 antigen. This method can be used for both commercially available and in-house ELISA tests, and has the advantage of being considerably simpler and less costly than alternative signal amplification methods. The photochemical signal amplification method is based on an autocatalytic photochemical reaction of a horseradish peroxidase (HRP) substrate, orthophenylenediamine (OPD). To compare the performance of PSAM-boosted ELISA with a conventional colorimetric ELISA for determination of HIV-1 p24 antigen we employed a PerkinElmer HIV-1 p24 ELISA kit, using conventional ELISA alongside ELISA + PSAM. In the present study, we show that PSAM technology allows one to increase the analytical sensitivity and dynamic range of a commercial HIV-1 p24 ELISA kit, with and without immune-complex disruption (ICD and Non-ICD ELISA), by a factor of approximately 40-fold. ELISA + PSAM is compatible with commercially available microtiter plate readers, requires only an inexpensive illumination device, and the PSAM amplification step takes no longer than 15 min. PMID:26090753

  12. Signal-to-Noise Enhancement of a Nanospring Redox-Based Sensor by Lock-in Amplification

    PubMed Central

    Bakharev, Pavel V.; McIlroy, David N.

    2015-01-01

    A significant improvement of the response characteristics of a redox chemical gas sensor (chemiresistor) constructed with a single ZnO coated silica nanospring has been achieved with the technique of lock-in signal amplification. The comparison of DC and analog lock-in amplifier (LIA) AC measurements of the electrical sensor response to toluene vapor, at the ppm level, has been conducted. When operated in the DC detection mode, the sensor exhibits a relatively high sensitivity to the analyte vapor, as well as a low detection limit at the 10 ppm level. However, at 10 ppm the signal-to-noise ratio is 5 dB, which is less than desirable. When operated in the analog LIA mode, the signal-to-noise ratio at 10 ppm increases by 30 dB and extends the detection limit to the ppb range. PMID:26053754

  13. Sensitive detection of multiple mycotoxins by SPRi with gold nanoparticles as signal amplification tags.

    PubMed

    Hu, Weihua; Chen, Hongming; Zhang, Huanhuan; He, Guangli; Li, Xin; Zhang, Xiaoxing; Liu, Yang; Li, Chang Ming

    2014-10-01

    Detection of multiple toxic mycotoxins is of importance in food quality control. Surface plasmon resonance imaging (SPRi) is an advanced tool for simultaneously multiple detections with accuracy; however, it suffers from limited sensitivity due to the instrumental constraint and small sizes of mycotoxins with only one epitope for an insensitive competitive immunoassay. In this work a gold nanoparticle (AuNP)-enhanced SPRi chip is designed to sensitively detect multiple mycotoxins using a competitive immunoassay format. The sensing surface is constructed by uniformly attaching dense mycotoxin antigens on poly[oligo(ethylene glycol) methacrylate-co-glycidyl methacrylate] (POEGMA-co-GMA) brush modified SPRi gold chip. After competitive binding in a sample solution containing respective monoclonal antibodies, secondary antibody-conjugated AuNPs are employed to bind with the captured monoclonal antibodies for further amplification of the SPRi signal. Highly specific and sensitive simultaneous detection is achieved for three typical mycotoxins including Aflatoxin B1 (AFB1), Ochratoxin A (OTA) and Zearalenone (ZEN) with low detection limits of 8, 30 and 15 pg mL(-1) and dynamic ranges covering three orders of magnitude. PMID:24992296

  14. Efficient Sub-Bandgap Light Absorption and Signal Amplification in Silicon Photodetectors

    NASA Astrophysics Data System (ADS)

    Liu, Yu-Hsin

    This thesis focuses on two areas in silicon photodetectors, the first being enhancing the sub-bandgap light absorption of IR wavelenghts in silicon, and the second being intrinsic signal amplification in silicon photodetectors. Both of these are achieved using heavily doped p-n junction devices which create localized states that relax the k-selection rule of indirect bandgap material. The probability of transitions between impurity band and the conduction/valence band would be much more efficient than the one between band-to-band transition. The waveguide-coupled epitaxial p-n photodetector was demonstrated for 1310 nm wavelength detection. Incorporated with the Franz-Keldysh effect and the quasi-confined epitaxial layer design, an absorption coefficient around 10 cm-1 has been measured and internal quantum efficiency nearly 100% at -2.5V. The absorption coefficient is calculated from the wave function of the electron and hole in p-n diode. The heavily doped impurity wave function can be formulated as a delta function, and the quasi-confined conduction band energy states, and the wave function on each level can be obtained from the Silvaco software. The calculated theoretical absorption coefficient increases with the increasing applied bias and the doping concentration, which matches the experimental results. To solve the issues of large excess noise and high operation bias for avalanche photodiodes based on impact ionization, I presented a detector using the Cycling Excitation Process (CEP) for signal amplification. This can be realized in a heavily doped and highly compensated Si p-n junction, showing ultra high gain about 3000 at very low bias (<4 V), and possessing an intrinsic, phonon-mediated regulation process to keep the device stable without any quenching device required in today's Geiger-mode avalanche detectors. The CEP can be formulated with the rate equations in conduction bands and impurity states. The gain expression, which is a function of the

  15. Multivalent interaction based carbohydrate biosensors for signal amplification

    PubMed Central

    Wang, Yanyan; Chalagalla, Srinivas; Li, Tiehai; Sun, Xue-long; Zhao, Wei; Wang, Peng; Zeng, Xiangqun

    2010-01-01

    Multivalent interaction between boronic acids immobilized on Quartz Crystal Microbalance (QCM) sensor surface and the carbohydrates modified Au - nanoparticle (AuNP) has been demonstrated for the development of a sensitive carbohydrate biosensor. Briefly, a boronic acid - containing polymer (boropolymer) as multivalent carbohydrate receptor was oriented immobilized on the cysteamine coated electrode through isourea bond formation. Carbohydrates were conjugated to AuNPs to generate a multivalent carbohydrates moiety to amplify the response signal. Thus, the binding of the carbohydrate conjugated AuNPs to the boropolymer surface are multivalent which could simultaneously increase the binding affinity and specificity. We systematically studied the binding between five carbohydrate conjugated AuNPs and the boropolymer. Our studies show that the associate constant (Ka) was in the order of fucose < glucose < mannose < galactose < maltose. A linear response in the range from 23 µM to 3.83 mM was observed for mannose conjugated AuNPs and the boropolymer recognition elements, with the lower detection limit of 1.5 µM for the carbohydrate analytes. Furthermore, the multivalent binding between carbohydrates and boronic acids are reversible and allow the regeneration of boropolymer surface by using 1M acetic acid so as to sequentially capture and release the carbohydrate analytes. PMID:20863680

  16. Asymmetric signal amplification for simultaneous SERS detection of multiple cancer markers with significantly different levels.

    PubMed

    Ye, Sujuan; Wu, Yanying; Zhai, Xiaomo; Tang, Bo

    2015-08-18

    Simultaneous detection of cancer biomarkers holds great promise for the early diagnosis of different cancers. However, in the presence of high-concentration biomarkers, the signals of lower-expression biomarkers are overlapped. Existing techniques are not suitable for simultaneously detecting multiple biomarkers at concentrations with significantly different orders of magnitude. Here, we propose an asymmetric signal amplification method for simultaneously detecting multiple biomarkers with significantly different levels. Using the bifunctional probe, a linear amplification mode responds to high-concentration markers, and quadratic amplification mode responds to low-concentration markers. With the combined biobarcode probe and hybridization chain reaction (HCR) amplification method, the detection limits of microRNA (miRNA) and ATP via surface-enhanced Raman scattering (SERS) detection are 0.15 fM and 20 nM, respectively, with a breakthrough of detection concentration difference over 11 orders of magnitude. Furthermore, successful determination of miRNA and ATP in cancer cells supports the practicability of the assay. This methodology promises to open an exciting new avenue for the detection of various types of biomolecules. PMID:26218034

  17. Signal-to-noise ratio enhancement of silicon nanowires biosensor with rolling circle amplification.

    PubMed

    Gao, Anran; Zou, Nengli; Dai, Pengfei; Lu, Na; Li, Tie; Wang, Yuelin; Zhao, Jianlong; Mao, Hongju

    2013-09-11

    Herein, we describe a novel approach for rapid, label-free and specific DNA detection by applying rolling circle amplification (RCA) based on silicon nanowire field-effect transistor (SiNW-FET) for the first time. Highly responsive SiNWs were fabricated with a complementary metal oxide semiconductor (CMOS) compatible anisotropic self-stop etching technique which eliminated the need for hybrid method. The probe DNA was immobilized on the surface of SiNW, followed by sandwich hybridization with the perfectly matched target DNA and RCA primer that acted as a primer to hybridize the RCA template. The RCA reaction created a long single-stranded DNA (ssDNA) product and thus enhanced the electronic responses of SiNW significantly. The signal-to-noise ratio (SNR) as a figure-of-merit was analyzed to estimate the signal enhancement and possible detection limit. The nanosensor showed highly sensitive concentration-dependent conductance change in response to specific target DNA sequences. Because of the binding of an abundance of repeated sequences of RCA products, the SNR of >20 for 1 fM DNA detection was achieved, implying a detection floor of 50 aM. This RCA-based SiNW biosensor also discriminated perfectly matched target DNA from one-base mismatched DNA with high selectivity due to the substantially reduced nonspecific binding onto the SiNW surface through RCA. The combination of SiNW FET sensor with RCA will increase diagnostic capacity and the ability of laboratories to detect unexpected viruses, making it a potential tool for early diagnosis of gene-related diseases. PMID:23937430

  18. Sensitive detection of Escherichia coli O157:H7 based on cascade signal amplification in ELISA.

    PubMed

    Shan, Shan; Liu, Daofeng; Guo, Qi; Wu, Songsong; Chen, Rui; Luo, Kai; Hu, Liming; Xiong, Yonghua; Lai, Weihua

    2016-09-01

    In this study, cascade signal amplification in ELISA involving double-antibody sandwich ELISA and indirectly competitive ELISA was established to sensitively detect Escherichia coli O157:H7. In the double-antibody sandwich ELISA, a complex was formed comprising anti-E. coli O157:H7 polyclonal antibody, E. coli O157:H7, biotinylated anti-E. coli O157:H7 monoclonal antibody, streptavidin, and biotinylated β-lactamase. Penicillin solution was then added into the ELISA well and hydrolyzed by β-lactamase. Afterward, the penicillin solution was transferred to indirectly competitive ELISA. The concentration of penicillin can be sensitively detected in indirectly competitive ELISA. In the cascade signal amplification system, increasing the amount of added E. coli O157:H7 resulted in more β-lactamase and less penicillin. The detection sensitivity of E. coli O157:H7, which was 20cfu/mL with the cascade signal amplification in ELISA, was 1,000-fold higher than that of traditional ELISA. Furthermore, the novel method can be used to detect E. coli O157:H7 in milk (2cfu/g). Therefore, this new signaling strategy will facilitate analyses of highly sensitive foodborne pathogens. PMID:27394946

  19. Deactivation of signal amplification by reversible exchange catalysis, progress towards in vivo application.

    PubMed

    Mewis, Ryan E; Fekete, Marianna; Green, Gary G R; Whitwood, Adrian C; Duckett, Simon B

    2015-06-18

    The catalyst which is used in the signal amplification by reversible exchange (SABRE) process facilitates substrate hyperpolarisation while acting to speed up the rate of relaxation. Consequently, the lifetime over which the hyperpolarised contrast agent is visible is drastically reduced. We show that the addition of a chelating ligand, such as bipyridine, rapidly deactivates the SABRE catalyst thereby lengthening the agent's relaxation times and improving the potential of SABRE for diagnostic MRI. PMID:25989727

  20. Tyramide Signal Amplification: Fluorescence In Situ Hybridization for Identifying Homoeologous Chromosomes.

    PubMed

    Fominaya, Araceli; Loarce, Yolanda; González, Juan M; Ferrer, Esther

    2016-01-01

    Tyramide signal amplification (TSA) fluorescence in situ hybridization (FISH) has been shown as a valuable molecular tool for visualizing specific amplified DNA sequences in chromosome preparations. This chapter describes how to perform TSA-FISH, paying special interest to its two critical steps: probe generation and metaphase plate generation. The potential of physically mapping 12S-globulin sequences by TSA-FISH as a means of identifying homeology among chromosome regions of Avena species was tested and is discussed. PMID:27511165

  1. mRNA-targeted Fluorescent in Situ Hybridization (FISH) of Gram-negative Bacteria Without Template Amplification or Tyramide Signal Amplification

    SciTech Connect

    Coleman, James R.; Culley, David E.; Chrisler, William B.; Brockman, Fred J.

    2007-12-01

    Technologies are needed to study gene expression at the level of individual cells within a population or microbial community. Fluorescent in situ hybridization (FISH) supplies high-resolution spatial information and has been widely applied to study microbial communities at the rRNA level. While mRNA-targeted FISH has been popular for studying gene expression in eukaryotic cells, very little success has been achieved with prokaryotes. At present, detection of specific mRNAs in individual prokaryotic cells requires the use of in situ-RT-PCR or tyramide signal amplification (TSA). In this study we used DNA oligonucleotide probes labeled with a single near-infrared dye in FISH assays to detect multicopy plasmid-based and endogenous mRNA molecules in Escherichia coli and Shewanella oneidensis MR-1. We took advantage of the fact there is much less background signal produced by biological materials and support matrices in the near-infrared spectrum and thus long camera exposure times could be used. In addition, we demonstrate that a combination of probes targeting both rRNA and mRNA could be successfully employed within the same FISH assay. These results, as well as ongoing R&D improvements in NIR and infrared dyes, indicate the FISH approach we demonstrated could be applied in certain environmental settings to monitor gene expression in mixed populations.

  2. Signal Amplification Technique (SAT): an approach for improving resolution and reducing image noise in computed tomography

    SciTech Connect

    Phelps, M.E.; Huang, S.C.; Hoffman, E.J.; Plummer, D.; Carson, R.

    1981-01-01

    Spatial resolution improvements in computed tomography (CT) have been limited by the large and unique error propagation properties of this technique. The desire to provide maximum image resolution has resulted in the use of reconstruction filter functions designed to produce tomographic images with resolution as close as possible to the intrinsic detector resolution. Thus, many CT systems produce images with excessive noise with the system resolution determined by the detector resolution rather than the reconstruction algorithm. CT is a rigorous mathematical technique which applies an increasing amplification to increasing spatial frequencies in the measured data. This mathematical approach to spatial frequency amplification cannot distinguish between signal and noise and therefore both are amplified equally. We report here a method in which tomographic resolution is improved by using very small detectors to selectively amplify the signal and not noise. Thus, this approach is referred to as the signal amplification technique (SAT). SAT can provide dramatic improvements in image resolution without increases in statistical noise or dose because increases in the cutoff frequency of the reconstruction algorithm are not required to improve image resolution. Alternatively, in cases where image counts are low, such as in rapid dynamic or receptor studies, statistical noise can be reduced by lowering the cutoff frequency while still maintaining the best possible image resolution. A possible system design for a positron CT system with SAT is described.

  3. Sensitive Method for Biomolecule Detection Utilizing Signal Amplification with Porphyrin Nanoparticles.

    PubMed

    Gibson, Lauren E; Wright, David W

    2016-06-01

    Disease diagnosis requires identification of biomarkers that occur in small quantities, making detection a difficult task. Effective diagnosis is an even greater challenge in low-resource areas of the world. Methods must be simple, stable, and sensitive so that tests can be easily administered and withstand uncontrolled environmental conditions. One approach to this issue is development of stable signal amplification strategies. In this work, we applied the nanocrystal-based signal amplification method to tetra(4-carboxyphenyl)porphyrin nanoparticles (TCPP NPs). The dissolution of the nanoparticle into thousands of porphyrin molecules results in amplified detection of the biomarker. By using nanoparticles as the signal-generating moiety, stability of the detection method is increased relative to commonly used enzyme-based assays. Additionally, the inherent fluorescent signal of TCPP molecules can be measured after nanoparticle dissolution. The ability to directly read the TCPP fluorescent signal increases assay simplicity by reducing the steps required for the test. This detection method was optimized by detecting rabbit IgG and then was applied to the detection of the malarial biomarker Plasmodium falciparum histidine-rich protein II (pfHRPII) from a complex matrix. The results for both biomarkers were assays with low picomolar limits of detection. PMID:27160976

  4. Signal amplification of glucosamine-6-phosphate based on ribozyme glmS.

    PubMed

    Zhao, Yongyun; Chen, Haodong; Du, Feng; Yasmeen, Afshan; Dong, Juan; Cui, Xin; Tang, Zhuo

    2014-12-15

    Ribozyme glmS based isothermal amplification assay is developed for the colorimetric detection of glucosamine-6-phosphate (GlcN6P). Upon binding to the metabolite target GlcN6P, self-cleavage of glmS ribozyme is initiated to release RNA fragment that can trigger the cascade signal amplification to release large amount of G-quadruplex DNAzymes as reporter for colorimetric detection. Given the importance of GlcN6P for cell wall biosynthesis, the glmS riboswitch has become a new drug target for the development of antibiotics. This assay not only offers a convenient detection of GlcN6P with high specificity and sensitivity, but also provides a platform for high-throughput screening of antibiotics based on glmS riboswitches. PMID:25038539

  5. Magnetic micro/nanoparticle flocculation-based signal amplification for biosensing

    PubMed Central

    Mzava, Omary; Taş, Zehra; İçöz, Kutay

    2016-01-01

    We report a time and cost efficient signal amplification method for biosensors employing magnetic particles. In this method, magnetic particles in an applied external magnetic field form magnetic dipoles, interact with each other, and accumulate along the magnetic field lines. This magnetic interaction does not need any biomolecular coating for binding and can be controlled with the strength of the applied magnetic field. The accumulation can be used to amplify the corresponding pixel area that is obtained from an image of a single magnetic particle. An application of the method to the Escherichia coli 0157:H7 bacteria samples is demonstrated in order to show the potential of the approach. A minimum of threefold to a maximum of 60-fold amplification is reached from a single bacteria cell under a magnetic field of 20 mT. PMID:27354793

  6. Magnetic micro/nanoparticle flocculation-based signal amplification for biosensing.

    PubMed

    Mzava, Omary; Taş, Zehra; İçöz, Kutay

    2016-01-01

    We report a time and cost efficient signal amplification method for biosensors employing magnetic particles. In this method, magnetic particles in an applied external magnetic field form magnetic dipoles, interact with each other, and accumulate along the magnetic field lines. This magnetic interaction does not need any biomolecular coating for binding and can be controlled with the strength of the applied magnetic field. The accumulation can be used to amplify the corresponding pixel area that is obtained from an image of a single magnetic particle. An application of the method to the Escherichia coli 0157:H7 bacteria samples is demonstrated in order to show the potential of the approach. A minimum of threefold to a maximum of 60-fold amplification is reached from a single bacteria cell under a magnetic field of 20 mT. PMID:27354793

  7. Lable-free quadruple signal amplification strategy for sensitive electrochemical p53 gene biosensing.

    PubMed

    Wang, Zonghua; Xia, Jianfei; Song, Daimin; Zhang, Feifei; Yang, Min; Gui, Rijun; Xia, Lin; Bi, Sai; Xia, Yanzhi

    2016-03-15

    A versatile label-free quadruple signal amplification biosensing platform for p53 gene (target DNA) detection was proposed. The chitosan-graphene (CS-GR) modified electrode with excellent electron transfer ability could provide a large specific surface for high levels of AuNPs-DNA attachment. The large amount of AuNPs could immobilize more capture probes and enhance the electrochemical signal with the excellent electrocatalytic activity. Furthermore, with the assist of N.BstNB I (the nicking endonuclease), target DNA could be reused and more G-quadruplex-hemin DNAzyme could be formed, allowing significant signal amplification in the presence of H2O2. Such strategy can enhance the oxidation-reduction reaction of adsorbed methylene blue (MB) and efficiently improve the sensitivity of the proposed biosensor. The morphologies of materials and the stepwise biosensor were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and cyclic voltammetry (CV). Differential pulse voltammetry (DPV) signals of MB provided quantitative measures of the concentrations of target DNA, with a linear calibration range of 1.0 × 10(-15)-1.0 × 10(-9)M and a detection limit of 3.0 × 10(-16)M. Moreover, the resulting biosensor also exhibited good specificity, acceptable reproducibility and stability, indicating that the present strategy was promising for broad potential application in clinic assay. PMID:26406456

  8. Signal amplification based on the local nonlinear Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Srivastava, Arpita; Gupta, Man Mohan; Medhekar, S.

    2012-03-01

    Using the phase modulation of spatial solitons, a new scheme for all-optical signal amplification has been proposed in this paper. The considered structure is composed of the nonlinear Mach-Zehnder interferometer (NMZI) with the straight control waveguide (CWG), the uniform nonlinear medium (NLM) and the linear output waveguide. The local NMZI functions like a phase shifter. The light-induced index changes in the local nonlinear MZI are responsible for the input beam routing in the uniform nonlinear medium. The coupling of the input beam to the output waveguide depends on its propagation direction in the NLM. It is shown that the signal launched at CWG can deflect the beam launched at the NMZI (input beam) and a modulated (amplified) output could be obtained at the output waveguide. Further, signal pulse may be reshaped by appropriately increasing the NLM length. In addition, amplification factor may be enhanced by increasing the NLM length and injecting an appropriate continuous wave beam along with the signal beam at CWG.

  9. Evolution and Design Governing Signal Precision and Amplification in a Bacterial Chemosensory Pathway

    PubMed Central

    Espinosa, Leon; Baronian, Grégory; Molle, Virginie; Mauriello, Emilia M. F.; Brochier-Armanet, Céline; Mignot, Tâm

    2015-01-01

    Understanding the principles underlying the plasticity of signal transduction networks is fundamental to decipher the functioning of living cells. In Myxococcus xanthus, a particular chemosensory system (Frz) coordinates the activity of two separate motility systems (the A- and S-motility systems), promoting multicellular development. This unusual structure asks how signal is transduced in a branched signal transduction pathway. Using combined evolution-guided and single cell approaches, we successfully uncoupled the regulations and showed that the A-motility regulation system branched-off an existing signaling system that initially only controlled S-motility. Pathway branching emerged in part following a gene duplication event and changes in the circuit structure increasing the signaling efficiency. In the evolved pathway, the Frz histidine kinase generates a steep biphasic response to increasing external stimulations, which is essential for signal partitioning to the motility systems. We further show that this behavior results from the action of two accessory response regulator proteins that act independently to filter and amplify signals from the upstream kinase. Thus, signal amplification loops may underlie the emergence of new connectivity in signal transduction pathways. PMID:26291327

  10. Thousand-fold fluorescent signal amplification for mHealth diagnostics.

    PubMed

    Balsam, Joshua; Rasooly, Reuven; Bruck, Hugh Alan; Rasooly, Avraham

    2014-01-15

    The low sensitivity of Mobile Health (mHealth) optical detectors, such as those found on mobile phones, is a limiting factor for many mHealth clinical applications. To improve sensitivity, we have combined two approaches for optical signal amplification: (1) a computational approach based on an image stacking algorithm to decrease the image noise and enhance weak signals, and (2) an optical signal amplifier utilizing a capillary tube array. These approaches were used in a detection system which includes multi-wavelength LEDs capable of exciting many fluorophores in multiple wavelengths, a mobile phone or a webcam as a detector, and capillary tube array configured with 36 capillary tubes for signal enhancement. The capillary array enables a ~100× increase in signal sensitivity for fluorescein, reducing the limit of detection (LOD) for mobile phones and webcams from 1000 nM to 10nM. Computational image stacking enables another ~10× increase in signal sensitivity, further reducing the LOD for webcam from 10nM to 1 nM. To demonstrate the feasibility of the device for the detection of disease-related biomarkers, adenovirus DNA labeled with SYBR green or fluorescein was analyzed by both our capillary array and a commercial plate reader. The LOD for the capillary array was 5 ug/mL, and that of the plate reader was 1 ug/mL. Similar results were obtained using DNA stained with fluorescein. The combination of the two signal amplification approaches enables a ~1000× increase in LOD for the webcam platform. This brings it into the range of a conventional plate reader while using a smaller sample volume (10 ul) than the plate reader requires (100 ul). This suggests that such a device could be suitable for biosensing applications where up to 10 fold smaller sample sizes are needed. The simple optical configuration for mHealth described in this paper employing the combined capillary and image processing signal amplification is capable of measuring weak fluorescent signals

  11. Amplification of optical signals in Bi{sub 12}TiO{sub 20} crystal by photorefractive surface waves

    SciTech Connect

    Khomenko, A.V.; Garcia-Weidner, A.; Kamshilin, A.A.

    1996-07-01

    We have demonstrated experimentally beam amplification by coupling between the signal beam and the photorefractive surfaces wave in Bi{sub 12}TiO{sub 20} crystal. A gain of 16,000 has been measured, with an output signal-to-noise ratio of {approx_gt}20 for weak input signals. {copyright} {ital 1996 Optical Society of America.}

  12. Fluorescent vesicles for signal amplification in reverse phase protein microarray assays.

    PubMed

    Bally, Marta; Syed, Shahida; Binkert, Andreas; Kauffmann, Ekkehard; Ehrat, Markus; Vörös, Janos

    2011-09-15

    Developments in microarray technology promise to lead to great advancements in the biomedical and biological field. However, implementation of these analytical tools often relies on signal amplification strategies that are essential to reach the sensitivity levels required for a variety of biological applications. This is true especially for reverse phase arrays where a complex biological sample is directly immobilized on the chip. We present a simple and generic method for signal amplification based on the use of antibody-tagged fluorescent vesicles as labels for signal generation. To assess the gain in assay sensitivity, we performed a model assay for the detection of rabbit immunoglobulin G (IgG) and compared the limit of detection (LOD) of the vesicle assay with the LOD of a conventional assay performed with fluorescent reporter molecules. We evaluated the improvements for two fluorescence-based transduction setups: a high-sensitivity microarray reader (ZeptoREADER) and a conventional confocal scanner. In all cases, our strategy led to an increase in sensitivity. However, gain in sensitivity widely depended on the type of illumination; whereas an approximately 2-fold increase in sensitivity was observed for readout based on evanescent field illumination, the contribution was as high as more than 200-fold for confocal scanning. PMID:21669176

  13. Catalytic signal amplification for the discrimination of ATP and ADP using functionalised gold nanoparticles.

    PubMed

    Pezzato, Cristian; Chen, Jack L-Y; Galzerano, Patrizia; Salvi, Michela; Prins, Leonard J

    2016-07-12

    Diagnostic assays that incorporate a signal amplification mechanism permit the detection of analytes with enhanced selectivity. Herein, we report a gold nanoparticle-based chemical system able to differentiate ATP from ADP by means of catalytic signal amplification. The discrimination between ATP and ADP is of relevance for the development of universal assays for the detection of enzymes which consume ATP. For example, protein kinases are a class of enzymes critical for the regulation of cellular functions, and act to modulate the activity of other proteins by transphosphorylation, transferring a phosphate group from ATP to give ADP as a byproduct. The system described here exploits the ability of cooperative catalytic head groups on gold nanoparticles to very efficiently catalyze chromogenic reactions such as the transphosphorylation of 2-hydroxypropyl-4-nitrophenyl phosphate (HPNPP). A series of chromogenic substrates have been synthesized and evaluated by means of Michaelis-Menten kinetics (compounds 2, 4-6). 2-Hydroxypropyl-(3-trifluoromethyl-4-nitro)phenyl phosphate (5) was found to display higher reactivity (kcat) and higher binding affinity (KM) when compared to HPNPP. This higher binding affinity allows phosphate 5 to compete with ATP and ADP to different extents for binding on the monolayer surface, thus enabling a catalytically amplified signal only when ATP is absent. Overall, this represents a viable new approach for monitoring the conversion of ATP into ADP with high sensitivity. PMID:27336846

  14. Electrochemical signal amplification for immunosensor based on 3D interdigitated array electrodes.

    PubMed

    Han, Donghoon; Kim, Yang-Rae; Kang, Chung Mu; Chung, Taek Dong

    2014-06-17

    We devised an electrochemical redox cycling based on three-dimensional interdigitated array (3D IDA) electrodes for signal amplification to enhance the sensitivity of chip-based immunosensors. The 3D IDA consists of two closely spaced parallel indium tin oxide (ITO) electrodes that are positioned not only on the bottom but also the ceiling, facing each other along a microfluidic channel. We investigated the signal intensities from various geometric configurations: Open-2D IDA, Closed-2D IDA, and 3D IDA through electrochemical experiments and finite-element simulations. The 3D IDA among the four different systems exhibited the greatest signal amplification resulting from efficient redox cycling of electroactive species confined in the microchannel so that the faradaic current was augmented by a factor of ∼100. We exploited the enhanced sensitivity of the 3D IDA to build up a chronocoulometric immunosensing platform based on the sandwich enzyme-linked immunosorbent assay (ELISA) protocol. The mouse IgGs on the 3D IDA showed much lower detection limits than on the Closed-2D IDA. The detection limit for mouse IgG measured using the 3D IDA was ∼10 fg/mL, while it was ∼100 fg/mL for the Closed-2D IDA. Moreover, the proposed immunosensor system with the 3D IDA successfully worked for clinical analysis as shown by the sensitive detection of cardiac troponin I in human serum down to 100 fg/mL. PMID:24842332

  15. Highly Sensitive Colorimetric Cancer Cell Detection Based on Dual Signal Amplification.

    PubMed

    Yu, Tao; Dai, Pan-Pan; Xu, Jing-Juan; Chen, Hong-Yuan

    2016-02-24

    Facile and efficient detection of cancer cells at their preclinical stages is one of the central challenges in cancer diagnostics. A direct, rapid, highly sensitive and specific biosensor for detection of cancer biomarkers is desirable in early diagnosis and prognosis of cancer. In this work, we developed, for the first time, an easy and intuitive dispersion-dominated colorimetric strategy for cancer cell detection based on combining multi-DNA released from an aptamer scaffold with cyclic enzymatic amplification, which was triggered by aptamer DNA conformational switch and demonstrated by non-cross-linking gold nanoparticles (Au NPs) aggregation. First, five kinds of messenger DNAs (mDNAs) were aligned on the cancer cell aptamers modified on magnetic beads (MBs) to form mDNAs-Apt-MBs biocompatible nanosensors. In the presence of target cells, the aptamer would bind to the receptors on the cell membranes, and mDNAs would be released, resulting in the first amplification that one biological binding event would cause the release of multiple kinds of mDNAs simultaneously. After magnetic separation, the released mDNAs were introduced into the cyclic enzymatic amplification to cleave more single strand DNA (ssDNA) fragments. Instead of modification of Au NPs, these fragments and mDNAs could be adsorbed on the surface of Au NPs to prevent particle aggregation and ensure the stability and color of solution in high salt environments. The linear response for HL-60 cells in a concentration range from 10 to 10(4) cells was obtained with a detection limit of four cells in buffer solution. Moreover, the feasibility of the proposed strategy was demonstrated in a diluted serum sample. This dual signal amplification method can be extended to other types of cancer cells, which has potential application in point-of-care cancer diagnosis. PMID:26824724

  16. Development of Fluorescent Polymerization-based Signal Amplification for Sensitive and Non-enzymatic Biodetection in Antibody Microarrays

    PubMed Central

    Avens, Heather J.; Bowman, Christopher N.

    2009-01-01

    Antibody microarrays are a critical tool for proteomics, requiring broad, highly sensitive detection of numerous low abundance biomarkers. Fluorescent polymerization-based amplification (FPBA) is presented as a novel, non-enzymatic signal amplification method that takes advantage of the chain-reaction nature of radical polymerization to achieve a highly amplified fluorescent response. A streptavidin-eosin conjugate localizes eosin photoinitiators for polymerization on the chip where biotinylated target protein is bound. The chip is contacted with acrylamide as a monomer, N-methyldiethanolamine as a coinitiator and yellow/green fluorescent nanoparticles (NPs) which, upon initiation, combine to form a macroscopically visible and highly fluorescent film. The rapid polymerization kinetics and the presence of cross-linker favor entrapment of the fluorescent NPs in the polymer, enabling highly sensitive fluorescent biodetection. This method is demonstrated as being appropriate for antibody microarrays and is compared to detection approaches which utilize streptavidin-FITC (SA-FITC) and streptavidin-labeled yellow/green NPs (SA-NPs). It is found that FPBA is able to detect 0.16 (+/− 0.01) biotin-antibody/µm2 (or 40 zeptomole surface-bound target molecules), while SA-FITC has a limit of detection of 31 (+/− 1) biotin-antibody/µm2 and SA-NPs fail to achieve any significant signal under the conditions evaluated here. Further, FPBA in conjunction with fluorescent stereomicroscopy yields equal or better sensitivity compared to fluorescent detection of SA-eosin using a much more costly microarray scanner. By facilitating highly sensitive detection, FPBA is expected to enable detection of low abundance antigens and also make possible a transition towards less expensive fluorescence detection instrumentation. PMID:19508906

  17. Development of fluorescent polymerization-based signal amplification for sensitive and non-enzymatic biodetection in antibody microarrays.

    PubMed

    Avens, Heather J; Bowman, Christopher N

    2010-01-01

    Antibody microarrays are a critical tool for proteomics, requiring broad, highly sensitive detection of numerous low abundance biomarkers. Fluorescent polymerization-based amplification (FPBA) is presented as a novel, non-enzymatic signal amplification method that takes advantage of the chain-reaction nature of radical polymerization to achieve a highly amplified fluorescent response. A streptavidin-eosin conjugate localizes eosin photoinitiators for polymerization on the chip where biotinylated target protein is bound. The chip is contacted with acrylamide as a monomer, N-methyldiethanolamine as a coinitiator and yellow/green fluorescent nanoparticles (NPs) which, upon initiation, combine to form a macroscopically visible and highly fluorescent film. The rapid polymerization kinetics and the presence of cross-linker favor entrapment of the fluorescent NPs in the polymer, enabling highly sensitive fluorescent biodetection. This method is demonstrated as being appropriate for antibody microarrays and is compared to detection approaches which utilize streptavidin-fluorescein isothiocyanate (SA-FITC) and streptavidin-labeled yellow/green NPs (SA-NPs). It is found that FPBA is able to detect 0.16 + or - 0.01 biotin-antibody microm(-2) (or 40 zmol surface-bound target molecules), while SA-FITC has a limit of detection of 31 + or - 1 biotin-antibody microm(-2) and SA-NPs fail to achieve any significant signal under the conditions evaluated here. Further, FPBA in conjunction with fluorescent stereomicroscopy yields equal or better sensitivity compared to fluorescent detection of SA-eosin using a much more costly microarray scanner. By facilitating highly sensitive detection, FPBA is expected to enable detection of low abundance antigens and also make possible a transition towards less expensive fluorescence detection instrumentation. PMID:19508906

  18. An electrochemical biosensor for sensitive detection of microRNA-155: combining target recycling with cascade catalysis for signal amplification.

    PubMed

    Wu, Xiaoyan; Chai, Yaqin; Zhang, Pu; Yuan, Ruo

    2015-01-14

    In this work, a new electrochemical biosensor based on catalyzed hairpin assembly target recycling and cascade electrocatalysis (cytochrome c (Cyt c) and alcohol oxidase (AOx)) for signal amplification was constructed for highly sensitive detection of microRNA (miRNA). It is worth pointing out that target recycling was achieved only based on strand displacement process without the help of nuclease. Moreover, porous TiO2 nanosphere was synthesized, which could offer more surface area for Pt nanoparticles (PtNPs) enwrapping and enhance the amount of immobilized DNA strand 1 (S1) and Cyt c accordingly. With the mimicking sandwich-type reaction, the cascade catalysis amplification strategy was carried out by AOx catalyzing ethanol to acetaldehyde with the concomitant formation of high concentration of H2O2, which was further electrocatalyzed by PtNPs and Cyt c. This newly designed biosensor provided a sensitive detection of miRNA-155 from 0.8 fM to 1 nM with a relatively low detection limit of 0.35 fM. PMID:25495913

  19. DNA-AuNPs based signal amplification for highly sensitive detection of DNA methylation, methyltransferase activity and inhibitor screening.

    PubMed

    Jing, Xiaoying; Cao, Xianqing; Wang, Li; Lan, Tian; Li, Yiyan; Xie, Guoming

    2014-08-15

    A sensitive and selective electrochemical method was developed for the detection of DNA methylation, determination of DNA methyltransferase (MTase) activity and screening of MTase inhibitor. Methylene blue (MB) was employed as electrochemical indicator and DNA-modified gold nanoparticles (AuNPs) were used as signal amplification unit because the DNA strands in this composite have strong adsorption ability for MB. First, the thiolated single-stranded DNA S1 was self-assembled on gold electrode, hybridization between the lower portion of DNA S1 and its complementary DNA S2 formed an identical double-stranded tetranucleotide target sequence for both DNA adenine methylation (Dam) MTase and methylation-resistant endonuclease Mbo I, then the upper portion of DNA S1 was hybridized with its complementary DNA S3 modified on AuNPs to bring the DNA S3-AuNPs amplification units onto the electrode. The DNA S1/S2/S3-AuNPs bioconjugate has lots of DNA strands, and they can adsorb abundant MB. Mbo I endounuclease could not cleave the identical target sequence after it was methylated by Dam MTase. On the contrary, the sequence without methylation could be cleaved, which would decrease the amount of adsorbed MB. The presence of redox-active MB was detected electrochemically by differential pulse voltammetry (DPV). Thus, the activity of Dam MTase and methylation status were sensitively converted to the DNA S3-AuNPs amplified DPV signals. The DPV signal demonstrated a linear relationship with logarithm of Dam concentration ranging from 0.075 to 30U/mL, achieving a detection limit of 0.02U/mL (S/N=3). Also, screening of Dam MTase inhibitor 5-fluorouracil was successfully investigated using this fabricated sensor. PMID:24613968

  20. A FRET based aptasensor coupled with non-enzymatic signal amplification for mercury (II) ion detection.

    PubMed

    Chu-Mong, Ketsarin; Thammakhet, Chongdee; Thavarungkul, Panote; Kanatharana, Proespichaya; Buranachai, Chittanon

    2016-08-01

    In this work, the idea of incorporating a non-enzymatic signal amplification with a regular aptasensor was tested. In this proof of principle, the sensor was designed for the detection of mercury (II) ions (Hg(2+)) based on the Förster Resonance Energy Transfer (FRET), and the catalyzed hairpin assembly (CHA) technique that was used as the signal amplification method. This sensor comprised a mercury aptamer-catalyst complex (Apt-C) and two types of hairpin DNA: H1 labeled with fluorescein and H2 labeled with tetramethylrhodamine. In the presence of Hg(2+), two facing thymine bases in the mercury aptamer strand were coordinated with one mercury ion. This caused the release of the catalyst for the catalyzed hairpin assembly (CHA) reaction that turned H1 and H2 hairpins into H1-H2 hybrids. FRET was then used to report the hairpin-duplex transformation. The sensor showed excellent specificity towards Hg(2+) over other possible interfering cations present at even a 100 fold greater concentrations. It had a linear range of 10.0-200.0nM, and a good detection limit of 7.03±0.18nM, which is lower than the regulatory mercury limit for drinking water (10nM or 2ppb). The sensor was used to detect spiked Hg(2+) in nine real surface water samples collected from three different areas. Acceptable recoveries and small standard deviations indicated that the sensor was practically applicable, and the proposed idea to incorporate a CHA amplification in a regular aptasensor was not only feasible but beneficial. The same principles can be applied to develop sensors for various different targets. PMID:27216687

  1. Signal amplification using colloidal gold in a biolayer interferometry-based immunosensor for the mycotoxin deoxynivalenol.

    PubMed

    Maragos, C M

    2012-01-01

    Deoxynivalenol (DON) is a toxin produced by certain species of Fusarium fungi that can infest wheat, barley and corn. The fungi cause diseases in crops worldwide and some of the secondary metabolites, such as DON, can adversely affect animal health and food safety. To monitor DON in wheat rapidly, a biosensor using the principle of biolayer interferometry (BLI) was developed. The signal from the sensor was substantially amplified through the use of a primary antibody-colloidal gold conjugate. The amplification was much greater in the presence of wheat matrix than in buffered solution, suggesting matrix components may have contributed to the enhancement. The improved signal provided by the amplification allowed for the development of rapid qualitative and quantitative assays. The limit of detection of the method was 0.09 mg kg(-1); the limit of quantitation was 0.35 mg kg(-1). Recovery from wheat spiked over the range from 0.2 to 5 mg kg(-1) averaged 103% (RSD = 12%). The quantitative assay compared favourably (r(2) = 0.9698) with a reference chromatographic method for 40 naturally contaminated wheats. The qualitative assay was able to classify accurately the same group of 40 samples as either above or below a 0.5 mg kg(-1) threshold. These results suggest that the BLI technique can be used to measure DON in wheat rapidly. PMID:22489824

  2. Enzymatic Amplification of DNA/RNA Hybrid Molecular Beacon Signaling in Nucleic Acid Detection

    PubMed Central

    Jacroux, Thomas; Rieck, Daniel C.; Cui, Rong; Ouyang, Yexin; Dong, Wen-Ji

    2012-01-01

    A rapid assay operable under isothermal or non-isothermal conditions is described wherein the sensitivity of a typical molecular beacon (MB) system is improved by utilizing thermostable RNase H to enzymatically cleave an MB comprised of a DNA stem and RNA loop (R/D-MB). Upon hybridization of the R/D-MB to target DNA, there was a modest increase in fluorescence intensity (~5.7x above background) due to an opening of the probe and concomitant reduction in the Förster resonance energy transfer efficiency. Addition of thermostable RNase H resulted in the cleavage of the RNA loop which eliminated energy transfer. The cleavage step also released bound target DNA, enabling it to bind to another R/D-MB probe and rendering the approach a cyclic amplification scheme. Full processing of R/D-MBs maximized the fluorescence signal to the fullest extent possible (12.9x above background), resulting in a ~2–2.8 fold increase in the signal-to-noise ratio observed isothermally at 50 °C following the addition of RNase H. The probe was also used to monitor real-time PCR reactions by measuring enhancement of donor fluorescence upon R/D-MB binding to amplified pUC19 template dilutions. Hence, the R/D-MB-RNase H scheme can be applied to a broad range of nucleic acid amplification methods. PMID:23000602

  3. Enzymatic amplification of DNA/RNA hybrid molecular beacon signaling in nucleic acid detection.

    PubMed

    Jacroux, Thomas; Rieck, Daniel C; Cui, Rong; Ouyang, Yexin; Dong, Wen-Ji

    2013-01-15

    A rapid assay operable under isothermal or nonisothermal conditions is described, where the sensitivity of a typical molecular beacon (MB) system is improved by using thermostable RNase H to enzymatically cleave an MB composed of a DNA stem and an RNA loop (R/D-MB). On hybridization of the R/D-MB to target DNA, there was a modest increase in fluorescence intensity (~5.7× above background) due to an opening of the probe and a concomitant reduction in the Förster resonance energy transfer efficiency. The addition of thermostable RNase H resulted in the cleavage of the RNA loop, which eliminated energy transfer. The cleavage step also released bound target DNA, enabling it to bind to another R/D-MB probe and rendering the approach a cyclic amplification scheme. Full processing of R/D-MBs maximized the fluorescence signal to the fullest extent possible (12.9× above background), resulting in an approximately 2- to 2.8-fold increase in the signal-to-noise ratio observed isothermally at 50 °C following the addition of RNase H. The probe was also used to monitor real-time polymerase chain reactions by measuring enhancement of donor fluorescence on R/D-MB binding to amplified pUC19 template dilutions. Hence, the R/D-MB-RNase H scheme can be applied to a broad range of nucleic acid amplification methods. PMID:23000602

  4. A graphene oxide-based enzyme-free signal amplification platform for homogeneous DNA detection.

    PubMed

    Zhang, Zhen; Liu, Yufei; Ji, Xinghu; Xiang, Xia; He, Zhike

    2014-10-01

    A graphene oxide (GO) based enzyme-free signal amplification platform for homogeneous DNA sensing is developed with simplicity and high sensitivity. In the absence of the target DNA, labeled hairpin probe 1 (H1) and probe 2 (H2) were adsorbed on the surface of GO, resulting in the fluorescence quenching of the dyes and minimizing the background fluorescence. The addition of the target DNA facilitated the formation of double-stranded DNA (dsDNA) between H1 and H2, causing the probes to separate from GO and release the target DNA through a strand displacement reaction. Meanwhile, the whole reaction started anew. This is an excellent isothermal signal amplification technique without the involvement of enzymes. By monitoring the change of the fluorescence intensity, the target DNA not only can be determined in buffer solution, but also can be detected in 1% serum solution spiked with a series of concentrations of the target DNA. In addition, the consumption amount of the probes in this method is lower than that in traditional molecular beacon methods. PMID:25058563

  5. A cascade signal amplification strategy for surface enhanced Raman spectroscopy detection of thrombin based on DNAzyme assistant DNA recycling and rolling circle amplification.

    PubMed

    Gao, Fenglei; Du, Lili; Tang, Daoquan; Lu, Yao; Zhang, Yanzhuo; Zhang, Lixian

    2015-04-15

    A sensitive protocol for surface enhanced Raman spectroscopy (SERS) detection of thrombin is designed with R6G-Ag NPs as a signal tag by combining DNAzyme assistant DNA recycling and rolling circle amplification (RCA). Molecular beacon (MB) as recognition probe immobilizes on the glass slides and performs the amplification procedure. After thrombin-induced structure-switching DNA hairpins of probe 1, the DNAzyme is liberated from the caged structure, which hybridizes with the MB for cleavage of the MB in the presence of cofactor Zn(2+) and initiates the DNA recycling process, leading to the cleavage of a large number of MB and the generation of numerous primers for triggering RCA reaction. The long amplified RCA product which contained hundreds of tandem-repeat sequences, which can bind with oligonucleotide functionalized Ag NPs reporters. The attached signal tags can be easily read out by SERS. Because of the cascade signal amplification, these newly designed protocols provides a sensitive SERS detection of thrombin down to the femolar level (2.3fM) with a linear range of 5 orders of magnitude (from 10(-14) to 10(-9)M) and have high selectivity toward its target protein. The proposed method is expected to be a good clinical tool for the diagnosis of a thrombotic disease. PMID:25497982

  6. The dynamics of signal amplification by macromolecular assemblies for the control of chromosome segregation

    PubMed Central

    Lee, Semin; Bolanos-Garcia, Victor M.

    2014-01-01

    The control of chromosome segregation relies on the spindle assembly checkpoint (SAC), a complex regulatory system that ensures the high fidelity of chromosome segregation in higher organisms by delaying the onset of anaphase until each chromosome is properly bi-oriented on the mitotic spindle. Central to this process is the establishment of multiple yet specific protein-protein interactions in a narrow time-space window. Here we discuss the highly dynamic nature of multi-protein complexes that control chromosome segregation in which an intricate network of weak but cooperative interactions modulate signal amplification to ensure a proper SAC response. We also discuss the current structural understanding of the communication between the SAC and the kinetochore; how transient interactions can regulate the assembly and disassembly of the SAC as well as the challenges and opportunities for the definition and the manipulation of the flow of information in SAC signaling. PMID:25324779

  7. Toward Biocompatible Nuclear Hyperpolarization Using Signal Amplification by Reversible Exchange: Quantitative in Situ Spectroscopy and High-Field Imaging

    PubMed Central

    2014-01-01

    Signal amplification by reversible exchange (SABRE) of a substrate and parahydrogen at a catalytic center promises to overcome the inherent insensitivity of magnetic resonance. In order to apply the new approach to biomedical applications, there is a need to develop experimental equipment, in situ quantification methods, and a biocompatible solvent. We present results detailing a low-field SABRE polarizer which provides well-controlled experimental conditions, defined spins manipulations, and which allows in situ detection of thermally polarized and hyperpolarized samples. We introduce a method for absolute quantification of hyperpolarization yield in situ by means of a thermally polarized reference. A maximum signal-to-noise ratio of ∼103 for 148 μmol of substance, a signal enhancement of 106 with respect to polarization transfer field of SABRE, or an absolute 1H-polarization level of ≈10–2 is achieved. In an important step toward biomedical application, we demonstrate 1H in situ NMR as well as 1H and 13C high-field MRI using hyperpolarized pyridine (d3) and 13C nicotinamide in pure and 11% ethanol in aqueous solution. Further increase of hyperpolarization yield, implications of in situ detection, and in vivo application are discussed. PMID:24397559

  8. Long-distance communication and signal amplification in systemic acquired resistance.

    PubMed

    Shah, Jyoti; Zeier, Jürgen

    2013-01-01

    Systemic acquired resistance (SAR) is an inducible defense mechanism in plants that confers enhanced resistance against a variety of pathogens. SAR is activated in the uninfected systemic (distal) organs in response to a prior (primary) infection elsewhere in the plant. SAR is associated with the activation of salicylic acid (SA) signaling and the priming of defense responses for robust activation in response to subsequent infections. The activation of SAR requires communication by the primary infected tissues with the distal organs. The vasculature functions as a conduit for the translocation of factors that facilitate long-distance intra-plant communication. In recent years, several metabolites putatively involved in long-distance signaling have been identified. These include the methyl ester of SA (MeSA), the abietane diterpenoid dehydroabietinal (DA), the dicarboxylic acid azelaic acid (AzA), and a glycerol-3-phosphate (G3P)-dependent factor. Long-distance signaling by some of these metabolites also requires the lipid-transfer protein DIR1 (DEFECTIVE IN INDUCED RESISTANCE 1). The relative contribution of these factors in long-distance signaling is likely influenced by environmental conditions, for example light. In the systemic leaves, the AGD2-LIKE DEFENSE RESPONSE PROTEIN1 (ALD1)-dependent production of the lysine catabolite pipecolic acid (Pip), FLAVIN-DEPENDENT MONOOXYGENASE1 (FMO1) signaling, as well as SA synthesis and downstream signaling are required for the activation of SAR. This review summarizes the involvement and interaction between long-distance SAR signals and details the recently discovered role of Pip in defense amplification and priming that allows plants to acquire immunity at the systemic level. Recent advances in SA signaling and perception are also highlighted. PMID:23440336

  9. Electrochemical sensor for glutathione detection based on mercury ion triggered hybridization chain reaction signal amplification.

    PubMed

    Wang, Yonghong; Jiang, Lun; Leng, Qinggang; Wu, Yaohui; He, Xiaoxiao; Wang, Kemin

    2016-03-15

    In this work, we design a new simple and highly sensitive strategy for electrochemical detection of glutathione (GSH) via mercury ion (Hg(2+)) triggered hybridization chain reaction (HCR) signal amplification. It is observed that in the absence of GSH, a specific thymine-Hg(2+)-thymine (T-Hg(2+)-T) coordination can fold into hairpin structures. While in the presence of GSH, it thus can be chelated with Hg(2+), resulting in Hg(2+) released from the T-Hg(2+)-T hairpin complex which then forms into ssDNA structure to further hybridize with the surface-immobilized capture DNA probe on the gold electrode with a sticky tail left. The presence of two hairpin helper probes through HCR leads to the formation of extended dsDNA superstructure on the electrode surface, which therefore causes the intercalation of numerous electroactive species ([Ru(NH3)6](3+)) into the dsDNA grooves, followed by a significantly amplified signal output whose intensity is related to the concentration of the GSH. Taking advantage of merits of enzyme-free amplification power of the HCR, the inherent high sensitivity of the electrochemical technique, and label-free detection which utilizes an electroactive species as a signaling molecule that binds to the anionic phosphate backbone of DNA strands via electrostatic force, not only does the proposed strategy enable sensitive detection of GSH, but show high selectivity against other amino acid, making our method a simple and sensitive addition to the amplified GSH detection. PMID:26528805

  10. Nearly noiseless amplification of microwave signals with a Josephson parametric amplifier

    NASA Astrophysics Data System (ADS)

    Castellanos-Beltran, Manuel

    2009-03-01

    A degenerate parametric amplifier transforms an incident coherent state by amplifying one of its quadrature components while deamplifying the other. This transformation, when performed by an ideal parametric amplifier, is completely deterministic and reversible; therefore the amplifier in principle can be noiseless. We attempt to realize a noiseless amplifier of this type at microwave frequencies with a Josephson parametric amplifier (JPA). To this end, we have built a superconducting microwave cavity containing many dc-SQUIDs. This arrangement creates a non-linear medium in a cavity and it is closely analogous to an optical parametric amplifier. In my talk, I will describe the current performance of this circuit, where I show I can amplify signals with less added noise than a quantum-limited amplifier that amplifies both quadratures. In addition, the JPA also squeezes the electromagnetic vacuum fluctuations by 10 dB. Finally, I will discuss our effort to put two such amplifiers in series in order to undo the first stage of squeezing with a second stage of amplification, demonstrating that the amplification process is truly reversible.[4pt] M. A. Castellanos-Beltran, K. D. Irwin, G. C. Hilton, L. R. Vale and K. W. Lehnert, Nature Physics, published on line, http://dx.doi.org/10.1038/nphys1090 (2008).

  11. Electrochemical detection of protein kinase activity based on carboxypeptidase Y digestion triggered signal amplification.

    PubMed

    Yin, Huanshun; Wang, Xinxu; Guo, Yunlong; Zhou, Yunlei; Ai, Shiyun

    2015-04-15

    An effective assay method for monitoring protein kinase activity and screening inhibitors is greatly beneficial to kinase-related drug discovery, early diagnosis of diseases, and therapeutic effect evaluation. Herein, we develop a simple electrochemical method for detecting the activity of casein kinase II (CK2) based on phosphorylation against carboxypeptidase Y (CPY) digestion triggered signal amplification, where CK2 catalyzed phosphorylation event protects the substrate peptide from the digestion of CPY, maintains the repulsive force of the substrate peptide towards the redox probe, and results in a weak electrochemical signal. Whereas, without phosphorylation, the substrate peptide is digested by CPY and a strong electrochemical signal is obtained. The detection feasibility is demonstrated for the assay of CK2 activity with low detection limit of 0.047unit/mL. Moreover, the biosensor was used for the analysis of kinase inhibition. Based on the electrochemical signal dependent inhibitor concentration, the IC50 value of ellagic acid was estimated to be 39.77nM. The proposed method is also successfully applied to analyze CK2 activity in cell lysates, proving the applicability in complex biological samples. PMID:25460885

  12. "Signal-on" photoelectrochemical biosensor for sensitive detection of human T-Cell lymphotropic virus type II DNA: dual signal amplification strategy integrating enzymatic amplification with terminal deoxynucleotidyl transferase-mediated extension.

    PubMed

    Shen, Qingming; Han, Li; Fan, Gaochao; Zhang, Jian-Rong; Jiang, Liping; Zhu, Jun-Jie

    2015-01-01

    A novel "signal-on" photoelectrochemical (PEC) biosensor for sensitive detection of human T-cell lymphotropic virus type II (HTLV-II) DNA was developed on the basis of enzymatic amplification coupled with terminal deoxynucleotidyl transferase (TdT)-mediated extension strategy. The intensity of the photocurrent signal was proportional to the concentration of the HTLV-II DNA-target DNA (tDNA) by dual signal amplification. In this protocol, GR-CdS:Mn/ZnS nanocomposites were used as photoelectric conversion material, while pDNA was used as the tDNA recognizing unit. Moreover, the TdT-mediated extension and the enzymatic signal amplification technique were used to enhance the sensitivity of detection. Using this novel dual signal amplification strategy, the prototype of PEC DNA sensor can detect as low as ∼0.033 fM of HTLV-II DNA with a linear range of 0.1-5000 fM, with excellent differentiation ability even for single-base mismatches. This PEC DNA assay opens a promising platform to detect various DNA targets at ultralow levels for early diagnoses of different diseases. PMID:25871300

  13. Sub-femtomolar electrochemical detection of DNA using surface circular strand-replacement polymerization and gold nanoparticle catalyzed silver deposition for signal amplification.

    PubMed

    Gao, Fenglei; Zhu, Zhu; Lei, Jianping; Geng, Yao; Ju, Huangxian

    2013-01-15

    A highly sensitive method was developed for detection of target DNA. This method combined circular strand-displacement polymerization (CSRP) with silver enhancement to achieve dual signal amplification. After molecular beacon (MB) hybridized with target DNA, the reporter gold nanoparticle (Au NPs) was attached to an electrode surface by hybridization between Au NP labeled primer and stem part of the MB to initiate a polymerization of DNA strand, which led to the release of target and another polymerization cycle. Thus the CSRP produced the multiplication of target-related reporter Au NPs on the surface. The Au NPs then catalyzed silver deposition for subsequent stripping analysis of silver. The dual signal amplification offered a dramatic enhancement of the stripping response. This signal could discriminate perfect matched target DNA from 1-base mismatch DNA. The dynamic range of the sequence-specific DNA detection was from 10(-16) to 10(-12)mol L(-1) with a detection limit down to sub-femtomolar level. This proposed method exhibited an efficient amplification performance, and would open new opportunities for sensitive detection of other biorecognition events. PMID:22883748

  14. A new architecture for neural signal amplification in implantable brain machine interfaces.

    PubMed

    ur Rehman, Sami; Kamboh, Awais M

    2013-01-01

    This paper reports a new architecture for variable gain-bandwidth amplification of neural signals to be used in implantable multi-channel recording systems. The two most critical requirements in such a front-end circuit are low power consumption and chip area, especially as number of channels increases. The presented architecture employs a single super-performing amplifier, with tunable gain and bandwidth, combined with several low-key preamplifiers and multiplexors for multi-channel recordings. This is in contrast to using copies of high performing amplifier for each channel as is typically reported in earlier literature. The resulting circuits consume lower power and require smaller area as compared to existing designs. Designed in 0.5 µmCMOS, the 8-channel prototype can simultaneously record Local Field Potentials and neural spikes, with an effective power consumption of 3.5 µW per channel and net core area of 0.407 mm(2). PMID:24110295

  15. NMR Signal Amplification by Reversible Exchange of Sulfur-Heterocyclic Compounds Found In Petroleum

    PubMed Central

    Coffey, Aaron M.; Goodson, Boyd M.; Chekmenev, Eduard Y.

    2016-01-01

    NMR hyperpolarization via Signal Amplification by Reversible Exchange (SABRE) was employed to investigate the feasibility of enhancing the NMR detection sensitivity of sulfur-heterocycles (specifically 2-methylthiophene and dibenzothiophenes), a family of compounds typically found in petroleum and refined petroleum products. SABRE hyperpolarization of sulfur-heterocycles (conducted in seconds) offers potential advantages of providing structural information about sulfur-containing contaminants in petroleum, thereby informing petroleum purification and refining to minimize sulfur content in refined products such as gasoline. Moreover, NMR spectroscopy sensitivity gains endowed by hyperpolarization potentially allows for performing structural assays using inexpensive, low-magnetic-field (ca. 1 T) high-resolution NMR spectrometers ideally suited for industrial applications in the field. PMID:27500206

  16. A simple colorimetric DNA detection by target-induced hybridization chain reaction for isothermal signal amplification.

    PubMed

    Ma, Cuiping; Wang, Wenshuo; Mulchandani, Ashok; Shi, Chao

    2014-07-15

    A novel DNA detection method is presented based on a gold nanoparticle (AuNP) colorimetric assay and hybridization chain reaction (HCR). In this method, target DNA hybridized with probe DNA modified on AuNP, and triggered HCR. The resulting HCR products with a large number of negative charges significantly enhanced the stability of AuNPs, inhibiting aggregation of AuNPs at an elevated salt concentration. The approach was highly sensitive and selective. Using this enzyme-free and isothermal signal amplification method, we were able to detect target DNA at concentrations as low as 0.5 nM with the naked eye. Our method also has great potential for detecting other analytes, such as metal ions, proteins, and small molecules, if the target analytes could make HCR products attach to AuNPs. PMID:24780220

  17. ASC filament formation serves as a signal amplification mechanism for inflammasomes

    PubMed Central

    Dick, Mathias S.; Sborgi, Lorenzo; Rühl, Sebastian; Hiller, Sebastian; Broz, Petr

    2016-01-01

    A hallmark of inflammasome activation is the ASC speck, a micrometre-sized structure formed by the inflammasome adaptor protein ASC (apoptosis-associated speck-like protein containing a CARD), which consists of a pyrin domain (PYD) and a caspase recruitment domain (CARD). Here we show that assembly of the ASC speck involves oligomerization of ASCPYD into filaments and cross-linking of these filaments by ASCCARD. ASC mutants with a non-functional CARD only assemble filaments but not specks, and moreover disrupt endogenous specks in primary macrophages. Systematic site-directed mutagenesis of ASCPYD is used to identify oligomerization-deficient ASC mutants and demonstrate that ASC speck formation is required for efficient processing of IL-1β, but dispensable for gasdermin-D cleavage and pyroptosis induction. Our results suggest that the oligomerization of ASC creates a multitude of potential caspase-1 activation sites, thus serving as a signal amplification mechanism for inflammasome-mediated cytokine production. PMID:27329339

  18. Weak signal amplification and detection by higher-order sensory neurons.

    PubMed

    Jung, Sarah N; Longtin, Andre; Maler, Leonard

    2016-04-01

    Sensory systems must extract behaviorally relevant information and therefore often exhibit a very high sensitivity. How the nervous system reaches such high sensitivity levels is an outstanding question in neuroscience. Weakly electric fish (Apteronotus leptorhynchus/albifrons) are an excellent model system to address this question because detailed background knowledge is available regarding their behavioral performance and its underlying neuronal substrate. Apteronotus use their electrosense to detect prey objects. Therefore, they must be able to detect electrical signals as low as 1 μV while using a sensory integration time of <200 ms. How these very weak signals are extracted and amplified by the nervous system is not yet understood. We studied the responses of cells in the early sensory processing areas, namely, the electroreceptor afferents (EAs) and pyramidal cells (PCs) of the electrosensory lobe (ELL), the first-order electrosensory processing area. In agreement with previous work we found that EAs cannot encode very weak signals with a spike count code. However, PCs can encode prey mimic signals by their firing rate, revealing a huge signal amplification between EAs and PCs and also suggesting differences in their stimulus encoding properties. Using a simple leaky integrate-and-fire (LIF) model we predict that the target neurons of PCs in the midbrain torus semicircularis (TS) are able to detect very weak signals. In particular, TS neurons could do so by assuming biologically plausible convergence rates as well as very simple decoding strategies such as temporal integration, threshold crossing, and combining the inputs of PCs. PMID:26843601

  19. Dual-primer self-generation SERS signal amplification assay for PDGF-BB using label-free aptamer.

    PubMed

    Ye, SuJuan; Zhai, XiaoMo; Wu, YanYing; Kuang, ShaoPing

    2016-05-15

    Highly sensitive detection of proteins, especially those associated with cancers, is essential to biomedical research as well as clinical diagnosis. In this work, a simple and novel one-two-three signal amplification surface-enhanced Raman scattering (SERS) method for the detection of protein is fabricated by using label-free aptamer and dual-primer self-generation. Platelet-derived growth factor B-chain (PDGF-BB) is selected as the model protein. The one-two-three cascade DNA amplification means one target-aptamer binding event, two hairpin DNA switches and three DNA amplification reactions. This strategy possesses some remarkable features compared to conventional signal amplification methods: (i) A smart probe including a label-free aptamer is fabricated, for suitable hybridization without hindering the affinity of the aptamer toward its target. (ii) Using the unique structure switch of the aptamer and cooperator, a one-two-three working mode is developed to amplify the SERS signal. The amplification efficiency is enhanced. Given the unique and attractive characteristics, a simple and universal strategy is designed to accomplish ultrasensitive detection of proteins. The detection limit of PDGF-BB via SERS detection is 0.42 pM, with the linear range from 1.0×10(-12)M to 10(-8)M. It is potentially universal because the aptamer can be easily designed for biomolecules whose aptamers undergo similar conformational changes. PMID:26703991

  20. Hyperbranched Hybridization Chain Reaction for Triggered Signal Amplification and Concatenated Logic Circuits.

    PubMed

    Bi, Sai; Chen, Min; Jia, Xiaoqiang; Dong, Ying; Wang, Zonghua

    2015-07-01

    A hyper-branched hybridization chain reaction (HB-HCR) is presented herein, which consists of only six species that can metastably coexist until the introduction of an initiator DNA to trigger a cascade of hybridization events, leading to the self-sustained assembly of hyper-branched and nicked double-stranded DNA structures. The system can readily achieve ultrasensitive detection of target DNA. Moreover, the HB-HCR principle is successfully applied to construct three-input concatenated logic circuits with excellent specificity and extended to design a security-mimicking keypad lock system. Significantly, the HB-HCR-based keypad lock can alarm immediately if the "password" is incorrect. Overall, the proposed HB-HCR with high amplification efficiency is simple, homogeneous, fast, robust, and low-cost, and holds great promise in the development of biosensing, in the programmable assembly of DNA architectures, and in molecular logic operations. PMID:26012841

  1. A New Ir-NHC Catalyst for Signal Amplification by Reversible Exchange in D2 O.

    PubMed

    Spannring, Peter; Reile, Indrek; Emondts, Meike; Schleker, Philipp P M; Hermkens, Niels K J; van der Zwaluw, Nick G J; van Weerdenburg, Bram J A; Tinnemans, Paul; Tessari, Marco; Blümich, Bernhard; Rutjes, Floris P J T; Feiters, Martin C

    2016-06-27

    NMR signal amplification by reversible exchange (SABRE) has been observed for pyridine, methyl nicotinate, N-methylnicotinamide, and nicotinamide in D2 O with the new catalyst [Ir(Cl)(IDEG)(COD)] (IDEG=1,3-bis(3,4,5-tris(diethyleneglycol)benzyl)imidazole-2-ylidene). During the activation and hyperpolarization steps, exclusively D2 O was used, resulting in the first fully biocompatible SABRE system. Hyperpolarized (1) H substrate signals were observed at 42.5 MHz upon pressurizing the solution with parahydrogen at close to the Earth's magnetic field, at concentrations yielding barely detectable thermal signals. Moreover, 42-, 26-, 22-, and 9-fold enhancements were observed for nicotinamide, pyridine, methyl nicotinate, and N-methylnicotinamide, respectively, in conventional 300 MHz studies. This research opens up new opportunities in a field in which SABRE has hitherto primarily been conducted in CD3 OD. This system uses simple hardware, leaves the substrate unaltered, and shows that SABRE is potentially suitable for clinical purposes. PMID:27258850

  2. Optimized ferrocene-functionalized ZnO nanorods for signal amplification in electrochemical immunoassay of Escherichia coli.

    PubMed

    Teng, Yingqiao; Zhang, Xinai; Fu, Ying; Liu, Huijie; Wang, Zhongchuan; Jin, Litong; Zhang, Wen

    2011-08-15

    A novel amplified electrochemical immunoassay based on ferrocene (Fc)-functionalized ZnO nanorods (NRs) was developed in the present work. The detection antibody ((d)Ab) and Fc were immobilized onto the surface of ZnO NRs, denoted as {(d)Ab-ZnO-Fc} bioconjugates. The amount of (d)Ab and Fc in the bioconjugates was investigated using the copper reduction/bicinchoninic acid reaction (BCA protein assay) and inductive coupled plasma-atomic emission spectroscopy (ICP-AES), respectively. Greatly amplified signal was achieved in the sandwich-type immunoassay when (d)Ab and Fc linked to ZnO NRs at a proper ratio. Using Escherichia coli (E. coli) as a model antigen, the designed immunoassay showed an excellent analytical performance, and exhibited a wide dynamic response range of E. coli concentration from 10(2) to 10(6)cfu/mL with a detection limit of 50 cfu/mL (S/N=3). By introducing a pre-enrichment step, the detection of 5 cfu/10 mL E. coli in hospital sewage water was realized. This proposed signal amplification strategy was promising and could be easily extended to monitor other biorecognition events. PMID:21733671

  3. Sensitive Immunosensor for Cancer Biomarker Based on Dual Signal Amplification Strategy of Graphene Sheets and Multi-Enzyme Functionalized Carbon Nanospheres

    SciTech Connect

    Du, Dan; Zou, Zhexiang; Shin, Yongsoon; Wang, Jun; Wu, Hong; Engelhard, Mark H.; Liu, Jun; Aksay, Ilhan A.; Lin, Yuehe

    2010-03-30

    A novel electrochemical immunosensor for sensitive detection of cancer biomarker α fetoprotein (AFP) is described that uses a graphene sheet sensor platform and functionalized carbon nanospheres (CNSs) labeling with horseradish peroxidase-secondary antibodies (HRP-Ab2). Greatly enhanced sensitivity for the cancer biomarker is based on a dual signal amplification strategy: first, the synthesized CNSs yielded a homogeneous and narrow size distribution, which allowed several binding events of HRP-Ab2 on each nanosphere. Enhanced sensitivity was achieved by introducing the multi-bioconjugates of HRP-Ab2-CNSs onto the electrode surface through sandwich immunoreactions. Secondly, functionalized graphene sheets used for the biosensor platform increased the surface area to capture a large amount of primary antibodies (Ab1), thus amplifying the detection response. This amplification strategy is a promising platform for clinical screening of cancer biomarkers and point-of-care diagnostics.

  4. Highly sensitive electrochemiluminescent cytosensing using carbon nanodot@Ag hybrid material and graphene for dual signal amplification.

    PubMed

    Wu, Li; Wang, Jiasi; Ren, Jinsong; Li, Wen; Qu, Xiaogang

    2013-06-25

    Here we use functionalized carbon nanodots (C-dots) as novel electrochemiluminescence (ECL) probes and graphene nanosheets as signal amplification agents for highly sensitive and selective cancer cell detection. The ECL cytosensor shows superior cell-capture ability and exhibits a wide linear range and a low detection limit for cancer cells. PMID:23682359

  5. Droplet-Free Digital Enzyme-Linked Immunosorbent Assay Based on a Tyramide Signal Amplification System.

    PubMed

    Akama, Kenji; Shirai, Kentaro; Suzuki, Seigo

    2016-07-19

    Digital enzyme-linked immunosorbent assay (ELISA) is a single molecule counting technology and is one of the most sensitive immunoassay methods. The key aspect of this technology is to concentrate enzyme reaction products from a single target molecule in femtoliter droplets. This study presents a novel Digital ELISA that does not require droplets; instead, enzyme reaction products are concentrated using a tyramide signal amplification system. In our method, tyramide substrate reacts with horseradish peroxidase (HRP) labeled with an immunocomplex on beads, and the substrate is converted into short-lived radical intermediates. By adjusting the bead concentration in the HRP-tyramide reaction and conducting the reaction using freely moving beads, tyramide radicals are deposited only on beads labeled with HRP and there is no diffusion to other beads. Consequently, the fluorescence signal is localized on a portion of the beads, making it possible to count the number of labeled beads digitally. The performance of our method was demonstrated by detecting hepatitis B surface antigen with a limit of detection of 0.09 mIU/mL (139 aM) and a dynamic range of over 4 orders of magnitude. The obtained limit of detection represents a >20-fold higher sensitivity than conventional ELISA. Our method has potential applications in simple in vitro diagnostic systems for detecting ultralow concentrations of protein biomarkers. PMID:27322525

  6. Multiple signal amplification electrogenerated chemiluminescence biosensors for sensitive protein kinase activity analysis and inhibition.

    PubMed

    Wang, Zonghua; Yan, Zhiyong; Sun, Na; Liu, Yang

    2015-06-15

    A novel electrogenerated chemiluminescence (ECL) biosensor was built for the detection of kinase activity based on multiple signal amplification nanoprobes. In this strategy, the Xanthine oxidase (XOD) and 5'-phosphate group end DNA conjugated AuNPs was integrated with the phosphorylated peptide by Zr(4+). The XOD on gold nanoparticles can catalyze dissolved oxygen to produce H2O2 in the presence of hypoxanthine (HA) which acts as a coreactor for luminol ECL reaction. In addition, due to the excellent catalytic activity of gold nanoparticle toward luminol ECL reaction and its large surface area that can accommodate large number of XOD and DNA on the surface, the ECL signal of luminol was significantly amplified, affording a highly sensitive ECL analysis of kinase activity. The as-proposed biosensor presents a low detection limit of 0.09 U mL(-1) for protein kinase A (PKA) activity, wide linear range (from 0.1 to 10 U mL(-1)) and excellent stability even in serum samples. This biosensor can also be applied for quantitative kinase inhibitor evaluation. The robust ECL biosensor provides a valuable tool for the high throughput assay in the applications of clinic diagnostic and therapeutic. PMID:25682506

  7. Genetic or Pharmacologic Amplification of Nrf2 Signaling Inhibits Acute Inflammatory Liver Injury in Mice

    PubMed Central

    Osburn, William O.; Yates, Melinda S.; Dolan, Patrick D.; Liby, Karen T.; Sporn, Michael B.; Taguchi, Keiko; Yamamoto, Masayuki; Kensler, Thomas W.

    2008-01-01

    thereby diminishing the sustained influx of inflammatory cells initially stimulated by the ConA challenge. Taken together, these results clearly illustrate that targeted cytoprotection of hepatocytes through Nrf2 signaling during inflammation prevents the amplification of inflammatory responses in the liver. PMID:18417483

  8. Signal Amplification in Field Effect-Based Sandwich Enzyme-Linked Immunosensing by Tuned Buffer Concentration with Ionic Strength Adjuster.

    PubMed

    Kumar, Satyendra; Kumar, Narendra; Panda, Siddhartha

    2016-04-01

    Miniaturization of the sandwich enzyme-based immunosensor has several advantages but could result in lower signal strength due to lower enzyme loading. Hence, technologies for amplification of the signal are needed. Signal amplification in a field effect-based electrochemical immunosensor utilizing chip-based ELISA is presented in this work. First, the molarities of phosphate buffer saline (PBS) and concentrations of KCl as ionic strength adjuster were optimized to maximize the GOx glucose-based enzymatic reactions in a beaker for signal amplification measured by change in the voltage shift with an EIS device (using 20 μl of solution) and validated with a commercial pH meter (using 3 ml of solution). The PBS molarity of 100 μM with 25 mM KCl provided the maximum voltage shift. These optimized buffer conditions were further verified for GOx immobilized on silicon chips, and similar trends with decreased PBS molarity were obtained; however, the voltage shift values obtained on chip reaction were lower as compared to the reactions occurring in the beaker. The decreased voltage shift with immobilized enzyme on chip could be attributed to the increased Km (Michaelis-Menten constant) values in the immobilized GOx. Finally, a more than sixfold signal enhancement (from 8 to 47 mV) for the chip-based sandwich immunoassay was obtained by altering the PBS molarity from 10 to 100 μM with 25 mM KCl. PMID:26801818

  9. Alternative configuration scheme for signal amplification with scanning ion conductance microscopy

    NASA Astrophysics Data System (ADS)

    Kim, Joonhui; Kim, Seong-Oh; Cho, Nam-Joon

    2015-02-01

    Scanning Ion Conductance Microscopy (SICM) is an emerging nanotechnology tool to investigate the morphology and charge transport properties of nanomaterials, including soft matter. SICM uses an electrolyte filled nanopipette as a scanning probe and detects current changes based on the distance between the nanopipette apex and the target sample in an electrolyte solution. In conventional SICM, the pipette sensor is excited by applying voltage as it raster scans near the surface. There have been attempts to improve upon raster scanning because it can induce collisions between the pipette sidewalls and target sample, especially for soft, dynamic materials (e.g., biological cells). Recently, Novak et al. demonstrated that hopping probe ion conductance microscopy (HPICM) with an adaptive scan method can improve the image quality obtained by SICM for such materials. However, HPICM is inherently slower than conventional raster scanning. In order to optimize both image quality and scanning speed, we report the development of an alternative configuration scheme for SICM signal amplification that is based on applying current to the nanopipette. This scheme overcomes traditional challenges associated with low bandwidth requirements of conventional SICM. Using our alternative scheme, we demonstrate successful imaging of L929 fibroblast cells and discuss the capabilities of this instrument configuration for future applications.

  10. Irreversible Catalyst Activation Enables Hyperpolarization and Water Solubility for NMR Signal Amplification by Reversible Exchange

    PubMed Central

    2015-01-01

    Activation of a catalyst [IrCl(COD)(IMes)] (IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene; COD = cyclooctadiene)] for signal amplification by reversible exchange (SABRE) was monitored by in situ hyperpolarized proton NMR at 9.4 T. During the catalyst-activation process, the COD moiety undergoes hydrogenation that leads to its complete removal from the Ir complex. A transient hydride intermediate of the catalyst is observed via its hyperpolarized signatures, which could not be detected using conventional nonhyperpolarized solution NMR. SABRE enhancement of the pyridine substrate can be fully rendered only after removal of the COD moiety; failure to properly activate the catalyst in the presence of sufficient substrate can lead to irreversible deactivation consistent with oligomerization of the catalyst molecules. Following catalyst activation, results from selective RF-saturation studies support the hypothesis that substrate polarization at high field arises from nuclear cross-relaxation with hyperpolarized 1H spins of the hydride/orthohydrogen spin bath. Importantly, the chemical changes that accompanied the catalyst’s full activation were also found to endow the catalyst with water solubility, here used to demonstrate SABRE hyperpolarization of nicotinamide in water without the need for any organic cosolvent—paving the way to various biomedical applications of SABRE hyperpolarization methods. PMID:25372972

  11. Hyperpolarization of “Neat” Liquids by NMR Signal Amplification by Reversible Exchange

    PubMed Central

    2016-01-01

    We report NMR Signal Amplification by Reversible Exchange (SABRE) hyperpolarization of the rare isotopes in “neat” liquids, each composed only of an otherwise pure target compound with isotopic natural abundance (n.a.) and millimolar concentrations of dissolved catalyst. Pyridine (Py) or Py derivatives are studied at 0.4% isotopic natural abundance 15N, deuterated, 15N enriched, and in various combinations using the SABRE-SHEATH variant (microTesla magnetic fields to permit direct 15N polarization from parahydrogen via reversible binding and exchange with an Ir catalyst). We find that the dilute n.a. 15N spin bath in Py still channels spin order from parahydrogen to dilute 15N spins, without polarization losses due to the presence of 14N or 2H. We demonstrate P15N ≈ 1% (a gain of 2900 fold relative to thermal polarization at 9.4 T) at high substrate concentrations. This fundamental finding has a significant practical benefit for screening potentially hyperpolarizable contrast agents without labeling. The capability of screening at n.a. level of 15N is demonstrated on examples of mono- and dimethyl-substituted Py (picolines and lutidines previously identified as promising pH sensors), showing that the presence of a methyl group in the ortho position significantly decreases SABRE hyperpolarization. PMID:26029349

  12. Mass Barcode Signal Amplification for Multiplex Allergy Diagnosis by MALDI-MS.

    PubMed

    Zhong, Xiaoqin; Qiao, Liang; Gasilova, Natalia; Liu, Baohong; Girault, Hubert H

    2016-06-21

    A highly sensitive method based on mass-barcoded gold nanoparticles (AuNPs) and immunomagnetic separation has been developed for multiplex allergy diagnosis by MALDI mass spectrometry in a component-resolved manner. Different analytical probes were prepared by coating AuNPs with individual allergenic proteins and mass barcode, represented by polyethylene glycol molecules of various chain lengths. Magnetic beads (MBs) functionalized with antihuman IgE antibodies (Abs) were used as immunomagnetic capture probes. IgE Abs were extracted from a patient's blood serum by the formation of a sandwich structure between the AuNPs and MBs. Multiple specific IgE Abs were simultaneously identified by mass spectrometry detection of the mass barcodes, providing an efficient component-resolved allergy diagnosis. Because of the signal amplification provided by the mass barcodes, the developed diagnosis method is very sensitive, with a limit of detection down to picograms per milliliter level for specific IgE Abs. The method can be potentially useful when the sample amount is highly limited and a multiplex diagnostic procedure is required. PMID:27244120

  13. Three different signal amplification strategies for the impedimetric sandwich detection of thrombin.

    PubMed

    Ocaña, Cristina; del Valle, Manel

    2016-03-17

    In this work, we report a comparative study on three highly specific amplification strategies for the ultrasensitive detection of thrombin with the use of aptamer sandwich protocol. The protocol consisted on the use of a first thrombin aptamer immobilized on the electrode surface, the recognition of thrombin protein, and the reaction with a second biotinylated thrombin aptamer forming the sandwich. Through the exposed biotin end, three variants have been tested to amplify the electrochemical impedance signal. The strategies included (a) silver enhancement treatment, (b) gold enhancement treatment and (c) insoluble product produced by the combination of the enzyme horseradish peroxidase (HRP) and 3-amino-9-ethylcarbazole (AEC). The properties of the sensing surface were probed by electrochemical impedance measurements in the presence of the ferrocyanide/ferricyanide redox marker. Insoluble product strategy and silver enhancement treatment resulted in the lowest detection limit (0.3 pM), while gold enhancement method resulted in the highest reproducibility, 8.8% RSD at the pM thrombin concentration levels. Results of silver and gold enhancement treatment also permitted direct inspection by scanning electron microscopy (SEM). PMID:26920780

  14. Alternative configuration scheme for signal amplification with scanning ion conductance microscopy.

    PubMed

    Kim, Joonhui; Kim, Seong-Oh; Cho, Nam-Joon

    2015-02-01

    Scanning Ion Conductance Microscopy (SICM) is an emerging nanotechnology tool to investigate the morphology and charge transport properties of nanomaterials, including soft matter. SICM uses an electrolyte filled nanopipette as a scanning probe and detects current changes based on the distance between the nanopipette apex and the target sample in an electrolyte solution. In conventional SICM, the pipette sensor is excited by applying voltage as it raster scans near the surface. There have been attempts to improve upon raster scanning because it can induce collisions between the pipette sidewalls and target sample, especially for soft, dynamic materials (e.g., biological cells). Recently, Novak et al. demonstrated that hopping probe ion conductance microscopy (HPICM) with an adaptive scan method can improve the image quality obtained by SICM for such materials. However, HPICM is inherently slower than conventional raster scanning. In order to optimize both image quality and scanning speed, we report the development of an alternative configuration scheme for SICM signal amplification that is based on applying current to the nanopipette. This scheme overcomes traditional challenges associated with low bandwidth requirements of conventional SICM. Using our alternative scheme, we demonstrate successful imaging of L929 fibroblast cells and discuss the capabilities of this instrument configuration for future applications. PMID:25725851

  15. A Sensitive Branched DNA HIV-1 Signal Amplification Viral Load Assay with Single Day Turnaround

    PubMed Central

    Baumeister, Mark A.; Zhang, Nan; Beas, Hilda; Brooks, Jesse R.; Canchola, Jesse A.; Cosenza, Carlo; Kleshik, Felix; Rampersad, Vinod; Surtihadi, Johan; Battersby, Thomas R.

    2012-01-01

    Branched DNA (bDNA) is a signal amplification technology used in clinical and research laboratories to quantitatively detect nucleic acids. An overnight incubation is a significant drawback of highly sensitive bDNA assays. The VERSANT® HIV-1 RNA 3.0 Assay (bDNA) (“Versant Assay”) currently used in clinical laboratories was modified to allow shorter target incubation, enabling the viral load assay to be run in a single day. To dramatically reduce the target incubation from 16–18 h to 2.5 h, composition of only the “Lysis Diluent” solution was modified. Nucleic acid probes in the assay were unchanged. Performance of the modified assay (assay in development; not commercially available) was evaluated and compared to the Versant Assay. Dilution series replicates (>950 results) were used to demonstrate that analytical sensitivity, linearity, accuracy, and precision for the shorter modified assay are comparable to the Versant Assay. HIV RNA-positive clinical specimens (n = 135) showed no significant difference in quantification between the modified assay and the Versant Assay. Equivalent relative quantification of samples of eight genotypes was demonstrated for the two assays. Elevated levels of several potentially interfering endogenous substances had no effect on quantification or specificity of the modified assay. The modified assay with drastically improved turnaround time demonstrates the viability of signal-amplifying technology, such as bDNA, as an alternative to the PCR-based assays dominating viral load monitoring in clinical laboratories. Highly sensitive bDNA assays with a single day turnaround may be ideal for laboratories with especially stringent cost, contamination, or reliability requirements. PMID:22479381

  16. Disposable electrochemical immunosensor by using carbon sphere/gold nanoparticle composites as labels for signal amplification.

    PubMed

    Xu, Qiunan; Yan, Feng; Lei, Jianping; Leng, Chuan; Ju, Huangxian

    2012-04-16

    This work designed a simple, sensitive, and low-cost immunosensor for the detection of protein marker by using a carbon sphere/gold nanoparticle (CNS/AuNP) composite as an electrochemical label. The nanoscale carbon spheres, prepared with a hydrothermal method by using glucose as raw material, were used to load AuNPs for labeling antibody by electrostatic interaction, which provided a feasible pathway for electron transfer due to the remarkable conductivity. The disposable immunosensor was constructed by coating a polyethylene glycol (PEG) film on a screen-printed carbon-working electrode and then immobilizing capture antibody on the film. With a sandwich-type immunoassay format, the analyte and then the CNS/AuNP-labeled antibody were successively bound to the immunosensor. The bound AuNPs were finally electro-oxidized in 0.1  M HCl to produce AuCl(4)(-) for differential pulse voltammetric (DPV) detection. The high-loading capability of AuNPs on CNS for the sandwich-type immunorecognition led to obvious signal amplification. By using human immunoglobulin G (IgG) as model target, the DPV signal of AuNPs after electro-oxidized at optimal potential of +1.40 V for 40 s showed a wide linear dependence on the logarithm of target concentration ranging from 10 pg  mL(-1) to 10 ng  mL(-1). The detection limit was around 9 pg  mL(-1). The immunosensor showed excellent analytical performance with cost effectivity, good fabrication reproducibility, and acceptable precision and accuracy, providing significant potential application in clinical analysis. PMID:22438025

  17. Sensitive colorimetric detection of K(I) using catalytically active gold nanoparticles triggered signal amplification.

    PubMed

    Chen, Zhengbo; Tan, Lulu; Wang, Shaoxiong; Zhang, Yimeng; Li, Yonghui

    2016-05-15

    In this work, we report a simple, ultrasensitive, and feasible colorimetric assay for metal ion (K(+), used as a model) via inherent peroxidase-like enzymatic amplification strategy of gold nanoparticles (AuNPs). It is shown that peroxidase-like activity of AuNPs can be improved dramatically by its surface activation with target-specific aptamer molecules. Whereas when the target exists, the aptamers leave the surface of AuNPs in a target concentration-dependent manner, resulting in a decrease of the nanoenzymatic catalytic ability of AuNPs. Thus, K(+) can be quantified in the presence of AuNPs by using a colorimetric sensing probe (3,3',5,5'-tetramethylbenzidine). The color change of the solution is relevant to the dose of the target, and this can be achieved with the naked eyes and monitored by UV-vis spectrometry. A linear dependence between the absorbance and target K(+) concentration is obtained under optimal conditions in the range from 0. 1 nM to 1 μM with a detection limit (LOD) of 0.06 nM estimated at the 3Sblank level. The sensitivity displays to be 2-9 orders of magnitude better than those of other K(+) detection methods. This sensing strategy may in principle be universally applicable for the detection of a range of environmental or biomedical molecules of interest. PMID:26774090

  18. Enhanced signal-to-noise ratios in frog hearing can be achieved through amplitude death

    PubMed Central

    Ahn, Kang-Hun

    2013-01-01

    In the ear, hair cells transform mechanical stimuli into neuronal signals with great sensitivity, relying on certain active processes. Individual hair cell bundles of non-mammals such as frogs and turtles are known to show spontaneous oscillation. However, hair bundles in vivo must be quiet in the absence of stimuli, otherwise the signal is drowned in intrinsic noise. Thus, a certain mechanism is required in order to suppress intrinsic noise. Here, through a model study of elastically coupled hair bundles of bullfrog sacculi, we show that a low stimulus threshold and a high signal-to-noise ratio (SNR) can be achieved through the amplitude death phenomenon (the cessation of spontaneous oscillations by coupling). This phenomenon occurs only when the coupled hair bundles have inhomogeneous distribution, which is likely to be the case in biological systems. We show that the SNR has non-monotonic dependence on the mass of the overlying membrane, and find out that the SNR has maximum value in the region of amplitude death. The low threshold of stimulus through amplitude death may account for the experimentally observed high sensitivity of frog sacculi in detecting vibration. The hair bundles' amplitude death mechanism provides a smart engineering design for low-noise amplification. PMID:23883956

  19. Laser-enhanced ionization of mercury atoms in an inert atmosphere with avalanche amplification of the signal.

    PubMed

    Clevenger, W L; Matveev, O I; Cabredo, S; Omenetto, N; Smith, B W; Winefordner, J D

    1997-07-01

    A new method for laser-enhanced ionization detection of mercury atoms in an inert gas atmosphere is described. The method, which is based on the avalanche amplification of the signal resulting from the ionization from a selected Rydberg level reached by a three-step laser excitation of mercury vapor in a simple quartz cell, can be applied to the determination of this element in various matrices by the use of conventional cold atomization techniques. The overall (collisional + photo) ionization efficiency is investigated at different temperatures, and the avalanche amplification effect is reported for Ar and P-10 gases at atmospheric pressure. It is shown that the amplified signal is related to the number of charges produced in the laser-irradiated volume. Under amplifier noise-limited conditions, a detection limit of ∼15 Hg atoms/laser pulse in the interaction region is estimated. PMID:21639354

  20. Amplification of ABA biosynthesis and signaling through a positive feedback mechanism in seeds.

    PubMed

    Nonogaki, Mariko; Sall, Khadidiatou; Nambara, Eiji; Nonogaki, Hiroyuki

    2014-05-01

    Abscisic acid is an essential hormone for seed dormancy. Our previous study using the plant gene switch system, a chemically induced gene expression system, demonstrated that induction of 9-cis-epoxycarotenoid dioxygenase (NCED), a rate-limiting ABA biosynthesis gene, was sufficient to suppress germination in imbibed Arabidopsis seeds. Here, we report development of an efficient experimental system that causes amplification of NCED expression during seed maturation. The system was created with a Triticum aestivum promoter containing ABA responsive elements (ABREs) and a Sorghum bicolor NCED to cause ABA-stimulated ABA biosynthesis and signaling, through a positive feedback mechanism. The chimeric gene pABRE:NCED enhanced NCED and ABF (ABRE-binding factor) expression in Arabidopsis Columbia-0 seeds, which caused 9- to 73-fold increases in ABA levels. The pABRE:NCED seeds exhibited unusually deep dormancy which lasted for more than 3 months. Interestingly, the amplified ABA pathways also caused enhanced expression of Arabidopsis NCED5, revealing the presence of positive feedback in the native system. These results demonstrated the robustness of positive feedback mechanisms and the significance of NCED expression, or single metabolic change, during seed maturation. The pABRE:NCED system provides an excellent experimental system producing dormant and non-dormant seeds of the same maternal origin, which differ only in zygotic ABA. The pABRE:NCED seeds contain a GFP marker which enables seed sorting between transgenic and null segregants and are ideal for comparative analysis. In addition to its utility in basic research, the system can also be applied to prevention of pre-harvest sprouting during crop production, and therefore contributes to translational biology. PMID:24520869

  1. Dual-cardiac marker capillary waveguide fluoroimmunosensor based on tyramide signal amplification.

    PubMed

    Niotis, Aristeidis E; Mastichiadis, Christos; Petrou, Panagiota S; Christofidis, Ion; Kakabakos, Sotirios E; Siafaka-Kapadai, Athanasia; Misiakos, Konstantinos

    2010-02-01

    The early diagnosis of acute myocardial infarction requires the determination of several markers in serum shortly after its incidence. The markers most widely employed are the isoenzyme MB of creatine kinase (CK-MB) and the cardiac troponin I (cTnI). In the present work, a capillary waveguide fluoroimmunosensor for fast and highly sensitive simultaneous determination of these markers in serum samples is demonstrated. The dual-analyte immunosensor was realized using glass capillaries internally modified with an ultrathin poly(dimethylsiloxane) film by creating discrete bands of analyte-specific antibodies. The capillary was then filled with a mixture of sample and biotinylated detection antibodies followed by reaction with streptavidin-horseradish peroxidase and incubation with a fluorescently labeled tyramide derivative to accumulate fluorescent labels onto immunoreaction bands. Upon scanning the capillary with a laser beam, part of the emitted fluorescence is trapped and waveguided through the capillary wall to a photomultiplier placed on one of its ends. The employment of tyramide signal amplification provided detection limits of 0.2 and 0.5 ng/mL for cTnI and CK-MB, respectively, in a total assay time of 30 min compared to 0.8 and 0.6 ng/mL obtained for the corresponding assays when the conventional fluorescent label R-phycoerythrin was used in a 65-min assay. In addition, the proposed immunosensor provided accurate and repeatable measurements (intra-assay and interassay coefficients of variation lower than 10%), and the values determined in serum samples were in good agreement with those obtained with commercially available enzyme immunoassays. Thus, the proposed capillary waveguide fluoroimmunosensor has all the required characteristics for fast and reliable diagnosis of acute myocardial infarction. PMID:19936719

  2. Signal Amplification in a Microchannel from Redox Cycling with Varied Electroactive Configurations of an Individually-Addressable Microband Electrode Array

    PubMed Central

    Lewis, Penny M.; Sheridan, Leah Bullard; Gawley, Robert E.; Fritsch, Ingrid

    2010-01-01

    Amperometric detection at microelectrodes in lab-on-a-chip (LOAC) devices lose advantages in signal-to-background ratio, reduced ohmic iR drop, and steady-state signal when volumes are so small that diffusion fields reach the walls before flux becomes fully radial. Redox-cycling of electroactive species between multiple, closely-spaced microelectrodes offsets that limitation and provides amplification capabilities. A device that integrates a microchannel with an individually-addressable microband electrode array has been used to study effects of signal amplification due to redox cycling in a confined, static solution with different configurations and numbers of active generators and collectors. The microfabricated device consists of a 22-μm high, 600-μm wide microchannel containing an array of 50-μm wide, 600-μm long gold microbands, separated by 25-μm gaps, interspersed with an 800-μm-wide counter electrode and 400-μm wide passive conductor, with a distant but on-chip 400-μm wide pseudoreference electrode. Investigations involve solutions of potassium chloride electrolyte containing potassium ferrocyanide. Amplification factors were as high as 7.60, even with these microelectrodes of fairly large dimensions (which are generally less expensive, easier, and more reproducible to fabricate), because of the significant role that passive and active (instrumentally induced) redox-cycling plays in confined volumes of enclosed microchannels. The studies are useful in optimizing designs for LOAC-devices. PMID:20108925

  3. Signal-on electrochemical detection of antibiotics at zeptomole level based on target-aptamer binding triggered multiple recycling amplification.

    PubMed

    Wang, Hongzhi; Wang, Yu; Liu, Su; Yu, Jinghua; Guo, Yuna; Xu, Ying; Huang, Jiadong

    2016-06-15

    In the work, a signal-on electrochemical DNA sensor based on multiple amplification for ultrasensitive detection of antibiotics has been reported. In the presence of target, the ingeniously designed hairpin probe (HP1) is opened and the polymerase-assisted target recycling amplification is triggered, resulting in autonomous generation of secondary target. It is worth noting that the produced secondary target could not only hybridize with other HP1, but also displace the Helper from the electrode. Consequently, methylene blue labeled HP2 forms a "close" probe structure, and the increase of signal is monitored. The increasing current provides an ultrasensitive electrochemical detection for antibiotics down to 1.3 fM. To our best knowledge, such work is the first report about multiple recycling amplification combing with signal-on sensing strategy, which has been utilized for quantitative determination of antibiotics. It would be further used as a general strategy associated with more analytical techniques toward the detection of a wide spectrum of analytes. Thus, it holds great potential for the development of ultrasensitive biosensing platform for the applications in bioanalysis, disease diagnostics, and clinical biomedicine. PMID:26878484

  4. One-step, multiplexed fluorescence detection of microRNAs based on duplex-specific nuclease signal amplification.

    PubMed

    Yin, Bin-Cheng; Liu, Yu-Qiang; Ye, Bang-Ce

    2012-03-21

    Traditional molecular beacons, widely applied for detection of nucleic acids, have an intrinsic limitation on sensitivity, as one target molecule converts only one beacon molecule to its fluorescent form. Herein, we take advantage of the duplex-specific nuclease (DSN) to create a new signal-amplifying mechanism, duplex-specific nuclease signal amplification (DSNSA), to increase the detection sensitivity of molecular beacons (Taqman probes). DSN nuclease is employed to recycle the process of target-assisted digestion of Taqman probes, thus, resulting in a significant fluorescence signal amplification through which one target molecule cleaves thousands of probe molecules. We further demonstrate the efficiency of this DSNSA strategy for rapid direct quantification of multiple miRNAs in biological samples. Our experimental results showed a quantitative measurement of sequence-specific miRNAs with the detection limit in the femtomolar range, nearly 5 orders of magnitude lower than that of conventional molecular beacons. This amplification strategy also demonstrated a high selectivity for discriminating differences between miRNA family members. Considering the superior sensitivity and specificity, as well as the multiplex and simple-to-implement features, this method promises a great potential of becoming a routine tool for simultaneously quantitative analysis of multiple miRNAs in tissues or cells, and supplies valuable information for biomedical research and clinical early diagnosis. PMID:22394262

  5. A SPR biosensor based on signal amplification using antibody-QD conjugates for quantitative determination of multiple tumor markers.

    PubMed

    Wang, Huan; Wang, Xiaomei; Wang, Jue; Fu, Weiling; Yao, Chunyan

    2016-01-01

    The detection of tumor markers is very important in early cancer diagnosis; however, tumor markers are usually present at very low concentrations, especially in the early stages of tumor development. Surface plasmon resonance (SPR) is widely used to detect biomolecular interactions; it has inherent advantages of being high-throughput, real-time, and label-free technique. However, its sensitivity needs essential improvement for practical applications. In this study, we developed a signal amplification strategy using antibody-quantum dot (QD) conjugates for the sensitive and quantitative detection of α-fetoprotein (AFP), carcinoembryonic antigen (CEA) and cytokeratin fragment 21-1 (CYFRA 21-1) in clinical samples. The use of a dual signal amplification strategy using AuNP-antibody and antibody-QD conjugates increased the signal amplification by 50-folds. The constructed SPR biosensor showed a detection limit as low as 0.1 ng/mL for AFP, CEA, and CYFRA 21-1. Moreover, the results obtained using this SPR biosensor were consistent with those obtained using the electrochemiluminescence method. Thus, the constructed SPR biosensor provides a highly sensitive and specific approach for the detection of tumor markers. This SPR biosensor can be expected to be readily applied for the detection of other tumor markers and can offer a potentially powerful solution for tumor screening. PMID:27615417

  6. Approaches towards molecular amplification for sensing.

    PubMed

    Goggins, Sean; Frost, Christopher G

    2016-06-01

    Diagnostic assays that rely on molecular interactions have come a long way; from initial reversible detection systems towards irreversible reaction indicator-based methods. More recently, the emergence of innovative molecular amplification methodologies has revolutionised sensing, allowing diagnostic assays to achieve ultra-low limits of detection. There have been a significant number of molecular amplification approaches developed over recent years to accommodate the wide variety of analytes that require sensitive detection. To celebrate this achievement, this comprehensive critical review has been compiled to give a broad overview of the many different approaches used to attain amplification in sensing with an aim to inspire the next generation of diagnostic assays looking to achieve the ultimate detection limit. This review has been created with the focus on how each conceptually unique molecular amplification methodology achieves amplification, not just its sensitivity, while highlighting any key processes. Excluded are any references that were not found to contain an obvious molecular amplifier or amplification component, or that did not use an appropriate signal readout that could be incorporated into a sensing application. Additionally, methodologies where amplification is achieved through advances in instrumentation are also excluded. Depending upon the type of approach employed, amplification strategies are divided into four categories: target, label, signal or receptor amplification. More recent, more complex protocols combine a number of approaches and are therefore categorised by which amplification component described within was considered as the biggest advancement. The advantages and disadvantages of each methodology are discussed along with any limits of detection, if stated in the original article. Any subsequent use of the methodology within sensing or any other application is also mentioned to draw attention to its practicality. The importance of

  7. Microelectrode miRNA sensors enabled by enzymeless electrochemical signal amplification.

    PubMed

    Wang, Tanyu; Viennois, Emilie; Merlin, Didier; Wang, Gangli

    2015-08-18

    Better detections of circulating microRNAs (miRNAs) as disease biomarkers could advance diseases diagnosis and treatment. Current analysis methods or sensors for research and applications are challenged by the low concentrations and wide dynamic range (from aM to nM) of miRNAs in a physiological sample. Here, we report a one-step label-free electrochemical sensor comprising a triple-stem DNA-redox probe structure on a gold microelectrode. A new signal amplification mechanism without the need of a redox enzyme is introduced. The novel strategy overcomes the fundamental limitations of microelectrode DNA sensors that fail to generate detectable current, which is primarily due to the limited amount of redox probes in response to the target analyte binding. By employing a reductant, tris(2-carboxyethyl) phosphine hydrochloride (TCEP) in the detection buffer solution, each redox molecule on the detection probe is cyclically oxidized at the electrode and reduced by the reductant; thus, the signal is amplified in situ during the detection period. The combined merits in the diagnosis power of cyclic voltammetry and the high sensitivity of pulse voltammetry enable parallel analysis for method validation and optimization previously inaccessible. As such, the detection limit of miRNA-122 was 0.1 fM via direct readout, with a wide detection range from sub fM to nM. The detection time is within minutes, which is a significant improvement over other macroscopic sensors and other relevant techniques such as quantitative reverse transcription polymerase chain reaction (qRT-PCR). The high selectivity of the developed sensors is demonstrated by the discrimination against two most similar family sequences: miR-122-3p present in serum and 2-mismatch synthetic RNA sequence. Interference such as nonspecific adsorption, a common concern in sensor development, is reduced to a negligible amount by adopting a multistep surface modification strategy. Importantly, unlike qRT-PCR, the

  8. Sub-femtomolar DNA detection based on layered molybdenum disulfide/multi-walled carbon nanotube composites, Au nanoparticle and enzyme multiple signal amplification.

    PubMed

    Huang, Ke-Jing; Liu, Yu-Jie; Wang, Hai-Bo; Wang, Ya-Ya; Liu, Yan-Ming

    2014-05-15

    A novel 2-dimensional graphene analog molybdenum disulfide/multi-walled carbon nanotube (MoS2/MWCNT) was synthesized by a simple hydrothermal method to achieve excellent electrochemical properties. An ultrasensitive electrochemical DNA biosensor was subsequently constructed by assembling a thiol-tagged DNA probe on a MoS2/MWCNT and gold nanoparticle (AuNP)-modified electrode that has already been coupled with glucose oxidase (GOD). In this work, GOD was used as a redox marker. The heteronanostructure formed on the biosensor surface appeared relatively good conductor for accelerating the electron transfer, while the modification of GOD and AuNPs provided multiple signal amplification for electrochemical biosensing. The multiple signal amplification strategy produced an ultrasensitive electrochemical detection of DNA down to 0.79 fM with a linear range from 10 fM to 10(7)fM, and appeared high selectivity to differentiate three-base mismatched DNA and one-base mismatched DNA. The developed approach provided a simple and reliable method for DNA detection with high sensitivity and specificity, and would open new opportunities for sensitive detection of other biorecognition events. PMID:24384259

  9. Sensitive electrochemical immunoassay of carcinoembryonic antigen with signal dual-amplification using glucose oxidase and an artificial catalase.

    PubMed

    Tang, Juan; Tang, Dianping; Li, Qunfang; Su, Biling; Qiu, Bin; Chen, Guonan

    2011-07-01

    A new dual-amplification strategy of electrochemical signal based on the catalytic recycling of the product was developed for the antigen-antibody interaction by glucose oxidase (GOD)- conjugated gold-silver hollow microspheres (AuAgHSs) coupled with an artificial catalase, Prussian blue nanoparticles (PB), on a graphene-based immunosensing platform. The first signal amplification introduced in this study was based on the labeled GOD on the AuAgHSs toward the catalytic oxidation of glucose. The generated H(2)O(2) was catalytically reduced by the immobilized PB on the graphene nanosheets with the second amplification. With a sandwich-type immunoassay format, carcinoembryonic antigen (CEA) was monitored as a model analyte by using the synthesized AuAgHSs as labels in pH 6.0 phosphate buffer containing 10mM glucose. Under optimal conditions, the electrochemical immunosensor exhibited a wide dynamic range of 0.005-50 ng mL(-1) with a low detection limit (LOD) of 1.0 pg mL(-1) CEA (at 3σ). Both the intra- and inter-assay coefficients of variation (CVs) were lower than 10%. The specificity and stability of the immunosensor were acceptable. In addition, the assay was evaluated for clinical serum specimens, and received a good correlation with those obtained by the referenced electrochemiluminescent (ECL). PMID:21641413

  10. Electrochemiluminescence signal amplification combined with a conformation-switched hairpin DNA probe for determining the methylation level and position in the Hsp53 tumor suppressor gene.

    PubMed

    Zhang, Hui; Li, Meixing; Fan, Mengxing; Gu, Jinxing; Wu, Ping; Cai, Chenxin

    2014-03-18

    We report a new strategy for detection of the methylation level and position in the Hsp53 tumor suppressor gene based on the electrochemiluminescence signal amplification combined with a conformation-switched hairpin DNA probe for improving selectivity. PMID:24501739

  11. Amplification of fluorescent in situ hybridisation signals in formalin fixed paraffin wax embedded sections of colon tumour using biotinylated tyramide.

    PubMed Central

    McKay, J A; Murray, G I; Keith, W N; McLeod, H L

    1997-01-01

    Fluorescent in situ hybridisation (FISH) is a powerful tool for the evaluation of chromosomal alterations in formalin fixed paraffin wax embedded sections of colorectal cancer. However, initial experiments using a two-step detection system for digoxigenin labelled chromosome specific centromeric probes resulted in a complete lack of hybridisation signal from a number of colorectal tumour sections. This was due to high levels of background autofluorescence observed in this tissue, which masked any relatively weak hybridisations present. To overcome this problem, a biotinylated tyramide mediated amplification system was incorporated into the FISH detection protocol. This involves the use of horseradish peroxidase to activate the biotinylated tyramide, resulting in the deposition of a large number of biotin molecules at the site of bound peroxidase, which corresponds directly to the location of hybridised probe. Final detection was by means of a streptavidin-FITC conjugate. Using this technique, a panel of 11 colorectal tumour samples studied to date have shown strong, specific hybridisation signals to the nucleus of tumour cells. Amplification of FISH signals by biotinylated tyramide has the potential to improve weak hybridisation signals in cells from numerous sources, using a variety of probe types, including single copy gene probes as well as centromere specific probes. Images PMID:9536283

  12. MOSFET analog memory circuit achieves long duration signal storage

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Memory circuit maintains the signal voltage at the output of an analog signal amplifier when the input signal is interrupted or removed. The circuit uses MOSFET /Metal Oxide Semiconductor Field Effect Transistor/ devices as voltage-controlled switches, triggered by an external voltage-sensing device.

  13. Electrochemical DNA sensor for specific detection of picomolar Hg(II) based on exonuclease III-assisted recycling signal amplification.

    PubMed

    Gan, Xiaorong; Zhao, Huimin; Chen, Shuo; Quan, Xie

    2015-03-21

    An ultrasensitive methodology was successfully developed for the quantitative detection of picomolar Hg(2+) based on the combination of thymine-Hg(2+)-thymine (T-Hg(2+)-T) coordination chemistry and exonuclease III-aided recycling signal amplification. Single-strand probe DNA was immobilized on an Au electrode via an Au-S bond. In the presence of Hg(2+), the probe DNA hybridized with the target DNA containing four thymine-thymine (T-T) mismatches via the Hg(2+)-mediated coordination of T-Hg(2+)-T base pairs. Then the probe DNA in the DNA duplex was specifically recognized and selectively digested by exonuclease III; in contrast the target DNA was safely dissociated from the DNA duplexes to subsequently hybridize with a new signal probe, leading to target recycling and signal amplification. As a result, the peak current caused by the electrostatic interactions of [Ru(NH3)6](3+) cations with the backbone of the probe DNA decreased by different degrees, corresponding to the Hg(2+) concentrations. Under the optimum conditions, the proposed electrochemical DNA biosensor showed a robust detection limit as low as 1 pM (S/N = 3), with a wide linear range from 0.01 to 500 nM and good selectivity. In addition, the proposed method was successfully applied to assay Hg(2+) in real environmental samples. PMID:25676090

  14. Amplification of FRS2 and activation of FGFR/FRS2 signaling pathway in high-grade liposarcoma.

    PubMed

    Zhang, Keqiang; Chu, Kevin; Wu, Xiwei; Gao, Hanlin; Wang, Jinhui; Yuan, Yate-Ching; Loera, Sofia; Ho, Kimberley; Wang, Yafan; Chow, Warren; Un, Frank; Chu, Peiguo; Yen, Yun

    2013-02-15

    Fibroblast growth factor (FGF) receptor (FGFR) substrate 2 (FRS2) is an adaptor protein that plays a critical role in FGFR signaling. FRS2 is located on chromosome 12q13-15 that is frequently amplified in liposarcomas. The significance of FRS2 and FGFR signaling in high-grade liposarcomas is unknown. Herein, we first comparatively examined the amplification and expression of FRS2 with CDK4 and MDM2 in dedifferentiated liposarcoma (DDLS) and undifferentiated high-grade pleomorphic sarcoma (UHGPS). Amplification and expression of the three genes were identified in 90% to 100% (9-11 of 11) of DDLS, whereas that of FRS2, CDK4, and MDM2 were observed in 55% (41 of 75), 48% (36 of 75), and 44% (33/75) of clinically diagnosed UHGPS, suggesting that these "UHGPS" may represent DDLS despite lacking histologic evidence of lipoblasts. Immunohistochemical analysis of phosphorylated FRS2 protein indicated that the FGFR/FRS2 signaling axis was generally activated in about 75% of FRS2-positive high-grade liposarcomas. Moreover, we found that FRS2 and FGFRs proteins are highly expressed and functional in three high-grade liposarcoma cell lines: FU-DDLS-1, LiSa-2, and SW872. Importantly, the FGFR selective inhibitor NVP-BGJ-398 significantly inhibited the growth of FU-DDLS-1 and LiSa-2 cells with a concomitant suppression of FGFR signal transduction. Attenuation of FRS2 protein in FU-DDLS-1 and LiSa-2 cell lines decreased the phosphorylated extracellular signal-regulated kinase 1/2 and AKT and repressed cell proliferation. These findings indicate that analysis of FRS2 in combination with CDK4 and MDM2 will more accurately characterize pathologic features of high-grade liposarcomas. Activated FGFR/FRS2 signaling may play a functional role in the development of high-grade liposarcomas, therefore, serve as a potential therapeutic target. PMID:23393200

  15. Linear light-scattering of gold nanostars for versatile biosensing of nucleic acids and proteins using exonuclease III as biocatalyst to signal amplification.

    PubMed

    Bi, Sai; Jia, Xiaoqiang; Ye, Jiayan; Dong, Ying

    2015-09-15

    Gold nanomaterials promise a wide range of potential applications in chemical and biological sensing, imaging, and catalysis. In this paper, we demonstrate a facile method for room-temperature synthesis of gold nanostars (AuNSs) with a size of ~50 nm via seeded growth. Significantly, the AuNSs are found to have high light-scattering properties, which are successfully used as labels for sensitive and selective detection of nucleic acids and proteins by using exonuclease III (Exo III) as a biocatalyst. For DNA detection, the binding of targets to the functionalized AuNS probes leads to the Exo III-stimulated cascade recycling amplification. As a result, a large amount of AuNSs are released from magnetic nanoparticles (MNPs) into solution, providing a greatly enhanced light-scattering signal for amplified sensing process. Moreover, a binding-induced DNA three-way junction (DNA TWJ) is introduced to thrombin detection, in which the binding of two aptamers to thrombin triggers assembly of the DNA motifs and initiates the subsequent DNA strand displacement reaction (SDR) and Exo III-assisted cascade recycling amplification. The detection limits of 89 fM and 5.6 pM are achieved for DNA and thrombin, respectively, which are comparable to or even exceed that of the reported isothermal amplification methods. It is noteworthy that based on the DNA TWJ strategy the sequences are independent on target proteins. Additionally, the employment of MNPs in the assays can not only simplify the operations but also improve the detection sensitivity. Therefore, the proposed amplified light-scattering assay with high sensitivity and selectivity, acceptable accuracy, and satisfactory versatility of analytes provides various applications in bioanalysis. PMID:25950939

  16. Intercalation of quantum dots as the new signal acquisition and amplification platform for sensitive electrochemiluminescent detection of microRNA.

    PubMed

    Chen, Ying; Xiang, Yun; Yuan, Ruo; Chai, Yaqin

    2015-09-01

    Herein, we report on the development of a simple and sensitive biosensor for electrochemiluminescent (ECL) detection of microRNAs (miRNA) based on the intercalation of doxorubicin-conjugated quantum dot nanoparticles (Dox-QDs) into the DNA/RNA hybrids as the new signal acquisition and amplification platform. The thiolated DNA capture probes are self-assembled onto gold electrodes via the formation of Au-S bonds. The sensing surface is then incubated in a target miRNA-containing buffer solution to form the double-stranded duplexes. In this case, massive Dox-QDs can intercalate into the base pairs of the hybrid duplexes, resulting in amplified ECL emissions due to their reactions with the coreactant [Formula: see text] and the dissolved oxygen in the detection buffer. The increase in ECL intensity proportional to the amount of target miRNA in the testing samples serves as the quantitative basis. Different from traditional QDs-based methods such as labeling and embedding, our sensor involves the employment of the intercalation of the Dox-QDs as the signal acquisition and amplification platform. The combination of the QDs intercalation amplification with the high sensitivity of the ECL technique enables us to detect miRNA down to the low femtomolar level. Moreover, our method is also coupled with acceptable selectivity in discriminating the target miRNA and against its family members as well as other interference sequence, and can monitor miRNAs from human prostate carcinoma (22Rv1) cell lysates. PMID:26388371

  17. A Broad Nanoparticle-Based Strategy for Tumor Imaging by Nonlinear Amplification of Microenvironment Signals

    PubMed Central

    Wang, Yiguang; Zhou, Kejin; Huang, Gang; Hensley, Chris; Huang, Xiaonan; Ma, Xinpeng; Zhao, Tian; Sumer, Baran D.; DeBerardinis, Ralph J.; Gao, Jinming

    2013-01-01

    Stimuli-responsive nanomaterials are increasingly important in a variety of applications such as biosensing, molecular imaging, drug delivery and tissue engineering. For cancer detection, a paramount challenge still exists in search of methods that can illuminate tumors universally regardless of their genotypes and phenotypes. Here we capitalized on the acidic, angiogenic tumor microenvironment to achieve broad detection of tumor tissues in a wide variety of mouse cancer models. This was accomplished using ultra-pH sensitive fluorescent nanoprobes that have tunable, exponential fluorescence activation upon encountering subtle, physiologically relevant pH transitions. These nanoprobes were silent in the circulation, then dramatically activated (>300 fold) in response to neovasculature or to the low extracellular pH in tumors. Thus, we have established non-toxic, fluorescent nanoreporters that can non-linearly amplify tumor microenvironmental signals, permitting identification of tumor tissue independently of histological type or driver mutation, and detection of acute treatment responses much more rapidly than conventional imaging approaches. PMID:24317187

  18. Triple signal amplification using gold nanoparticles, bienzyme and platinum nanoparticles functionalized graphene as enhancers for simultaneous multiple electrochemical immunoassay.

    PubMed

    Jia, Xinle; Chen, Xia; Han, Jingman; Ma, Jie; Ma, Zhanfang

    2014-03-15

    Here we demonstrated an ultrasensitive electrochemical immunoassay employing graphene, platinum nanoparticles (PtNPs), glucose oxidase (GOD) and horseradish peroxidase (HRP) as enhancers to simultaneously detect carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP). This immunosensor is based on the observation that multiple-labeled antibodies (thionine-labeled anti-CEA and ferrocene-labeled anti-AFP) recognition event yielded a distinct voltammetric peak through "sandwich" immunoreaction, whose position and size reflected the identity and level of the corresponding antigen. Greatly enhanced sensitivity for cancer markers is based on a triple signal amplification strategy. Experimental results revealed that the immunoassay enabled simultaneous determination of CEA and AFP in a single run with wide working ranges of 0.01-100 ng mL(-1). The detection limits reached 1.64 pg mL(-1) for CEA and 1.33 pg mL(-1) for AFP. No obvious cross-talk was observed during the experiment. In addition, through the analysis of clinical serum samples, the proposed method received a good correlation with ELISA as a reference. The signal amplification strategy could be easily modified and extended to detect other multiple targets. PMID:24113435

  19. Towards the use of protein A-tagged gold nanoparticles for signal amplification of electrochemical immunosensors in virus detection

    NASA Astrophysics Data System (ADS)

    Tran, Quang Huy; Mai, Anh Tuan; Thuy Nguyen, Thanh; Chung Pham, Van; Hanh Nguyen, Thi Hong

    2012-06-01

    In this paper we represent a study on the potential use of protein A-tagged gold nanoparticles applied for signal amplification of electrochemical immunosensors. Gold nanoparticles (GNPs) were synthesized by the chemical reduction of tetrachloroauric (III) acid trihydrate using sodium ascorbate, and then tagged with protein A (PrA) via ultracentrifugation. UV-Vis spectroscopy and transmission electron microscopy were used to verify the characteristics of formed GNPs/PrA complex. The analyzed results indicate that GNPs were found spherically, homogeneously, and with an average diameter of about 10 nm. Immunoelectron microscopy was then used to investigate the bioactivity of the GNPs/PrA complex in solution by the effective binding of GNPs to viral particles. Scanning electron and fluorescence microscopies were also used to investigate the distribution and the bioactivity of the GNPs/PrA complex on the surface of the interdigitated sensor. Consequently, this study provided some assumptions of the potential application of protein A-tagged gold nanoparticles for signal amplification of electrochemical immunosensors in virus detection from clinical samples.

  20. A network signal amplification strategy of ultrasensitive photoelectrochemical immunosensing carcinoembryonic antigen based on CdSe/melamine network as label.

    PubMed

    Li, Jiaojiao; Zhang, Yong; Kuang, Xuan; Wang, Zhiling; Wei, Qin

    2016-11-15

    Taking advantage of CdSe/melamine network as label and Au-TiO2 as substrate, this work developed a novel kind of signal amplification strategy for fabricating photoelectrochemical (PEC) immunoassay. The melamine, a star-shaped triamino molecule, was firstly used for readily capturing CdSe QDs and forming a CdSe/melamine network, which was formed through strong interactions between the carboxyl groups of TGA-stabilized CdSe QDs and the three amino groups of each melamine molecule. In this strategy, the primary antibody (Ab1) was immobilized onto Au-TiO2 substrate, which made the photoelectric conversion efficiency increase significantly. After the formed Ab2-CdSe/melamine network labels were captured onto the electrode surface via the specific antibody-antigen interaction, the photoelectric activity could be further enhanced via the interaction between the Au-TiO2 substrate and CdSe/melamine network. Due to this amplification of PEC signals and the special structure of the label, the fabricated PEC immunosensor was applied for sensitive and specific detection of cancer biomarker carcinoembryonic antigen (CEA), and displayed a wide linear range (0.005-1000ngmL(-1)) and low detection limit (5pgmL(-1)). In addition, the immunosensor was performed with good stability and reproducibility, and the results to analyze human serum samples were satisfactory. PMID:27281106

  1. Cdk4 and Nek2 Signal Binucleation and Centrosome Amplification in a Her2+ Breast Cancer Model

    PubMed Central

    Harrison Pitner, Mary Kathryn; Saavedra, Harold I.

    2013-01-01

    Centrosome amplification (CA) is a contributor to carcinogenesis, generating aneuploidy, and chromosome instability. Previous work shows that breast adenocarcinomas have a higher frequency of centrosome defects compared to normal breast tissues. Abnormal centrosome phenotypes are found in pre-malignant lesions, suggesting an early role in breast carcinogenesis. However, the role of CA in breast cancers remains elusive. Identification of pathways and regulatory molecules involved in the generation of CA is essential to understanding its role in breast tumorigenesis. We established a breast cancer model of CA using Her2-positive cells. Our goal was to identify centrosome cycle molecules that are deregulated by aberrant Her2 signaling and the mechanisms driving CA. Our results show some Her2+ breast cancer cell lines harbor both CA and binucleation. Abolishing the expression of Cdk4 abrogated both CA and binucleation in these cells. We also found the source of binucleation in these cells to be defective cytokinesis that is normalized by downregulation of Cdk4. Protein levels of Nek2 diminish upon Cdk4 knockdown and vice versa, suggesting a molecular connection between Cdk4 and Nek2. Knockdown of Nek2 reduces CA and binucleation in this model while its overexpression further enhances centrosome amplification. We conclude that CA is modulated through Cdk4 and Nek2 signaling and that binucleation is a likely source of CA in Her2+ breast cancer cells. PMID:23776583

  2. Ultrasensitive sandwich-type electrochemical immunosensor based on a novel signal amplification strategy using highly loaded toluidine blue/gold nanoparticles decorated KIT-6/carboxymethyl chitosan/ionic liquids as signal labels.

    PubMed

    Wang, Yulan; Li, Xiaojian; Cao, Wei; Li, Yueyun; Li, He; Du, Bin; Wei, Qin

    2014-11-15

    An ultrasensitive sandwich-type electrochemical immunosensor for the quantitative detection of carcinoembryonic antigen (CEA) was designed based on a novel signal amplification strategy. Gold nanoparticles decorated mesoporous silica KIT-6 (Au@KIT-6) with large specific surface area and good adsorption properties was used as a label matrix to immobilize both the secondary antibodies (Ab2) and the electron transfer mediator toluidine blue (TB). Ab2 was loaded on KIT-6 due to the presence of gold nanoparticles (Au NPs) and TB was loaded on KIT-6 by physical adsorption. Ionic liquids (ILs) doped carboxymethyl chitosan (CMC) was used to prevent the leak of TB and facilitate the electron transfer. For the immobilization of primary antibodies (Ab1), gold nanoparticles decorated 3-aminopropyltriethoxysilane functionalized graphene sheets (Au@APTES-GS) were used as transducing materials to modify glassy carbon electrodes (GCE). High sensitivity was achieved for the designed immunosensor based on this novel signal amplification strategy. Under optimal conditions, the immunosensor exhibited an extremely low detection limit of 3.3 fg/mL and wide liner range from 10(-5) ng/mL to 10(2) ng/mL for CEA. Moreover, it exhibited good selectivity, acceptable reproducibility and stability, indicating potential application promising in clinical monitoring of tumor biomarkers. PMID:24967751

  3. An ultrasensitive "on-off-on" photoelectrochemical aptasensor based on signal amplification of a fullerene/CdTe quantum dots sensitized structure and efficient quenching by manganese porphyrin.

    PubMed

    Li, Mengjie; Zheng, Yingning; Liang, Wenbin; Yuan, Yali; Chai, Yaqin; Yuan, Ruo

    2016-06-21

    In this work, an ultrasensitive "on-off-on" photoelectrochemical (PEC) aptasensor was proposed based on the signal amplification of a fullerene/CdTe quantum dot (nano-C60/CdTe QDs) sensitized structure and efficient signal quenching of nano-C60/CdTe QDs by a manganese porphyrin (MnPP). PMID:27272457

  4. Phase regeneration for polarization-division multiplexed signals based on vector dual-pump nondegenerate phase sensitive amplification.

    PubMed

    Yang, Weili; Yu, Yu; Ye, Mengyuan; Chen, Guanyu; Zhang, Chi; Zhang, Xinliang

    2015-02-01

    The polarization-division multiplexing (PDM) technology is a practical method to double the transmission capacity, and the corresponding phase regeneration (PR) for PDM signals is meaningful and necessary to extend the transmission distance and increase the transparency for the phase-encoded PDM system. Those reported PDM PR schemes either utilized polarization-diversity technique or required special PDM format. In order to overcome these issues, the PR for the PDM phase-modulated signals is proposed and theoretically demonstrated in this paper, based on the vector dual-pump nondegenerate phase sensitive amplification (PSA). The theoretical model is established and the detailed characteristics are investigated to optimize the PR performance. Results show an obvious phase squeezing for the degraded 80 Gbit/s PDM differential phase-shift keying (DPSK) signals, and the error vector magnitude (EVM) of the regenerated signals on dual polarization states can be improved from 22.58% and 21.39% to 4.57% and 4.63%, respectively. Furthermore, the applicability of the proposed scheme for PDM quaternary-phase shift keying (QPSK) signals is investigated. The proposed scheme can be useful and promising in current PDM based coherent fiber-optic communication. PMID:25836072

  5. Electrochemical biosensor based on enzyme substrate as a linker: Application for aldolase activity with pectin-thionine complex as recognization element and signal amplification probe.

    PubMed

    Wang, Xiaonan; Wang, Meiwen; Zhang, Yuanyuan; Miao, Xiaocao; Huang, Yuanyuan; Zhang, Juan; Sun, Lizhou

    2016-09-15

    A new strategy to fabricate electrochemical biosensor is reported based on the linkage of enzyme substrate, thereby an electrochemical method to detect aldolase activity is established using pectin-thionine complex (PTC) as recognization element and signal probe. The linkage effect of fructose-1,6-bisphosphate (FBP), the substrate of aldolase, can be achieved via its strong binding to magnetic nanoparticles (MNPs)/aminophenylboronic acid (APBA) and the formation of phosphoramidate bond derived from its reaction with p-phenylenediamine (PDA) on the surface of electrode. Aldolase can reversibly catalyze the substrates into the products which have no binding capacity with MNPs/APBA, resulting in the exposure of the corresponding binding sites and its subsequent recognization on signal probe. Meanwhile, signal amplification can be accomplished by using the firstly prepared PTC which can bind with MNPs/APBA, and accuracy can be strengthened through magnetic separation. With good precision and accuracy, the established sensor may be extended to other proteins with reversible catalyzed ability. PMID:27107145

  6. Ultrasensitive electrochemical detection of microRNA with star trigon structure and endonuclease mediated signal amplification.

    PubMed

    Miao, Peng; Wang, Bidou; Yu, Zhiqiang; Zhao, Jing; Tang, Yuguo

    2015-01-15

    MicroRNAs play important roles in gene regulation. They can be used as effective biomarkers for diagnosis and prognosis of diseases like cancers. Due to their intrinsic properties of short length, low abundance and sequence homology among family members, it is difficult to realize sensitive and selective detection with economical use of time and cost. Herein, we report an ultrasensitive electrochemical method for microRNA analysis employing two oligonucleotides and one endonuclease. Generally, a glassy carbon electrode is first covered with gold nanoparticles (AuNPs) mediated by poly(diallyldimethylammonium chloride) (PDDA). Then, thiolated capture probe (CP) with methylene blue (MB) labeled at 5' end is modified on the pretreated electrode. Hybridization occurs among target microRNA, CP and auxiliary probe (AP), forming a star trigon structure on the electrode surface. Subsequently, endonuclease recognizes and cleaves CP on CP/AP duplex, releasing microRNA and AP back to the solution. The two regenerated elements can then form another star trigon with other CP molecules, initiating cycles of CP cleavage and MB departure. Significant decrease of electrochemical signals is thus observed, which can be used to reflect the concentration of microRNA. This proposed method has a linear response to microRNA in a wide range from 100 aM to 1 nM and the sensitivity of attomolar level can be achieved. Moreover, it has high selectivity against single-base mismatch sequences and can be used directly in serum samples. Therefore, this method shows great feasibility for the detection of microRNA and may have potential applications in cancer diagnosis and prognosis. PMID:25127470

  7. Hetero-enzyme-based two-round signal amplification strategy for trace detection of aflatoxin B1 using an electrochemical aptasensor.

    PubMed

    Zheng, Wanli; Teng, Jun; Cheng, Lin; Ye, Yingwang; Pan, Daodong; Wu, Jingjing; Xue, Feng; Liu, Guodong; Chen, Wei

    2016-06-15

    An electrochemical aptasensor for trace detection of aflatoxin B1 (AFB1) was developed by using an aptamer as the recognition unit while adopting the telomerase and EXO III based two-round signal amplification strategy as the signal enhancement units. The telomerase amplification was used to elongate the ssDNA probes on the surface of gold nanoparticles, by which the signal response range of the signal-off model electrochemical aptasensor could be correspondingly enlarged. Then, the EXO III amplification was used to hydrolyze the 3'-end of the dsDNA after the recognition of target AFB1, which caused the release of bounded AFB1 into the sensing system, where it participated in the next recognition-sensing cycle. With this two-round signal amplified electrochemical aptasensor, target AFB1 was successfully measured at trace concentrations with excellent detection limit of 0.6*10(-4)ppt and satisfied specificity due to the excellent affinity of the aptamer against AFB1. Based on this designed two-round signal amplification strategy, both the sensing range and detection limit were greatly improved. This proposed ultrasensitive electrochemical aptasensor method was also validated by comparison with the classic instrumental methods. Importantly, this hetero-enzyme based two-round signal amplified electrochemical aptasensor offers a great promising protocol for ultrasensitive detection of AFB1 and other mycotoxins by replacing the core recognition sequence of the aptamer. PMID:26896792

  8. Enzyme-free detection of sequence-specific microRNAs based on nanoparticle-assisted signal amplification strategy.

    PubMed

    Li, Ru-Dong; Wang, Qian; Yin, Bin-Cheng; Ye, Bang-Ce

    2016-03-15

    Developing direct and convenient methods for microRNAs (miRNAs) analysis is of great significance in understanding biological functions of miRNAs, and early diagnosis of cancers. We have developed a rapid, enzyme-free method for miRNA detection based on nanoparticle-assisted signal amplification coupling fluorescent metal nanoclusters as signal output. The proposed method involves two processes: target miRNA-mediated nanoparticle capture, which consists of magnetic microparticle (MMP) probe and CuO nanoparticle (NP) probe, and nanoparticle-mediated amplification for signal generation, which consists of fluorescent DNA-Cu/Ag nanocluster (NC) and 3-mercaptopropionic acid (MPA). In the presence of target miRNA, MMP probe and NP probe sandwich-capture the target miRNA via their respective complementary sequence. The resultant sandwich complex (MMP probe-miRNA-CuO NP probe) is separated using a magnetic field and further dissolved by acidolysis to turn CuO NP into a great amount of copper (II) ions (Cu(2+)). Cu(2+) could disrupt the interactions between thiol moiety of MPA and the fluorescent Cu/Ag NCs by preferentially reacting with MPA to form a disulfide compound as intermediate. By this way, the fluorescence emission of the DNA-Cu/Ag NCs in the presence of MPA increases upon the increasing concentration of Cu(2+), which is directly proportional to the amount of target miRNA. The proposed method allows quantitative detection of a liver-specific miR-221-5p in the range of 5 pM to 1000 pM with a detection limit of ~0.73 pM, and shows a good ability to discriminate single-base difference. Moreover, the detection assay can be applied to detect miRNA in cancerous cell lysates in excellent agreement with that from a commercial miRNA detection kit. PMID:26547010

  9. Electrochemical biosensor for microRNA detection based on poly(U) polymerase mediated isothermal signal amplification.

    PubMed

    Zhou, Yunlei; Yin, Huanshun; Li, Jie; Li, Bingchen; Li, Xue; Ai, Shiyun; Zhang, Xiansheng

    2016-05-15

    MicroRNAs play crucial role in post-transcriptional regulation for gene expression in animals, plants, and viruses. For the better understanding of microRNA and its functions, it is very important to develop effectively analytical method for microRNA detection. Herein, a novel electrochemical biosensor was fabricated for sensitive and selective detection of microRNA based on poly(U) polymerase mediated isothermal signal amplification, where poly(U) polymerase can catalyze the template independent addition of UMP from UTP to the 3' end of RNA. Using this activity, the target microRNA can be successfully labeled with biotin conjugated UMPs at its 3'-end using biotin conjugated UTP (biotin-UTP) as donor. Then, the avidin conjugated alkaline phosphatase can be further captured to the 3'-end of the target microRNA based on the specific interaction between biotin and avidin. Finally, under the catalytic activity of alkaline phosphatase, the substrate of p-nitrophenyl phosphate disodium salt hexahydrate can be hydrolyzed to produce 4-nitrophenol. According to the relationship between the electrochemical signal of p-nitrophenol and the concentration of microRNA-319a, the content of microRNA-319a can be detected. This signal amplification method is simple and sensitive. The developed method can detect as low as 1.7 fM microRNA and produce precise and accurate linear dynamic range from 10 to 1000 fM. The fabricated biosensor was further applied to detect the expression level change of microRNA-319a in rice seedlings after incubation with five kinds of different phytohormones. PMID:26700579

  10. An exonuclease-assisted amplification electrochemical aptasensor of thrombin coupling "signal on/off" strategy.

    PubMed

    Bao, Ting; Wen, Wei; Zhang, Xiuhua; Wang, Shengfu

    2015-02-20

    In this work, a dual-signaling electrochemical aptasensor based on exonuclease-catalyzed target recycling was developed for thrombin detection. The proposed aptasensor coupled "signal-on" and "signal-off" strategies. As to the construction of the aptasensor, ferrocene (Fc) labeled thrombin binding aptamer (TBA) could perfectly hybridize with the methylene blue (MB) modified thiolated capture DNA to form double-stranded structure, hence emerged two different electrochemical signals. In the presence of thrombin, TBA could form a G-quadruplex structure with thrombin, leading to the dissociation of TBA from the duplex DNA and capture DNA formed hairpin structure. Exonuclease could selectively digest single-stranded TBA in G-quadruplex structure and released thrombin to realize target recycling. As a consequence, the electrochemical signal of MB enhanced significantly, which realized "signal on" strategy, meanwhile, the deoxidization peak current of Fc decreased distinctly, which realized "signal off" strategy. The employment of exonuclease and superposition of two signals significantly improved the sensitivity of the aptasensor. In this way, an aptasensor with high sensitivity, good stability and selectivity for quantitative detection of thrombin was constructed, which exhibited a good linear range from 5 pM to 50 nM with a detection limit of 0.9 pM (defined as S/N=3). In addition, this design strategy could be applied to the detection of other proteins and small molecules. PMID:25682249

  11. Silver nanowires-based signal amplification for CdSe quantum dots electrochemiluminescence immunoassay.

    PubMed

    Huang, Tingyu; Meng, Qingmin; Jie, Guifen

    2015-04-15

    A novel silver-cysteine hybrid nanowires (SCNWs) with many reactive carboxyl and amine groups were prepared, which enable them to be used as idea signal amplifying labels in bioassays. A large number of CdSe quantum dots (QDs) were loaded on the SCNWs to develop amplified SCNWs-QDs electrochemiluminescence (ECL) signal probe. The PAMAM dendrimer-SCNWs nanohybrids covered on the electrode constructed an effective antibody immobilization matrix and made the immobilized biomolecules hold high stability and bioactivity. Based on the specific sandwich immunoreaction strategy, the detection antibody (Ab2)-SCNWs-QDs ECL signal probe was applied to the sensitive signal-on ECL immunoassay of human IgG. The SCNWs-QDs ECL not only opens promising new ECL emitting species, but also promotes the development of novel ECL signal-transition platforms for biosensing devices. PMID:25460886

  12. Robust nonenzymatic hybrid nanoelectrocatalysts for signal amplification toward ultrasensitive electrochemical cytosensing.

    PubMed

    Zheng, Tingting; Zhang, Qingfeng; Feng, Sheng; Zhu, Jun-Jie; Wang, Qian; Wang, Hui

    2014-02-12

    We have discovered that magnetic Fe3O4 nanoparticles exhibit an intrinsic catalytic activity toward the electrochemical reduction of small dye molecules. Metallic nanocages, which act as efficient signal amplifiers, can be attached to the surface of Fe3O4 beads to further enhance the catalytic electrochemical signals. The Fe3O4@nanocage core-satellite hybrid nanoparticles show significantly more robust electrocatalytic activities than the enzymatic peroxidase/H2O2 system. We have further demonstrated that these nonenzymatic nanoelectrocatalysts can be used as signal-amplifying nanoprobes for ultrasensitive electrochemical cytosensing. PMID:24467322

  13. Hairpin DNA Switch for Ultrasensitive Spectrophotometric Detection of DNA Hybridization Based on Gold Nanoparticles and Enzyme Signal Amplification

    SciTech Connect

    Zhang, Youyu; Tang, Zhiwen; Wang, Jun; Wu, Hong; Maham, Aihui; Lin, Yuehe

    2010-08-01

    A novel DNA detection platform based on a hairpin-DNA switch, nanoparticles, and enzyme signal amplification for ultrasensitive detection of DNA hybridization has been developed in this work. In this DNA assay, a “stem-loop” DNA probe dually labeled with a thiol at its 5’ end and a biotin at its 3’ end, respectively, was used. This probe was immobilized on the gold nanoparticles (AuNPs) anchored by a protein, globulin, on a 96-well microplate. In the absence of target DNA, the immobilized probe with the stem-loop structure shields the biotin from being approached by a bulky horseradish peroxidase linked-avidin (avidin-HRP) conjugate due to the steric hindrance. However, in the presence of target DNA, the hybridization between the hairpin DNA probe and the target DNA causes significant conformational change of the probe, which forces biotin away from the surface of AuNPs. As a result, the biotin becomes accessible by the avidin-HRP, and the target hybridization event can be sensitively detected via the HRP catalyzed substrate 3, 3', 5, 5'-tetramethylbenzidine using spectrophometric method. Some experimental parameters governing the performance of the assay have been optimized. At optimal conditions, this DNA assay can detect DNA at the concentration of femtomolar level by means of a signal amplification strategy based on the combination of enzymes and nanoparticles. This approach also has shown excellent specificity to distinguish single-base mismatches of DNA targets because of the intrinsic high selectivity of the hairpin DNA probe.

  14. Ultrasensitive electrochemical immunosensor employing glucose oxidase catalyzed deposition of gold nanoparticles for signal amplification.

    PubMed

    Zhang, Jie; Pearce, Mark C; Ting, Boon Ping; Ying, Jackie Y

    2011-09-15

    This paper describes a novel enzymatic amplification strategy for ultrasensitive electrochemical immunosensing. This approach utilizes glucose oxidase for the enzymatic deposition of gold nanoparticles onto an indium tin oxide (ITO) electrode surface using a novel gold developer solution consisting of 20 mM of glucose, 20 mM of NaSCN, 0.5 M of p-benzoquinone (PBQ) and 1 mM of AuCl(4)(-) dissolved in 0.1 M of pH 7.5 phosphate buffer solution. The amount of gold deposited was quantified electrochemically by monitoring the reduction of gold oxide in an aqueous solution of 0.5 M of H(2)SO(4), which was correlated to the amount of antigens in the solution. The effectiveness of this strategy was demonstrated experimentally through the construction of an immunosensor for the detection of mouse IgG using a sandwich immunoassay in a linear dynamic range of 5 pg/ml to 50 ng/ml. A good mean apparent recovery in the range of 88-102% was obtained over the entire linear dynamic range of the sensor response in the serum samples. This suggested that the immunosensor would be useful for the testing of proteins in real clinical samples. PMID:21782410

  15. Rapid pathogen detection by lateral-flow immunochromatographic assay with gold nanoparticle-assisted enzyme signal amplification.

    PubMed

    Cho, Il-Hoon; Bhunia, Arun; Irudayaraj, Joseph

    2015-08-01

    To date most LF-ICA format for pathogen detection is based on generating color signals from gold nanoparticle (AuNP) tracers that are perceivable by naked eye but often these methods exhibit sensitivity lower than those associated with the conventional enzyme-based immunological methods or mandated by the regulatory guidelines. By developing AuNP avidin-biotin constructs in which a number of enzymes can be labeled we report on an enhanced LF-ICA system to detect pathogens at very low levels. With this approach we show that as low as 100 CFU/mL of Escherichia coli O157:H7 can be detected, indicating that the limit of detection can be increased by about 1000-fold due to our signal amplification approach. In addition, extensive cross-reactivity experiments were conducted (19 different organisms were used) to test and successfully validate the specificity of the assay. Semi-quantitative analysis can be performed using signal intensities which were correlated with the target pathogen concentrations for calibration by image processing. PMID:25955290

  16. Linewidth Enhancement Factor and Amplification of Angle-Modulated Optical Signals in Injection-Locked Quantum Cascade Lasers

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Taraprasad; Bhattacharyya, Prosenjit

    2016-03-01

    This paper presents a nonlinear analysis of the effect of linewidth enhancement factor (LEF) on the amplification of angle-modulated optical signals in injection-locked mid-infrared (IR) quantum cascade lasers (QCLs). A higher value of LEF tends to conserve the output angle modulation index of the amplified mid-IR signal particularly in the low-modulation frequency region. Further, a higher value of signal injection ratio produces a wider bandwidth of the locked QCL amplifier. The LEF introduces asymmetry in the lockband (LB) of the injection-locked QCL and this asymmetry increases with the increase in the value of LEF. Typically ratio of calculated lower-side LB to upper-side LB for an injection power level of - 20 dB and a LEF of unity is 1.67. The electron relaxation time in the uppermost subband lasing level in a three-level system has a profound effect on the LB asymmetry in a QCL.

  17. Label-free electrochemical immunosensor based on enhanced signal amplification between Au@Pd and CoFe2O4/graphene nanohybrid

    PubMed Central

    Zhang, Yong; Li, Jiaojiao; Wang, Zhiling; Ma, Hongmin; Wu, Dan; Cheng, Qianhe; Wei, Qin

    2016-01-01

    The improvement of sensitivity of electrochemical immunosensor can be achieved via two approaches: increasing loading capacities of antibody and enlarging responding electrochemical signals. Based on these, CoFe2O4/graphene nanohybrid (CoFe2O4/rGO) as support was firstly used for preparing electrochemical biosensor, and with the addition of Au@Pd nanorods (NRs) as mimic enzyme, a label-free electrochemical immunosensor was prepared. Due to the high electrical conductivity, open porous structure and large loading capacities of CoFe2O4/rGO, the enhanced signal amplification between Au@Pd NRs and CoFe2O4/rGO was studied. Fabricated as a novel substrate, the prepared immunosensor had a good analytical performance and exhibited a wide linear range from 0.01 to 18.0 ng·mL−1 with a low detection limit of 3.3 pg·mL−1 for estradiol, which was succeeded in applying to detect estradiol in the natural water. PMID:26987503

  18. Magnetic Particle-Based Immunoassay of Phosphorylated p53 Using Protein-Cage Templated Lead Phosphate and Carbon Nanospheres for Signal Amplification

    SciTech Connect

    Chen, Aiqiong; Bao, Yuanwu; Ge, Xiaoxiao; Shin, Yongsoon; Du, Dan; Lin, Yuehe

    2012-11-20

    Phosphorylated p53 at serin 15 (phospho-p53-15) is a potential biomarker of Gamma-radiation exposure. In this paper, we described a new magnetic particles (MPs)-based electrochemical immunoassay of human phospho-p53-15 using carbon nanospheres (CNS) and protein-cage templated lead phosphate nanoparticles for signal amplification. Greatly enhanced sensitivity was achieved by three aspects: 1) The protein-cage nanoparticle (PCN) and p53-15 signal antibody (p53-15 Ab2) are linked to CNS (PCNof each apoferritin; 3) MPs capture a large amount of primary antibodies. Using apoferritin templated metallic phosphate instead of enzyme as label has the advantage of eliminating the addition of mediator or immunoreagents and thus makes the immunoassay system simpler. The subsequent stripping voltammetric analysis of the released lead ions were detected on a disposable screen printed electrode. The response current was proportional to the phospho-p53-15 concentration in the range of 0.02 to 20 ng mL-1 with detection limit of 0.01 ng mL-1. This method shows a good stability, reproducibility and recovery.

  19. Glucose deprivation activates a metabolic and signaling amplification loop leading to cell death

    PubMed Central

    Graham, Nicholas A; Tahmasian, Martik; Kohli, Bitika; Komisopoulou, Evangelia; Zhu, Maggie; Vivanco, Igor; Teitell, Michael A; Wu, Hong; Ribas, Antoni; Lo, Roger S; Mellinghoff, Ingo K; Mischel, Paul S; Graeber, Thomas G

    2012-01-01

    The altered metabolism of cancer can render cells dependent on the availability of metabolic substrates for viability. Investigating the signaling mechanisms underlying cell death in cells dependent upon glucose for survival, we demonstrate that glucose withdrawal rapidly induces supra-physiological levels of phospho-tyrosine signaling, even in cells expressing constitutively active tyrosine kinases. Using unbiased mass spectrometry-based phospho-proteomics, we show that glucose withdrawal initiates a unique signature of phospho-tyrosine activation that is associated with focal adhesions. Building upon this observation, we demonstrate that glucose withdrawal activates a positive feedback loop involving generation of reactive oxygen species (ROS) by NADPH oxidase and mitochondria, inhibition of protein tyrosine phosphatases by oxidation, and increased tyrosine kinase signaling. In cells dependent on glucose for survival, glucose withdrawal-induced ROS generation and tyrosine kinase signaling synergize to amplify ROS levels, ultimately resulting in ROS-mediated cell death. Taken together, these findings illustrate the systems-level cross-talk between metabolism and signaling in the maintenance of cancer cell homeostasis. PMID:22735335

  20. Detection of biological molecules using chemical amplification and optical sensors

    SciTech Connect

    Antwerp, W.P. van; Mastrototaro, J.J.

    2000-01-04

    Methods are provided for the determination of the concentration of biological levels of polyhydroxylated compounds, particularly glucose. The methods utilize an amplification system that is an analyte transducer immobilized in a polymeric matrix, where the system is implantable and biocompatible. Upon interrogation by an optical system, the amplification system produces a signal capable of detection external to the skin of the patient. Quantitation of the analyte of interest is achieved by measurement of the emitted signal.

  1. Detection of biological molecules using chemical amplification and optical sensors

    DOEpatents

    Van Antwerp, William Peter; Mastrototaro, John Joseph

    2000-01-01

    Methods are provided for the determination of the concentration of biological levels of polyhydroxylated compounds, particularly glucose. The methods utilize an amplification system that is an analyte transducer immobilized in a polymeric matrix, where the system is implantable and biocompatible. Upon interrogation by an optical system, the amplification system produces a signal capable of detection external to the skin of the patient. Quantitation of the analyte of interest is achieved by measurement of the emitted signal.

  2. Detection of biological molecules using chemical amplification and optical sensors

    DOEpatents

    Van Antwerp, William Peter; Mastrototaro, John Joseph

    2004-10-12

    Methods are provided for the determination of the concentration of biological levels of polyhydroxylated compounds, particularly glucose. The methods utilize an amplification system that is an analyte transducer immobilized in a polymeric matrix, where the system is implantable and biocompatible. Upon interrogation by an optical system, the amplification system produces a signal capable of detection external to the skin of the patient. Quantitation of the analyte of interest is achieved by measurement of the emitted signal.

  3. Significant Chiral Signal Amplification of Langmuir Monolayers Probed by Second Harmonic Generation.

    PubMed

    Lv, Kai; Lin, Lu; Wang, Xiaoyu; Zhang, Li; Guo, Yuan; Lu, Zhou; Liu, Minghua

    2015-05-01

    With the development of the nonlinear optical technique such as SHG (second harmonic generation), the in situ measurements of the chirality in the monolayers at the air/water interface have become possible. However, when performing the SHG measurement of the chirality in a monolayer, it is still a great challenge to obtain the chiral signals with a good S/N (signal-to-noise) ratio. In this Letter, interfacial assemblies with induced supramolecular chirality were used to amplify the weak chiral SHG signals from the monolayers at the air/water interface. Tetrakis(4-sulfonatophenyl) porphyrin (TPPS) J aggregates were used as the subphase, and when chiral amphiphilic molecules were spread on it, chiral domains of the amphiphile/TPPS J aggregates were formed and then significantly amplified chiral signals that otherwise could not be detected. Moreover, the sign of the DCE (degree of chiral excess) changed with the chirality of the amphiphilic molecules, thus providing a possible way to obtain the absolute chiral information in situ in the monolayers. PMID:26263339

  4. A signal amplification strategy using the cascade catalysis of gold nanoclusters and glucose dehydrogenase for ultrasensitive detection of thrombin.

    PubMed

    Han, Jing; Zhuo, Ying; Chai, Yaqin; Gui, Guofeng; Zhao, Min; Zhu, Qiang; Yuan, Ruo

    2013-12-15

    This work reports a novel signal amplification strategy for ultrasensitive detection of thrombin by cascade catalysis of gold nanoclusters (AuNCs) and glucose dehydrogenase (GDH). Herein, the AuNCs prepared by using polyamidoamine dendrimer as template were constructed not only as nanocarriers for anchoring the large amounts of secondary thrombin aptamers but also as nanocatalysts to catalyze the oxidation of NADH efficiently. Moreover, a large amount of GDH was loaded through the immobilization technology of DNA hybridization and a large amount of toluidine blue (Tb) was intercalated into the DNA grooves via electrostatic interaction. Significantly, the electrochemical signal was greatly enhanced based on cascade catalysis: firstly, GDH catalyzed the oxidation of glucose to gluconolactone with the concomitant generation of NADH in the presence of NAD(+). Then, AuNCs as nanocatalysts could effectively catalyze NADH to produce NAD(+) with the help of Tb as redox probe. Under the optimal conditions, the proposed aptasensor exhibits a linear range of 1.0×10(-14)-5×10(-9) M with a low detection limit of 3.3×10(-15) M for thrombin detection and shows high sensitivity and good specificity. PMID:23850783

  5. Nicking enzyme and graphene oxide-based dual signal amplification for ultrasensitive aptamer-based fluorescence polarization assays.

    PubMed

    Huang, Yong; Liu, Xiaoqian; Zhang, Liangliang; Hu, Kun; Zhao, Shulin; Fang, Baizong; Chen, Zhen-Feng; Liang, Hong

    2015-01-15

    In this work, two different configurations for novel amplified fluorescence polarization (FP) aptasensors based on nicking enzyme signal amplification (NESA) and graphene oxide (GO) enhancement have been developed for ultrasensitive and selective detection of biomolecules in homogeneous solution. One approach involves the aptamer-target binding induced the stable hybridization between an aptamer probe and a fluorophore-labeled DNA probe linked to GO, and forms a nicking site-containing duplex DNA region due to the enhancement of base stacking. The second analytical method involves the target induced the assembly of two aptamer subunits into an aptamer-target complex, and then hybridizes with a fluorophore-labeled DNA probe linked to GO, forming a nicking site-containing duplex DNA region. The formation of the duplex DNA region in both methods triggers the NESA process, resulting in the release of many short DNA fragments carrying the fluorophore from GO, generating a significant decrease of the FP value that provides the readout signal for the amplified sensing process. By using the NESA coupled GO enhancement path, the sensitivity of the developed aptasensors can be significantly improved by four orders of magnitude over traditional aptamer-based homogeneous assays. Moreover, these aptasensors also exhibit high specificity for target molecules, which are capable of detecting target molecule in biological samples. Considering these qualities, the proposed FP aptasensors based NESA and GO enhancement can be expected to provide an ultrasensitive platform for amplified analysis of target molecules. PMID:25087158

  6. Collective Signal Processing in Cluster Chemotaxis: Roles of Adaptation, Amplification, and Co-attraction in Collective Guidance

    PubMed Central

    Camley, Brian A.; Zimmermann, Juliane; Levine, Herbert; Rappel, Wouter-Jan

    2016-01-01

    Single eukaryotic cells commonly sense and follow chemical gradients, performing chemotaxis. Recent experiments and theories, however, show that even when single cells do not chemotax, clusters of cells may, if their interactions are regulated by the chemoattractant. We study this general mechanism of “collective guidance” computationally with models that integrate stochastic dynamics for individual cells with biochemical reactions within the cells, and diffusion of chemical signals between the cells. We show that if clusters of cells use the well-known local excitation, global inhibition (LEGI) mechanism to sense chemoattractant gradients, the speed of the cell cluster becomes non-monotonic in the cluster’s size—clusters either larger or smaller than an optimal size will have lower speed. We argue that the cell cluster speed is a crucial readout of how the cluster processes chemotactic signals; both amplification and adaptation will alter the behavior of cluster speed as a function of size. We also show that, contrary to the assumptions of earlier theories, collective guidance does not require persistent cell-cell contacts and strong short range adhesion. If cell-cell adhesion is absent, and the cluster cohesion is instead provided by a co-attraction mechanism, e.g. chemotaxis toward a secreted molecule, collective guidance may still function. However, new behaviors, such as cluster rotation, may also appear in this case. Co-attraction and adaptation allow for collective guidance that is robust to varying chemoattractant concentrations while not requiring strong cell-cell adhesion. PMID:27367541

  7. Amplification and attenuation of a probe signal by doubly dressed states

    NASA Astrophysics Data System (ADS)

    Shevchenko, S. N.; Oelsner, G.; Greenberg, Ya. S.; Macha, P.; Karpov, D. S.; Grajcar, M.; Hübner, U.; Omelyanchouk, A. N.; Il'ichev, E.

    2014-05-01

    We analyze a system composed of a qubit coupled to the electromagnetic fields in two high quality quantum oscillators. A particular realization of such a system is the superconducting qubit coupled to a transmission-line resonator driven by two signals with frequencies close to the resonator's harmonics. This doubly driven system can be described in terms of the doubly dressed qubit states. Our calculations demonstrate the possibility to change the number of photons in the resonator and the transmission of the fundamental-mode signal over a wide parameter range exploiting resonances with the dressed qubit. Experiments show that in the case of high quality resonators the dressed energy levels and corresponding resonance conditions can be probed, even for high driving amplitudes. The interaction of the qubit with photons of two harmonics can be used for the creation of quantum amplifiers or attenuators.

  8. In-line phase-sensitive amplification of QPSK signal using multiple quasi-phase matched LiNbO₃ waveguide.

    PubMed

    Asobe, Masaki; Umeki, Takeshi; Takenouchi, Hirokazu; Miyamoto, Yutaka

    2014-11-01

    Phase-sensitive amplifiers (PSA) using periodically poled (PPLN) LiNbO₃ waveguides are promising as low-noise optical amplifiers. However, it is difficult to realize in-line operation for multi-level phase modulated signals using a PPLN based PSA with the conventional configuration. In this paper, we report a PPLN based in-line PSA that can regenerate quadrature phase shift keying (QPSK) signals. Multi-stage frequency mixing in a multiple quasi-phase matched LiNbO₃waveguide allows carrier phase recovery from a QPSK signal. Non-degenerate parametric amplification enables the phase-sensitive amplification of a QPSK signal. Amplitude and phase regeneration is examined utilizing gain saturation and phase squeezing capability. PMID:25401814

  9. pH-Induced aggregated melanin nanoparticles for photoacoustic signal amplification

    NASA Astrophysics Data System (ADS)

    Ju, Kuk-Youn; Kang, Jeeun; Pyo, Jung; Lim, Joohyun; Chang, Jin Ho; Lee, Jin-Kyu

    2016-07-01

    We present a new melanin-like nanoparticle (MelNP) and its performance evaluation results. This particle is proposed as an exogenous contrast agent for photoacoustic (PA) imaging. Conventional PA contrast agents are based on non-biological materials. In contrast, the MelNPs are organic nanoparticles inspired by natural melanin. Melanin is an endogenous chromophore that has the ability to produce a PA signal in vivo. The developed MelNPs are capable of aggregating with one another under mildly acidic conditions after introducing hydrolysis-susceptible citraconic amide on the surface of bare MelNPs. We ascertained that the physical aggregation of the MelNPs resulted in an increased PA signal strength in the near-infrared window of biological tissue (i.e., 700 nm) without absorption tuning. This phenomenon is likely because of the overlapping thermal fields of the developed MelNPs. The PA signal produced from the developed MelNPs, after exposure to mildly acidic conditions (i.e., pH 6), is 8.1 times stronger than under neutral conditions. This unique characteristic found in this study can be utilized in a practical strategy for highly sensitive in vivo cancer target imaging in response to its acidic microenvironment. This approach to amplify the PA response of MelNPs in clusters could accelerate the use of MelNPs as an alternative to non-biological nanoprobes, so that MelNPs may be applicable in PA imaging and functional PA imaging such as stimuli sensitive, multimodal, and theranostic imaging.We present a new melanin-like nanoparticle (MelNP) and its performance evaluation results. This particle is proposed as an exogenous contrast agent for photoacoustic (PA) imaging. Conventional PA contrast agents are based on non-biological materials. In contrast, the MelNPs are organic nanoparticles inspired by natural melanin. Melanin is an endogenous chromophore that has the ability to produce a PA signal in vivo. The developed MelNPs are capable of aggregating with one

  10. pH-Induced aggregated melanin nanoparticles for photoacoustic signal amplification.

    PubMed

    Ju, Kuk-Youn; Kang, Jeeun; Pyo, Jung; Lim, Joohyun; Chang, Jin Ho; Lee, Jin-Kyu

    2016-08-14

    We present a new melanin-like nanoparticle (MelNP) and its performance evaluation results. This particle is proposed as an exogenous contrast agent for photoacoustic (PA) imaging. Conventional PA contrast agents are based on non-biological materials. In contrast, the MelNPs are organic nanoparticles inspired by natural melanin. Melanin is an endogenous chromophore that has the ability to produce a PA signal in vivo. The developed MelNPs are capable of aggregating with one another under mildly acidic conditions after introducing hydrolysis-susceptible citraconic amide on the surface of bare MelNPs. We ascertained that the physical aggregation of the MelNPs resulted in an increased PA signal strength in the near-infrared window of biological tissue (i.e., 700 nm) without absorption tuning. This phenomenon is likely because of the overlapping thermal fields of the developed MelNPs. The PA signal produced from the developed MelNPs, after exposure to mildly acidic conditions (i.e., pH 6), is 8.1 times stronger than under neutral conditions. This unique characteristic found in this study can be utilized in a practical strategy for highly sensitive in vivo cancer target imaging in response to its acidic microenvironment. This approach to amplify the PA response of MelNPs in clusters could accelerate the use of MelNPs as an alternative to non-biological nanoprobes, so that MelNPs may be applicable in PA imaging and functional PA imaging such as stimuli sensitive, multimodal, and theranostic imaging. PMID:27406260

  11. Quenching of Unincorporated Amplification Signal Reporters in Reverse-Transcription Loop-Mediated Isothermal Amplification Enabling Bright, Single-Step, Closed-Tube, and Multiplexed Detection of RNA Viruses.

    PubMed

    Ball, Cameron S; Light, Yooli K; Koh, Chung-Yan; Wheeler, Sarah S; Coffey, Lark L; Meagher, Robert J

    2016-04-01

    Reverse-transcription-loop-mediated isothermal amplification (RT-LAMP) has frequently been proposed as an enabling technology for simplified diagnostic tests for RNA viruses. However, common detection techniques used for LAMP and RT-LAMP have drawbacks, including poor discrimination capability, inability to multiplex targets, high rates of false positives, and (in some cases) the requirement of opening reaction tubes postamplification. Here, we present a simple technique that allows closed-tube, target-specific detection, based on inclusion of a dye-labeled primer that is incorporated into a target-specific amplicon if the target is present. A short, complementary quencher hybridizes to unincorporated primer upon cooling down at the end of the reaction, thereby quenching fluorescence of any unincorporated primer. Our technique, which we term QUASR (for quenching of unincorporated amplification signal reporters, read "quasar"), does not significantly reduce the amplification efficiency or sensitivity of RT-LAMP. Equipped with a simple LED excitation source and a colored plastic gel filter, the naked eye or a camera can easily discriminate between positive and negative QUASR reactions, which produce a difference in signal of approximately 10:1 without background subtraction. We demonstrate that QUASR detection is compatible with complex sample matrices such as human blood, using a novel LAMP primer set for bacteriophage MS2 (a model RNA virus particle). Furthermore, we demonstrate single-tube duplex detection of West Nile virus (WNV) and chikungunya virus (CHIKV) RNA. PMID:26980448

  12. Highly sensitive fluorescence assay of DNA methyltransferase activity via methylation-sensitive cleavage coupled with nicking enzyme-assisted signal amplification.

    PubMed

    Zhao, Yongxi; Chen, Feng; Wu, Yayan; Dong, Yanhua; Fan, Chunhai

    2013-04-15

    Herein, using DNA adenine methylation (Dam) methyltransferase (MTase) as a model analyte, a simple, rapid, and highly sensitive fluorescence sensing platform for monitoring the activity and inhibition of DNA MTase was developed on the basis of methylation-sensitive cleavage and nicking enzyme-assisted signal amplification. In the presence of Dam MTase, an elaborately designed hairpin probe was methylated. With the help of methylation-sensitive restriction endonuclease DpnI, the methylated hairpin probe could be cleaved to release a single-stranded DNA (ssDNA). Subsequently, this released ssDNA would hybridize with the molecular beacon (MB) to open its hairpin structure, resulting in the restoration of fluorescence signal as well as formation of the double-stranded recognition site for nicking enzyme Nt.BbvCI. Eventually, an amplified fluorescence signal was observed through the enzymatic recycling cleavage of MBs. Based on this unique strategy, a very low detection limit down to 0.06 U/mL was achieved within a short assay time (60 min) in one step, which is superior to those of most existing approaches. Owing to the specific site recognition of MTase toward its substrate, the proposed sensing system was able to readily discriminate Dam MTase from other MTase such as M.SssI and even detect the target in complex biological matrix. Furthermore, the application of the proposed sensing strategy for screening Dam MTase inhibitors was also demonstrated with satisfactory results. This novel method not only provides a promising platform for monitoring activity and inhibition of DNA MTases, but also shows great potentials in biological process researches, drugs discovery and clinical diagnostics. PMID:23202331

  13. Improving oral implant osseointegration in a murine model via Wnt signal amplification

    PubMed Central

    Mouraret, Sylvain; Hunter, Daniel J.; Bardet, Claire; Popelut, Antoine; Brunski, John B.; Chaussain, Catherine; Bouchard, Philippe; Helms, Jill A.

    2016-01-01

    Aim To determine the key biological events occurring during implant failure and then we use this knowledge to develop new biology-based strategies that improve osseointegration. Materials and Methods Wild-type and Axin2LacZ/LacZ adult male mice underwent oral implant placement, with and without primary stability. Peri-implant tissues were evaluated using histology, alkaline phosphatase (ALP) activity, tartrate resistant acid phosphatase (TRAP) activity and TUNEL staining. In addition, mineralization sites, collagenous matrix organization and the expression of bone markers in the peri-implant tissues were assessed. Results Maxillary implants lacking primary stability show histological evidence of persistent fibrous encapsulation and mobility, which recapitulates the clinical problems of implant failure. Despite histological and molecular evidence of fibrous encapsulation, osteoblasts in the gap interface exhibit robust ALP activity. This mineralization activity is counteracted by osteoclast activity that resorbs any new bony matrix and consequently, the fibrous encapsulation remains. Using a genetic mouse model, we show that implants lacking primary stability undergo osseointegration, provided that Wnt signalling is amplified. Conclusions In a mouse model of oral implant failure caused by a lack of primary stability, we find evidence of active mineralization. This mineralization, however, is outpaced by robust bone resorption, which culminates in persistent fibrous encapsulation of the implant. Fibrous encapsulation can be prevented and osseointegration assured if Wnt signalling is elevated at the time of implant placement. PMID:24164629

  14. The MEMSamp: using (RF-)MEMS switches for the micromechanical amplification of electronic signals

    NASA Astrophysics Data System (ADS)

    Merlijn van Spengen, W.; Roobol, Sander B.; Klaassen, Wouter P.; Oosterkamp, Tjerk H.

    2010-12-01

    Semiconductor-based electronic amplifiers are ubiquitous in the modern world, but have fundamental limitations, such as the impossibility of using them at extreme temperatures and their sensitivity to ionizing radiation. Also, they inherently have various sources of electronic noise. We have developed a MEMS (micro-electromechanical systems) switch based amplifier in which an electronic signal is mechanically amplified in power: the MEMSamp. The new device is suitable for the same applications as semiconductor-based amplifiers, with the additional advantage of a purely mechanical operation, circumventing the limitations mentioned above. A thermal noise analysis shows that a MEMSamp may be operated with much lower input noise than state-of-the-art semiconductor amplifiers. We expect optimized amplifiers based on this principle to be applicable in fields ranging from low-noise preamplifiers to radiation-hard power amplifiers, and from ultra-high temperature electronics to spacecrafts.

  15. A protein tagging system for signal amplification in gene expression and fluorescence imaging

    PubMed Central

    Tanenbaum, Marvin E.; Gilbert, Luke A.; Qi, Lei S.; Weissman, Jonathan S.; Vale, Ronald D.

    2014-01-01

    Summary Signals in many biological processes can be amplified by recruiting multiple copies of regulatory proteins to a site of action. Harnessing this principle, we have developed a novel protein scaffold, a repeating peptide array termed SunTag, which can recruit multiple copies of an antibody-fusion protein. We show that the SunTag can recruit up to 24 copies of GFP, thereby enabling long-term imaging of single protein molecules in living cells. We also use the SunTag to create a potent synthetic transcription factor by recruiting multiple copies of a transcriptional activation domain to a nuclease-deficient CRISPR/Cas9 protein and demonstrate strong activation of endogenous gene expression and re-engineered cell behavior with this system. Thus, the SunTag provides a versatile platform for multimerizing proteins on a target protein scaffold and is likely to have many applications in imaging and in controlling biological outputs. PMID:25307933

  16. Gradient sensing by a bistable regulatory motif enhances signal amplification but decreases accuracy in individual cells

    NASA Astrophysics Data System (ADS)

    Sharma, Rati; Roberts, Elijah

    2016-06-01

    Many vital eukaryotic cellular functions require the cell to respond to a directional gradient of a signaling molecule. The first two steps in any eukaryotic chemotactic/chemotropic pathway are gradient detection and cell polarization. Like many processes, such chemotactic and chemotropic decisions are made using a relatively small number of molecules and are thus susceptible to internal and external fluctuations during signal transduction. Large cell-to-cell variations in the magnitude and direction of a response are therefore possible and do, in fact, occur in natural systems. In this work we use three-dimensional probabilistic modeling of a simple gradient sensing pathway to study the capacity for individual cells to accurately determine the direction of a gradient, despite fluctuations. We include a stochastic external gradient in our simulations using a novel gradient boundary condition modeling a point emitter a short distance away. We compare and contrast three different variants of the pathway, one monostable and two bistable. The simulation data show that an architecture combining bistability with spatial positive feedback permits the cell to both accurately detect and internally amplify an external gradient. We observe strong polarization in all individual cells, but in a distribution of directions centered on the gradient. Polarization accuracy in our study was strongly dependent upon a spatial positive feedback term that allows the pathway to trade accuracy for polarization strength. Finally, we show that additional feedback links providing information about the gradient to multiple levels in the pathway can help the cell to refine initial inaccuracy in the polarization direction.

  17. A novel signal amplification strategy of an electrochemical aptasensor for kanamycin, based on thionine functionalized graphene and hierarchical nanoporous PtCu.

    PubMed

    Qin, Xiaoli; Yin, Yan; Yu, Huijing; Guo, Wenjuan; Pei, Meishan

    2016-03-15

    An ultrasensitive electrochemical aptasensor for the quantitative detection of kanamycin antibiotic was fabricated based on a novel signal amplification strategy. This aptasensor was developed using thionine functionalized graphene (GR-TH) and hierarchical nanoporous (HNP) PtCu alloy as biosensing substrates for the first time. HNP-PtCu alloy with controllable bimodal ligament/pore distributions was successfully prepared by two-step dealloying of a well-designed PtCuAl precursor alloy combined with an annealing operation. GR-TH composite was synthesized by one-step reduction of graphene oxide (GO) in TH solution. Greatly amplified sensitivity was achieved by using GR-TH/HNP-PtCu composite owing to its large specific surface and good electron-transfer ability. Under the optimized conditions, the proposed aptasensor exhibited a high sensitivity and a wider linearity to kanamycin in the range 5 × 10(-7)-5 × 10(-2) μgmL(-1) with a low detection limit of 0.42 pgmL(-1). This aptasensor also displayed a satisfying electrochemical performance with good stability, selectivity and reproducibility. The as-prepared aptasensor was successfully used for the determination of kanamycin in animal derived food. PMID:26513281

  18. The Spatial Pattern of Cochlear Amplification

    PubMed Central

    Fisher, Jonathan A.N.; Nin, Fumiaki; Reichenbach, Tobias; Uthaiah, Revathy C.; Hudspeth, A.J.

    2012-01-01

    SUMMARY Sensorineural hearing loss, which stems primarily from the failure of mechanosensory hair cells, changes the traveling waves that transmit acoustic signals along the cochlea. However, the connection between cochlear mechanics and the amplificatory function of hair cells remains unclear. Using an optical technique that permits the targeted inactivation of prestin, a protein of outer hair cells that generates forces on the basilar membrane, we demonstrate that these forces interact locally with cochlear traveling waves to achieve enormous mechanical amplification. By perturbing amplification in narrow segments of the basilar membrane, we further show that a cochlear traveling wave accumulates gain as it approaches its peak. Analysis of these results indicates that cochlear amplification produces negative damping that counters the viscous drag impeding traveling waves; targeted photoinactivation locally interrupts this compensation. These results reveal the locus of amplification in cochlear traveling waves and connect the characteristics of normal hearing to molecular forces. PMID:23217746

  19. The 'window' component of the low threshold Ca2+ current produces input signal amplification and bistability in cat and rat thalamocortical neurones.

    PubMed Central

    Williams, S R; Tóth, T I; Turner, J P; Hughes, S W; Crunelli, V

    1997-01-01

    1. The mechanism underlying a novel form of input signal amplification and bistability was investigated by intracellular recording in rat and cat thalamocortical (TC) neurones maintained in slices and by computer simulation with a biophysical model of these neurones. 2. In a narrow membrane potential range centred around -60 mV, TC neurones challenged with small (10-50 pA), short (50-200 ms) current steps produced a stereotyped, large amplitude hyperpolarization (> 20 mV) terminated by the burst firing of action potentials, leading to amplification of the duration and amplitude of the input signal, that is hereafter referred to as input signal amplification. 3. In the same voltage range centred around -60 mV, single evoked EPSPs and IPSPs also produced input signal amplification, indicating that this behaviour can be triggered by physiologically relevant stimuli. In addition, a novel, intrinsic, low frequency oscillation, characterized by a peculiar voltage dependence of its frequency and by the presence of plateau potentials on the falling phase of low threshold Ca2+ potentials, was recorded. 4. Blockade of pure Na+ and K+ currents by tetrodotoxin (1 microM) and Ba2+ (0.1-2.0 mM), respectively, did not affect input signal amplification, neither did the presence of excitatory or inhibitory amino acid receptor antagonists in the perfusion medium. 5. A decrease in [Ca2+]o (from 2 to 1 mM) and an increase in [Mg2+]o (from 2 to 10 mM), or the addition of Ni2+ (2-3 mM), abolished input signal amplification, while an increase in [Ca2+]o (from 2 to 8 mM) generated this behaviour in neurones where it was absent in control conditions. These results indicate the involvement of the low threshold Ca2+ current (IT) in input signal amplification, since the other Ca2+ currents of TC neurones are activated at potentials more positive than -40 mV. 6. Blockade of the slow inward mixed cationic current (Ih) by 4-(N-ethyl-N-phenylamino)-1,2-dimethyl-6-(methylamino

  20. Detection of Q Fever Specific Antibodies Using Recombinant Antigen in ELISA with Peroxidase Based Signal Amplification

    PubMed Central

    Chen, Hua-Wei; Zhang, Zhiwen; Glennon, Erin; Ching, Wei-Mei

    2014-01-01

    Currently, the accepted method for Q fever serodiagnosis is indirect immunofluorescent antibody assay (IFA) using the whole cell antigen. In this study, we prepared the recombinant antigen of the 27-kDa outer membrane protein (Com1) which has been shown to be recognized by Q fever patient sera. The performance of recombinant Com1 was evaluated in ELISA by IFA confirmed serum samples. Due to the low titers of IgG and IgM in Q fever patients, the standard ELISA signals were further amplified by using biotinylated anti-human IgG or IgM plus streptavidin-HRP polymer. The modified ELISA can detect 88% (29 out of 33) of Q fever patient sera collected from Marines deployed to Iraq. Less than 5% (5 out of 156) of the sera from patients with other febrile diseases reacted with the Com1. These results suggest that the modified ELISA using Com1 may have the potential to improve the detection of Q fever specific antibodies. PMID:26904739

  1. Spontaneous oscillations, signal amplification and synchronization in a model of active hair bundle mechanics

    PubMed Central

    Han, Lijuan; Neiman, Alexander B.

    2010-01-01

    We study spontaneous dynamics and signal transduction in a model of active hair bundle mechanics of sensory hair cells. The hair bundle motion is subjected to internal noise resulted from thermal fluctuations and stochastic dynamics of mechano-electrical transduction ion channels. Similar to other studies we found that in the presence of noise the coherence of stochastic oscillations is maximal at a point on the bifurcation diagram away from the Andronov-Hopf bifurcation and is close to the point of maximum sensitivity of the system to weak periodic mechanical perturbations. Despite decoherent effect of noise the stochastic hair bundle oscillations can be synchronized by external periodic force of few pN amplitude in a finite range of control parameters. We then study effects of receptor potential oscillations on mechanics of the hair bundle and show that the hair bundle oscillations can be synchronized by oscillating receptor voltage. Moreover, using a linear model for the receptor potential we show that bi-directional coupling of the hair bundle and the receptor potential results in significant enhancement of the coherence of spontaneous oscillations and of the sensitivity to the external mechanical perturbations. PMID:20481759

  2. An electrochemical dopamine aptasensor incorporating silver nanoparticle, functionalized carbon nanotubes and graphene oxide for signal amplification.

    PubMed

    Bahrami, Shokoh; Abbasi, Amir Reza; Roushani, Mahmoud; Derikvand, Zohreh; Azadbakht, Azadeh

    2016-10-01

    In this work, immobilization of a dopamine (DA) aptamer was performed at the surface of an amino functionalized silver nanoparticle-carbon nanotube graphene oxide (AgNPs/CNTs/GO) nanocomposite. A 58-mer DA-aptamer was immobilized through the formation of phosphoramidate bonds between the amino group of chitosan and the phosphate group of the aptamer at the 5' end. An AgNPs/CNTs/GO nanocomposite was employed as a highly catalytic label for electrochemical detection of DA based on electrocatalytic activity of the nanocomposite toward hydrogen peroxide (H2O2). Interaction of DA with the aptamer caused conformational changes of the aptamer which, in turn, decreased H2O2 oxidation and reduction peak currents. On the other hand, the presumed folding of the DA-aptamer complexes on the sensing interface inhibited the electrocatalytic activity of AgNPs/CNTs/GO toward H2O2. Sensitive quantitative detection of DA was carried out by monitoring the decrease of differential pulse voltammetric (DPV) responses of AgNPs/CNTs/GO nanocomposite toward H2O2 oxidation. The DPV signal linearly decreased with increased concentration of DA from 3 to 110nmolL(-1) with a detection limit of 700±19.23pmolL(-1). Simple preparation, low operation cost, speed and validity are the decisive factors of this method motivating its application to biosensing investigation. PMID:27474313

  3. Glucose oxidase-doped magnetic silica nanostrutures as labels for localized signal amplification of electrochemical immunosensors

    NASA Astrophysics Data System (ADS)

    Ren, Jingjing; Tang, Dianping; Su, Biling; Tang, Juan; Chen, Guonan

    2010-07-01

    Herein, we report a novel glucose oxidase (GOD)-doped magnetic silica nanostructure and its possible application in the clinical immunoassays. The doped nanostructures were initially synthesized using the reverse micelle method, and ferritin antibodies (anti-Ft) were then labeled to the surface of the nanostructures, which were employed as signal antibodies for ultrasensitive detection of ferritin (Ft) in the sandwich-type electrochemical enzyme immunoassays. The doped nanostructures were characterized using transmission electron microscopy (TEM), UV-vis absorption spectrometry and vibrating sample magnetometer (VSM). The advantages of the doped nanostructures as labels were investigated in comparison with the conventional label method. Under the optimal conditions, the nanostructures-based immunoassay toward ferritin standards displays a wide dynamic range from 0.1 to 400 ng mL-1 with a low detection limit of 10 pg mL-1 ferritin (at 3σ), which is three-fold higher in the sensitivity than that of directly using GOD-labeled antibodies. The assay results for clinical serum samples with the developed method received in excellent accordance with results obtained from the referenced standard enzyme-linked immunosorbent assay (ELISA) method.

  4. Multifunctional reduced graphene oxide trigged chemiluminescence resonance energy transfer: Novel signal amplification strategy for photoelectrochemical immunoassay of squamous cell carcinoma antigen.

    PubMed

    Zhang, Yan; Sun, Guoqiang; Yang, Hongmei; Yu, Jinghua; Yan, Mei; Song, Xianrang

    2016-05-15

    Herein, a photoelectrochemical (PEC) immunoassay is constructed for squamous cell carcinoma antigen (SCCA) detection using zinc oxide nanoflower-bismuth sulfide (Bi2S3) composites as photoactive materials and reduced graphene oxide (rGO) as signal labels. Horseradish peroxidase is used to block sites against nonspecific binding, and then participated in luminol-based chemiluminescence (CL) system. The induced CL emission is acted as an inner light source to excite photoactive materials, simplifying the instrument. A novel signal amplification strategy is stem from rGO because of the rGO acts as an energy acceptor, while luminol serves as a donor to rGO, triggering the CL resonance energy transfer phenomenon between luminol and rGO. Thus, the efficient CL emission to photoactive materials decreases. Furthermore, the signal amplification caused by rGO labeled signal antibodies is related to photogenerated electron-hole pairs: perfect matching of energy levels between rGO and Bi2S3 makes rGO a sink to capture photogenerated electrons from Bi2S3; the increased steric hindrance hinders the electron donor to the surface of Bi2S3 for reaction with the photogenerated holes. On the basis of the novel signal amplification strategy, the proposed immunosensor exhibits excellent analytical performance for PEC detection of SCCA, ranging from 0.8 pg mL(-1) to 80 ng mL(-1) with a low detection limit of 0.21 pg mL(-1). Meanwhile, the designed signal amplification strategy provides a general format for future development of PEC assays. PMID:26686924

  5. Ultrasensitive sandwich-type electrochemical immunosensor based on trimetallic nanocomposite signal amplification strategy for the ultrasensitive detection of CEA.

    PubMed

    Tian, Lihui; Liu, Li; Li, Yueyuan; Wei, Qin; Cao, Wei

    2016-01-01

    A novel and ultrasensitive sandwich-type electrochemical immunosensor was designed for the quantitative detection of carcino-embryonic antigen (CEA). This immunosensor was developed by using the trimetallic NiAuPt nanoparticles on graphene nanosheets (NGs) nanosheets (NiAuPt-NGs) as excellent labels and β-cyclodextrin functionalized reduced graphene oxide nanosheets (CD-NGs) as the platform. The CD-NGs with high specific surface area good biocompatibility and the ideal dispersibility was used to capture the primary antibodies (Ab1) efficiently. The trimetallic NiAuPt-NGs nanocomposites were used as the labels for signal amplification, showing better electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2), which is much better than that the monometallic Pt-NGs, bimetallic NiPt-NGs and AuPt-NGs due to the synergetic effect presented in NiAuPt-NGs. The NiAuPt-NGs nanocomposites consist of tightly coupled nanostructures of Au, Ni and Pt, which have neither an alloy nor a core-shell structure. Under the optimal conditions, a linear range from 0.001-100 ng/mL and a low detection limit of 0.27 pg/mL were obtained for CEA. The proposed electrochemical sandwich-type immunosensor may have a promising application in bioassay and it enriches the electrochemical immunoassays. PMID:27488806

  6. Ultrasensitive sandwich-type electrochemical immunosensor based on trimetallic nanocomposite signal amplification strategy for the ultrasensitive detection of CEA

    PubMed Central

    Tian, Lihui; Liu, Li; Li, Yueyuan; Wei, Qin; Cao, Wei

    2016-01-01

    A novel and ultrasensitive sandwich-type electrochemical immunosensor was designed for the quantitative detection of carcino-embryonic antigen (CEA). This immunosensor was developed by using the trimetallic NiAuPt nanoparticles on graphene nanosheets (NGs) nanosheets (NiAuPt-NGs) as excellent labels and β-cyclodextrin functionalized reduced graphene oxide nanosheets (CD-NGs) as the platform. The CD-NGs with high specific surface area good biocompatibility and the ideal dispersibility was used to capture the primary antibodies (Ab1) efficiently. The trimetallic NiAuPt-NGs nanocomposites were used as the labels for signal amplification, showing better electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2), which is much better than that the monometallic Pt-NGs, bimetallic NiPt-NGs and AuPt-NGs due to the synergetic effect presented in NiAuPt-NGs. The NiAuPt-NGs nanocomposites consist of tightly coupled nanostructures of Au, Ni and Pt, which have neither an alloy nor a core-shell structure. Under the optimal conditions, a linear range from 0.001–100 ng/mL and a low detection limit of 0.27 pg/mL were obtained for CEA. The proposed electrochemical sandwich-type immunosensor may have a promising application in bioassay and it enriches the electrochemical immunoassays. PMID:27488806

  7. Determination of knockdown resistance allele frequencies in global human head louse populations using the serial invasive signal amplification reaction

    PubMed Central

    Hodgdon, Hilliary E.; Yoon, Kyong Sup; Previte, Domenic J.; Kim, Hyo Jeong; Aboelghar, Gamal E.; Lee, Si Hyeock; Clark, J. Marshall

    2010-01-01

    BACKGROUND Pediculosis is the most prevalent parasitic infestation of humans. Resistance to pyrethrin- and pyrethroid-based pediculicides is due to knockdown (kdr)-type point mutations in the voltage-sensitive sodium channel α-subunit gene. Early detection of resistance is crucial for the selection of effective management strategies. RESULTS Kdr allele frequencies of lice from 14 countries were determined using serial invasive signal amplification reaction. Lice collected from Uruguay, UK and Australia had kdr allele frequencies of 100% while lice from Ecuador, Papua New Guinea, South Korea and Thailand had kdr allele frequencies of 0%. The remaining 7 countries investigated, including seven US populations, two Argentina, Brazil, Denmark, Czech Republic, Egypt and Israel, displayed variable kdr allele frequencies, ranging from 11% to 97%. CONCLUSION The newly developed and validated SISAR method is suitable for accurate monitoring of kdr allele frequencies in head lice. Proactive management is needed where kdr-type resistance is not yet saturated. Based on sodium channel insensitivity and its occurrence in louse populations resistant to pyrethrin- and pyrethroid-based pediculicides, the T917I mutation appears a key marker for resistance. Results from the Egyptian population, however, indicate that phenotypic resistance of lice with single or double mutations (M815I and/or L920F) should also be determined. PMID:20564731

  8. Electrochemical immunosensor for α-fetoprotein detection using ferroferric oxide and horseradish peroxidase as signal amplification labels.

    PubMed

    Wang, Huan; Li, Xiaojian; Mao, Kexia; Li, Yan; Du, Bin; Zhang, Yihe; Wei, Qin

    2014-11-15

    An electrochemical immunosensor for quantitative detection of α-fetoprotein (AFP) in human serum was developed using graphene sheets (GS) and thionine (TH) as electrode materials and mesoporous silica nanoparticles (MSNs) loaded with ferroferric oxide (Fe3O4) nanoparticles and horseradish peroxidase (HRP) as labels for signal amplification. In this study, the compound of GS and TH (GS-TH) was used as a substrate for promoting electron transfer and immobilization of primary antibody of AFP (Ab1). MSNs were used as a carrier for immobilization of secondary antibody of AFP (Ab2), Fe3O4, and HRP. The synergistic effect occurred between Fe3O4 and HRP and greatly improved the sensitivity of the immunosensor. This method could detect AFP over a wide concentration range from 0.01 to 25 ng ml(-1) with a detection limit of 4 pg ml(-1). This strategy may find wide potential application in clinical analysis or detection of other tumor markers. PMID:25168193

  9. Fluorescence detection of telomerase activity in cancer cell extracts based on autonomous exonuclease III-assisted isothermal cycling signal amplification.

    PubMed

    Ding, Caifeng; Li, Xiaoqian; Wang, Wei; Chen, Yaoyao

    2016-09-15

    Based on the extension reaction of a telomerase substrate (TS) primer in the presence of the telomerase, strand-displacement process to perform more stable longer duplex chain, and stepwise hydrolysis of mononucleotides from the blunt or the recessed 3'-hydroxyl termini of duplex DNA in the presence of Exonuclease III (Exo III), an amplified fluorescence detection of telomerase activity in the cancer cells was described in this manuscript. A fluorescence probe DNA, a quencher DNA, and a TS primer were mixed to construct a three-chain DNA structure and a two-chain DNA structure because the amount of the TS primer was less than the other two DNA. In the presence of the telomerase, the quencher DNA was replaced from the probe DNA and the telomerase activity could be determined with the fluorescence enhancement. The telomerase activity in HeLa extracts equivalent to 6-2000 cells was detected by this method. Moreover, the strategy was further proved by using telomerase extracted from Romas cells. With the multiple rounds of isothermal strand displacement and the hydrolysis process, constituted consecutive of signal amplification for the novel detection paradigm that allowed measuring of telomerase activity in crude cancer cell extracts confirmed the reliability and practicality of the protocol, which reveal this platform holds great promise in the biochemical assay for the telomerase activity in early diagnosis for cancers. PMID:27108253

  10. Ultra-sensitive biosensor for K-ras gene detection using enzyme capped gold nanoparticles conjugates for signal amplification.

    PubMed

    Fang, Xian; Bai, Lijuan; Han, Xiaowei; Wang, Jiao; Shi, Anqi; Zhang, Yuzhong

    2014-09-01

    In this study, an ultra-sensitive hairpin DNA-based electrochemical DNA biosensor for K-ras gene detection is described. Gold nanoparticles (Au-NPs) and horseradish peroxidase (HRP)-streptavidin capped Au-NPs (HAS) conjugates are used for signal amplification. Initially, hairpin DNA dually labeled with thiol at its 5' end and with biotin at its 3' end is immobilized on the surface of Au-NPs modified electrode, and the hairpin DNA is in a "closed" state; hence, the HAS conjugates are shielded from being approached by the biotin due to steric hindrance. However, in the presence of target DNA, the target DNA hybridizes with the loop structure of hairpin DNA and causes conformational change, resulting in biotin forced away from the electrode surface, thereby becoming accessible for the HAS conjugates. Thus, the HAS conjugates are linked to the electrode surface via the specific interaction between biotin and streptavidin. Electrochemical detection was performed in phosphate-buffered saline (PBS) containing tetramethylbenzidine (TMB) and H2O2. Under optimal conditions, the peak current differences (ΔI) are linear with the target DNA in the range from 0.1 fM to 1 nM with a detection limit of 0.035 fM. Furthermore, this biosensor also demonstrates its excellent specificity for single-base mismatched DNA. PMID:24939462

  11. Glucose encapsulating liposome for signal amplification for quantitative detection of biomarkers with glucometer readout.

    PubMed

    Zhao, Yuting; Du, Dan; Lin, Yuehe

    2015-10-15

    A new technology was developed to quantitatively detect a broad range of disease biomarkers and proven to be portable, economical, and conveniently accessible. Measurements were performed based on releasing encapsulated glucose from antibody-tagged liposomes and subsequently detecting the released glucose using a commercial personal glucose meter (GM). The innovative aspect of this approach lies in the quantification of target biomarkers through the detection of glucose, thus expanding the applicability of the GM by broadening the range of target biomarkers instead of detecting only one analyte, glucose. Because of the bilayer membrane of liposomes, which can accommodate tens of thousands of glucose molecules, the sensitivity was greatly enhanced by using glucose encapsulating liposomes as a signal output and an amplifier. Here, the model analyte, protein 53 phosphorylated on Serine 15 (phospho-p53(15)), was captured by primary antibodies bound on magnetic Fe3O4 nanoparticles and then recognized by reporting antibodies conjugated to glucose encapsulating liposomes. Finally, the target phospho-p53(15) was detected by lysing the bound liposomes to release the encapsulated glucose (4 × 10(5) glucose molecules per liposome), which is detected with the GM. This approach was demonstrated to be a universal technology that can be easily produced to quantify a wide variety of biomarkers in medical diagnostics, food safety, public health, and environmental monitoring. In the near future, it is expected that these sensors, in combination with a portable GM, can be used in many fields such as physicians' laboratories, hospitals and the common household. PMID:26005847

  12. CB[7]-mediated signal amplification approach for sensitive surface plasmon resonance spectroscopy.

    PubMed

    Gao, Yanmin; Zou, Fei; Wu, Beiping; Wang, Xingxin; Zhang, Jiangjiang; Koh, Kwangnak; Chen, Hongxia

    2016-07-15

    Cucurbit[7]uril (CB[7]) has received increasing attention because of its unique structure and multiple recognition properties. To improve the sensitivity of surface plasmon resonance (SPR) biosensors, we designed a novel strategy in which caspase-3 serves as the model analyte and CB[7]-modified AuNPs (CB[7]-AuNPs) act as the intermedium. The substrate peptides can be cleaved and replaced with a new N-terminal Phe residue in presence of caspase-3. The CB[7]-AuNPs combine with the N-terminal Phe on the gold chip surface through incorporating the side chain within the nonpolar CB[7] cavity and chelating the N-terminal ammonium group with CB[7] carbonyl oxygen. Then CB[7]-AuNPs integrate with short peptide-modified AuNPs containing Phe at the N-terminal of the peptide. SPR signals are significantly improved through the layer-by-layer assembly of AuNPs. The well-designed sensing platform allows the detection of caspase-3 in a linear range from 10fg/mL to 10(3)fg/mL with a detection limit of 2.2 fg/mL. Given its high specificity and desirable sensitivity, this CB[7]-assisted SPR method may be a useful tool for the assay of caspase-3 in the future. This work may also afford a new model to improve the sensitivity and selectivity of SPR biosensors in other protein detection experiments and disease diagnosis. PMID:26950645

  13. A sensitive electrochemiluminescent aptasensor based on perylene derivatives as a novel co-reaction accelerator for signal amplification.

    PubMed

    Yu, Yan-Qing; Zhang, Hai-Yu; Chai, Ya-Qin; Yuan, Ruo; Zhuo, Ying

    2016-11-15

    Herein, a novel signal amplification strategy was designed using the perylene derivative as the co-reaction accelerator toward graphene-CdTe quantum dots (G-CdTe)/S2O8(2-) system to construct a highly sensitive electrochemiluminescent (ECL) aptasensor for thrombin (TB) detection. Firstly, the G-CdTe nanocomposites were prepared by one-step method of in situ generating CdTe quantum dots onto the surface of the graphene oxide by using 3-mercaptopropionic acid as the CdTe QDs stabilizer. Then, a kind of perylene derivative (PTC-Lys), was synthesized by covalently binding L-lysine to 3,4,9,10-perylenetetracarboxylic acid, which was further immobilized onto the G-CdTe by the π-π* stacking and cross-linked the detection thrombin aptamer (TBA II) to obtain the TBA II/PTC-Lys/G-CdTe signal probes. It is worth pointing out that PTC-Lys acting as an efficient co-reaction accelerator interacted with the co-reactant of S2O8(2-) rather than G-CdTe to promote the more oxidant mediators of SO4(•-), which could further react with G-CdTe to produce excited state species G-CdTe* for emitting light. Compared with the G-CdTe/S2O8(2-) ECL system, our proposed strategy with the introduction of co-reaction accelerator of PTC-Lys exhibited ultra-high sensitivity to quantify the concentration of TB from 1.0×10(-7)nM to 10nM with a detection limit of 34aM. PMID:27148827

  14. Optical filtering enabled by cascaded parametric amplification.

    PubMed

    McKinstrie, C J; Dailey, J M; Agarwal, A; Toliver, P

    2016-06-27

    A cascaded parametric amplifier consists of a first parametric amplifier, which amplifies an input signal and generates an idler, which is a copy of the signal, a signal processor, which controls the phases of the signal and idler, and a second parametric amplifier, which combines the signal and idler in a phase-sensitive manner. In this paper, cascaded parametric amplification is modeled and the conditions required to maximize the constructive-destructive extinction ratio are determined. The results show that a cascaded parametric amplifier can be operated as a filter: A desired signal-idler pair is amplified, whereas undesired signal-idler pairs are deamplified. For the desired signal and idler, the noise figures of the filtering process (input signal-to-noise ratio divided by the output ratios) are only slightly higher than those of the copying process: Signal-processing functionality can be achieved with only a minor degradation in signal quality. PMID:27410581

  15. Novel One-Tube-One-Step Real-Time Methodology for Rapid Transcriptomic Biomarker Detection: Signal Amplification by Ternary Initiation Complexes.

    PubMed

    Fujita, Hiroto; Kataoka, Yuka; Tobita, Seiji; Kuwahara, Masayasu; Sugimoto, Naoki

    2016-07-19

    We have developed a novel RNA detection method, termed signal amplification by ternary initiation complexes (SATIC), in which an analyte sample is simply mixed with the relevant reagents and allowed to stand for a short time under isothermal conditions (37 °C). The advantage of the technique is that there is no requirement for (i) heat annealing, (ii) thermal cycling during the reaction, (iii) a reverse transcription step, or (iv) enzymatic or mechanical fragmentation of the target RNA. SATIC involves the formation of a ternary initiation complex between the target RNA, a circular DNA template, and a DNA primer, followed by rolling circle amplification (RCA) to generate multiple copies of G-quadruplex (G4) on a long DNA strand like beads on a string. The G4s can be specifically fluorescence-stained with N(3)-hydroxyethyl thioflavin T (ThT-HE), which emits weakly with single- and double-stranded RNA/DNA but strongly with parallel G4s. An improved dual SATIC system, which involves the formation of two different ternary initiation complexes in the RCA process, exhibited a wide quantitative detection range of 1-5000 pM. Furthermore, this enabled visual observation-based RNA detection, which is more rapid and convenient than conventional isothermal methods, such as reverse transcription-loop-mediated isothermal amplification, signal mediated amplification of RNA technology, and RNA-primed rolling circle amplification. Thus, SATIC methodology may serve as an on-site and real-time measurement technique for transcriptomic biomarkers for various diseases. PMID:27347743

  16. Label-free and sensitive fluorescence detection of nucleic acid, based on combination of a graphene oxid /SYBR green I dye platform and polymerase assisted signal amplification

    NASA Astrophysics Data System (ADS)

    Zhu, Xiao; Xing, Da

    2012-12-01

    A new label-free isothermal fluorescence amplification detection for nucleic acid has been developed. In this paper, we first developed a novel sensitive and specific detection platform with an unmodified hairpin probe (HP) combination of the graphene oxid (GO)/ SYBR green I dye (SG), which was relied on the selective principle of adsorption and the high quenching efficiency of GO. Then for the application of this new strategy, we used Mirco RNA-21 (Mir-21) as the target to evaluate this working principle of our design. When the target was hybridizing with the HP and inducing its conformation of change, an efficient isothermal circular strand-displacement polymerization reaction was activating to assist the first signal amplification. In this format, the formed complex conformation of DNA would interact with its high affinity dye, then detached from the surface of GO after incubating with the platform of GO/intercalating dye. This reaction would accompany with obvious fluorescence recovery, and accomplish farther signal enhancement by a mass of intercalating dye inserting into the minor groove of the long duplex replication product. By taking advantage of the multiple amplification of signal, this method exerted substantial enhancement in sensitivity and could be used for rapid and selective detection of Mir-21 with attomole range. It is expected that this cost-effective GO based sensor might hold considerable potential to apply in bioanalysis studies.

  17. A signal-on electrochemical aptasensor for ultrasensitive detection of endotoxin using three-way DNA junction-aided enzymatic recycling and graphene nanohybrid for amplification

    NASA Astrophysics Data System (ADS)

    Bai, Lijuan; Chai, Yaqin; Pu, Xiaoyun; Yuan, Ruo

    2014-02-01

    Endotoxin, also known as lipopolysaccharide (LPS), is able to induce a strong immune response on its internalization into mammalian cells. To date, aptamer-based biosensors for LPS detection have been rarely reported. This work describes a new signal-on electrochemical aptasensor for the ultrasensitive detection of LPS by combining the three-way DNA hybridization process and nanotechnology-based amplification. With the help of DNA1 (associated with the concentration of target LPS), the capture probe hybridizes with DNA1 and the assistant probe to open its hairpin structure and form a ternary ``Y'' junction structure. The DNA1 can be released from the structure in the presence of nicking endonuclease to initiate the next hybridization process. Then a great deal of cleaved capture probe produced in the cyclic process can bind with DNA2-nanocomposite, which contains the electroactive toluidine blue (Tb) with the amplification materials graphene (Gra) and gold nanoparticles (AuNPs). Thus, an enhanced electrochemical signal can be easily read out. With the cascade signal amplification, this newly designed protocol provides an ultrasensitive electrochemical detection of LPS down to the femtogram level (8.7 fg mL-1) with a linear range of 6 orders of magnitude (from 10 fg mL-1 to 50 ng mL-1). Moreover, the high sensitivity and specificity make this method versatile for the detection of other biomolecules by changing the corresponding sequences of the capture probe and the assistant probe.

  18. A signal-on electrochemical aptasensor for ultrasensitive detection of endotoxin using three-way DNA junction-aided enzymatic recycling and graphene nanohybrid for amplification.

    PubMed

    Bai, Lijuan; Chai, Yaqin; Pu, Xiaoyun; Yuan, Ruo

    2014-03-01

    Endotoxin, also known as lipopolysaccharide (LPS), is able to induce a strong immune response on its internalization into mammalian cells. To date, aptamer-based biosensors for LPS detection have been rarely reported. This work describes a new signal-on electrochemical aptasensor for the ultrasensitive detection of LPS by combining the three-way DNA hybridization process and nanotechnology-based amplification. With the help of DNA1 (associated with the concentration of target LPS), the capture probe hybridizes with DNA1 and the assistant probe to open its hairpin structure and form a ternary "Y" junction structure. The DNA1 can be released from the structure in the presence of nicking endonuclease to initiate the next hybridization process. Then a great deal of cleaved capture probe produced in the cyclic process can bind with DNA2-nanocomposite, which contains the electroactive toluidine blue (Tb) with the amplification materials graphene (Gra) and gold nanoparticles (AuNPs). Thus, an enhanced electrochemical signal can be easily read out. With the cascade signal amplification, this newly designed protocol provides an ultrasensitive electrochemical detection of LPS down to the femtogram level (8.7 fg mL(-1)) with a linear range of 6 orders of magnitude (from 10 fg mL(-1) to 50 ng mL(-1)). Moreover, the high sensitivity and specificity make this method versatile for the detection of other biomolecules by changing the corresponding sequences of the capture probe and the assistant probe. PMID:24477782

  19. Prolactin-induced prostate tumorigenesis links sustained Stat5 signaling with the amplification of basal/stem cells and emergence of putative luminal progenitors.

    PubMed

    Sackmann-Sala, Lucila; Chiche, Aurélie; Mosquera-Garrote, Nerea; Boutillon, Florence; Cordier, Corinne; Pourmir, Ivan; Pascual-Mathey, Luz; Kessal, Karima; Pigat, Natascha; Camparo, Philippe; Goffin, Vincent

    2014-11-01

    Current androgen ablation therapies for prostate cancer are initially successful, but the frequent development of castration resistance urges the generation of alternative therapies and represents an important health concern. Prolactin/signal transducer and activator of transcription 5 (STAT5) signaling is emerging as a putative target for alternative treatment for prostate cancer. However, mechanistic data for its role in development or progression of prostate tumors are scarce. In vivo mouse studies found that local prolactin induced the amplification of prostate epithelial basal/stem cells. Because these cells are proposed cells of origin for prostate cancer and disease recurrence, we looked further into this amplification. Our results indicated that sustained Stat5 activation was associated with the occurrence of abnormal basal/stem cell clusters in prostate epithelium of prostate-specific prolactin-transgenic mice. Analysis of epithelial areas containing these clusters found high proliferation, Stat5 activation, and expression of stem cell antigen 1. Furthermore, enhanced prolactin signaling also led to amplification of a luminal cell population that was positive for stem cell antigen 1. These cells may originate from amplified basal/stem cells and might represent important progenitors for tumor development in prostate epithelium. These data provide a deeper understanding of the initial stages of prostate tumorigenesis induced by prolactin to help determine whether this hormone or its downstream messengers could be useful targets for prostate cancer treatment in the future. PMID:25193592

  20. Membrane conductances involved in amplification of small signals by sodium channels in photoreceptors of drone honey bee.

    PubMed Central

    Vallet, A M; Coles, J A; Eilbeck, J C; Scott, A C

    1992-01-01

    1. Voltage signals of about 1 mV evoked in photoreceptors of the drone honey bee by shallow modulation of a background illumination of an intensity useful for behaviour are thought to be amplified by voltage-dependent Na+ channels. To elucidate the roles of the various membrane conductances in this amplification we have studied the effects of the Na+ channel blocker tetrodotoxin (TTX) and various putative K+ channel blockers on the membrane potential, Vm. 2. Superfusion of a slice of retina with 0.5-10 mM-4-aminopyridine (4-AP) depolarized the membrane and, in fifty of sixty-three cells induced repetitive action potentials. Ionophoretic injection of tetraethylammonium produced similar effects. 3. In order to measure the depolarization caused by 4-AP, action potentials were prevented by application of TTX: 4-AP was applied when the membrane was depolarized to different levels by light. 4-AP induced an additional depolarization at all membrane potentials tested (-64 to -27 mV). We conclude that there are 4-AP-sensitive K+ channels that are open at constant voltage over this range. 4. 4-AP slowed down the recovery phase of the action potential induced by a light flash by a factor that ranged from 0.51 to 0.16. This reduction could be accounted for by the reduction in a voltage-independent K+ conductance estimated from the steady-state depolarization. 5. After the voltage-gated Na+ channels had been blocked by TTX, exposure to 4-AP further changed the amplitude of the response to a small (approximately 10%) decremental light stimulus. The change was an increase when the background illumination brought Vm to potentials more negative than about -40 mV; it was a decrease when Vm > -40 mV. The data could be fitted by a circuit representation of the membrane with a light-activated conductance and a K+ conductance (EK = -66 mV) that was partly blocked by 4-AP. The voltage range studied was from -52 to -27 mV; neither conductance in the model was voltage dependent. 6. The

  1. Sensitive magnetic nanoparticle-based immunoassay of phosphorylated acetylcholinesterase using protein cage templated lead phosphate for signal amplification with graphite furnace atomic absorption spectrometry detection

    PubMed Central

    Liang, Pei; Kang, Caiyan; Yang, Enjian; Ge, Xiaoxiao; Du, Dan; Lin, Yuehe

    2016-01-01

    We developed a new magnetic nanoparticles sandwich-like immunoassay using protein cage nanoparticles (PCN) for signal amplification together with graphite furnace atomic absorption spectrometry (GFAAS) for quantification of organophosphorylated acetylcholinesterase adduct (OP-AChE), the biomarker of exposure to organophosphate pesticides (OPs) and nerve agents. OP-AChE adducts were firstly captured by titanium dioxide coated magnetic nanoparticles (TiO2-MNPs) from the sample matrixes through metal chelation with phospho-moieties, and then selectively recognized by anti-AChE antibody labeled on PCN which was packed with lead phosphate in its cavity (PCN-anti-AChE). The sandwich-like immunoreaction was performed among TiO2-MNPs, OP-AChE and PCN-anti-AChE to form TiO2-MNPs/OP-AChE/PCN-anti-AChE immunocomplex. The complex could be easily isolated from the sample solution with the help of magnet, and the released lead ions from PCN were detected by GFAAS for the quantification of OP-AChE. Greatly enhanced sensitivity was achieved because PCN increased the amount of metal ions in the cavity of each apoferritin. The proposed immunoassay yielded a linear response over a broad OP-AChE concentrations from 0.01 nM to 2 nM, with a detection limit of 2 pM, which has enough sensitivity for monitoring of low-dose exposure to OPs. This new method showed an acceptable stability and reproducibility and was validated with OP-AChE spiked human plasma. PMID:26953358

  2. A sensitive magnetic nanoparticle-based immunoassay of phosphorylated acetylcholinesterase using protein cage templated lead phosphate for signal amplification with graphite furnace atomic absorption spectrometry detection.

    PubMed

    Liang, Pei; Kang, Caiyan; Yang, Enjian; Ge, Xiaoxiao; Du, Dan; Lin, Yuehe

    2016-04-01

    We developed a new magnetic nanoparticle sandwich-like immunoassay using protein cage nanoparticles (PCN) for signal amplification together with graphite furnace atomic absorption spectrometry (GFAAS) for the quantification of an organophosphorylated acetylcholinesterase adduct (OP-AChE), the biomarker of exposure to organophosphate pesticides (OPs) and nerve agents. OP-AChE adducts were firstly captured by titanium dioxide coated magnetic nanoparticles (TiO2-MNPs) from the sample matrixes through metal chelation with phospho-moieties, and then selectively recognized by anti-AChE antibody labeled on PCN which was packed with lead phosphate in its cavity (PCN-anti-AChE). The sandwich-like immunoreaction was performed among TiO2-MNPs, OP-AChE and PCN-anti-AChE to form a TiO2-MNP/OP-AChE/PCN-anti-AChE immunocomplex. The complex could be easily isolated from the sample solution with the help of magnet, and the released lead ions from PCN were detected by GFAAS for the quantification of OP-AChE. Greatly enhanced sensitivity was achieved because PCN increased the amount of metal ions in the cavity of each apoferritin. The proposed immunoassay yielded a linear response over a broad range of OP-AChE concentrations from 0.01 nM to 2 nM, with a detection limit of 2 pM, which has enough sensitivity for monitoring of low-dose exposure to OPs. This new method showed an acceptable stability and reproducibility and was validated with OP-AChE spiked human plasma. PMID:26953358

  3. Nanocrystal-based electrochemiluminescence sensor for cell detection with Au nanoparticles and isothermal circular double-assisted signal amplification.

    PubMed

    Dai, Pan-Pan; Li, Jin-Yi; Yu, Tao; Xu, Jing-Juan; Chen, Hong-Yuan

    2015-08-15

    Here we have developed a sensitive cancer cell amplified detection method which combined Au NPs enhanced electrochemiluminescence (ECL) of CdS nanocrystals (NCs) film, with isothermal circular amplification reaction of polymerase. In DNA circular amplification detection system, hairpin DNA beacon/Au NPs composite modified CdS NCs film was used as an ECL emitter. Messenger DNA is hybridized with the aptamer modified on magnetic beads (MBs) to form MB-Au bioconjugates. In the presence of HL-60 cell, the aptamer would conjugate with the glycoprotein at cell surface and messenger DNA sequence would be released. The released messenger DNA sequence was then introduced into the cycle amplification system to trigger circular polymerizations. This assay allows us to determine the released messenger DNA equivalent to 10 cells and exhibits a significant specificity for HL-60 cells. PMID:25966387

  4. Phase-diversity phase-sensitive amplification in fiber loop with polarization beam splitter

    NASA Astrophysics Data System (ADS)

    Inoue, K.

    2015-10-01

    In this paper, we propose a parametric amplification scheme based on phase-sensitive amplification in an optical fiber. The proposed system consists of a nonlinear fiber and a dispersive medium in a loop configuration with a polarization beam splitter, where phase-sensitive amplification occurs bi-directionally. The dispersive medium shifts the relative phase between signal and pump lights, due to which the amplified signal light is always obtained regardless of the signal input phase, i.e., a phase-diversity operation is achieved, while the output phase is digitized as in conventional phase-sensitive amplifiers.

  5. A Graphene-enhanced imaging of microRNA with enzyme-free signal amplification of catalyzed hairpin assembly in living cells.

    PubMed

    Liu, Haiyun; Tian, Tian; Ji, Dandan; Ren, Na; Ge, Shenguang; Yan, Mei; Yu, Jinghua

    2016-11-15

    In situ imaging of miRNA in living cells could help us to monitor the miRNA expression in real time and obtain accurate information for studying miRNA related bioprocesses and disease. Given the low-level expression of miRNA, amplification strategies for intracellular miRNA are imperative. Here, we propose an amplification strategy with a non-destructive enzyme-free manner in living cells using catalyzed hairpin assembly (CHA) based on graphene oxide (GO) for cellular miRNA imaging. The enzyme-free CHA exhibits stringent recognition and excellent signal amplification of miRNA in the living cells. GO is a good candidate as a fluorescence quencher and cellular carrier. Taking the advantages of the CHA and GO, we can monitor the miRNA at low level in living cells with a simple, sensitive and real-time manner. Finally, imaging of miRNAs in the different expression cells is realized. The novel method could supply an effective tool to visualize intracellular low-level miRNAs and help us to further understand the role of miRNAs in cellular processes. PMID:27315515

  6. Kerr nonlinearity mitigation in 5 × 28-GBd PDM 16-QAM signal transmission over a dispersion-uncompensated link with backward-pumped distributed Raman amplification.

    PubMed

    Sackey, Isaac; Da Ros, Francesco; Jazayerifar, Mahmoud; Richter, Thomas; Meuer, Christian; Nölle, Markus; Molle, Lutz; Peucheret, Christophe; Petermann, Klaus; Schubert, Colja

    2014-11-01

    We present experimental and numerical investigations of Kerr nonlinearity compensation in a 400-km standard single-mode fiber link with distributed Raman amplification with backward pumping. A dual-pump polarization-independent fiber-based optical parametric amplifier is used for mid-link spectral inversion of 5 × 28-GBd polarization-multiplexed 16-QAM signals. Signal quality factor (Q-factor) improvements of 1.1 dB and 0.8 dB were obtained in the cases of a single-channel and a five-channel wavelength-division multiplexing (WDM) system, respectively. The experimental results are compared to numerical simulations with good agreement. It is also shown with simulations that a maximum transmission reach of 2400 km enabled by the optical phase conjugator is possible for the WDM signal. PMID:25401887

  7. Novel signal amplification strategy for ultrasensitive sandwich-type electrochemical immunosensor employing Pd-Fe3O4-GS as the matrix and SiO2 as the label.

    PubMed

    Wang, Yulan; Ma, Hongmin; Wang, Xiaodong; Pang, Xuehui; Wu, Dan; Du, Bin; Wei, Qin

    2015-12-15

    An ultrasensitive sandwich-type electrochemical immunosensor based on a novel signal amplification strategy was developed for the quantitative determination of human immunoglobulin G (IgG). Pd nanocubes functionalized magnetic graphene sheet (Pd-Fe3O4-GS) was employed as the matrix to immobilize the primary antibodies (Ab1). Owing to the synergetic effect between Pd nanocubes and magnetic graphene sheet (Fe3O4-GS), Pd-Fe3O4-GS can provide an obviously increasing electrochemical signal by electrochemical catalysis towards hydrogen peroxide (H2O2). Silicon dioxide (SiO2) was functionalized as the label to conjugate with the secondary antibodies (Ab2). Due to the larger steric hindrance of the obtained conjugate (SiO2@Ab2), the sensitive decrease of the electrochemical signal can be achieved after the specific recognition between antibodies and antigens. In this sense, this proposed immunosensor can achieve a high sensitivity, especially in the presence of low concentrations of IgG. Under optimum conditions, the proposed immunosensor offered an ultrasensitive and specific determination of IgG down to 3.2 fg/mL. This immunoassay method would open up a new promising platform to detect various tumor markers at ultralow levels for early diagnoses of different cancers. PMID:26120810

  8. Target-induced formation of gold amalgamation on DNA-based sensing platform for electrochemical monitoring of mercury ion coupling with cycling signal amplification strategy.

    PubMed

    Chen, Jinfeng; Tang, Juan; Zhou, Jun; Zhang, Lan; Chen, Guonan; Tang, Dianping

    2014-01-31

    Heavy metal ion pollution poses severe risks in human health and environmental pollutant, because of the likelihood of bioaccumulation and toxicity. Driven by the requirement to monitor trace-level mercury ion (Hg(2+)), herein we construct a new DNA-based sensor for sensitive electrochemical monitoring of Hg(2+) by coupling target-induced formation of gold amalgamation on DNA-based sensing platform with gold amalgamation-catalyzed cycling signal amplification strategy. The sensor was simply prepared by covalent conjugation of aminated poly-T(25) oligonucleotide onto the glassy carbon electrode by typical carbodiimide coupling. Upon introduction of target analyte, Hg(2+) ion was intercalated into the DNA polyion complex membrane based on T-Hg(2+)-T coordination chemistry. The chelated Hg(2+) ion could induce the formation of gold amalgamation, which could catalyze the p-nitrophenol with the aid of NaBH4 and Ru(NH3)6(3+) for cycling signal amplification. Experimental results indicated that the electronic signal of our system increased with the increasing Hg(2+) level in the sample, and has a detection limit of 0.02nM with a dynamic range of up to 1000nM Hg(2+). The strategy afforded exquisite selectivity for Hg(2+) against other environmentally related metal ions. In addition, the methodology was evaluated for the analysis of Hg(2+) in spiked tap-water samples, and the recovery was 87.9-113.8%. PMID:24439499

  9. Direct RNA detection without nucleic acid purification and PCR: Combining sandwich hybridization with signal amplification based on branched hybridization chain reaction.

    PubMed

    Xu, Yao; Zheng, Zhi

    2016-05-15

    We have developed a convenient, robust and low-cost RNA detection system suitable for high-throughput applications. This system uses a highly specific sandwich hybridization to capture target RNA directly onto solid support, followed by on-site signal amplification via 2-dimensional, branched hybridizing chain polymerization through toehold-mediated strand displacement reaction. The assay uses SYBR Green to detect targets at concentrations as low as 1pM, without involving nucleic acid purification or any enzymatic reaction, using ordinary oligonucleotides without modification or labeling. The system was demonstrated in the detection of malaria RNA in blood and GAPDH gene expression in cell lysate. PMID:26761615

  10. DNA detection by strand displacement amplification and fluorescence polarization with signal enhancement using a DNA binding protein.

    PubMed

    Walker, G T; Linn, C P; Nadeau, J G

    1996-01-15

    Strand displacement amplification (9SDA) is an isothermal in vitro method of amplifying a DNA sequence prior to its detection. We have combined SDA with fluorescence polarization detection. A 5'-fluorescein-labelled oligodeoxynucleotide detector probe hybridizes to the amplification product that rises in concentration during SDA and the single- to double strand conversion is monitored through an increase in fluorescence polarization. Detection sensitivity can be enhanced by using a detector probe containing an EcoRI recognition sequence at its 5'-end that is not homologous to the target sequence. During SDA the probe is converted to a fully double-stranded form that specifically binds a genetically modified form of the endonuclease EcoRI which lacks cleavage activity but retains binding specificity. We have applied this SDA detection system to a target sequence specific for Mycobacterium tuberculosis. PMID:8628661

  11. Detection of biological molecules using boronate-based chemical amplification and optical sensors

    SciTech Connect

    Antwerp, W.P. van; Mastrototaro, J.J.; Lane, S.M.; Satcher, J.H. Jr.; Darrow, C.B.; Peyser, T.A.; Harder, J.

    1999-12-14

    Methods are provided for the determination of the concentration of biological levels of polyhydroxylated compounds, particularly glucose. The methods utilize an amplification system that is an analyte transducer immobilized in a polymeric matrix, where the system is implantable and biocompatible. Upon interrogation by an optical system, the amplification system produces a signal capable of detection external to the skin of the patient. Quantitation of the analyte of interest is achieved by measurement of the emitted signal.

  12. Detection of biological molecules using boronate-based chemical amplification and optical sensors

    DOEpatents

    Van Antwerp, William Peter; Mastrototaro, John Joseph; Lane, Stephen M.; Satcher, Jr., Joe H.; Darrow, Christopher B.; Peyser, Thomas A.; Harder, Jennifer

    1999-01-01

    Methods are provided for the determination of the concentration of biological levels of polyhydroxylated compounds, particularly glucose. The methods utilize an amplification system that is an analyte transducer immobilized in a polymeric matrix, where the system is implantable and biocompatible. Upon interrogation by an optical system, the amplification system produces a signal capable of detection external to the skin of the patient. Quantitation of the analyte of interest is achieved by measurement of the emitted signal.

  13. Detection of biological molecules using boronate-based chemical amplification and optical sensors

    DOEpatents

    Van Antwerp, William Peter; Mastrototaro, John Joseph; Lane, Stephen M.; Satcher, Jr., Joe H.; Darrow, Christopher B.; Peyser, Thomas A.; Harder, Jennifer

    2004-06-15

    Methods are provided for the determination of the concentration of biological levels of polyhydroxylated compounds, particularly glucose. The methods utilize an amplification system that is an analyte transducer immobilized in a polymeric matrix, where the system is implantable and biocompatible. Upon interrogation by an optical system, the amplification system produces a signal capable of detection external to the skin of the patient. Quantitation of the analyte of interest is achieved by measurement of the emitted signal.

  14. Single-cell mass cytometry of TCR signaling: amplification of small initial differences results in low ERK activation in NOD mice.

    PubMed

    Mingueneau, Michael; Krishnaswamy, Smita; Spitzer, Matthew H; Bendall, Sean C; Stone, Erica L; Hedrick, Stephen M; Pe'er, Dana; Mathis, Diane; Nolan, Garry P; Benoist, Christophe

    2014-11-18

    Signaling from the T-cell receptor (TCR) conditions T-cell differentiation and activation, requiring exquisite sensitivity and discrimination. Using mass cytometry, a high-dimensional technique that can probe multiple signaling nodes at the single-cell level, we interrogate TCR signaling dynamics in control C57BL/6 and autoimmunity-prone nonobese diabetic (NOD) mice, which show ineffective ERK activation after TCR triggering. By quantitating signals at multiple steps along the signaling cascade and parsing the phosphorylation level of each node as a function of its predecessors, we show that a small impairment in initial pCD3ζ activation resonates farther down the signaling cascade and results in larger defects in activation of the ERK1/2-S6 and IκBα modules. This nonlinear property of TCR signaling networks, which magnifies small initial differences during signal propagation, also applies in cells from B6 mice activated at different levels of intensity. Impairment in pCD3ζ and pSLP76 is not a feedback consequence of a primary deficiency in ERK activation because no proximal signaling defect was observed in Erk2 KO T cells. These defects, which were manifest at all stages of T-cell differentiation from early thymic pre-T cells to memory T cells, may condition the imbalanced immunoregulation and tolerance in NOD T cells. More generally, this amplification of small initial differences in signal intensity may explain how T cells discriminate between closely related ligands and adopt strongly delineated cell fates. PMID:25362052

  15. Single-cell mass cytometry of TCR signaling: Amplification of small initial differences results in low ERK activation in NOD mice

    PubMed Central

    Mingueneau, Michael; Krishnaswamy, Smita; Spitzer, Matthew H.; Bendall, Sean C.; Stone, Erica L.; Hedrick, Stephen M.; Pe'er, Dana; Mathis, Diane; Nolan, Garry P.; Benoist, Christophe

    2014-01-01

    Signaling from the T-cell receptor (TCR) conditions T-cell differentiation and activation, requiring exquisite sensitivity and discrimination. Using mass cytometry, a high-dimensional technique that can probe multiple signaling nodes at the single-cell level, we interrogate TCR signaling dynamics in control C57BL/6 and autoimmunity-prone nonobese diabetic (NOD) mice, which show ineffective ERK activation after TCR triggering. By quantitating signals at multiple steps along the signaling cascade and parsing the phosphorylation level of each node as a function of its predecessors, we show that a small impairment in initial pCD3ζ activation resonates farther down the signaling cascade and results in larger defects in activation of the ERK1/2–S6 and IκBα modules. This nonlinear property of TCR signaling networks, which magnifies small initial differences during signal propagation, also applies in cells from B6 mice activated at different levels of intensity. Impairment in pCD3ζ and pSLP76 is not a feedback consequence of a primary deficiency in ERK activation because no proximal signaling defect was observed in Erk2 KO T cells. These defects, which were manifest at all stages of T-cell differentiation from early thymic pre-T cells to memory T cells, may condition the imbalanced immunoregulation and tolerance in NOD T cells. More generally, this amplification of small initial differences in signal intensity may explain how T cells discriminate between closely related ligands and adopt strongly delineated cell fates. PMID:25362052

  16. Nicking endonuclease-assisted signal amplification of a split molecular aptamer beacon for biomolecule detection using graphene oxide as a sensing platform.

    PubMed

    Li, Xiang; Ding, Xuelian; Fan, Jing

    2015-12-01

    Sensitive and selective detection of ultralow concentrations of specific biomolecules is important in early clinical diagnoses and biomedical applications. Many types of aptasensors have been developed for the detection of various biomolecules, but usually suffer from false positive signals and high background signals. In this work, we have developed an amplified fluorescence aptasensor platform for ultrasensitive biomolecule detection based on enzyme-assisted target-recycling signal amplification and graphene oxide. By using a split molecular aptamer beacon and a nicking enzyme, the typical problem of false positive signals can be effectively resolved. Only in the presence of a target biomolecule, the sensor system is able to generate a positive signal, which significantly improves the selectivity of the aptasensor. Moreover, using graphene oxide as a super-quencher can effectively reduce the high background signal of a sensing platform. We select vascular endothelial growth factor (VEGF) and adenosine triphosphate (ATP) as model analytes in the current proof-of-concept experiments. It is shown that under optimized conditions, our strategy exhibits high sensitivity and selectivity for the quantification of VEGF and ATP with a low detection limit (1 pM and 4 nM, respectively). In addition, this biosensor has been successfully utilized in the analysis of real biological samples. PMID:26502364

  17. Outstanding Scientific Achievement Award Lecture 2010: deconstructing leptin: from signals to circuits.

    PubMed

    Myers, Martin G

    2010-11-01

    Martin G. Myers Jr., MD, PhD, received the American Diabetes Association's prestigious 2010 Outstanding Scientific Achievement Award at the Association's 70th Scientific Sessions in Orlando, Florida, on 28 June 2010. The Outstanding Scientific Achievement Award recognizes outstanding scientific achievement in the field of diabetes, taking into consideration independence of thought and originality. Currently the Marilyn H. Vincent Professor of Diabetes Research at the University of Michigan, Ann Arbor, and Associate Professor in internal medicine and in molecular and integrative physiology at the University of Michigan Medical School, Dr. Myers began his impressive track record in diabetes research as a graduate student in the laboratory of Dr. Morris White at the Joslin Diabetes Center/Harvard Medical School. There, Dr. Myers deciphered many of the insulin signaling pathways engaged by insulin receptor substrate proteins. Following his graduation from the Harvard MD-PhD Program in 1997, Dr. Myers was promoted to instructor in medicine at the Joslin Diabetes Center/Harvard Medical School. He began his independent work by building a molecular framework for understanding the mechanisms of leptin signaling, including how individual phosphorylation sites on the leptin receptor recruit distinct signaling molecules. He was promoted to assistant professor at Harvard in 1999. In 2004, Dr. Myers moved to the University of Michigan, where he built upon the molecular framework of leptin signaling to probe the regulation of metabolism by individual leptin signals. Dr. Myers' laboratory revealed the specificity of leptin signals in metabolic control, including the role for leptin-STAT3 signaling in the regulation of energy balance and glucose homeostasis. His group also defined roles for leptin receptor feedback inhibition and hypothalamic mTor signaling in metabolism. Dr. Myers' laboratory has recently developed novel molecular approaches to elucidate the leptin-regulated brain

  18. A nanoparticle-based strategy for the imaging of a broad range of tumours by nonlinear amplification of microenvironment signals

    NASA Astrophysics Data System (ADS)

    Wang, Yiguang; Zhou, Kejin; Huang, Gang; Hensley, Christopher; Huang, Xiaonan; Ma, Xinpeng; Zhao, Tian; Sumer, Baran D.; Deberardinis, Ralph J.; Gao, Jinming

    2014-02-01

    Stimuli-responsive nanomaterials are increasingly important in a variety of applications such as biosensing, molecular imaging, drug delivery and tissue engineering. For cancer detection, a paramount challenge still exists in the search for methods that can illuminate tumours universally regardless of their genotypes and phenotypes. Here we capitalized on the acidic, angiogenic tumour microenvironment to achieve the detection of tumour tissues in a wide variety of mouse cancer models. This was accomplished using ultra pH-sensitive fluorescent nanoprobes that have tunable, exponential fluorescence activation on encountering subtle, physiologically relevant pH transitions. These nanoprobes were silent in the circulation, and then strongly activated (>300-fold) in response to the neovasculature or to the low extracellular pH in tumours. Thus, we have established non-toxic, fluorescent nanoreporters that can nonlinearly amplify tumour microenvironmental signals, permitting the identification of tumour tissue independently of histological type or driver mutation, and detection of acute treatment responses much more rapidly than conventional imaging approaches.

  19. Novel electrochemical dual-aptamer-based sandwich biosensor using molybdenum disulfide/carbon aerogel composites and Au nanoparticles for signal amplification.

    PubMed

    Fang, Lin-Xia; Huang, Ke-Jing; Liu, Yang

    2015-09-15

    A new electrochemical aptamer biosensor for the platelet-derived growth factor BB (PDGF-BB) detection has been developed based on the signal amplification of MoS2/carbon aerogel composites (MoS2/CA) and sandwich assay. A facile hydrothermal route assisted by L-cysteine was applied to synthesize CA incorporated flower-like MoS2 with the large surface active sites and good conductivity. The electrochemical aptasensor was constructed by sandwiching the PDGF-BB between a glassy carbon electrode modified with thiol-terminated PDGF-BB aptamer-1 (Apt1)/gold nanoparticles (AuNPs)/MoS2/CA and the AuNPs with thiol-terminated PDGF-BB aptamer-2 (Apt2) and 6-ferrocenyl hexanethiol (Fc). Fc-AuNPs-Apt2 acted as tracer and AuNPs/MoS2/CA were utilized as the biosensor platform to immobilize a large amount of capture aptamers, owing to their layered structure and high surface-to-volume ratio. Based on the sandwich format, a dual signal amplification strategy had been successfully developed with a wide linear response in the range of 0.001-10nM and a limit of detection of 0.3 pM. The developed assay demonstrated good selectivity and high sensitivity, indicating potential applications in bioanalysis and biomedicine. PMID:25909336

  20. Signal amplification strategy using gold/N-trimethyl chitosan/iron oxide magnetic composite nanoparticles as a tracer tag for high-sensitive electrochemical detection.

    PubMed

    Shirazi, Hanieh; Ahmadi, Anita; Darzianiazizi, Maedeh; Kashanian, Susan; Kashanian, Soheila; Omidfar, Kobra

    2016-02-01

    This study presents a novel signal amplification method for high-sensitive electrochemical immunosensing. Gold (Au)/N-trimethyl chitosan (TMC)/iron oxide (Fe3O4) (shell/shell/core) nanocomposite was used as a tracing tag to label antibody. The tag was shown to be capable of amplifying the recognition signal by high-density assembly of Au nanoparticles (NPs) on TMC/Fe3O4 particles. The remarkable conductivity of AuNPs provides a feasible pathway for electron transfer. The method was found to be simple, reliable and capable of high-sensitive detection of human serum albumin as a model, down to 0.2 pg/ml in the range of 0.25-1000 pg/ml. Findings of the present study would create new opportunities for sensitive and rapid detection of various analytes. PMID:26766869

  1. Detection of biological molecules using chemical amplification and optical sensors

    DOEpatents

    Van Antwerp, William Peter; Mastrototaro, John Joseph

    2001-01-01

    Methods are provided for the determination of the concentration of biological levels of polyhydroxylated compounds, particularly glucose. The methods utilize an amplification system that is an analyte transducer immobilized in a polymeric matrix, where the system is implantable and biocompatible. Upon interrogation by an optical system, the amplification system produces a signal capable of detection external to the skin of the patient. Quantitation of the analyte of interest is achieved by measurement of the emitted signal. Specifically, the analyte transducer immobilized in a polymeric matrix can be a boronic acid moiety.

  2. Label-free and ultrasensitive fluorescence detection of cocaine based on a strategy that utilizes DNA-templated silver nanoclusters and the nicking endonuclease-assisted signal amplification method.

    PubMed

    Zhang, Kai; Wang, Ke; Zhu, Xue; Zhang, Jue; Xu, Lan; Huang, Biao; Xie, Minhao

    2014-01-01

    A general and reliable strategy for the detection of cocaine was proposed utilizing DNA-templated silver nanoclusters as signal indicators and the nicking endonuclease-assisted signal amplification method. This strategy can detect cocaine specifically with a detection limit as low as 2 nM by using a small volume of 5 μL. PMID:24217291

  3. Quantum Feedback Amplification

    NASA Astrophysics Data System (ADS)

    Yamamoto, Naoki

    2016-04-01

    Quantum amplification is essential for various quantum technologies such as communication and weak-signal detection. However, its practical use is still limited due to inevitable device fragility that brings about distortion in the output signal or state. This paper presents a general theory that solves this critical issue. The key idea is simple and easy to implement: just a passive feedback of the amplifier's auxiliary mode, which is usually thrown away. In fact, this scheme makes the controlled amplifier significantly robust, and furthermore it realizes the minimum-noise amplification even under realistic imperfections. Hence, the presented theory enables the quantum amplification to be implemented at a practical level. Also, a nondegenerate parametric amplifier subjected to a special detuning is proposed to show that, additionally, it has a broadband nature.

  4. Isothermal amplification detection of nucleic acids by a double-nicked beacon.

    PubMed

    Shi, Chao; Zhou, Meiling; Pan, Mei; Zhong, Guilin; Ma, Cuiping

    2016-03-01

    Isothermal and rapid amplification detection of nucleic acids is an important technology in environmental monitoring, foodborne pathogen detection, and point-of-care clinical diagnostics. Here we have developed a novel method of isothermal signal amplification for single-stranded DNA (ssDNA) detection. The ssDNA target could be used as an initiator, coupled with a double-nicked molecular beacon, to originate amplification cycles, achieving cascade signal amplification. In addition, the method showed good specificity and strong anti-jamming capability. Overall, it is a one-pot and isothermal strand displacement amplification method without the requirement of a stepwise procedure, which greatly simplifies the experimental procedure and decreases the probability of contamination of samples. With its advantages, the method would be very useful to detect nucleic acids in point-of-care or field use. PMID:26706801

  5. Design and development of PCR-free highly sensitive electrochemical assay for detection of telomerase activity using Nano-based (liposomal) signal amplification platform.

    PubMed

    Alizadeh-Ghodsi, Mohammadreza; Zavari-Nematabad, Ali; Hamishehkar, Hamed; Akbarzadeh, Abolfazl; Mahmoudi-Badiki, Tohid; Zarghami, Faraz; Pourhassan Moghaddam, Mohammad; Alipour, Esmaeel; Zarghami, Nosratollah

    2016-06-15

    Telomerase, which has been detected in almost all kinds of cancer tissues, is considered as an important tumor marker for early cancer diagnostics. In the present study, an electrochemical method based on liposomal signal amplification platform is proposed for simple, PCR-free, and highly sensitive detection of human telomerase activity, extracted from A549 cells. In this strategy, telomerase reaction products, which immobilized on streptavidin-coated microplate, hybridized with biotinylated capture probes. Then, dopamine-loaded biotinylated liposomes are attached through streptavidin to biotinylated capture probes. Finally, liposomes are ruptured by methanol and the released-dopamine is subsequently measured using differential pulse voltammetry technique by multi-walled carbon nanotubes modified glassy carbon electrode. Using this strategy, the telomerase activity extracted from 10 cultured cancer cells could be detected. Therefore, this approach affords high sensitivity for telomerase activity detection and it can be regarded as an alternative to telomeric repeat amplification protocol assay, having the advantages of simplicity and less assay time. PMID:26874110

  6. Assistant DNA recycling with nicking endonuclease and molecular beacon for signal amplification using a target-complementary arched structure.

    PubMed

    Gao, Fenglei; Lei, Jianping; Ju, Huangxian

    2013-05-11

    A simple and universal method for ultrasensitive "signal on" detection of DNA was developed with a target-complementary arched structure to release assistant DNA, which was recycled with nicking endonuclease to amplify the detectable fluorescent signal of molecular beacons. PMID:23563493

  7. A low cost technique for synthesis of gold nanoparticles using microwave heating and its application in signal amplification for detecting Escherichia Coli O157:H7 bacteria

    NASA Astrophysics Data System (ADS)

    Thanh Ngo, Vo Ke; Giang Nguyen, Dang; Phat Huynh, Trong; Lam, Quang Vinh

    2016-09-01

    In the present work a low cost technique for preparation of gold nanoparticles (AuNPs) using microwave heating was developed. The effect of different elements (precursor reagents, irradiation time, and microwave radiation power) on the final morphology of AuNPs obtained through the microwave assisted technique has been investigated. The characterization of the samples has been carried out by transmission electron microscopy, UV–vis absorption spectroscopy, Fourier transform infrared spectroscopy, and powder x-ray diffraction. The results showed that to some extent the above-mentioned characterizations influenced the size of synthetized nanoparticles and application of microwave heating has many advantages such as low cost, rapid preparation and highly uniform particles. As an application in quartz crystal microbalance (QCM) immunosensor, AuNPs are conjugated with the Escherichia coli (E.coli) O157:H7 antibodies for signal amplification to detect E.coli O157:H7 bacteria residual in QCM system.

  8. A functional glycoprotein competitive recognition and signal amplification strategy for carbohydrate-protein interaction profiling and cell surface carbohydrate expression evaluation

    NASA Astrophysics Data System (ADS)

    Wang, Yangzhong; Chen, Zhuhai; Liu, Yang; Li, Jinghong

    2013-07-01

    A simple and sensitive carbohydrate biosensor has been suggested as a potential tool for accurate analysis of cell surface carbohydrate expression as well as carbohydrate-based therapeutics for a variety of diseases and infections. In this work, a sensitive biosensor for carbohydrate-lectin profiling and in situ cell surface carbohydrate expression was designed by taking advantage of a functional glycoprotein of glucose oxidase acting as both a multivalent recognition unit and a signal amplification probe. Combining the gold nanoparticle catalyzed luminol electrogenerated chemiluminescence and nanocarrier for active biomolecules, the number of cell surface carbohydrate groups could be conveniently read out. The apparent dissociation constant between GOx@Au probes and Con A was detected to be 1.64 nM and was approximately 5 orders of magnitude smaller than that of mannose and Con A, which would arise from the multivalent effect between the probe and Con A. Both glycoproteins and gold nanoparticles contribute to the high affinity between carbohydrates and lectin. The as-proposed biosensor exhibits excellent analytical performance towards the cytosensing of K562 cells with a detection limit of 18 cells, and the mannose moieties on a single K562 cell were determined to be 1.8 × 1010. The biosensor can also act as a useful tool for antibacterial drug screening and mechanism investigation. This strategy integrates the excellent biocompatibility and multivalent recognition of glycoproteins as well as the significant enzymatic catalysis and gold nanoparticle signal amplification, and avoids the cell pretreatment and labelling process. This would contribute to the glycomic analysis and the understanding of complex native glycan-related biological processes.A simple and sensitive carbohydrate biosensor has been suggested as a potential tool for accurate analysis of cell surface carbohydrate expression as well as carbohydrate-based therapeutics for a variety of diseases and

  9. A upconversion luminescene biosensor based on dual-signal amplification for the detection of short DNA species of c-erbB-2 oncogene

    PubMed Central

    Lan, Jianming; Liu, Yingxin; Li, Li; Wen, Fadi; Wu, Fang; Han, Zhizhong; Sun, Weiming; Li, Chunyan; Chen, Jinghua

    2016-01-01

    High-sensitivity detection of trace amounts of c-erbB-2 oncogene was reported to be equal to or surpass the ability of CA 15-3 for early diagnosis and/or follow-up recurrent screening of breast cancer. Therefore, in the current study, by using upconversion nanoparticles (UCNPs), rare earth-doped NaYF4:Yb3+/Er3+ as the luminescent labels, a upconversion luminescent (UCL) biosensor based on dual-signal amplification of exonuclease III (ExoIII)-assisted target cycles and long-range self-assembly DNA concatamers was developed for the detection of c-erbB-2 oncogene. The proposed biosensor exhibited ultrasensitive detection with limit as low as 40 aM, which may express the potential of being used in trace analysis of c-erbB-2 oncogene and early diagnosis of breast cancer. PMID:27098295

  10. A functional glycoprotein competitive recognition and signal amplification strategy for carbohydrate-protein interaction profiling and cell surface carbohydrate expression evaluation.

    PubMed

    Wang, Yangzhong; Chen, Zhuhai; Liu, Yang; Li, Jinghong

    2013-08-21

    A simple and sensitive carbohydrate biosensor has been suggested as a potential tool for accurate analysis of cell surface carbohydrate expression as well as carbohydrate-based therapeutics for a variety of diseases and infections. In this work, a sensitive biosensor for carbohydrate-lectin profiling and in situ cell surface carbohydrate expression was designed by taking advantage of a functional glycoprotein of glucose oxidase acting as both a multivalent recognition unit and a signal amplification probe. Combining the gold nanoparticle catalyzed luminol electrogenerated chemiluminescence and nanocarrier for active biomolecules, the number of cell surface carbohydrate groups could be conveniently read out. The apparent dissociation constant between GOx@Au probes and Con A was detected to be 1.64 nM and was approximately 5 orders of magnitude smaller than that of mannose and Con A, which would arise from the multivalent effect between the probe and Con A. Both glycoproteins and gold nanoparticles contribute to the high affinity between carbohydrates and lectin. The as-proposed biosensor exhibits excellent analytical performance towards the cytosensing of K562 cells with a detection limit of 18 cells, and the mannose moieties on a single K562 cell were determined to be 1.8 × 10(10). The biosensor can also act as a useful tool for antibacterial drug screening and mechanism investigation. This strategy integrates the excellent biocompatibility and multivalent recognition of glycoproteins as well as the significant enzymatic catalysis and gold nanoparticle signal amplification, and avoids the cell pretreatment and labelling process. This would contribute to the glycomic analysis and the understanding of complex native glycan-related biological processes. PMID:23824149

  11. Ultrasensitive electroanalysis of low-level free microRNAs in blood by maximum signal amplification of catalytic silver deposition using alkaline phosphatase-incorporated gold nanoclusters.

    PubMed

    Si, Yanmei; Sun, Zongzhao; Zhang, Ning; Qi, Wei; Li, Shuying; Chen, Lijun; Wang, Hua

    2014-10-21

    An ultrasensitive sandwich-type analysis method has been initially developed for probing low-level free microRNAs (miRNAs) in blood by a maximal signal amplification protocol of catalytic silver deposition. Gold nanoclusters (AuNCs) were first synthesized and in-site incorporated into alkaline phosphatase (ALP) to form the ALP-AuNCs. Unexpectedly, the so incorporated AuNCs could dramatically enhance the catalysis activities of ALP-AuNCs versus native ALP. A sandwiched hybridization protocol was then proposed using ALP-AuNCs as the catalytic labels of the DNA detection probes for targeting miRNAs that were magnetically caught from blood samples by DNA capture probes, followed by the catalytic ligation of two DNA probes complementary to the targets. Herein, the ALP-AuNC labels could act as the bicatalysts separately in the ALP-catalyzed substrate dephosphorylation reaction and the AuNCs-accelerated silver deposition reaction. The signal amplification of ALP-AuNCs-catalyzed silver deposition was thereby maximized to be measured by the electrochemical outputs. The developed electroanalysis strategy could allow for the ultrasensitive detection of free miRNAs in blood with the detection limit as low as 21.5 aM, including the accurate identification of single-base mutant levels in miRNAs. Such a sandwich-type analysis method may circumvent the bottlenecks of the current detection techniques in probing short-chain miRNAs. It would be tailored as an ultrasensitive detection candidate for low-level free miRNAs in blood toward the diagnosis of cancer and the warning or monitoring of cancer metastasis in the clinical laboratory. PMID:25242013

  12. Highly Sensitive and Selective Photoelectrochemical Biosensor for Hg(2+) Detection Based on Dual Signal Amplification by Exciton Energy Transfer Coupled with Sensitization Effect.

    PubMed

    Zhao, Ming; Fan, Gao-Chao; Chen, Jing-Jia; Shi, Jian-Jun; Zhu, Jun-Jie

    2015-12-15

    A highly sensitive and selective photoelectrochemical (PEC) biosensor for Hg(2+) detection was developed on the basis of the synergistic effect of exciton energy transfer (EET) between CdS quantum dots (QDs) and Au nanoparticles (NPs) coupled with sensitization of rhodamine 123 (Rh123) for signal amplification. First, the TiO2/CdS hybrid structure obtained by depositing CdS QDs on TiO2 film was employed as a matrix for immobilizing probe DNA (pDNA). Next, Rh123 was introduced into the pDNA terminal, and then Au NP labeled target DNA (Au-tDNA) was hybridized with pDNA to form a rod-like double helix structure. The detection of Hg(2+) was based on a conformational change of the pDNA after incubating with Hg(2+). In the absence of Hg(2+), Rh123 was located away from the electrode surface due to the DNA hybridization, leading to inhibition of the sensitization effect, and meanwhile, the occurrence of EET between CdS QDs and Au NPs resulted in a photocurrent decrease. However, after incubating with Hg(2+), the rod-like double helix was disrupted, and the energy transfer was broken. In this case, the photocurrent recovered, and meanwhile, the folded pDNA made the labeled Rh123 move closer to the electrode surface, leading to the formation of the sensitization structure, which evidently increased the photocurrent intensity. The sensitivity of the biosensor for Hg(2+) detection was greatly enhanced for the dual signal amplification strategy. The linear range was 10 fM to 200 nM, with a detection limit of 3.3 fM. This biosensor provides a promising new platform for detecting various heavy metal ions at ultralow levels. PMID:26599580

  13. An electrochemical microRNAs biosensor with the signal amplification of alkaline phosphatase and electrochemical-chemical-chemical redox cycling.

    PubMed

    Xia, Ning; Zhang, Youjuan; Wei, Xin; Huang, Yaping; Liu, Lin

    2015-06-01

    MicroRNAs (MiRNAs) have been regarded as clinically important biomarkers and drug discovery targets. In this work, we reported a simple and ultrasensitive electrochemical method for miRNAs detection based on single enzyme amplification and electrochemical-chemical-chemical (ECC) redox cycling. Specifically, upon contact with the target miRNAs, the hairpin structure of biotinylated DNA immobilized on gold electrode was destroyed and the biotin group in DNA was forced away from the electrode surface, allowing for the coupling of streptavidin-conjugated alkaline phosphatase (SA-ALP). Then, ascorbic acid (AA, the enzymatic product of ALP) triggered the ECC redox cycling with ferrocene methanol (FcM) and tris(2-carboxyethyl)phosphine (TCEP) as the redox mediator and the chemical reducing reagent, respectively. The method was more sensitive than that with horseradish peroxidase (HRP) or glucose oxidase (GOx) triggered recycling since one ALP molecule captured by one target miRNA molecule promoted the production of thousands of AA. Analytical merits (e.g., detection limit, dynamic range, specificity, regeneration and reproducibility) were evaluated. The feasibility of the method for analysis of miRNA-21 in human serum has also been demonstrated. PMID:26002330

  14. MeV-GeV neutrino propagation as a signal of magnetic field amplification in neutron star merger

    NASA Astrophysics Data System (ADS)

    Fraija, N.

    2016-09-01

    Short gamma-ray bursts (sGRBs) have widely been accepted to arise from a compact object binary merger; neutron star-neutron star or neutron star-black hole. During the merger of a binary neutron star system, magnetic field can be amplified beyond magnetar field strength (∼1015-1016 G) by Kelvin-Helmholtz instabilities. Considering this effect on the GRB "fireball" dynamics, we study the emission, propagation and oscillation of multi MeV-GeV neutrinos through their self-energies and using these we compute the neutrino effective potential up to order MW-4. Additionally, we calculate the number of neutrino events and neutrino flavor ratios that we would expect on Hyper-Kamiokande and DeepCore experiments. We found that MeV neutrinos in a strong magnetic field could provide information of the topology of the field, and that the number of GeV neutrinos expected in DeepCore detector would be directly affected by the strength of the field. It is worth noting that our estimates correspond to the only trustworthy method for verifying the effect of the magnetic field amplification.

  15. Fe₃O₄@Ag magnetic nanoparticles for microRNA capture and duplex-specific nuclease signal amplification based SERS detection in cancer cells.

    PubMed

    Pang, Yuanfeng; Wang, Chongwen; Wang, Jing; Sun, Zhiwei; Xiao, Rui; Wang, Shengqi

    2016-05-15

    A functionalized Fe3O4@Ag magnetic nanoparticle (NP) biosensor for microRNA (miRNA) capture and ultrasensitive detection in total RNA extract from cancer cells was reported in this paper. Herein, Raman tags-DNA probes modified Fe3O4@Ag NPs were designed both as surface-enhanced Raman scattering (SERS) SERS and duplex-specific nuclease signal amplification (DSNSA) platform. Firstly, target miRNAs were captured to the surface of Fe3O4@Ag NPs through DNA/RNA hybridization. In the presence of endonuclease duplex specific nuclease (DSN), one target miRNA molecule could rehybrid thousands of DNA probes to trigger the signal-amplifying recycling. Base on the superparamagnetic of Fe3O4@Ag NPs, target miRNA let-7b can be captured, concentrated and direct quantified within a PE tube without any PCR preamplification treatment. The detection limit was 0.3fM (15 zeptomole, 50μL), nearly 3 orders of magnitude lower than conventional fluorescence based DSN biosensors for miRNA(∼100fM), even single-base difference between the let-7 family members can be discriminated. The result provides a novel proposal to combine the perfect single-base recognition and signal-amplifying ability of the endonuclease DSN with cost-effective SERS strategy for miRNA point-of-care (POC) clinical diagnostics. PMID:26749099

  16. Dual signal amplification of glucose oxidase-functionalized nanocomposites as a trace label for ultrasensitive simultaneous multiplexed electrochemical detection of tumor markers.

    PubMed

    Lai, Guosong; Yan, Feng; Ju, Huangxian

    2009-12-01

    A novel tracer, glucose oxidase-functionalized nanocomposite, was designed to label the signal antibodies for ultrasensitive multiplexed measurement of tumor markers using a disposable immunosensor array. The immunosensor array was constructed by coating layer-by-layer colloidal Prussian blue (PB), gold nanoparticles, and capture antibodies on screen-printed carbon electrodes. The preparation of glucose oxidase-functionalized nanocomposites and the labeling of antibody were performed by one-pot assembly of glucose oxidase and antibody on gold nanoparticles attached carbon nanotubes. The PB immobilized on immunosensor surface acted as a mediator to catalyze the reduction of H2O2 produced in the enzymatic cycle. Both the high-content glucose oxidase and carbon nanotubes in the tracer amplified the detectable signal for the sandwich-type immunoassay. Using carcinoembryonic antigen and alpha-fetoprotein as model analytes, the simultaneous multiplexed immunoassay method using the immunosensor array and the designed tracer showed linear ranges of 3 orders of magnitude with the detection limits down to 1.4 and 2.2 pg/mL, respectively. The assay results of serum samples with the proposed method were in an acceptable agreement with the reference values. The dual signal amplification of glucose oxidase-functionalized nanocomposites provided a promising ultrasensitive simultaneous multiplexed immunoassay approach for clinical applications. PMID:19863072

  17. Early amplification options.

    PubMed

    Gabbard, Sandra Abbott; Schryer, Jennifer

    2003-01-01

    Children with permanent hearing loss have been remediated with hearing amplification devices for decades. The influx of young infants identified with hearing loss through successful newborn hearing screening programs has established a need for amplification resources for infants within the first six months of life. For the approximately two of every 1000 infants born who are identified with bilateral hearing loss [Mehl and Thomson, 1998, Pediatrics 101, p. e4], the use of amplification is commonly the first step in treating the sequella of their loss. The use of hearing aids, combined with early intervention, has been shown to significantly improve the speech and language skills of young children with hearing loss [Yoshinaga-Itano, 2000, Seminars in Hearing 21, p. 309]. Speech and language delays have contributed to compromised academic performance of school aged children with hearing loss [Johnson et al., 1997, Educational Audiology Handbook, Singular Publishing, San Diego]. Most hard-of-hearing and deaf children use hearing aids and other assistive listening devices every day throughout their lifetime and the life expectancy of a hearing aid is only five to eight years. The current challenge for pediatric audiologists is selecting and evaluating the available amplification to provide the best options for children and their families. Amplification technology has seen an explosion in growth the past few years and the options continue to expand rapidly. This article examines currently available amplification technology and reviews the selection criteria that may be used for infants and young children. Issues such as style, type, amplification features, signal processing strategies, and verification and validation tools are also discussed. PMID:14648816

  18. Ultrasensitive sensing platform for platelet-derived growth factor BB detection based on layered molybdenum selenide-graphene composites and Exonuclease III assisted signal amplification.

    PubMed

    Huang, Ke-Jing; Shuai, Hong-Lei; Zhang, Ji-Zong

    2016-03-15

    A highly sensitive and ultrasensitive electrochemical aptasensor for platelet-derived growth factor BB (PDGF-BB) detection is fabricated based on layered molybdenum selenide-graphene (MoSe2-Gr) composites and Exonuclease III (Exo III)-aided signal amplification. MoSe2-Gr is prepared by a simple hydrothermal method and used as a promising sensing platform. Exo III has a specifical exo-deoxyribonuclease activity for duplex DNAs in the direction from 3' to 5' terminus, however its activity is limited on the duplex DNAs with more than 4 mismatched terminal bases at 3' ends. Herein, aptamer and complementary DNA (cDNA) sequences are designed with four thymine bases on 3' ends. In the presence of target protein, the aptamer associates with it and facilitates the formation of duplex DNA between cDNA and signal DNA. The duplex DNA then is digested by Exo III and releases cDNA, which hybridizes with signal DNA to perform a new cleavage process. Nevertheless, in the absence of target protein, the aptamer hybridizes with cDNA will inhibit the Exo III-assisted nucleotides cleavage. The signal DNA then hybridizes with capture DNA on the electrode. Subsequently, horse radish peroxidase is fixed on electrode by avidin-biotin reaction and then catalyzes hydrogen peroxide and hydroquinone to produce electrochemical response. Therefore, a bridge can be established between the concentration of target protein and the degree of the attenuation of the obtained signal, providing a quantitative measure of target protein with a broad detection range of 0.0001-1 nM and a detection limit of 20 fM. PMID:26386905

  19. Graphene Ambipolar Nanoelectronics for High Noise Rejection Amplification.

    PubMed

    Liu, Che-Hung; Chen, Qi; Liu, Chang-Hua; Zhong, Zhaohui

    2016-02-10

    In a modern wireless communication system, signal amplification is critical for overcoming losses during multiple data transformations/processes and long-distance transmission. Common mode and differential mode are two fundamental amplification mechanisms, and they utilize totally different circuit configurations. In this paper, we report a new type of dual-gate graphene ambipolar device with capability of operating under both common and differential modes to realize signal amplification. The signal goes through two stages of modulation where the phase of signal can be individually modulated to be either in-phase or out-of-phase at two stages by exploiting the ambipolarity of graphene. As a result, both common and differential mode amplifications can be achieved within one single device, which is not possible in the conventional circuit configuration. In addition, a common-mode rejection ratio as high as 80 dB can be achieved, making it possible for low noise circuit application. These results open up new directions of graphene-based ambipolar electronics that greatly simplify the RF circuit complexity and the design of multifunction device operation. PMID:26808093

  20. A signal amplification electrochemical aptasensor for the detection of breast cancer cell via free-running DNA walker.

    PubMed

    Cai, Shuxian; Chen, Mei; Liu, Mengmeng; He, Wenhui; Liu, Zhijing; Wu, Dongzhi; Xia, Yaokun; Yang, Huanghao; Chen, Jinghua

    2016-11-15

    Herein, a signal magnification electrochemical aptasensor for the detection of breast cancer cell via free-running DNA walker is constructed. Theoretically, just one DNA walker, released by target cell-responsive reaction, can automatically cleave all D-RNA (a chimeric DNA/RNA oligonucleotide with a cleavage point rArU) anchored on electrode into shorter produces, giving rise to considerably detectable signal finally. Under the optimal conditions, the electrochemical signal decreased linearly with the concentration of MCF-7 cell. The linear range is from 0 to 500 cells mL(-1) with a detection limit of 47 cellsmL(-1). In a word, this approach may have advantages over traditional reported DNA machines for bioassay, particularly in terms of ease of operation, cost efficiency, free of labeling and of complex track design, which may hold great potential for wide application. PMID:27176917

  1. Amplification of the Signal Intensity of Fluorescence-Based Fiber-Optic Biosensors Using a Fabry-Perot Resonator Structure

    PubMed Central

    Hsieh, Meng-Chang; Chiu, Yi-Hsin; Lin, Sheng-Fu; Chang, Jenq-Yang; Chang, Chia-Ou; Chiang, Huihua Kenny

    2015-01-01

    Fluorescent biosensors have been widely used in biomedical applications. To amplify the intensity of fluorescence signals, this study developed a novel structure for an evanescent wave fiber-optic biosensor by using a Fabry-Perot resonator structure. An excitation light was coupled into the optical fiber through a laser-drilled hole on the proximal end of the resonator. After entering the resonator, the excitation light was reflected back and forth inside the resonator, thereby amplifying the intensity of the light in the fiber. Subsequently, the light was used to excite the fluorescent molecules in the reactive region of the sensor. The experimental results showed that the biosensor signal was amplified eight-fold when the resonator reflector was formed using a 92% reflective coating. Furthermore, in a simulation, the biosensor signal could be amplified 20-fold by using a 99% reflector. PMID:25690548

  2. The Effect of Classroom Amplification on the Signal-to-Noise Ratio in Classrooms while Class Is in Session

    ERIC Educational Resources Information Center

    Larsen, Jeffery B.; Blair, James C.

    2008-01-01

    Purpose: The purpose of this study was to measure the signal-to-noise ratios in classrooms while class was in session and students were interacting with the teacher and each other. Method: Measurements of noise and reverberation were collected for 5 different classrooms in 3 different schools while class was in session. Activities taking place…

  3. The flat fielding and achievable signal-to-noise of the MAMA detectors

    NASA Technical Reports Server (NTRS)

    Kaiser, Mary Elizabeth; Lindler, Don J.; Bohlin, Ralph C.

    1997-01-01

    The Space Telescope Imaging Spectrograph (STIS) was designed to achieve a signal-to-noise (S/N) of at least 100:1 per resolution element. Multi-Anode Microchannel Arrays (MAMA) observations during Servicing Mission Orbital Verification (SMOV) confirm that this specification can be met. From analysis of a single spectrum of GD153, with counting statistics of approximately 165 a S/N of approximately 125 is achieved per spectral resolution element in the far ultraviolet (FUV) over the spectral range of 1280A to 1455A. Co-adding spectra of GRW+7OD5824 to increase the counting statistics to approximately 300 yields a S/N of approximately 190 per spectral resolution element over the region extending from 1347A to 1480A in the FUV. In the near ultraviolet (NUV), a single spectrum of GRW+7OD5824 with counting statistics of approximately 200 yields a S/N of approximately 150 per spectral resolution element over the spectral region extending from 2167 to 2520A. Details of the flat field construction, the spectral extraction, and the definition of a spectral resolution element will be described in the text.

  4. A sensitive electrochemical biosensor for detection of protein kinase A activity and inhibitors based on Phos-tag and enzymatic signal amplification.

    PubMed

    Yin, Huanshun; Wang, Mo; Li, Bingchen; Yang, Zhiqing; Zhou, Yunlei; Ai, Shiyun

    2015-01-15

    A simple, highly sensitive and selective electrochemical assay is developed for the detection of protein kinase A (PKA) activity based on the specific recognition utility of Phos-tag for kinase-induced phosphopeptides and enzymatic signal amplification. When the substrate peptide was phosphorylated by PKA reaction, they could specifically bind with Phos-tag-biotin in the presence of Zn(2+) through the formation of a specific noncovalent complex with the phosphomonoester dianion in phosphorylated peptides. Through the further specific interaction between biotin and avidin, avidin functionalized horseradish peroxidase (HRP) can be captured on the electrode surface. Under the catalytic effect of HRP, a sensitive electrochemical signal for benzoquinone was obtained, which was related to PKA activity. Under the optimal experiment conditions, the proposed electrochemical method presented dynamic range from 0.5 to 25 unit/mL with low detection limit of 0.15 unit/mL. This new detection strategy was also successfully applied to analyze the inhibition effect of inhibitors (ellagic acid and H-89) on PKA activity and monitored the PKA activity in cell lysates. Therefore, this Phos-tag-based electrochemical assay offers an alternative platform for PKA activity assay and inhibitor screening, and thus it might be a valuable tool for development of targeted therapy and clinical diagnosis. PMID:25048450

  5. A simple and rapid detection assay for peptides based on the specific recognition of aptamer and signal amplification of hybridization chain reaction.

    PubMed

    Ma, Chao; Liu, Haiyun; Tian, Tian; Song, Xianrang; Yu, Jinghua; Yan, Mei

    2016-09-15

    A simple and rapid assay for the detection of peptides is designed based on the specific recognition of aptamer, the quenching effect of graphene oxide (GO) and the efficient signal amplification of hybrid chain reaction (HCR). In this assay, the hairpin structure of aptamer is opened after binding with targets, and the initiation sequence could be exposed to hairpin probe 1 (H1) to open its hairpin structure. Then the opened H1 will open the hairpin structure of hairpin probe 2 (H2), and in turn, the opened initiation sequence of H2 continues to open H1. As a result, the specific recognition of target and fluorescent signals are accumulated through the process in short 1h. Attentively, the aptamer can not only identify target peptides, but also initiate the HCR between H1 and H2. More importantly, the HCR is initiated only after the target recognition of aptamer. After HCR, the excess hairpin probes will be anchored on the GO surface, and the background is greatly reduced due to the quenching effect of GO. By using Mucin-1(MUC1) as a model peptide, the assay has a wide linear range as two orders of magnitude and the detection range is from 0.01 to 5nM with low detection limit of 3.33pM. Therefore, the simple and rapid detection of the target can be realized, and the novel assay has great potential in detecting various peptides and even cancer cells. PMID:27093485

  6. Indole-3-acetic acid biosensor based on G-rich DNA labeled AuNPs as chemiluminescence probe coupling the DNA signal amplification

    NASA Astrophysics Data System (ADS)

    Hun, Xu; Mei, Zhenghua; Wang, Zhouping; He, Yunhua

    2012-09-01

    A highly sensitive chemiluminescence (CL) method for detection of phytohormone indole-3-acetic acid (IAA) was developed by using G-rich DNA labeled gold nanoparticles (AuNPs) as CL probe coupling the DNA signal amplification technology. The IAA antibody was immobilized on carboxyl terminated magnetic beads (MBs). In the presence of IAA, antibody labeled AuNPs were captured by antibody functionalized MBs. The DNA on AuNPs is released by a ligand exchange process induced by the addition of DTT. The released DNA is then acted as the linker and hybridized with the capture DNA on MBs and probe DNA on AuNPs CL probe. The CL signal is obtained via the instantaneous derivatization reaction between a specific CL reagent, 3,4,5-trimethoxyl-phenylglyoxal (TMPG), and the G-rich DNA on AuNPs CL probe. IAA can be detected in the concentration range from 0.02 ng/mL to 30 ng/mL, and the limit of detection is 0.01 ng/mL.

  7. Specific sorting of single bacterial cells with microfabricated fluorescence-activated cell sorting and tyramide signal amplification fluorescence in situ hybridization.

    PubMed

    Chen, Chun H; Cho, Sung H; Chiang, Hsin-I; Tsai, Frank; Zhang, Kun; Lo, Yu-Hwa

    2011-10-01

    When attempting to probe the genetic makeup of diverse bacterial communities that elude cell culturing, researchers face two primary challenges: isolation of rare bacteria from microbial samples and removal of contaminating cell-free DNA. We report a compact, low-cost, and high-performance microfabricated fluorescence-activated cell sorting (μFACS) technology in combination with a tyramide signal amplification fluorescence in situ hybridization (TSA-FISH) to address these two challenges. The TSA-FISH protocol that was adapted for flow cytometry yields a 10-30-fold enhancement in fluorescence intensity over standard FISH methods. The μFACS technology, capable of enhancing its sensitivity by ~18 dB through signal processing, was able to enrich TSA-FISH-labeled E. coli cells by 223-fold. The μFACS technology was also used to remove contaminating cell-free DNA. After two rounds of sorting on E. coli mixed with λ-phage DNA (10 ng/μL), we demonstrated over 100,000-fold reduction in λ-DNA concentration. The integrated μFACS and TSA-FISH technologies provide a highly effective and low-cost solution for research on the genomic complexity of bacteria as well as single-cell genomic analysis of other sample types. PMID:21809842

  8. Electrochemical Impedance Immunosensor Based on Self-Assembled Monolayers for Rapid Detection of Escherichia coli O157:H7 with Signal Amplification Using Lectin.

    PubMed

    Li, Zhanming; Fu, Yingchun; Fang, Weihuan; Li, Yanbin

    2015-01-01

    Escherichia coli O157:H7 is a predominant foodborne pathogen with severe pathogenicity, leading to increasing attention given to rapid and sensitive detection. Herein, we propose an impedance biosensor using new kinds of screen-printed interdigitated microelectrodes (SPIMs) and wheat germ agglutinin (WGA) for signal amplification to detect E. coli O157:H7 with high sensitivity and time-efficiency. The SPIMs integrate the high sensitivity and short response time of the interdigitated electrodes and the low cost of the screen-printed electrodes. Self-assembling of bi-functional 3-dithiobis-(sulfosuccinimidyl-propionate) (DTSP) on the SPIMs was investigated and was proved to be able to improve adsorption quantity and stability of biomaterials. WGA was further adopted to enhance the signal taking advantage of the abundant lectin-binding sites on the bacteria surface. The immunosensor exhibited a detection limit of 102 cfu·mL(-1), with a linear detection range from 10(2) to 10(7) cfu·mL(-1) (r2 = 0.98). The total detection time was less than 1 h, showing its comparable sensitivity and rapid response. Furthermore, the low cost of one SPIM significantly reduced the detection cost of the biosensor. The biosensor may have great promise in food safety analysis and lead to a portable biosensing system for routine monitoring of foodborne pathogens. PMID:26251911

  9. Electrochemical Impedance Immunosensor Based on Self-Assembled Monolayers for Rapid Detection of Escherichia coli O157:H7 with Signal Amplification Using Lectin

    PubMed Central

    Li, Zhanming; Fu, Yingchun; Fang, Weihuan; Li, Yanbin

    2015-01-01

    Escherichia coli O157:H7 is a predominant foodborne pathogen with severe pathogenicity, leading to increasing attention given to rapid and sensitive detection. Herein, we propose an impedance biosensor using new kinds of screen-printed interdigitated microelectrodes (SPIMs) and wheat germ agglutinin (WGA) for signal amplification to detect E. coli O157:H7 with high sensitivity and time-efficiency. The SPIMs integrate the high sensitivity and short response time of the interdigitated electrodes and the low cost of the screen-printed electrodes. Self-assembling of bi-functional 3-dithiobis-(sulfosuccinimidyl-propionate) (DTSP) on the SPIMs was investigated and was proved to be able to improve adsorption quantity and stability of biomaterials. WGA was further adopted to enhance the signal taking advantage of the abundant lectin-binding sites on the bacteria surface. The immunosensor exhibited a detection limit of 102 cfu·mL−1, with a linear detection range from 102 to 107 cfu·mL−1 (r2 = 0.98). The total detection time was less than 1 h, showing its comparable sensitivity and rapid response. Furthermore, the low cost of one SPIM significantly reduced the detection cost of the biosensor. The biosensor may have great promise in food safety analysis and lead to a portable biosensing system for routine monitoring of foodborne pathogens. PMID:26251911

  10. Amplification of a bi-phase shift-key modulated signal by a mm-wave FEL

    SciTech Connect

    Prosnitz, D.; Scharlemann, E.T.; Sheaffer, M.K.

    1991-10-01

    Bi-phase shift keying (BPSK) is a modulation scheme used in communications and radar in which the phase of a transmitted rf signal is switched in a coded pattern between discrete values differing by {pi} radians. The transmitted information rate (in communications) or resolution (in imaging radar) depends on the rate at which the transmitted signal can be modulated. Modulation rates of greater than 1 GHz are generally desired. Although the instantaneous gain bandwidth of a mm-wave FEL amplifier can be much greater than 10 GHz, slippage may limit the BPSK modulation rate that can be amplified. Qualitative slippage arguments would limit the modulation rate to relatively low values; nevertheless, simulations with a time-dependent FEL code (GINGER) indicate that rates of 2 GHz or more are amplified without much loss in modulation integrity. In this paper we describe the effects of slippage in the simulations and discuss the limits of simple arguments.

  11. Amplification of a bi-phase shift-key modulated signal by a mm-wave FEL

    NASA Astrophysics Data System (ADS)

    Prosnitz, D.; Scharlemann, E. T.; Sheaffer, M. K.

    1991-10-01

    Bi-phase shift keying (BPSK) is a modulation scheme used in communications and radar in which the phase of a transmitted RF signal is switched in a coded pattern between discrete values differing by (pi) radians. The transmitted information rate (in communications) or resolution (in imaging radar) depends on the rate at which the transmitted signal can be modulated. Modulation rates of greater than 1 GHz are generally desired. Although the instantaneous gain bandwidth of a mm-wave FEL amplifier can be much greater than 10 GHz, slippage may limit the BPSK modulation rate that can be amplified. Qualitative slippage arguments would limit the modulation rate to relatively low values; nevertheless, simulations with a time-dependent FEL code (GINGER) indicate that rates of 2 GHz or more are amplified without much loss in modulation integrity. In this paper we describe the effects of slippage in the simulations and discuss the limits of simple arguments.

  12. Amplification of a bi-phase shift-key modulated signal by a mm-wave FEL

    NASA Astrophysics Data System (ADS)

    Prosnitz, D.; Scharlemann, E. T.; Sheaffer, M. K.

    1992-07-01

    Bi-phase shift keying (BPSK) is a modulation scheme used in communications and radar in which the phase of a transmitted rf signal is switched in a coded pattern between discrete values differing by π radians. The transmitted information rate (in communications) or resolution (in imaging radar) depends on the rate at which the transmitted signal can be modulated. Modulation rates of greater than 1 GHz are generally desired. Although the instantaneous gain bandwidth of a mm-wave FEL amplifier can be much greater than 10 GHz, slippage may limit the BPSK modulation rate that can be amplified. Qualitative slippage arguments would limit the modulation rate to relatively low values; nevertheless, simulations with a time-dependent FEL code (GINGER) indicate that rates of 2 GHz or more are amplified without much loss in modulation integrity. In this paper we describe the effects of slippage in the simulations and discuss the limits of simple slippage arguments.

  13. Ultrasensitive electrochemical detection of protein tyrosine kinase-7 by gold nanoparticles and methylene blue assisted signal amplification.

    PubMed

    Miao, Xiangmin; Li, Zongbing; Zhu, Aihua; Feng, Zhaozhong; Tian, Jun; Peng, Xue

    2016-09-15

    We present here an ultrasensitive and simple strategy for protein tyrosine kinase-7 (PTK7) detection based on the recognition-induced structure change of sgc8 aptamer, and the signal change of methylene blue (MB) that interacted with sandwiched DNA complex. To construct such a sensor, an homogeneous nano-surface was formed firstly on the glass carbon electrode (GCE) by using negatively charged Nafion (Nf) as the inner layer and positively charged gold nanoparticles ((+)AuNPs) as the outer layer, followed by the immobilization of sgc8 aptamer based on Au-S bond. In the presence of helper probe (HP), sandwiched DNA complex was formed between the sgc8 aptamer and the DNA modified gold nanoparticle probe (DNA-AuNPs). Then, a strong current signal was produced due to the capture of abundant MB molecules by both the sandwiched DNA complex and the multiple DNAs that modified on AuNPs surface. However, the specific binding of sgc8 aptamer with PNK7 would trigger a structure transition of it, and directly prevented the following formation of sandwiched structure and the capture of MB. Thus, PTK7 detection could be realized based on monitoring the signal reduction of MB upon incubation of sgc8 aptamer with PTK7. Under optimal conditions, a low detection limit of 372 fM was obtained for PNK7 detection. Due to the employment of sgc8 aptamer, the proposed biosensor exhibited high selectivity to PNK7. Moreover, satisfactory results were obtained when the proposed method was applied for PNK7 detection in cellular debris. PMID:27101533

  14. Electrochemical Detection of Amyloid-β Oligomers Based on the Signal Amplification of a Network of Silver Nanoparticles.

    PubMed

    Xia, Ning; Wang, Xin; Zhou, Binbin; Wu, Yangyang; Mao, Wenhui; Liu, Lin

    2016-08-01

    Amyloid-β oligomers (AβOs) are the most important toxic species in the brain of Alzheimer's disease (AD) patient. AβOs, therefore, are considered reliable molecular biomarkers for the diagnosis of AD. Herein, we reported a simple and sensitive electrochemical method for the selective detection of AβOs using silver nanoparticles (AgNPs) as the redox reporters and PrP(95-110), an AβOs-specific binding peptide, as the receptor. Specifically, adamantine (Ad)-labeled PrP(95-110), denoted as Ad-PrP(95-110), induced the aggregation and color change of AgNPs and the follow-up formation of a network of Ad-PrP(95-110)-AgNPs. Then, Ad-PrP(95-110)-AgNPs were anchored onto a β-cyclodextrin (β-CD)-covered electrode surface through the host-guest interaction between Ad and β-CD, thus producing an amplified electrochemical signal through the solid-state Ag/AgCl reaction by the AgNPs. In the presence of AβOs, Ad-PrP(95-110) interacted specifically with the AβOs, thus losing the capability to bind AgNPs and to induce the formation of an AgNPs-based network on the electrode surface. Consequently, the electrochemical signal decreased with an increase in the concentration of AβOs in the range of 20 pM to 100 nM. The biosensor had a detection limit of 8 pM and showed no response to amyloid-β monomers (AβMs) and fibrils (AβFs). On the basis of the well-defined and amplified electrochemical signal of the AgNPs-based network architecture, these results should be valuable for the design of novel electrochemical biosensors by marrying specific receptors. PMID:27414520

  15. A pH-activatable nanoparticle with signal-amplification capabilities for non-invasive imaging of tumour malignancy

    NASA Astrophysics Data System (ADS)

    Mi, Peng; Kokuryo, Daisuke; Cabral, Horacio; Wu, Hailiang; Terada, Yasuko; Saga, Tsuneo; Aoki, Ichio; Nishiyama, Nobuhiro; Kataoka, Kazunori

    2016-08-01

    Engineered nanoparticles that respond to pathophysiological parameters, such as pH or redox potential, have been developed as contrast agents for the magnetic resonance imaging (MRI) of tumours. However, beyond anatomic assessment, contrast agents that can sense these pathological parameters and rapidly amplify their magnetic resonance signals are desirable because they could potentially be used to monitor the biological processes of tumours and improve cancer diagnosis. Here, we report an MRI contrast agent that rapidly amplifies magnetic resonance signals in response to pH. We confined Mn2+ within pH-sensitive calcium phosphate (CaP) nanoparticles comprising a poly(ethylene glycol) shell. At a low pH, such as in solid tumours, the CaP disintegrates and releases Mn2+ ions. Binding to proteins increases the relaxivity of Mn2+ and enhances the contrast. We show that these nanoparticles could rapidly and selectively brighten solid tumours, identify hypoxic regions within the tumour mass and detect invisible millimetre-sized metastatic tumours in the liver.

  16. A pH-activatable nanoparticle with signal-amplification capabilities for non-invasive imaging of tumour malignancy.

    PubMed

    Mi, Peng; Kokuryo, Daisuke; Cabral, Horacio; Wu, Hailiang; Terada, Yasuko; Saga, Tsuneo; Aoki, Ichio; Nishiyama, Nobuhiro; Kataoka, Kazunori

    2016-08-01

    Engineered nanoparticles that respond to pathophysiological parameters, such as pH or redox potential, have been developed as contrast agents for the magnetic resonance imaging (MRI) of tumours. However, beyond anatomic assessment, contrast agents that can sense these pathological parameters and rapidly amplify their magnetic resonance signals are desirable because they could potentially be used to monitor the biological processes of tumours and improve cancer diagnosis. Here, we report an MRI contrast agent that rapidly amplifies magnetic resonance signals in response to pH. We confined Mn(2+) within pH-sensitive calcium phosphate (CaP) nanoparticles comprising a poly(ethylene glycol) shell. At a low pH, such as in solid tumours, the CaP disintegrates and releases Mn(2+) ions. Binding to proteins increases the relaxivity of Mn(2+) and enhances the contrast. We show that these nanoparticles could rapidly and selectively brighten solid tumours, identify hypoxic regions within the tumour mass and detect invisible millimetre-sized metastatic tumours in the liver. PMID:27183055

  17. A sandwich-hybridization assay for simultaneous determination of HIV and tuberculosis DNA targets based on signal amplification by quantum dots-PowerVision™ polymer coding nanotracers.

    PubMed

    Yan, Zhongdan; Gan, Ning; Zhang, Huairong; Wang, De; Qiao, Li; Cao, Yuting; Li, Tianhua; Hu, Futao

    2015-09-15

    A novel sandwich-hybridization assay for simultaneous electrochemical detection of multiple DNA targets related to human immune deficiency virus (HIV) and tuberculosis (TB) was developed based on the different quantum dots-PowerVision(TM) polymer nanotracers. The polymer nanotracers were respectively fabricated by immobilizing SH-labeled oligonucleotides (s-HIV or s-TB), which can partially hybrid with virus DNA (HIV or TB), on gold nanoparticles (Au NPs) and then modified with PowerVision(TM) (PV) polymer-encapsulated quantum dots (CdS or PbS) as signal tags. PV is a dendrimer enzyme linked polymer, which can immobilize abundant QDs to amplify the stripping voltammetry signals from the metal ions (Pb or Cd). The capture probes were prepared through the immobilization of SH-labeled oligonucleotides, which can complementary with HIV and TB DNA, on the magnetic Fe3O4@Au (GMPs) beads. After sandwich-hybridization, the polymer nanotracers together with HIV and TB DNA targets were simultaneously introduced onto the surface of GMPs. Then the two encoding metal ions (Cd(2+) and Pb(2+)) were used to differentiate two viruses DNA due to the different subsequent anodic stripping voltammetric peaks at -0.84 V (Cd) and -0.61 V (Pb). Because of the excellent signal amplification of the polymer nanotracers and the great specificity of DNA targets, this assay could detect targets DNA as low as 0.2 femtomolar and exhibited excellent selectivity with the dynamitic range from 0.5 fM to 500 pM. Those results demonstrated that this electrochemical coding assay has great potential in applications for screening more viruses DNA while changing the probes. PMID:25911447

  18. Site-selective in situ growth of fluorescent polymer-antibody conjugates with enhanced antigen detection by signal amplification.

    PubMed

    Zhang, Libin; Zhao, Wenguo; Liu, Xinyu; Wang, Guilin; Wang, Yang; Li, Dong; Xie, Liangzhi; Gao, Yan; Deng, Haiteng; Gao, Weiping

    2015-09-01

    This paper reports a new and general in situ methodology to grow fluorescent polymer conjugates from the interchain disulfide bridging sites of a monoclonal antibody. Atom transfer radical polymerization (ATRP) initiators were attached to a monoclonal antibody at its interchain disulfide bridging sites by disulfide re-bridging to yield a macroinitiator. Subsequent in situ ATRP of PEG-like monomers with dye-functionalized monomers from the macroinitiator formed antibody-polymer-dye conjugates with site-selectivity and tunable dye-to-antibody ratios. Notably, these conjugates can amplify antigen detection signal by reducing label-density dependent fluorescence quenching and by increasing dye-to-antibody ratios. The method developed may be applicable to a variety of antibodies, dyes and drugs to create a number of antibody-polymer-dye/drug conjugates for advanced diagnosis and therapy of diseases. PMID:26102329

  19. Kinetic insulation as an effective mechanism for achieving pathway specificity in intracellular signaling networks

    PubMed Central

    Behar, Marcelo; Dohlman, Henrik G.; Elston, Timothy C.

    2007-01-01

    Intracellular signaling pathways that share common components often elicit distinct physiological responses. In most cases, the biochemical mechanisms responsible for this signal specificity remain poorly understood. Protein scaffolds and cross-inhibition have been proposed as strategies to prevent unwanted cross-talk. Here, we report a mechanism for signal specificity termed “kinetic insulation.” In this approach signals are selectively transmitted through the appropriate pathway based on their temporal profile. In particular, we demonstrate how pathway architectures downstream of a common component can be designed to efficiently separate transient signals from signals that increase slowly over time. Furthermore, we demonstrate that upstream signaling proteins can generate the appropriate input to the common pathway component regardless of the temporal profile of the external stimulus. Our results suggest that multilevel signaling cascades may have evolved to modulate the temporal profile of pathway activity so that stimulus information can be efficiently encoded and transmitted while ensuring signal specificity. PMID:17913886

  20. Quartz Crystal Microbalance Aptasensor for Sensitive Detection of Mercury(II) Based on Signal Amplification with Gold Nanoparticles

    PubMed Central

    Dong, Zong-Mu; Zhao, Guang-Chao

    2012-01-01

    We show that a short mercury-specific aptamer (MSA) along with gold nanoparticles (Au-NPs) can be used to determine Hg(II) ion by a combination of a QCM-based sensor and a flow system. The MSA binds specifically to Hg(II), and the Au-NPs can amplify the signal to enhance sensitivity. Specifically, the short thiolated MSAs are immobilized on the surface of the QCM as the capture probe, and the MSAs are linked to the Au-NPs as the linking probe. The two components can form a sandwich structure of the T-Hg(II)-T type in the presence of Hg(II) ions. This leads to change in the mass on the QCM and a change in the resonance frequency. Hg(II) can be determined with a detection limit of 0.24 ± 0.06 nM which is better by three orders of magnitude than previous methods. The sensor can be regenerated by disrupting the T-Hg(II)-T base pairs with a solution of cysteine. PMID:22969338

  1. Simultaneous electrochemical detection of multiple analytes based on dual signal amplification of single-walled carbon nanotubes and multi-labeled graphene sheets.

    PubMed

    Bai, Lijuan; Yuan, Ruo; Chai, Yaqin; Zhuo, Ying; Yuan, Yali; Wang, Yan

    2012-02-01

    In this work, a sandwich-type electrochemical aptasensor for simultaneous sensitive detection of platelet-derived growth factor (PDGF) and thrombin is fabricated. Reduced graphene oxide sheets (rGS) are used as matrices to immobilize the redox probes, which are subsequently coated with platinum nanoparticles (PtNPs) to form the PtNPs-redox probes-rGS nanocomposites. With the employment of the as prepared nanocomposites, a signal amplification strategy was described based on bienzyme (glucose oxidase and horseradish peroxidase) modified PtNPs-redox probes-rGS nanocomposites as the tracer labels for secondary aptamers (Apt II) through sandwiched assay. Gold nanoparticles functionalized single-walled carbon nanotubes (AuNPs@SWCNTs) as the biosensor platform enhance the surface area to capture a large amount of primary aptamers (Apt I), thus amplifying the detection response. The experiment results show that the multi-labeled PtNPs-redox probes-rGS nanocomposites display satisfying electrochemical redox activity and highly electrocatalytic activity of PtNPs and bienzyme, which exhibit high sensitivity for detection of proteins. The linear range of PDGF is 0.01-35 nM with a detection limit of 8 pM, while the linear ranges from 0.02 to 45 nM and a detection limit of 11 pM for thrombin are obtained. PMID:22061494

  2. Ultrasensitive electrochemical immunosensor for carbohydrate antigen 72-4 based on dual signal amplification strategy of nanoporous gold and polyaniline-Au asymmetric multicomponent nanoparticles.

    PubMed

    Fan, Haixia; Guo, Zhankui; Gao, Liang; Zhang, Yong; Fan, Dawei; Ji, Guanglei; Du, Bin; Wei, Qin

    2015-02-15

    A sandwich electrochemical immunosensor is described for carbohydrate antigen 72-4 (CA72-4) based on a dual amplification strategy with nanoporous gold (NPG) film as the sensor platform and polyaniline-Au asymmetric multicomponent nanoparticles (PANi-Au AMNPs) as labels. In this study, the second anti-CA72-4 antibody (Ab2) adsorbed onto the Au of the PANi-Au AMNPs, which could be simply synthesized by interfacial reaction and have many characteristics of polyaniline and Au nanoparticle, such as well-controlled size, high conductivity, biocompatibility and catalysis. NPG film was used as electrode substrate material to fix a large number of antibodies, due to its unique properties: good biocompatibility, high conductivity, large surface area, and stability. The synergetic of NPG film and PANi-Au AMNPs could increase signal response, and significantly improve sensitivity of the immunosensor. The proposed immunosensor exhibited a wide linear range from 2 to 200 U/mL, with a detection limit of 0.10 U/mL CA72-4, good reproducibility, selectivity and stability. This new type of labels for immunosensors may provide many potential applications in the detection of carbohydrate antigen in immunoassays. PMID:25194795

  3. A Graphene Oxide-Based Sensing Platform for the Determination of Methicillin-Resistant Staphylococcus aureus Based on Strand-Displacement Polymerization Recycling and Synchronous Fluorescent Signal Amplification.

    PubMed

    Ning, Yi; Gao, Qiang; Zhang, Xiaoqing; Wei, Ke; Chen, Lingli

    2016-09-01

    To develop new technology for detecting methicillin-resistant Staphylococcus aureus (MRSA), a novel fluorescent biosensor based on Klenow fragment (KF)-assisted target recycling amplification and synchronous fluorescence analysis was created. Carboxy-fluorescein (FAM)-labeled single-stranded DNA (ssDNA) containing a capture probe and a signal probe was adsorbed onto the surface of graphene oxide (GO) via π-stacking interactions, resulting in the fluorescence quenching of the dye. When target and primer were introduced, the fluorescence was restored due to P0 being completely released from the surface of the GO. Meanwhile, by using the KF and exploiting the synergistic effect of FAM and the double-stranded DNA (dsDNA)-SYBR Green I duplex structure, the fluorescence in this detection system was considerably amplified and the sensitivity was improved. The proposed strategy for mecA gene analysis showed a good linear range from 1 to 40 nmol/L, with a lower limit of detection of 0.5 nmol/L. In addition, a bacterial sample harboring the mecA gene was also detected, and its lower detection limit was up to 300 colony-forming units (CFU)/mL. Accordingly, this biosensor exhibits high sensitivity and selectivity and has great potential for early clinical diagnosis and treatment. PMID:27286718

  4. G-quadruplex DNAzyme-based electrochemiluminescence biosensing strategy for VEGF165 detection: Combination of aptamer-target recognition and T7 exonuclease-assisted cycling signal amplification.

    PubMed

    Zhang, Hui; Li, Meixing; Li, Caihong; Guo, Zhihui; Dong, Huilei; Wu, Ping; Cai, Chenxin

    2015-12-15

    The expression profile of vascular endothelial growth factor (VEGF) is highly correlated with the occurrence and development of cancer. This work reports an electrochemiluminescence (ECL) approach for highly sensitive detection of VEGF165. This approach comprises aptamer-target recognition, T7 exonuclease (T7 Exo)-assisted cycling signal amplification and efficient quenching of ECL of CdS:Eu nanocrystals (NCs) by using DNAzyme. In this assay, CdS:Eu NCs were used as the ECL substrate, A guanine (G)-rich single-stranded DNA (ssDNA) sequence and VEGF165 aptamer were co-immobilized on the surface of the CdS:Eu NCs modified glassy carbon electrode. After recognition and binding to VEGF165, the aptamer moved away from the electrode surface and induced the proposed cyclic cleavage of the target DNA with T7 Exo. A large amount of G-rich ssDNA was released on the CdS:Eu film and folded into G-quadruplex/hemin DNAzyme in the presence of hemin and K(+), consequently decreasing the ECL intensity of CdS:Eu. A good linearity was obtained for VEGF165 detection within the range of 1 pM to 20 nM with a detection limit of 0.2 pM. This assay could be a universal and promising protocol for detection of various biomarkers for early clinical diagnosis. PMID:26120816

  5. A competitive photoelectrochemical immunosensor based on a CdS-induced signal amplification strategy for the ultrasensitive detection of dexamethasone.

    PubMed

    Wang, Xueping; Yan, Tao; Li, Yan; Liu, Yixin; Du, Bin; Ma, Hongmin; Wei, Qin

    2015-01-01

    A novel photoelectrochemical immunosensor based on the competitive strategy is proposed for the specific detection of dexamethasone (DXM). Graphitic carbon nitride coupled with bismuth sulfide are used as the sensing matrix for the immobilization of BSA-DXM on the electrode surface, while cadmium sulfide functionalized titanium dioxide (TiO2@CdS) is used as the photoelectric active labels of anti-DXM. Due to the perfect matching of energy levels between TiO2 and CdS, the in situ prepared composite labels show excellent photocurrent response under visible lights. The competitive binding of DXM in sample solutions and BSA-DXM on the electrode surface reduces the specific attachment of labels to the electrode, resulting in a decrease of the photocurrent intensity. Greatly enhanced sensitivity is achieved after the optimization of the detection conditions. Under the optimal detection condition, the well-designed immunosensor for DXM exhibits a low detection limit of 2 pg ∙ mL(-1). Additionally, the proposed immunoassay system shows high specificity, good reproducibility and acceptable stability, which is also expected to become a promising platform for the detection of other small molecules. PMID:26648409

  6. A competitive photoelectrochemical immunosensor based on a CdS-induced signal amplification strategy for the ultrasensitive detection of dexamethasone

    PubMed Central

    Wang, Xueping; Yan, Tao; Li, Yan; Liu, Yixin; Du, Bin; Ma, Hongmin; Wei, Qin

    2015-01-01

    A novel photoelectrochemical immunosensor based on the competitive strategy is proposed for the specific detection of dexamethasone (DXM). Graphitic carbon nitride coupled with bismuth sulfide are used as the sensing matrix for the immobilization of BSA-DXM on the electrode surface, while cadmium sulfide functionalized titanium dioxide (TiO2@CdS) is used as the photoelectric active labels of anti-DXM. Due to the perfect matching of energy levels between TiO2 and CdS, the in situ prepared composite labels show excellent photocurrent response under visible lights. The competitive binding of DXM in sample solutions and BSA-DXM on the electrode surface reduces the specific attachment of labels to the electrode, resulting in a decrease of the photocurrent intensity. Greatly enhanced sensitivity is achieved after the optimization of the detection conditions. Under the optimal detection condition, the well-designed immunosensor for DXM exhibits a low detection limit of 2 pg∙mL−1. Additionally, the proposed immunoassay system shows high specificity, good reproducibility and acceptable stability, which is also expected to become a promising platform for the detection of other small molecules. PMID:26648409

  7. Cancer biomarker detection in serum samples using surface plasmon resonance and quartz crystal microbalance sensors with nanoparticle signal amplification.

    PubMed

    Uludag, Yildiz; Tothill, Ibtisam E

    2012-07-17

    Early detection of cancer is vital for the successful treatment of the disease. Hence, a rapid and sensitive diagnosis is essential before the cancer is spread out to the other body organs. Here we describe the development of a point-of-care immunosensor for the detection of the cancer biomarker (total prostate-specific antigen, tPSA) using surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) sensor platforms in human serum samples. K(D) of the antibody used toward PSA was calculated as 9.46 × 10(-10) M, indicating high affinity of the antibody used in developing the assay. By performing a sandwich assay using antibody-modified nanoparticles concentrations of 2.3 ng mL(-1) (Au, 20 nm) and 0.29 ng mL(-1) (8.5 pM) (Au, 40 nm) tPSA in 75% human serum were detected using the developed assay on an SPR sensor chip. The SPR sensor results were found to be comparable to that achieved using a QCM sensor platform, indicating that both systems can be applied for disease biomarkers screening. The clinical applicability of the developed immunoassay can therefore be successfully applied to patient's serum samples. This demonstrates the high potential of the developed sensor devices as platforms for clinical prostate cancer diagnosis and prognosis. PMID:22681722

  8. Ag(I)-coordinated hairpin DNA for homogenous electronic monitoring of hepatitis C virus accompanying isothermal cycling signal amplification strategy.

    PubMed

    Lu, Minghua; Xu, Linfang; Zhang, Xiaona; Xiao, Rui; Wang, Youmei

    2015-11-15

    This work designs a new homogenous electronic monitoring platform for sensitive detection of hepatitis C virus (HCV) on an immobilization-free Ag(I)-assisted hairpin DNA through the cytosine-Ag(+)-cytosine coordination chemistry. The assay consists of target-induced Ag(+) dissociation from hairpin DNA and an isothermal circular strand-displacement polymerization (ICSDP) reaction. Upon target analyte introduction, HCV DNA initially hybridizes with hairpin DNA to disrupt the Ag(I)-coordinated hairpin probe and releases the coordinated Ag(+) ion, then the newly formed DNA duplex induces the ICSDP reaction with the aid of primer and polymerase, and then the displaced target DNA retriggers Ag(I)-coordinated hairpin DNA with target recycling, thereby resulting in formation of numerous free Ag(+) ions in the detection cell. The released Ag(+) ions can be readily captured by the negatively charged screen-printed carbon electrode, and subsequent anodic-stripping voltammetric detection of the captured Ag(+) ions are conducted to form the anodic current for the production of the electrochemical signal within the applied potential. Under optimal conditions, the ICSDP-based homogenous sensing system can be utilized for the detection of HCV DNA at a concentration as low as 2.3 pM. Intra- and inter-assay coefficients of variation with identical batches are below 9.5% and 10.5%, respectively. The analysis in 5 clinical serum specimens shows good accordance between results obtained by the developed method and commercial Cobas® Amplicor HCV Test Analyzer. PMID:26071691

  9. Powerful Amplification Cascades of FRET-Based Two-Layer Nonenzymatic Nucleic Acid Circuits.

    PubMed

    Quan, Ke; Huang, Jin; Yang, Xiaohai; Yang, Yanjing; Ying, Le; Wang, He; Xie, Nuli; Ou, Min; Wang, Kemin

    2016-06-01

    Nucleic acid circuits have played important roles in biological engineering and have increasingly attracted researchers' attention. They are primarily based on nucleic acid hybridizations and strand displacement reactions between nucleic acid probes of different lengths. Signal amplification schemes that do not rely on protein enzyme show great potential in analytical applications. While the single amplification circuit often achieves linear amplification that may not meet the need for detection of target in a very small amount, it is very necessary to construct cascade circuits that allow for larger amplification of inputs. Herein, we have successfully engineered powerful amplification cascades of FRET-based two-layer nonenzymatic nucleic acid circuits, in which the outputs of catalyzed hairpin assembly (CHA) activate hybridization chain reactions (HCR) circuits to induce repeated hybridization, allowing real-time monitoring of self-assembly process by FRET signal. The cascades can yield 50000-fold signal amplification with the help of the well-designed and high-quality nucleic acid circuit amplifiers. Subsequently, with coupling of structure-switching aptamer, as low as 200 pM adenosine is detected in buffer, as well as in human serum. To our knowledge, we have for the first time realized real-time monitoring adaptation of HCR to CHA circuits and achieved amplified detection of nucleic acids and small molecules with relatively high sensitivity. PMID:27142084

  10. Ultrasensitive electrochemical immunosensor based on dual signal amplification process for p16(INK4a) cervical cancer detection in clinical samples.

    PubMed

    Duangkaew, Pattasuda; Tapaneeyakorn, Satita; Apiwat, Chayachon; Dharakul, Tararaj; Laiwejpithaya, Somsak; Kanatharana, Proespichaya; Laocharoensuk, Rawiwan

    2015-12-15

    The p16(INK4a) (p16) is a cyclin-dependent kinase inhibitor, which has been evaluated in several studies as a diagnostic marker of cervical cancer. Immunostaining using p16 specific antibody has confirmed an over-expression of p16 protein in cervical cancer cells and its association with disease progression. This article reports an ultrasensitive electrochemical immunosensor for specific detection of p16 and demonstrates its performance for detection of solubilized p16 protein in cell lysates obtained from patients. Sandwich-based immunoreaction couple with double signal amplification strategy based on catalytic enlargement of particle tag was used for high sensitivity and specificity. The conditions were optimized to create an immunoassay protocol. Disposable screen-printed electrode modified with capture antibodies (Ab1) was selected for further implementation towards point-of-care diagnostics. Small gold nanoparticles (15 nm diameter) conjugated with detection antibodies (Ab2) were found to better serve as a detection label due to limited interference with antigen-antibody interaction. Double signal enhancement was performed by sequential depositions of gold and silver layers. This gave the sensitivity of 1.78 μA mL(ng GST-p16)(-1) cm(-2) and detection limit of 1.3 ng mL(-1) for GST-p16 protein which is equivalent to 0.49 ng mL(-1) for p16 protein and 28 cells for HeLa cervical cancer cells. In addition to purified protein, the proposed immunosensor effectively detected elevated p16 level in cervical swab samples obtained from 10 patients with positive result from standard Pap smear test, indicating that an electrochemical immunosensors hold an excellent promise for detection of cervical cancer in clinical setting. PMID:26201985

  11. Pulse Recycling and Weak Value Amplification for Precision Metrology

    NASA Astrophysics Data System (ADS)

    Graham, Trent; Byard, Courtney; Kwiat, Paul; Jordan, Andrew

    2015-05-01

    Weak-value measurements have been shown to be useful for making precision optical measurements, owing to the huge amplification of tiny effects which is achievable with the technique (Hosten 2008, Dixon 2009, Egan 2012, Viza 2013). This amplification is especially helpful in the case where technical noise limits the resolution. However, if the intrinsic shot noise limits the resolution, weak-value measurements offer no advantage because the amplification is achieved via a postselection which discards most of the photons input into the measuring system. The reduction in photon number cancels the increase in signal from the amplification, and the resolution is not increased. To overcome this, we implement a method for recycling the discarded photons. We show that, for a given number of photons input to the system, recycling gives an improvement over the resolution of a conventional measurement. Our work with a simple double-pass recycling system demonstrated a 1.4x improvement over the standard shot-noise limit. We also present our work toward achieving a many-pass recycling system, for which we expect a five-fold improvement over the shot-noise limit. Such a weak-measurement recycling system could be combined with quantum states to further enhance the achievable resolution.

  12. NASBA: A detection and amplification system uniquely suited for RNA

    SciTech Connect

    Sooknanan, R.; Malek, L.T.

    1995-06-01

    The invention of PCR (polymerase chain reaction) has revolutionized our ability to amplify and manipulate a nucleic acid sequence in vitro. The commercial rewards of this revolution have driven the development of other nuclei acid amplification and detection methodologies. This has created an alphabet soup of technologies that use different amplification methods, including NASBA (nucleic acid sequence-based amplification), LCR (ligase chain reaction), SDA (strand displacement amplification), QBR (Q-beta replicase), CPR (cycling probe reaction), and bDNA (branched DNA). Despite the differences in their processes, these amplification systems can be separated into two broad categories based on how they achieve their goal: sequence-based amplification systems, such as PCR, NASBA, and SDA, amplify a target nucleic acid sequence. Signal-based amplification systems, such as LCR, QBR, CPR and bDNA, amplify or alter a signal from a detection reaction that is target-dependent. While the various methods have relative strengths and weaknesses, only NASBA offers the unique ability to homogeneously amplify an RNA analyte in the presence of homologous genomic DNA under isothermal conditions. Since the detection of RNA sequences almost invariably measures biological activity, it is an excellent prognostic indicator of activities as diverse as virus production, gene expression, and cell viability. The isothermal nature of the reaction makes NASBA especially suitable for large-scale manual screening. These features extend NASBA`s application range from research to commercial diagnostic applications. Field test kits are presently under development for human diagnostics as well as the burgeoning fields of food and environmental diagnostic testing. These developments suggest future integration of NASBA into robotic workstations for high-throughput screening as well. 17 refs., 1 tab.

  13. Voltage Amplification using Plasma

    SciTech Connect

    Farias, E. E.; Cavalcanti, G. H.; Santiago, M. A. M.

    2006-12-04

    The purpose of this work is to present experimental results about voltage amplification using plasma produced by a simple neon lamp, series connected with a signal generator and discrete circuit elements. The main advantage of employing plasma as an amplifier is due to its ability to drive larger power and potentially to operate in a larger frequency range compared with traditional amplifiers. Our results show that both, the voltage gain and the frequency range where the gain is bigger than one, are related to the plasma density which may be adjusted by a proper control of electrical discharge conditions. The plasma produced into the neon lamp exhibits a diode characteristic that is the principal responsible by the nonlinear plasma response. The amplification occurs when the plasma shows a negative conductance. In this regime the lamp works as an active amplifier and voltage gain higher than 18 was obtained.

  14. In Situ Generation of Electron Donor to Assist Signal Amplification on Porphyrin-Sensitized Titanium Dioxide Nanostructures for Ultrasensitive Photoelectrochemical Immunoassay.

    PubMed

    Shu, Jian; Qiu, Zhenli; Zhuang, Junyang; Xu, Mingdi; Tang, Dianping

    2015-10-28

    An ultrasensitive photoelectrochemical (PEC) immunoassay protocol for quantitative detection of low-abundant proteins at a low potential was designed by utilizing porphyrin-sensitized titanium dioxide (TiO2) nanostructures. Experimental results demonstrated that the water-soluble 5,10,15,20-tetra(4-sulfophenyl)-21H,23H-porphyrin (TSPP) could be bound onto titanium dioxide via the sulfonic group. TSPP-sensitized TiO2 nanostructures exhibited better photoelectrochemical responses and stability in comparison with TiO2 nanoparticles alone under continuous illumination. Using carcinoembryonic antigen (CEA) as a model analyte, a typical PEC immunosensor by using TSPP-TiO2 as the affinity support of anti-CEA capture antibody (Ab1) to facilitate the improvement of photocurrent response was developed. Bioconjugates of secondary antibody and glucose oxidase with gold nanoparticles (Ab2/GOx-AuNPs) was introduced by an antigen-antibody immunoreaction. AuNP acted as a powerful scaffold to bind with bioactive molecules, while GOx catalyzed glucose to in situ generate hydrogen peroxide (H2O2). The generated H2O2 as a sacrificial electron donor could be oxidized by the photogenerated holes to assist the signal amplification at a low potential under light excitation, thus eliminating interference from other species coexisting in the samples. Under optimal conditions, the PEC immunosensor showed a good linear relationship ranging from 0.02 to 40 ng mL(-1) with a low detection limit of 6 pg mL(-1) CEA. The precision, reproducibility, and specificity were acceptable. In addition, the method accuracy was also evaluated for quantitatively monitoring human serum samples, giving results matching with the referenced CEA ELISA kit. PMID:26451956

  15. Prussian blue mediated amplification combined with signal enhancement of ordered mesoporous carbon for ultrasensitive and specific quantification of metolcarb by a three-dimensional molecularly imprinted electrochemical sensor.

    PubMed

    Yang, Yukun; Cao, Yaoyu; Wang, Xiaomin; Fang, Guozhen; Wang, Shuo

    2015-02-15

    In this work, we presented a three-dimensional (3D) molecularly imprinted electrochemical sensor (MIECS) with novel strategy for ultrasensitive and specific quantification of metolcarb based on prussian blue (PB) mediated amplification combined with signal enhancement of ordered mesoporous carbon. The molecularly imprinted polymers were synthesized by electrochemically induced redox polymerization of para aminobenzoic acid (p-ABA) in the presence of template metolcarb. Ordered mesoporous carbon material (CMK-3) was introduced to enhance the electrochemical response by improving the structure of the modified electrodes and facilitating charge transfer processes of PB which was used as an inherent electrochemical active probe. The modification process for the working electrodes of the MIECS was characterized by scanning electron microscope (SEM) and cyclic voltammetry (CV), and several important parameters controlling the performance of the MIECS were investigated and optimized in detail. The MIECS with 3D structure had the advantages of ease of preparation, high porous surface structure, speedy response, ultrasensitivity, selectivity, reliable stability, good reproducibility and repeatability. Under the optimal conditions, the MIECS offered an excellent current response for metolcarb in the linear response range of 5.0 × 10(-10)-1.0 × 10(-4) mol L(-1) and the limit of detection (LOD) was calculated to be 9.3 × 10 (-11)mol L(-1) (S/N = 3). The proposed MIECS has been successfully applied for the determination of metolcarb in real samples with satisfactory recoveries. Furthermore, the construction route of this ultrasensitive 3D MIECS may provide a guideline for the determination of non-electroactive analytes in environmental control and food safety. PMID:25240126

  16. Efficient GLP-1 gene delivery using two-step transcription amplification plasmid system with a secretion signal peptide and arginine-grafted bioreducible polymer.

    PubMed

    Kim, Tae-Il; Lee, Minhyung; Kim, Sung Wan

    2012-01-30

    Glucagon-like peptide (GLP-1) encoding dual plasmid (pDNA) system (TSTA (SP-GLP-1)) which is composed of pβ-Gal4-p65 and pUAS-SP-GLP-1 was constructed to improve the production and secretion of expressed GLP-1 by combining the advantages of signal peptide (SP) and two-step transcription amplification (TSTA) system. Its potential for GLP-1 gene delivery system was investigated with employment of arginine-grafted bioreducible polymer (ABP) as a gene carrier. Their polyplexes have about 140nm-sizes and 20mV Zeta-potential values. ABP showed no cytotoxicity contrary to PEI25k. It was found in RT-PCR experiments that TSTA-SP pDNA systems showed increased GLP-1 gene transcription level in comparison with mono pDNA system (pβ-GLP-1). It was also observed in GLP-1 ELISA that GLP-1 secretion level of TSTA (SP-GLP-1) pDNA system was 2.7-3.4 times higher than those of pβ-GLP-1 and 1.5-1.7 times than TSTA (GLP-1). Additionally, 2.5-3.5 folds increased level of GLP-1 secretion was found in ABP gene carrier system in comparison with PEI25k. When transfection medium containing secreted GLP-1 was transferred to NIT-1 insulinoma cells, the highest secretion level of insulin was induced in ABP/TSTA (SP-GLP-1) polyplex medium-treated cells. Therefore, this novel system could be utilized as a safe and efficient GLP-1 gene delivery system for type 2 diabetes therapy. PMID:21945681

  17. Signaling Diversity of PKA Achieved Via a Ca2+-cAMP-PKA Oscillatory Circuit

    PubMed Central

    Ni, Qiang; Ganesan, Ambhighainath; Aye-Han, Nwe-Nwe; Gao, Xinxin; Allen, Michael D.; Levchenko, Andre; Zhang, Jin

    2010-01-01

    Many protein kinases are key nodal signaling molecules that regulate a wide range of cellular functions. These functions may require complex spatiotemporal regulation of kinase activities. Here, we show that Protein Kinase A (PKA), Ca2+ and cAMP oscillate in sync in insulin-secreting MIN6 β cells, forming a highly integrated oscillatory circuit. We found that PKA activity was essential for this oscillatory circuit, and was capable of not only initiating the signaling oscillations but also modulating their frequency, thereby diversifying the spatiotemporal control of downstream signaling. Our findings suggest that exquisite temporal control of kinase activity, mediated via signaling circuits resulting from cross-regulation of signaling pathways, can encode diverse inputs into temporal parameters such as oscillation frequency, which in turn contributes to proper regulation of complex cellular functions in a context-dependent manner. PMID:21102470

  18. A plasmonic aptasensor for ultrasensitive detection of thrombin via arrested rolling circle amplification.

    PubMed

    Wang, Sai; Bi, Sai; Wang, Zonghua; Xia, Jianfei; Zhang, Feifei; Yang, Min; Gui, Rijun; Li, Yanhui; Xia, Yanzhi

    2015-05-01

    A sensitive signal generation mechanism for gold nanoparticle growth by reducing gold ions with hydrogen peroxide is applied in a plasmonic aptasensor, achieving naked-eye detection of thrombin at the single-molecule level based on the specific interaction of aptamer-thrombin via an arrested rolling circle amplification to yield horseradish peroxidase (HRP)-mimicking DNAzymes as biocatalysts. PMID:25864665

  19. Stacking nonenzymatic circuits for high signal gain

    PubMed Central

    Chen, Xi; Briggs, Neima; McLain, Jeremy R.; Ellington, Andrew D.

    2013-01-01

    Signal amplification schemes that do not rely on protein enzymes show great potential in areas as abstruse as DNA computation and as applied as point-of-care molecular diagnostics. Toehold-mediated strand displacement, a programmable form of dynamic DNA hybridization, can be used to design powerful amplification cascades that can achieve polynomial or exponential amplification of input signals. However, experimental implementation of such amplification cascades has been severely hindered by circuit leakage due to catalyst-independent side reactions. In this study, we systematically analyzed the origins, characteristics, and outcomes of circuit leakage in amplification cascades and devised unique methods to obtain high-quality DNA circuits that exhibit minimal leakage. We successfully implemented a two-layer cascade that yielded 7,000-fold signal amplification and a two-stage, four-layer cascade that yielded upward of 600,000-fold signal amplification. Implementation of these unique methods and design principles should greatly empower molecular programming in general and DNA-based molecular diagnostics in particular. PMID:23509255

  20. Characterisation of signal enhancements achieved when utilizing a photon diode in deep Raman spectroscopy of tissue.

    PubMed

    Vardaki, Martha Z; Matousek, Pavel; Stone, Nicholas

    2016-06-01

    We characterise the performance of a beam enhancing element ('photon diode') for use in deep Raman spectroscopy (DRS) of biological tissues. The optical component enhances the number of laser photons coupled into a tissue sample by returning escaping photons back into it at the illumination zone. The method is compatible with transmission Raman spectroscopy, a deep Raman spectroscopy concept, and its implementation leads to considerable enhancement of detected Raman photon rates. In the past, the enhancement concept was demonstrated with a variety of samples (pharmaceutical tablets, tissue, etc) but it was not systematically characterized with biological tissues. In this study, we investigate the enhancing properties of the photon diode in the transmission Raman geometry as a function of: a) the depth and b) the optical properties of tissue samples. Liquid tissue phantoms were employed to facilitate systematic variation of optical properties. These were chosen to mimic optical properties of human tissues, including breast and prostate. The obtained results evidence that a photon diode can enhance Raman signals of tissues by a maximum of × 2.4, although it can also decrease the signals created towards the back of samples that exhibit high scattering or absorption properties. PMID:27375932

  1. Characterisation of signal enhancements achieved when utilizing a photon diode in deep Raman spectroscopy of tissue

    PubMed Central

    Vardaki, Martha Z.; Matousek, Pavel; Stone, Nicholas

    2016-01-01

    We characterise the performance of a beam enhancing element (‘photon diode’) for use in deep Raman spectroscopy (DRS) of biological tissues. The optical component enhances the number of laser photons coupled into a tissue sample by returning escaping photons back into it at the illumination zone. The method is compatible with transmission Raman spectroscopy, a deep Raman spectroscopy concept, and its implementation leads to considerable enhancement of detected Raman photon rates. In the past, the enhancement concept was demonstrated with a variety of samples (pharmaceutical tablets, tissue, etc) but it was not systematically characterized with biological tissues. In this study, we investigate the enhancing properties of the photon diode in the transmission Raman geometry as a function of: a) the depth and b) the optical properties of tissue samples. Liquid tissue phantoms were employed to facilitate systematic variation of optical properties. These were chosen to mimic optical properties of human tissues, including breast and prostate. The obtained results evidence that a photon diode can enhance Raman signals of tissues by a maximum of × 2.4, although it can also decrease the signals created towards the back of samples that exhibit high scattering or absorption properties. PMID:27375932

  2. Ultrasensitive electrochemical aptasensor for the detection of thrombin based on dual signal amplification strategy of Au@GS and DNA-CoPd NPs conjugates.

    PubMed

    Wang, Yaoguang; Zhang, Yong; Yan, Tao; Fan, Dawei; Du, Bin; Ma, Hongmin; Wei, Qin

    2016-06-15

    In this work, an ultrasensitive electrochemical aptasensor for the detection of thrombin was developed based on Au nanoparticles decorated graphene sheet (Au@GS) and CoPd binary nanoparticles (CoPd NPs). A sulfydryl-labeled thrombin capture probe (Apt1) and a biotin-labeled thrombin reporter probe (Apt2) were designed to achieve a sandwich-type strategy. Au@GS was used as a sensing platform for the facile immobilization of Apt1 through Au-S bond, forming a sensing interface for thrombin. The specific recognition of thrombin induced the attachment of Apt2-CoPd NPs to the electrode. The labeled CoPd NPs showed good catalytic properties toward the reduction of H2O2, resulting in an amperometric signal. The amperometric response was correlated to the thrombin concentration in sample solutions. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) confirmed the successful fabrication of the aptasensor. A linear response to thrombin in the range of 0.01-2.00 ng mL(-1) with a low detection limit (5 pg mL(-1)) was achieved. The proposed aptasensor showed good selectivity, good reproducibility and acceptable stability. This proposed strategy may find many potential applications in the detection of other biomolecules. PMID:26908183

  3. Optical pulse synthesis using brillouin selective sideband amplification

    NASA Technical Reports Server (NTRS)

    Yao, X. Steve (Inventor)

    2002-01-01

    Techniques for producing optical pulses based on Brillouin selective sideband amplification by using a common modulation control signal to modulate both a signal beam to produce multiple sideband signals and a single pump beam to produce multiple pump beams.

  4. Plasma-based laser-pulse amplification via strongly coupled Brillouin scattering

    NASA Astrophysics Data System (ADS)

    Chiaramello, Marco; Amiranoff, François; Weber, Stefan; Lancia, Livia; Grech, Michael; Vinci, Tommaso; Marqués, Jean-Raphael; Fuchs, Julien; Riconda, Caterina; Luli, Upmc-Ecole Polytechnique-Cnrs-75252 Paris Team; Eli-Beamlines, Ipas, 18221 Prague, Czech Republic Collaboration; Sapienza, University Of Rome, Dip. Sbai, 00161 Rome, Italy Collaboration

    2015-11-01

    The use of plasma as an amplification medium for laser pulses is currently discussed because it can overcome current solid-state technology limitations in terms of maximum achievable intensity. Via parametric scattering off a plasma oscillation the energy from a long pump pulse can be transferred into a short seed pulse. Brillouin scattering has the potential to become a robust amplification process. In this presentation we will show theoretical and numerical (PIC) studies aimed at better understanding the role on the amplification mechanism of each plasma parameter, such as the interaction length, the shape of the density profile, the duration of the long pump signal, the relative delay between the seed and pump signals, the role of the chirp of the long pump laser pulse. Comparisons with recent experiments will be performed.

  5. Feedback Amplification of Neutrophil Function.

    PubMed

    Németh, Tamás; Mócsai, Attila

    2016-06-01

    As the first line of innate immune defense, neutrophils need to mount a rapid and robust antimicrobial response. Recent studies implicate various positive feedback amplification processes in achieving that goal. Feedback amplification ensures effective migration of neutrophils in shallow chemotactic gradients, multiple waves of neutrophil recruitment to the site of inflammation, and the augmentation of various effector functions of the cells. We review here such positive feedback loops including intracellular and autocrine processes, paracrine effects mediated by lipid (LTB4), chemokine, and cytokine mediators, and bidirectional interactions with the complement system and with other immune and non-immune cells. These amplification mechanisms are not only involved in antimicrobial immunity but also contribute to neutrophil-mediated tissue damage under pathological conditions. PMID:27157638

  6. An electrochemical aptasensor for thrombin using synergetic catalysis of enzyme and porous Au@Pd core-shell nanostructures for signal amplification.

    PubMed

    Xu, Wenju; Yi, Huayu; Yuan, Yali; Jing, Pei; Chai, Yaqin; Yuan, Ruo; Wilson, George S

    2015-02-15

    In this work, a sensitive electrochemical aptasensor for thrombin (TB) based on synergetic catalysis of enzyme and porous Au@Pd core-shell nanostructure has been constructed. With the advantages of large surface area and outstanding catalytic performance, porous Au@Pd core-shell nanostructures were firstly employed as the nanocarrier for the immobilization of electroactive toluidine blue (Tb), hemin/G-quadruplex formed by intercalating hemin into the TB aptamer (TBA) and glucose oxidase (GOx). As a certain amount of glucose was added into the detection cell, GOx rapidly catalyzed the oxidation of glucose, coupling with the local generation of H2O2 in the presence of dissolved O2. Then, porous Au@Pd nanoparticles and hemin/G-quadruplex as the peroxidase mimics efficiently catalyzed the reduction of H2O2, amplifying the electrochemical signal and improving the sensitivity. Finally, a detection limit of 0.037pM for TB was achieved. The excellent performance of the aptasensor indicated its promising prospect as a valuable tool in simple and cost-effective TB detection in clinical application. PMID:25280342

  7. Achieving 1% NMR polarization in water in less than 1 min using SABRE

    PubMed Central

    Zeng, Haifeng; Xu, Jiadi; McMahon, Michael T.; Lohman, Joost A.B.; van Zijl, Peter C.M.

    2015-01-01

    The development of biocompatible hyperpolarized media is a crucial step towards application of hyperpolarization in vivo. This article describes the achievement of 1% hyperpolarization of 3-amino-1,2,4-triazine protons in water using the parahydrogen induced polarization technique based on signal amplification by reversible exchange (SABRE). Polarization was achieved in less than 1 min. PMID:25123540

  8. Weak value amplification via second-order correlated technique

    NASA Astrophysics Data System (ADS)

    Ting, Cui; Jing-Zheng, Huang; Xiang, Liu; Gui-Hua, Zeng

    2016-02-01

    We propose a new framework combining weak measurement and second-order correlated technique. The theoretical analysis shows that weak value amplification (WVA) experiment can also be implemented by a second-order correlated system. We then build two-dimensional second-order correlated function patterns for achieving higher amplification factor and discuss the signal-to-noise ratio influence. Several advantages can be obtained by our proposal. For instance, detectors with high resolution are not necessary. Moreover, detectors with low saturation intensity are available in WVA setup. Finally, type-one technical noise can be effectively suppressed. Project supported by the Union Research Centre of Advanced Spaceflight Technology (Grant No. USCAST2013-05), the National Natural Science Foundation of China (Grant Nos. 61170228, 61332019, and 61471239), and the High-Tech Research and Development Program of China (Grant No. 2013AA122901).

  9. Hybrid chirped pulse amplification system

    DOEpatents

    Barty, Christopher P.; Jovanovic, Igor

    2005-03-29

    A hybrid chirped pulse amplification system wherein a short-pulse oscillator generates an oscillator pulse. The oscillator pulse is stretched to produce a stretched oscillator seed pulse. A pump laser generates a pump laser pulse. The stretched oscillator seed pulse and the pump laser pulse are directed into an optical parametric amplifier producing an optical parametric amplifier output amplified signal pulse and an optical parametric amplifier output unconverted pump pulse. The optical parametric amplifier output amplified signal pulse and the optical parametric amplifier output laser pulse are directed into a laser amplifier producing a laser amplifier output pulse. The laser amplifier output pulse is compressed to produce a recompressed hybrid chirped pulse amplification pulse.

  10. Camera-based ratiometric fluorescence transduction of nucleic acid hybridization with reagentless signal amplification on a paper-based platform using immobilized quantum dots as donors.

    PubMed

    Noor, M Omair; Krull, Ulrich J

    2014-10-21

    Paper-based diagnostic assays are gaining increasing popularity for their potential application in resource-limited settings and for point-of-care screening. Achievement of high sensitivity with precision and accuracy can be challenging when using paper substrates. Herein, we implement the red-green-blue color palette of a digital camera for quantitative ratiometric transduction of nucleic acid hybridization on a paper-based platform using immobilized quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET). A nonenzymatic and reagentless means of signal enhancement for QD-FRET assays on paper substrates is based on the use of dry paper substrates for data acquisition. This approach offered at least a 10-fold higher assay sensitivity and at least a 10-fold lower limit of detection (LOD) as compared to hydrated paper substrates. The surface of paper was modified with imidazole groups to assemble a transduction interface that consisted of immobilized QD-probe oligonucleotide conjugates. Green-emitting QDs (gQDs) served as donors with Cy3 as an acceptor. A hybridization event that brought the Cy3 acceptor dye in close proximity to the surface of immobilized gQDs was responsible for a FRET-sensitized emission from the acceptor dye, which served as an analytical signal. A hand-held UV lamp was used as an excitation source and ratiometric analysis using an iPad camera was possible by a relative intensity analysis of the red (Cy3 photoluminescence (PL)) and green (gQD PL) color channels of the digital camera. For digital imaging using an iPad camera, the LOD of the assay in a sandwich format was 450 fmol with a dynamic range spanning 2 orders of magnitude, while an epifluorescence microscope detection platform offered a LOD of 30 fmol and a dynamic range spanning 3 orders of magnitude. The selectivity of the hybridization assay was demonstrated by detection of a single nucleotide polymorphism at a contrast ratio of 60:1. This work provides an

  11. MicroRNA-mediated signal amplification coupled with GNP/dendrimers on a mass-sensitive biosensor and its applications in intracellular microRNA quantification.

    PubMed

    Guo, Yingshu; Wang, Yujie; Yang, Guangxu; Xu, Jing-Juan; Chen, Hong-Yuan

    2016-11-15

    Here, a mass-sensitive microRNA sensing surface is developed by utilizing a probe DNA/gold nanoparticles (GNP)/dendrimer composite coupling with an enzymatic amplification process. The probe DNA/GNP/dendrimer composite is prepared via the covalent coupling between the NH2 groups in PAMAM or DNA and the COOH group on GNP. Target microRNA binds to a stem-loop-structured DNA on maganatic NPs, forming a heteroduplex. By enzyme recycling amplification, a large number of linker sequences are produced on MNPs. Via the combination of probe DNA, the linker DNA on MNPs and a capture DNA on gold chip, the DNA/GNP/dendrimer probe could be assembled on the surface of gold chip inducing a sensitive frequency response. It presents an excellent performance in microRNA-203 quantification with a detection linear range of 1.0×10(-11)-1.0×10(-9)M. Both the success in discriminating expressing miroRNA-203 in MCF-7 cell and the well agreement with the commercial qRT-PCR detection method implied its potential application in early cancer diagnosis for future. PMID:27311115

  12. Can Anomalous Amplification be Attained without Postselection?

    NASA Astrophysics Data System (ADS)

    Martínez-Rincón, Julián; Liu, Wei-Tao; Viza, Gerardo I.; Howell, John C.

    2016-03-01

    We present a parameter estimation technique based on performing joint measurements of a weak interaction away from the weak-value-amplification approximation. Two detectors are used to collect full statistics of the correlations between two weakly entangled degrees of freedom. Without discarding of data, the protocol resembles the anomalous amplification of an imaginary-weak-value-like response. The amplification is induced in the difference signal of both detectors allowing robustness to different sources of technical noise, and offering in addition the advantages of balanced signals for precision metrology. All of the Fisher information about the parameter of interest is collected. A tunable phase controls the strength of the amplification response. We experimentally demonstrate the proposed technique by measuring polarization rotations in a linearly polarized laser pulse. We show that in the presence of technical noise the effective sensitivity and precision of a split detector is increased when compared to a conventional continuous-wave balanced detection technique.

  13. Can Anomalous Amplification be Attained without Postselection?

    PubMed

    Martínez-Rincón, Julián; Liu, Wei-Tao; Viza, Gerardo I; Howell, John C

    2016-03-11

    We present a parameter estimation technique based on performing joint measurements of a weak interaction away from the weak-value-amplification approximation. Two detectors are used to collect full statistics of the correlations between two weakly entangled degrees of freedom. Without discarding of data, the protocol resembles the anomalous amplification of an imaginary-weak-value-like response. The amplification is induced in the difference signal of both detectors allowing robustness to different sources of technical noise, and offering in addition the advantages of balanced signals for precision metrology. All of the Fisher information about the parameter of interest is collected. A tunable phase controls the strength of the amplification response. We experimentally demonstrate the proposed technique by measuring polarization rotations in a linearly polarized laser pulse. We show that in the presence of technical noise the effective sensitivity and precision of a split detector is increased when compared to a conventional continuous-wave balanced detection technique. PMID:27015468

  14. Cochlear amplification, outer hair cells and prestin

    PubMed Central

    Dallos, Peter

    2008-01-01

    Mechanical amplification of acoustic signals is apparently a common feature of vertebrate auditory organs. In non-mammalian vertebrates amplification is produced by stereociliary processes, related to the mechanotransducer channel complex and probably to the phenomenon of fast adaptation. The extended frequency range of the mammalian cochlea has likely co-evolved with a novel hair cell type, the outer hair cell and its constituent membrane protein, prestin. Cylindrical outer hair cells are motile and their somatic length changes are voltage driven and powered by prestin. One of the central outstanding problems in mammalian cochlear neurobiology is the relation between the two amplification processes. PMID:18809494

  15. Photon number amplification/duplication through parametric conversion

    NASA Technical Reports Server (NTRS)

    Dariano, G. M.; Macchiavello, C.; Paris, M.

    1993-01-01

    The performance of parametric conversion in achieving number amplification and duplication is analyzed. It is shown that the effective maximum gains G(sub *) remain well below their integer ideal values, even for large signals. Correspondingly, one has output Fano factors F(sub *) which are increasing functions of the input photon number. On the other hand, in the inverse (deamplifier/recombiner) operating mode quasi-ideal gains G(sub *) and small factors F(sub *) approximately equal to 10 percent are obtained. Output noise and non-ideal gains are ascribed to spontaneous parametric emission.

  16. A comparative study of the energy resolution achievable with digital signal processors in x-ray spectroscopy

    SciTech Connect

    Geraci, A.; Zambusi, M.; Ripamonti, G.

    1996-04-01

    Interest for digital processing of signals from radiation detectors is subject to a growing attention due to its intrinsic adaptivity, easiness of calibration, etc. This work compares two digital processing methods: a multiple-delay-line (DL){sup N} filter and a least-mean-squares (LMS) adaptive filter for applications in high resolution X-ray spectroscopy. The signal pulse, as appears at the output of a proper analog conditioning circuit, is digitized; the samples undergo a digital filtering procedure. Both digital filters take advantage of the possibility of synthesizing the best possible weighting function with respect to the actual noise conditions. A noticeable improvement of more than 10% in energy resolution has been achieved with both systems with respect to state-of-the-art systems based on analog circuitry. In particular, the two digital processors are shown to be the best choice respectively; for on-line use with critical ballistic deficit conditions and for very-high-resolution spectroscopy systems, ultimately limited by 1/f noise.

  17. A double signal amplification platform for ultrasensitive and simultaneous detection of ascorbic acid, dopamine, uric acid and acetaminophen based on a nanocomposite of ferrocene thiolate stabilized Fe₃O₄@Au nanoparticles with graphene sheet.

    PubMed

    Liu, Meiling; Chen, Qiong; Lai, Cailang; Zhang, Youyu; Deng, Jianhui; Li, Haitao; Yao, Shouzhuo

    2013-10-15

    A double signal amplification platform for ultrasensitive and simultaneous detection of ascorbic acid (AA), dopamine (DA), uric acid (UA) and acetaminophen (AC) was fabricated by a nanocomposite of ferrocene thiolate stabilized Fe₃O₄@Au nanoparticles with graphene sheet. The platform was constructed by coating a newly synthesized phenylethynyl ferrocene thiolate (Fc-SAc) modified Fe₃O₄@Au NPs coupling with graphene sheet/chitosan (GS-chitosan) on a glassy carbon electrode (GCE) surface. The Fe₃O₄@Au-S-Fc/GS-chitosan modified GCE exhibits a synergistic catalytic and amplification effect toward AA, DA, UA and AC oxidation. The oxidation peak currents of the four compounds on the electrode were linearly dependent on AA, DA, UA and AC concentrations in the ranges of 4-400 μM, 0.5-50 μM, 1-300 μM and 0.3-250 μM in the individual detection of each component, respectively. By simultaneously changing the concentrations of AA, DA, UA and AC, their electrochemical oxidation peaks appeared at -0.03, 0.15, 0.24 and 0.35 V, and good linear current responses were obtained in the concentration ranges of 6-350, 0.5-50, 1-90 and 0.4-32 μM with the detection limits of 1, 0.1, 0.2 and 0.05 μM (S/N=3), respectively. PMID:23651571

  18. Ultrasensitive DNA detection based on two-step quantitative amplification on magnetic nanoparticles.

    PubMed

    Jin, Mingliang; Liu, Xia; van den Berg, Albert; Zhou, Guofu; Shui, Lingling

    2016-08-19

    Sensitive detection of a specific deoxyribo nucleic acid (DNA) sequence is important for biomedical applications. In this report, a two-step amplification strategy is developed based on magnetic nanoparticles (MNPs) to achieve ultrasensitive DNA fluorescence detection. The first level amplification is obtained from multiple binding sites on MNPs to achieve thousands of probe DNA molecules on one nanoparticle surface. The second level amplification is gained by enzymatic reaction to achieve fluorescence signal enhancement. MNPs functionalized by probe DNA (DNAp) are bound to target DNA (t-DNA) molecules with a ratio of 1:1 on a substrate with capture DNA (DNAc). After the MNPs with DNAp are released from the substrate, alkaline phosphatase (AP) is labelled to MNPs via hybridization reaction between DNAp on MNPs and detection DNAs (DNAd) with AP. The AP on MNPs catalyses non-fluorescent 4-methylumbelliferyl phosphate (4-MUP) to fluorescent 4-methylumbelliferone (4-MU) with high intensity. Finally, fluorescence intensity of the 4-MU is detected by a conventional fluorescence spectrophotometer. With this two-step amplification strategy, the limit of detection (LOD) of 2.8 × 10(-18) mol l(-1) for t-DNA has been achieved. PMID:27378514

  19. Ultrasensitive DNA detection based on two-step quantitative amplification on magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Jin, Mingliang; Liu, Xia; van den Berg, Albert; Zhou, Guofu; Shui, Lingling

    2016-08-01

    Sensitive detection of a specific deoxyribo nucleic acid (DNA) sequence is important for biomedical applications. In this report, a two-step amplification strategy is developed based on magnetic nanoparticles (MNPs) to achieve ultrasensitive DNA fluorescence detection. The first level amplification is obtained from multiple binding sites on MNPs to achieve thousands of probe DNA molecules on one nanoparticle surface. The second level amplification is gained by enzymatic reaction to achieve fluorescence signal enhancement. MNPs functionalized by probe DNA (DNAp) are bound to target DNA (t-DNA) molecules with a ratio of 1:1 on a substrate with capture DNA (DNAc). After the MNPs with DNAp are released from the substrate, alkaline phosphatase (AP) is labelled to MNPs via hybridization reaction between DNAp on MNPs and detection DNAs (DNAd) with AP. The AP on MNPs catalyses non-fluorescent 4-methylumbelliferyl phosphate (4-MUP) to fluorescent 4-methylumbelliferone (4-MU) with high intensity. Finally, fluorescence intensity of the 4-MU is detected by a conventional fluorescence spectrophotometer. With this two-step amplification strategy, the limit of detection (LOD) of 2.8 × 10‑18 mol l‑1 for t-DNA has been achieved.

  20. Photonic radio frequency phase-shift amplification by radio frequency interferometry.

    PubMed

    Ayun, Moshe Ben; Schwarzbaum, Arye; Rosenberg, Seva; Pinchas, Monika; Sternklar, Shmuel

    2015-11-01

    We present a new technique for radio frequency (RF) phase-shift amplification based on RF interferometry and demonstrate it in an optical system. A striking feature of this amplifier is that the input phase noise is not amplified together with the input phase signal, so the phase sensitivity improves with higher phase amplification. We also predict that in the case of correlated amplitude noise, the sensitivity is not affected by the amplitude noise. With 600 MHz of modulated light and a phase amplification of 100, we demonstrate a phase resolution of 0.2 mrad, giving a distance resolution of 8 μm. We postulate that nanometric distance resolution can be achieved with sub-gigahertz modulation. PMID:26512469

  1. Spheromak Impedance and Current Amplification

    SciTech Connect

    Fowler, T K; Hua, D D; Stallard, B W

    2002-01-31

    It is shown that high current amplification can be achieved only by injecting helicity on the timescale for reconnection, {tau}{sub REC}, which determines the effective impedance of the spheromak. An approximate equation for current amplification is: dI{sub TOR}{sup 2}/dt {approx} I{sup 2}/{tau}{sub REC} - I{sub TOR}{sup 2}/{tau}{sub closed} where I is the gun current, I{sub TOR} is the spheromak toroidal current and {tau}{sub CLOSED} is the ohmic decay time of the spheromak. Achieving high current amplification, I{sub TOR} >> I, requires {tau}{sub REC} <<{tau}{sub CLOSED}. For resistive reconnection, this requires reconnection in a cold zone feeding helicity into a hot zone. Here we propose an impedance model based on these ideas in a form that can be implemented in the Corsica-based helicity transport code. The most important feature of the model is the possibility that {tau}{sub REC} actually increases as the spheromak temperature increases, perhaps accounting for the ''voltage sag'' observed in some experiments, and a tendency toward a constant ratio of field to current, B {proportional_to} I, or I{sub TOR} {approx} I. Program implications are discussed.

  2. "Smart" gold nanoparticles for photoacoustic imaging: an imaging contrast agent responsive to the cancer microenvironment and signal amplification via pH-induced aggregation.

    PubMed

    Song, Jaejung; Kim, Jeesu; Hwang, Sekyu; Jeon, Mansik; Jeong, Sanghwa; Kim, Chulhong; Kim, Sungjee

    2016-07-01

    'Smart' gold nanoparticles can respond to mild acidic environments, rapidly form aggregates, and shift the absorption to red and near-infrared. They were used as a photoacoustic imaging agent responsive to the cancer microenvironment, and have demonstrated the cancer-specific accumulation at the cellular level and an amplified signal which is twice higher than the control in vivo. PMID:27292365

  3. NAIMA: target amplification strategy allowing quantitative on-chip detection of GMOs.

    PubMed

    Morisset, Dany; Dobnik, David; Hamels, Sandrine; Zel, Jana; Gruden, Kristina

    2008-10-01

    We have developed a novel multiplex quantitative DNA-based target amplification method suitable for sensitive, specific and quantitative detection on microarray. This new method named NASBA Implemented Microarray Analysis (NAIMA) was applied to GMO detection in food and feed, but its application can be extended to all fields of biology requiring simultaneous detection of low copy number DNA targets. In a first step, the use of tailed primers allows the multiplex synthesis of template DNAs in a primer extension reaction. A second step of the procedure consists of transcription-based amplification using universal primers. The cRNA product is further on directly ligated to fluorescent dyes labelled 3DNA dendrimers allowing signal amplification and hybridized without further purification on an oligonucleotide probe-based microarray for multiplex detection. Two triplex systems have been applied to test maize samples containing several transgenic lines, and NAIMA has shown to be sensitive down to two target copies and to provide quantitative data on the transgenic contents in a range of 0.1-25%. Performances of NAIMA are comparable to singleplex quantitative real-time PCR. In addition, NAIMA amplification is faster since 20 min are sufficient to achieve full amplification. PMID:18710880

  4. NAIMA: target amplification strategy allowing quantitative on-chip detection of GMOs

    PubMed Central

    Morisset, Dany; Dobnik, David; Hamels, Sandrine; Žel, Jana; Gruden, Kristina

    2008-01-01

    We have developed a novel multiplex quantitative DNA-based target amplification method suitable for sensitive, specific and quantitative detection on microarray. This new method named NASBA Implemented Microarray Analysis (NAIMA) was applied to GMO detection in food and feed, but its application can be extended to all fields of biology requiring simultaneous detection of low copy number DNA targets. In a first step, the use of tailed primers allows the multiplex synthesis of template DNAs in a primer extension reaction. A second step of the procedure consists of transcription-based amplification using universal primers. The cRNA product is further on directly ligated to fluorescent dyes labelled 3DNA dendrimers allowing signal amplification and hybridized without further purification on an oligonucleotide probe-based microarray for multiplex detection. Two triplex systems have been applied to test maize samples containing several transgenic lines, and NAIMA has shown to be sensitive down to two target copies and to provide quantitative data on the transgenic contents in a range of 0.1–25%. Performances of NAIMA are comparable to singleplex quantitative real-time PCR. In addition, NAIMA amplification is faster since 20 min are sufficient to achieve full amplification. PMID:18710880

  5. Amplification and modulation of fluorescent signals by using hybridization chain reactions for multiplexed sensing of biomolecules in a one-pot

    NASA Astrophysics Data System (ADS)

    Nishimura, Takahiro; Ogura, Yusuke; Yamada, Kenji; Ohno, Yuko; Tanida, Jun

    2014-02-01

    Fluorescence readout of molecular information is a promising approach for biomolecular sensing. For detection of enormous biomolecules via uorescence, biomolecular information should be converted to codes that can be readout easily and simultaneously. For the purpose, we study a biomolecule uorescence color (B/F) encoders that modulate uorescence signals by control of uorescence resonance energy transfer (FRET). The B/F encoder converts biomolecular signals into uorescent color codes represented with uorescent wavelengths and intensity levels. The combination offers a great number of codes for representing the biomolecular information. In this study, we discuss multiplexed detection of target biomolecules using B/F encoders. Use of the B/F encoders would offer a multiplexed biomolecular sensing in a one-pot without micro-fabrication like DNA microarray. In the experiments, we prepared B/F encoders based on two kinds of hybridization chain reactions (HCR) that make long double-stranded DNA polymers to control positions of uorescence and quencher molecules. In the B/F encoders, target molecules trigger to start assembling the polymer structures. The uorescent molecules in the absence of the targets are near the quenchers and the output uorescence is suppressed by FRET. The polymerization process separates the uorescent and quencher dyes and the uorescent signal increase. The experimental results show that the B/F encoders based on HCRs have linear and independent response to each target, and temporal signals during the encoding reactions are usable for multiplexed readout. This result leads to the multiplexed sensing in a one-pot by uorescent ampli cation and multiple uorescent color-coding.

  6. Reactivation of IgG-switched memory B cells by BCR-intrinsic signal amplification promotes IgG antibody production.

    PubMed

    Lutz, Johannes; Dittmann, Kai; Bösl, Michael R; Winkler, Thomas H; Wienands, Jürgen; Engels, Niklas

    2016-01-01

    Secondary antibody responses are marked by faster kinetics, improved antibody affinity and a switch from IgM to other immunoglobulin isotypes, most notably IgG, compared with primary responses. These changes protect from reinfection and represent the principle of most vaccination strategies. Yet, the molecular mechanisms that underlie B-cell memory responses are unclear. Here we show, by inactivating the immunoglobulin tail tyrosine (ITT) signalling motif of membrane-bound IgG1 in the mouse, that the ITT facilitates maintenance and reactivation of IgG-switched memory B cells in vivo. The ITT motif equips IgG-switched cells with enhanced BCR signalling capacity, which supports their competitiveness in secondary immune reactions and drives the formation of IgG-secreting plasma cells even in the absence of T-cell help. Our results demonstrate that ITT signalling promotes the vigorous production of IgG antibodies and thus provide a molecular basis for humoral immunological memory. PMID:26815242

  7. Reactivation of IgG-switched memory B cells by BCR-intrinsic signal amplification promotes IgG antibody production

    PubMed Central

    Lutz, Johannes; Dittmann, Kai; Bösl, Michael R; Winkler, Thomas H; Wienands, Jürgen; Engels, Niklas

    2015-01-01

    Secondary antibody responses are marked by faster kinetics, improved antibody affinity and a switch from IgM to other immunoglobulin isotypes, most notably IgG, compared with primary responses. These changes protect from reinfection and represent the principle of most vaccination strategies. Yet, the molecular mechanisms that underlie B-cell memory responses are unclear. Here we show, by inactivating the immunoglobulin tail tyrosine (ITT) signalling motif of membrane-bound IgG1 in the mouse, that the ITT facilitates maintenance and reactivation of IgG-switched memory B cells in vivo. The ITT motif equips IgG-switched cells with enhanced BCR signalling capacity, which supports their competitiveness in secondary immune reactions and drives the formation of IgG-secreting plasma cells even in the absence of T-cell help. Our results demonstrate that ITT signalling promotes the vigorous production of IgG antibodies and thus provide a molecular basis for humoral immunological memory. PMID:26815242

  8. Multiplexed enzyme-free electrochemical immunosensor based on ZnO nanorods modified reduced graphene oxide-paper electrode and silver deposition-induced signal amplification strategy.

    PubMed

    Sun, Guoqiang; Zhang, Lina; Zhang, Yan; Yang, Hongmei; Ma, Chao; Ge, Shenguang; Yan, Mei; Yu, Jinghua; Song, Xianrang

    2015-09-15

    Herein, an origami multiplexed enzyme-free electrochemical (EC) immunodevice is developed for the first time. Typically, ZnO nanorods (ZNRs) modified reduced graphene oxide (rGO)-paper electrode is used as a sensor platform, in which rGO improves the electronic transmission rate and ZNRs provide abundant sites for capture probes binding. Furthermore, by combining the large surface area of rGO and high catalytic activity of bovine serum protein (BSA)-stabilized silver nanoparticles (Ag@BSA) toward H2O2 reduction, rGO/Ag@BSA composites can be used as an excellent signal labels. The current signal is generated from the reduction of H2O2 and further amplified by a subsequent signal labels-promoted deposition of silver. Under optimal conditions, the proposed immunoassays exhibit excellent precision, high sensitivity and a wide linear range of 0.002-120 mIU mL(-1) for human chorionic gonadotropin, 0.001-110 ng mL(-1) for prostate-specific antigen, and 0.001-100 ng mL(-1) for carcinoembryonic antigen. The results for real sample analysis demonstrate that the newly constructed immunosensor arrays provide a simple and cost-effective method for clinical applications. PMID:25884731

  9. Cascade DNA nanomachine and exponential amplification biosensing.

    PubMed

    Xu, Jianguo; Wu, Zai-Sheng; Shen, Weiyu; Xu, Huo; Li, Hongling; Jia, Lee

    2015-11-15

    DNA is a versatile scaffold for the assembly of multifunctional nanostructures, and potential applications of various DNA nanodevices have been recently demonstrated for disease diagnosis and treatment. In the current study, a powerful cascade DNA nanomachine was developed that can execute the exponential amplification of p53 tumor suppressor gene. During the operation of the newly-proposed DNA nanomachine, dual-cyclical nucleic acid strand-displacement polymerization (dual-CNDP) was ingeniously introduced, where the target trigger is repeatedly used as the fuel molecule and the nicked fragments are dramatically accumulated. Moreover, each displaced nicked fragment is able to activate the another type of cyclical strand-displacement amplification, increasing exponentially the value of fluorescence intensity. Essentially, one target binding event can induce considerable number of subsequent reactions, and the nanodevice was called cascade DNA nanomachine. It can implement several functions, including recognition element, signaling probe, polymerization primer and template. Using the developed autonomous operation of DNA nanomachine, the p53 gene can be quantified in the wide concentration range from 0.05 to 150 nM with the detection limit of 50 pM. If taking into account the final volume of mixture, the detection limit is calculated as lower as 6.2 pM, achieving an desirable assay ability. More strikingly, the mutant gene can be easily distinguished from the wild-type one. The proof-of-concept demonstrations reported herein is expected to promote the development and application of DNA nanomachine, showing great potential value in basic biology and medical diagnosis. PMID:26042874

  10. Prostaglandin E2 promotes Th1 differentiation via synergistic amplification of IL-12 signalling by cAMP and PI3-kinase

    PubMed Central

    Yao, Chengcan; Hirata, Takako; Soontrapa, Kitipong; Ma, Xiaojun; Takemori, Hiroshi; Narumiya, Shuh

    2013-01-01

    T helper 1 (Th1) cells have critical roles in various autoimmune and proinflammatory diseases. cAMP has long been believed to act as a suppressor of IFN-γ production and Th1 cell-mediated immune inflammation. Here we show that cAMP actively promotes Th1 differentiation by inducing gene expression of cytokine receptors involved in this process. PGE2 signalling through EP2/EP4 receptors mobilizes the cAMP-PKA pathway, which induces CREB- and its co-activator CRTC2-mediated transcription of IL-12Rβ2 and IFN-γR1. Meanwhile, cAMP-mediated suppression of T-cell receptor signalling is overcome by simultaneous activation of PI3-kinase through EP2/EP4 and/or CD28. Loss of EP4 in T cells restricts expression of IL-12Rβ2 and IFN-γR1, and attenuates Th1 cell-mediated inflammation in vivo. These findings clarify the molecular mechanisms and pathological contexts of cAMP-mediated Th1 differentiation and have clinical and therapeutic implications for deployment of cAMP modulators as immunoregulatory drugs. PMID:23575689

  11. CdTe quantum dots@luminol as signal amplification system for chrysoidine with chemiluminescence-chitosan/graphene oxide-magnetite-molecularly imprinting sensor

    NASA Astrophysics Data System (ADS)

    Duan, Huimin; Li, Leilei; Wang, Xiaojiao; Wang, Yanhui; Li, Jianbo; Luo, Chuannan

    2016-01-01

    A sensitive chemiluminescence (CL) sensor based on chemiluminescence resonance energy transfer (CRET) in CdTe quantum dots@luminol (CdTe QDs@luminol) nanomaterials combined with chitosan/graphene oxide-magnetite-molecularly imprinted polymer (Cs/GM-MIP) for sensing chrysoidine was developed. CdTe QDs@luminol was designed to not only amplify the signal of CL but also reduce luminol consumption in the detection of chrysoidine. On the basis of the abundant hydroxy and amino, Cs and graphene oxide were introduced into the GM-MIP to improve the adsorption ability. The adsorption capacities of chrysoidine by both Cs/GM-MIP and non-imprinted polymer (Cs/GM-NIP) were investigated, and the CdTe QDs@luminol and Cs/GM-MIP were characterized by UV-vis, FTIR, SEM and TEM. The proposed sensor can detect chrysoidine within a linear range of 1.0 × 10- 7 - 1.0 × 10- 5 mol/L with a detection limit of 3.2 × 10- 8 mol/L (3δ) due to considerable chemiluminescence signal enhancement of the CdTe quantum dots@luminol detector and the high selectivity of the Cs/GM-MIP system. Under the optimal conditions of CL, the CdTe QDs@luminol-Cs/GM-MIP-CL sensor was used for chrysoidine determination in samples with satisfactory recoveries in the range of 90-107%.

  12. Construction and 13C NMR signal-amplification efficiency of a dynamic nuclear polarizer at 6.4 T and 1.4 K

    NASA Astrophysics Data System (ADS)

    Kiswandhi, Andhika; Niedbalski, Peter; Parish, Christopher; Ferguson, Sarah; Taylor, David; McDonald, George; Lumata, Lloyd

    Dissolution dynamic nuclear polarization (DNP) is a rapidly emerging technique in biomedical and metabolic imaging since it amplifies the liquid-state nuclear magnetic resonance (NMR) and imaging (MRI) signals by >10,000-fold. Originally used in nuclear scattering experiments, DNP works by creating a non-Boltzmann nuclear spin distribution by transferring the high electron (γ = 28,000 MHz/T) thermal polarization to the nuclear spins via microwave irradiation of the sample at high magnetic field and low temperature. A dissolution device is used to rapidly dissolve the frozen sample and consequently produces an injectable ``hyperpolarized'' liquid at physiologically-tolerable temperature. Here we report the construction and performance evaluation of a dissolution DNP hyperpolarizer at 6.4 T and 1.4 K using a continuous-flow cryostat. The solid and liquid-state 13C NMR signal enhancement levels of 13C acetate samples doped with trityl OX063 and 4-oxo-TEMPO free radicals will be discussed and compared with the results from the 3.35 T commercial hyperpolarizer. This work is supported by US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

  13. Polymerase chain reaction coupling with magnetic nanoparticles-based biotin-avidin system for amplification of chemiluminescent detection signals of nucleic acid.

    PubMed

    Li, Zhiyang; He, Lei; He, Nongyue; Deng, Yan; Shi, Zhiyang; Wang, Hua; Li, Song; Liu, Hongna; Wang, Zhifei; Wang, Daxin

    2011-02-01

    A novel method was established through the detection of chemiluminescent signals of nucleic acid hybridization based on magnetic nanoparticles (MNPs) and PCR. 5' amino- modified specific probes were immobilized on the surface of silanized MNPs by Schiff reaction between amino and aldehyde group. The probes were used to capture the synthetic biotin-dUTP-labeled DNA fragments which were obtained by polymerase chain reaction (PCR). Then these complexes were bonded with streptavidin-modified alkaline phosphatase (SA-AP). Finally the chemiluminescent signals were detected by adding 3-(2'-spiroadamantane)- 4-methoxy -4-(3"-phosphoryloxy) phenyl-1, 2-dioxetane (AMPPD) which was the substrate reagent of AP. The concentration of probes which were immobilized on the surface of MNPs was studied, how to reduce the adsorption of SA-AP on the surface of MNPs was also researched. It was shown that 12.5 pmol of probes were immobilized on 1 mg of MNPs. Aldehyde-MNPs modified with probes could adsorb SA-AP, affecting the sensitivity of chemiluminescene consequently. Reduction of aldehyde group by sodium borohydride and blocking the bare position of MNPs with bovine serum albumin (BSA) could decrease the background of chemiluminescence, and this method has good specificity in detection of chloramphenicol acetyltransferase (CAT) gene. PMID:21456141

  14. A sandwich-type electrochemical immunosensor for carcinoembryonic antigen based on signal amplification strategy of optimized ferrocene functionalized Fe₃O₄@SiO₂ as labels.

    PubMed

    Feng, Taotao; Qiao, Xiuwen; Wang, Haining; Sun, Zhao; Hong, Chenglin

    2016-05-15

    A sandwich-type electrochemical immunosensor was developed for sensitive detection of carcinoembryonic antigen (CEA) by using ferroferric oxide@silica-amino groups (Fe3O4@SiO2-NH2) as carriers and gold nanoparticles-graphene oxide (GO-AuNPs) as platform. The Fe3O4@SiO2-NH2 surface was used as linked reagents for co-immobilization of ferrocenecarboxylic acid (Fc-COOH) and secondary anti-CEA (Ab2) to prepare the signal probe, and it also could hasten the decomposition of hydrogen peroxide (H2O2) to amplify signals. Differential pulse voltammetry (DPV) was successfully used to quantify CEA. Under the optimized conditions, the designed immunosensor shows an excellent analytical performance wide dynamic response range of CEA concentration from 0.001 ng mL(-1) to 80 ng mL(-1) with a relatively low detection limit of 0.0002 ng mL(-1) (S/N=3), and high specificity and good reproducibility. The proposed immunosensor was successfully used to determine CEA in spiked human serum samples. PMID:26686923

  15. Optical Pattern Recognition With Self-Amplification

    NASA Technical Reports Server (NTRS)

    Liu, Hua-Kuang

    1994-01-01

    In optical pattern recognition system with self-amplification, no reference beam used in addressing mode. Polarization of laser beam and orientation of photorefractive crystal chosen to maximize photorefractive effect. Intensity of recognition signal is orders of magnitude greater than other optical correlators. Apparatus regarded as real-time or quasi-real-time optical pattern recognizer with memory and reprogrammability.

  16. Novel glucometer-based immunosensing strategy suitable for complex systems with signal amplification using surfactant-responsive cargo release from glucose-encapsulated liposome nanocarriers.

    PubMed

    Tang, Juan; Huang, Yapei; Liu, Huiqiong; Zhang, Cengceng; Tang, Dianping

    2016-05-15

    Methods based on surfactant-responsive controlled release systems of cargoes from nanocontainers have been developed for bioanalytical applications, but most were utilized for drug delivery and a few reports were focused on immunoassays. Herein we design an in situ amplified immunoassay protocol for high-efficient detection of aflatoxins (aflatoxin B1, AFB1 used in this case) based on surfactant-responsive cargo release from glucose-encapsulated liposome nanocarriers with sensitivity enhancement. Initially, biotinylated liposome nanocarrier encapsulated with glucose was synthesized using a reverse-phase evaporation method. Thereafter, the nanocarrier was utilized as the signal-generation tag on capture antibody-coating microplate through classical biotin-avidin linkage after reaction with biotinylated detection antibody. Upon addition of buffered surfactant (1X PBS-Tween 20 buffer) into the medium, the surfactant immediately hydrolyzed the conjugated liposome, and released the encapsulated glucose from the nanocarriers, which could be quantitatively determined by using a low-cost personal glucometer (PGM). The detectable signal increased with the increment of target analyte. Under the optimal conditions, the assay could allow PGM detection toward target AFB1 as low as 0.6 pg mL(-1) (0.6 ppt). Moreover, the methodology also showed good reproducibility and high specificity toward target AFB1 against other mycotoxins and proteins, and was applicable for quantitatively monitoring target AFB1 in the complex systems, e.g., naturally contaminated/spiked peanut samples and serum specimens, with the acceptable results. Taking these advantages of simplification, low cost, universality and sensitivity, our design provides a new horizon for development of advanced immunoassays in future point-of-care testing. PMID:26748368

  17. G-quadruplex based two-stage isothermal exponential amplification reaction for label-free DNA colorimetric detection.

    PubMed

    Nie, Ji; Zhang, De-Wen; Tie, Cai; Zhou, Ying-Lin; Zhang, Xin-Xiang

    2014-06-15

    A novel G-quadruplex based two-stage isothermal exponential amplification reaction (GQ-EXPAR) was developed for label-free DNA colorimetric detection in this work. The exponential amplified trigger DNA in the first stage can convert into G-quadruplex sequence EAD2 by a linear amplification circuit in the second stage. Created EAD2 can form G-quadruplex/hemin DNAzyme to act as a direct signal readout element. The GQ-EXPAR combines the exponential amplification of DNA sequence and the peroxidase-mimicking DNAzyme induced signal amplification, which achieves tandem dual-amplification. Taking advantages of isothermal incubation, this label-free homogeneous assay obviates the need of thermal cycling . As no complex synthesis or extra downstream operation is needed, the whole easy handling procedure can be finished in no more than 1h. This assay allows the sensing of the model DNA with the limit of detection to be 2.5pM. Moreover, it demonstrates good discrimination of mismatched sequences. The strategy has also been successfully implemented to sensitively detect Tay-Sachs genetic disorder mutant. PMID:24508547

  18. Rapid detection of avian influenza virus H5N1 in chicken tracheal samples using an impedance aptasensor with gold nanoparticles for signal amplification.

    PubMed

    Karash, Sardar; Wang, Ronghui; Kelso, Lisa; Lu, Huaguang; Huang, Tony Jun; Li, Yanbin

    2016-10-01

    Highly pathogenic avian influenza virus H5N1 is a continuous threat to public health and poultry industry. The recurrence of the H5N1 led us to develop a robust, specific, and rapid detection method for the virus. In this study, an impedance aptasensor was developed for the virus detection using specific H5N1 aptamer and a gold interdigitated microelectrode. Streptavidin was immobilized on the microelectrode surface and biotin labeled H5N1 aptamer was bound to the immobilized streptavidin. The microelectrode was blocked with the polyethylene glycol and the bound aptamer captured the virus. The impedance change caused by the captured virus was measured using an impedance analyzer. To enhance impedance signal, a nanoparticle-based amplifier was designed and implemented by forming a network-like gold nanoparticles/H5N1-aptamer/thiocyanuric acid. The detection limit of the impedance aptasensor was 0.25 HAU for the pure virus and 1 HAU for the tracheal chicken swab samples spiked with the H5N1 virus. The detection time of aptasensor without employing the amplifier was less than an hour. The amplifier increased impedance by a 57-fold for the 1 HAU samples. Only negligible impedance change was observed for non-target viruses such as H5N2, H5N3, H7N2, H1N1, and H2N2. This aptasensor provides a foundation for the development of a portable aptasensor instrument. PMID:27452670

  19. A novel photoelectrochemical sensor based on photocathode of PbS quantum dots utilizing catalase mimetics of bio-bar-coded platinum nanoparticles/G-quadruplex/hemin for signal amplification.

    PubMed

    Wang, Guang-Li; Liu, Kang-Li; Shu, Jun-Xian; Gu, Tian-Tian; Wu, Xiu-Ming; Dong, Yu-Ming; Li, Zai-Jun

    2015-07-15

    Photocathode based on p-type PbS quantum dots (QDs) combing a novel signal amplification strategy utilizing catalase (CAT) mimetics was designed and utilized for sensitive photoelectrochemical (PEC) detection of DNA. The bio-bar-coded Pt nanoparticles (NPs)/G-quadruplex/hemin exhibited high CAT-like activity following the Michaelis-Menten model for decomposing H2O2 to water and oxygen, whose activity even slightly exceeded that of natural CAT. The bio-bar-code as a catalytic label was conjugated onto the surface of PbS QDs modified electrodes through the formed sandwich-type structure due to DNA hybridization. Oxygen in situ generated by the CAT mimetics of the bio-bar-code of Pt NPs/G-quadruplex/hemin acted as an efficient electron acceptor of illuminated PbS QDs, promoting charge separation and enhancing cathodic photocurrent. Under optimal conditions, the developed PEC biosensor for target DNA exhibited a dynamic range of 0.2pmol/L to 1.0nmol/L with a low detection limit of 0.08pmol/L. The high sensitivity of the method was resulted from the sensitive response of PbS QDs to oxygen and the highly efficient CAT-like catalytic activity of the bio-bar-coded Pt NPs/G-quadruplex/hemin. PMID:25723768

  20. A sensitive photoelectrochemical biosensor for AFP detection based on ZnO inverse opal electrodes with signal amplification of CdS-QDs.

    PubMed

    Xu, Ru; Jiang, Yandong; Xia, Lei; Zhang, Tianxiang; Xu, Lin; Zhang, Shuang; Liu, Dali; Song, Hongwei

    2015-12-15

    In this work, ZnO inverse opals structure (IOs) based photoelectrochemical (PEC) electrode was fabricated for alpha-fetoprotein (AFP) detection. Then, the uniform CdS quantum dots (QDs) were hydrothermally synthesized, which allowed the binding of AFP and glucose oxidase (GOD) on CdS QDs, forming the AFP-CdS-GOD composite. The competitive immunosensor of AFP and the AFP-CdS-GOD composite with anti-AFP antibodies (Ab) immobilized on FTO (fluorine-doped tin oxide) /ZnO IOs electrode was successfully applied to the detection of AFP. GOD could catalyze glucose to produce hydrogen peroxide (H2O2) acting as an electron donor to scavenge photogenerated holes in the valence band of CdS QDs, reducing the recombination of electrons and holes of CdS QDs. Also the effective energy level matching between the conduction bands of CdS QDs and ZnO widened the range of light absorption, allowing for electron injection from excited CdS QDs to ZnO upon visible light irradiation, which enhanced the photocurrent. The results show that the immunosensor of AFP possesses a large linear detection range of 0.1-500 ng/ml with a detection limit of 0.01 ng/ml. It also exhibits excellent anti-interference property and acceptable stability. This work provides a promising method for achieving excellent photoelectrochemical biosensor detection of other proteins. PMID:26164013

  1. Enhanced beam amplification in a photorefractive Bi{sub 12}TiO{sub 20} crystal by internal reflections

    SciTech Connect

    Khomenko, A.V.; Garcia-Weidner, A.; Tentori, D.

    1996-06-01

    We demonstrate experimentally that internal reflections of a signal and (or) a pump beam allow one to increase beam amplification by two-beam coupling in a long Bi{sub 12}TiO{sub 20} crystal. When fanning is negligible, we achieve an enhancement of the amplification by adjustment of the spatial period of the transformation of the beam{close_quote}s polarization states with periodic reflections of the beams on the crystal boundaries. For the case of strong fanning the fanned beam is redirected by the reflections on the crystal surface, which allows one to use it as a pump beam, thus increasing net amplification gain. {copyright} {ital 1996 Optical Society of America.}

  2. Heralded photon amplification for quantum communication

    NASA Astrophysics Data System (ADS)

    Osorio, C. I.; Bruno, N.; Sangouard, N.; Zbinden, H.; Gisin, N.; Thew, R. T.

    2012-08-01

    Heralded noiseless amplification based on single-photon sources and linear optics is ideally suited for long-distance quantum communication tasks based on discrete variables. We experimentally demonstrate such an amplifier, operating at telecommunication wavelengths. Coherent amplification is performed with a gain of G=1.98±0.20 for a state with a maximum expected gain G=2. We also demonstrate that there is no need for a stable phase reference between the initial signal state and the local auxiliary photons used by the amplifier. We discuss these results in the context of experimental device-independent quantum key distribution based on heralded qubit amplification, and we highlight several key challenges for its realization.

  3. Remote fiber sensors and optical amplification

    NASA Astrophysics Data System (ADS)

    Pontes, M. J.; Coelho, Thiago V. N.; Carvalho, Joel P.; Santos, J. L.; Guerreiro, A.

    2013-11-01

    This work discusses remote fiber sensors enabled by optical amplification. Continuous wave numerical modeling based on the propagation of pumps and signal lasers coupled to optical fibers explores Raman amplification schemes to predict the sensor's behavior. Experimental analyses report the results to a temperature remote optical sensor with 50 km distance between the central unit and the sensor head. An electrical interrogation scheme is used due to their low cost and good time response. Different architectures in remote sensor systems are evaluated, where diffraction gratings are the sensor element. A validation of calculated results is performed by experimental analyses and, as an application, the noise generated by Raman amplification in the remote sensors systems is simulated applying such numerical modeling. The analyses of sensors systems based on diffraction gratings requires optical broadband sources to interrogate the optical sensor unit, mainly in long period gratings that shows a characteristic rejection band. Therefore, the sensor distance is limited to a few kilometers due to the attenuation in optical fibers. Additional attenuation is introduced by the sensor element. Hence, to extend the distance in the optical sensor system, the optical amplification system is needed to compensate the losses in the optical fibers. The Raman amplification technology was selected mainly due to the flexibility in the gain bandwidth. The modeling can be applied to sensor systems that monitor sites located at long distances, or in places that the access is restricted due to harsh environment conditions in such cases conventional sensors are relatively fast deteriorated.

  4. Investigation of anti-Stokes Raman processes at phonon-polariton resonance: from Raman oscillation, frequency upconversion to Raman amplification.

    PubMed

    Ding, Yujie J

    2015-03-01

    Raman oscillation, frequency upconversion, and Raman amplification can be achieved in a second-order nonlinear medium at the phonon-polariton resonance. By beating two optical fields, a second-order nonlinear polarization is generated inside the medium. Such a polarization induces a spatially uniform nonpropagating electric field at the beat frequency, which in turn mixes with the input optical field at the lower frequency to generate or amplify the anti-Stokes optical field. Raman oscillation can be efficiently reached for the copropagating configuration. In comparison, efficient frequency upconversion and large amplifications are achievable for the counterpropagating configuration. These Raman processes can be used to effectively remove transverse-optical phonons before decaying to lower-frequency phonons, achieve laser cooling, and significantly enhance coherent anti-Stokes Raman scattering. The counterpropagating configuration offers advantages for amplifying extremely weak signals. PMID:25723418

  5. Mismatch characteristics of optical parametric chirped pulse amplification

    NASA Astrophysics Data System (ADS)

    Novák, O.; Turčičová, H.; Divoký, M.; Huynh, J.; Straka, P.

    2014-02-01

    The stability of an optical parametric chirped pulse amplifier (OPCPA) is influenced by time and the angular matching of the input beams. We derived the Gaussian dependence of the monochromatic signal gain on the small mismatch between the signal and pump beams. Gain characteristics were also calculated for polychromatic amplification and the impact of different beam mismatches and interaction geometries was explained. The asymmetry of the energy gain, and the square root dependence of the phase matched wavelength on beam angles were found. The predicted dependences were verified in a noncollinear OPCPA system with LBO and KDP crystal amplifying pulses of a Ti:sapphire laser around a central wavelength of 800 nm, pumped by the third harmonic frequency of an iodine gas laser at a wavelength of 438 nm. The widths of the gain curves in the dependence on both the pump-signal or the phase matching angles varied from several tenths to a few milliradians. The gain curve widths dependent on the pump-signal pulse delay were about two thirds of the pump pulse width for moderate pumping and about a half of the pump pulse width for pumping on the order of GW cm-2. A stable gain output is achieved if angular and temporal fluctuations are fractions of the measured gain curve widths, and when the signal direction is between the pump and the crystal principal axis (i.e. in the psz geometry).

  6. On soliton amplification

    NASA Technical Reports Server (NTRS)

    Leibovich, S.; Randall, J. D.

    1979-01-01

    The paper considers a modified Korteweg-de Vries equation that permits wave amplification or damping. A 'terminal similarity' solution is identified for large times in amplified systems. Numerical results are given which confirm that the terminal similarity solution is a valid local approximation for mu t sufficiently large and positive, even though the approximation is not uniformly valid in space.

  7. Questioning cochlear amplification

    NASA Astrophysics Data System (ADS)

    van der Heijden, Marcel; Versteegh, Corstiaen P. C.

    2015-12-01

    Thirty years ago it was hypothesized that motile processes inject mechanical energy into cochlear traveling waves. This mechanical amplification, alternatively described as negative damping, is invoked to explain both the sensitivity and the nonlinear compression of cochlear responses. There is a recent trend to present cochlear amplification as an established fact, even though the evidence is at most circumstantial and several thorny problems have remained unresolved. We analyze several of these issues, and present new basilar membrane recordings that allowed us to quantify cochlear energy flow. Specifically, we address the following questions: (1) Does auditory sensitivity require narrowband amplification? (2) Has the "RC problem" (lowpass filtering of outer hair cell receptor potential) been resolved? (3) Can OHC motility improve auditory sensitivity? (4) Is there a net power gain between neighboring locations on the basilar membrane? The analyses indicate that mechanical amplification in the cochlea is neither necessary nor useful, and that realizing it by known forms of motility would reduce sensitivity rather than enhance it. Finally, our experimental data show that the peaking of the traveling wave is realized by focusing the acoustic energy rather than amplifying it. (Abbreviations. BM: basilar membrane; CF: characteristic frequency; IHC: inner hair cell; ME: middle ear; MT; mechanotransducer; OHC: outer hair cell; SPL: sound pressure level.)

  8. Improved PCR Amplification of Broad Spectrum GC DNA Templates

    PubMed Central

    Guido, Nicholas; Starostina, Elena; Leake, Devin; Saaem, Ishtiaq

    2016-01-01

    Many applications in molecular biology can benefit from improved PCR amplification of DNA segments containing a wide range of GC content. Conventional PCR amplification of DNA sequences with regions of GC less than 30%, or higher than 70%, is complex due to secondary structures that block the DNA polymerase as well as mispriming and mis-annealing of the DNA. This complexity will often generate incomplete or nonspecific products that hamper downstream applications. In this study, we address multiplexed PCR amplification of DNA segments containing a wide range of GC content. In order to mitigate amplification complications due to high or low GC regions, we tested a combination of different PCR cycling conditions and chemical additives. To assess the fate of specific oligonucleotide (oligo) species with varying GC content in a multiplexed PCR, we developed a novel method of sequence analysis. Here we show that subcycling during the amplification process significantly improved amplification of short template pools (~200 bp), particularly when the template contained a low percent of GC. Furthermore, the combination of subcycling and 7-deaza-dGTP achieved efficient amplification of short templates ranging from 10–90% GC composition. Moreover, we found that 7-deaza-dGTP improved the amplification of longer products (~1000 bp). These methods provide an updated approach for PCR amplification of DNA segments containing a broad range of GC content. PMID:27271574

  9. Antigen retrieval, blocking, detection and visualisation systems in immunohistochemistry: a review and practical evaluation of tyramide and rolling circle amplification systems.

    PubMed

    Warford, Anthony; Akbar, Hameed; Riberio, Deise

    2014-11-01

    To achieve specificity and sensitivity using immunohistochemistry it is necessary to combine the application of validated primary antibodies with optimised pre-treatment, detection and visualisation steps. The influence of these surrounding procedures is reviewed. A practical evaluation of tyramide signal amplification and rolling circle amplification detection methods is provided in which formalin fixed paraffin embedded sections of adenocarcinomas of breast, colon and lung together with squamous metaplasia of lung were immunostained with CD20 and CK19 primary antibodies. The results indicate that the detection systems are of comparable sensitivity and specificity. PMID:24631890

  10. Weak-value amplification of the fast-light effect in rubidium vapor

    NASA Astrophysics Data System (ADS)

    Mirhosseini, Mohammad; Viza, Gerardo I.; Magaña-Loaiza, Omar S.; Malik, Mehul; Howell, John C.; Boyd, Robert W.

    2016-05-01

    We use weak-value amplification to enhance the polarization-sensitive fast-light effect from induced Raman absorption in hot rubidium vapor. We experimentally demonstrate that projecting the output signal into an appropriate polarization state enables a pulse advancement of 4.2 μ s , which is more than 15 times larger than that naturally caused by dispersion. More significantly, we show that combining weak-value amplification with the dispersive response of an atomic system provides a clear advantage in terms of the maximum pulse advance achievable for a given value of loss. This technique has potential applications for designing novel quantum-information-processing gates and optical buffers for telecommunication systems.

  11. The development of nanostructure assisted isothermal amplification in biosensors.

    PubMed

    Duan, Ruixue; Lou, Xiaoding; Xia, Fan

    2016-03-21

    Developing simple and inexpensive methods to ultrasensitively detect biomarkers is important for medical diagnosis, food analysis and environmental security. In recent years, isothermal amplifications with sensitivity, high speed, specificity, accuracy, and automation have been designed based on interdisciplinary approaches among chemistry, biology, and materials science. In this article, we summarize the advances in nanostructure assisted isothermal amplification in the past two decades for the detection of commercial biomarkers, or biomarkers extracted from cultured cells or patient samples. This article has been divided into three parts according to the ratio of target-to-signal probe in the detection strategy, namely, the N : N amplification ratio, the 1 : N amplification ratio, and the 1 : N(2) amplification ratio. PMID:26812957

  12. Enzyme-free amplification for sensitive electrochemical detection of DNA via target-catalyzed hairpin assembly assisted current change.

    PubMed

    Qian, Yong; Wang, Chunyan; Gao, Fenglei

    2014-12-01

    An isothermal, enzyme-free and sensitive method for electrochemical detection of DNA is proposed based on target catalyzed hairpin assembly and for signal amplification. Molecular beacon 1 (MB1) contains a ferrocene (Fc) tag, which was immobilized on the gold electrode as recognition probe to hybridize with target DNA. Then, molecular beacon 2 hybridized with the opened MB1, allowing the target to be displaced. The displaced target again triggered the next round of strand exchange reaction resulting in many Fc far away from the GE to achieve signal amplification for sensitive DNA detection. The current signal amplification strategy is relatively simple and inexpensive owing to avoid the use of any kind of enzyme or sophisticated equipment. It can achieve a sensitivity of 42 fM with a wide linear dynamic range from 10(-13) to 10(-9)M and discriminate mismatched DNA from perfect matched target DNA with a high selectivity. The proposed method showed excellent specificity, high sensitivity and low detection limit, and could be applied in analysis of real samples. PMID:25159376

  13. Amplification of trace amounts of nucleic acids

    DOEpatents

    Church, George M.; Zhang, Kun

    2008-06-17

    Methods of reducing background during amplification of small amounts of nucleic acids employ careful analysis of sources of low level contamination. Ultraviolet light can be used to reduce nucleic acid contaminants in reagents and equipment. "Primer-dimer" background can be reduced by judicious design of primers. We have shown clean signal-to-noise with as little as starting material as one single human cell (.about.6 picogram), E. coli cell (.about.5 femtogram) or Prochlorococcus cell (.about.3 femtogram).

  14. Gravitomagnetic amplification in cosmology

    SciTech Connect

    Tsagas, Christos G.

    2010-02-15

    Magnetic fields interact with gravitational waves in various ways. We consider the coupling between the Weyl and the Maxwell fields in cosmology and study the effects of the former on the latter. The approach is fully analytical and the results are gauge invariant. We show that the nature and the outcome of the gravitomagnetic interaction depends on the electric properties of the cosmic medium. When the conductivity is high, gravitational waves reduce the standard (adiabatic) decay rate of the B field, leading to its superadiabatic amplification. In poorly conductive environments, on the other hand, Weyl-curvature distortions can result into the resonant amplification of large-scale cosmological magnetic fields. Driven by the gravitational waves, these B fields oscillate with an amplitude that is found to diverge when the wavelengths of the two sources coincide. We present technical and physical aspects of the gravitomagnetic interaction and discuss its potential implications.

  15. Light amplification using semiconductors

    SciTech Connect

    Dupuis, R.D.

    1987-06-01

    During the summer of 1953, John von Neumann discussed his ideas concerning light amplification using semiconductors with Edward Teller. In September of that year, von Neumann sent a manuscript containing his ideas and calculations on this subject to Teller for his comments. To the best of our knowledge, von Neumann did not take time to work further on these ideas, and the manuscript remained unpublished. These previously unpublished writings of John von Neumann on the subject of light amplification in semiconductors are printed as a service to the laser community. While von Neumann's original manuscript and his letter to Teller are available to anyone who visits the Library of Congress, it is much more convenient to have this paper appear in an archival journal.

  16. Social amplification of risk: a conceptual framework

    SciTech Connect

    Kasperson, R.E.; Renn, O.; Slovic, P.; Brown, H.S.; Emel, J.; Goble, R.; Kasperson, J.X.; Ratick, S.

    1988-06-01

    One of the most perplexing problems in risk analysis is why some relatively minor risks or risk events, as assessed by technical experts, often elicit strong public concerns and result in substantial impacts upon society and economy. This article sets forth a conceptual framework that seeks to link systematically the technical assessment of risk with psychological, sociological, and cultural perspectives of risk perception and risk-related behavior. The main thesis is that hazards interact with psychological, social, institutional, and cultural processes in ways that may amplify or attenuate public responses to the risk or risk event. A structural description of the social amplification of risk is now possible. Amplification occurs at two stages: in the transfer of information about the risk, and in the response mechanisms of society. Signals about risk are processed by individual and social amplification stations, including the scientist who communicates the risk assessment, the news media, cultural groups, interpersonal networks, and others. Key steps of amplifications can be identified at each stage. The amplified risk leads to behavioral responses, which, in turn, result in secondary impacts. Models are presented that portray the elements and linkages in the proposed conceptual framework.

  17. Quantum Amplification by Superradiant Emission of Radiation

    NASA Astrophysics Data System (ADS)

    Svidzinsky, Anatoly A.; Yuan, Luqi; Scully, Marlan O.

    2013-10-01

    A laser generates light through stimulated emission of radiation and requires population inversion. Quantum interference can yield lasing without inversion. However, such phase-sensitive quantum amplification still requires some atomic population in the excited state. Here, we present a new kind of quantum amplifier based on collective superradiant emission which does not need any population in the excited state. We show that parametric resonance between the driving (e.g., infrared) field and collective superradiant oscillations of the atomic polarization can yield light amplification at high (e.g., XUV) frequencies. To achieve gain, one must suppress a time-dependent Stark shift caused by the driving field. The resulting superradiant amplifier is many orders of magnitude more efficient than the usual nonlinear multiphoton excitation and holds promise for a new kind of generator of high-frequency coherent radiation. In addition to a detailed analytical analysis, confirmed by numerical simulations, we provide a physically appealing explanation of the quantum amplification by superradiant emission of radiation (QASER) operation in terms of coupled classical oscillators. We also present an experiment that demonstrates the QASER amplification mechanism in an electronic circuit, which, to the best of our knowledge, is the first experimental demonstration of the difference combination resonance.

  18. Dichroism for orbital angular momentum using parametric amplification

    NASA Astrophysics Data System (ADS)

    Lowney, J.; Roger, T.; Faccio, D.; Wright, E. M.

    2014-11-01

    We theoretically analyze parametric amplification as a means to produce dichroism based on the orbital angular momentum (OAM) of an incident signal field. The nonlinear interaction is shown to provide differential gain between signal states of differing OAM, the peak gain occurring at half the OAM of the pump field.

  19. An investigation of signal performance enhancements achieved through innovative pixel design across several generations of indirect detection, active matrix, flat-panel arrays

    SciTech Connect

    Antonuk, Larry E.; Zhao Qihua; El-Mohri, Youcef; Du Hong; Wang Yi; Street, Robert A.; Ho, Jackson; Weisfield, Richard; Yao, William

    2009-07-15

    Active matrix flat-panel imager (AMFPI) technology is being employed for an increasing variety of imaging applications. An important element in the adoption of this technology has been significant ongoing improvements in optical signal collection achieved through innovations in indirect detection array pixel design. Such improvements have a particularly beneficial effect on performance in applications involving low exposures and/or high spatial frequencies, where detective quantum efficiency is strongly reduced due to the relatively high level of additive electronic noise compared to signal levels of AMFPI devices. In this article, an examination of various signal properties, as determined through measurements and calculations related to novel array designs, is reported in the context of the evolution of AMFPI pixel design. For these studies, dark, optical, and radiation signal measurements were performed on prototype imagers incorporating a variety of increasingly sophisticated array designs, with pixel pitches ranging from 75 to 127 {mu}m. For each design, detailed measurements of fundamental pixel-level properties conducted under radiographic and fluoroscopic operating conditions are reported and the results are compared. A series of 127 {mu}m pitch arrays employing discrete photodiodes culminated in a novel design providing an optical fill factor of {approx}80% (thereby assuring improved x-ray sensitivity), and demonstrating low dark current, very low charge trapping and charge release, and a large range of linear signal response. In two of the designs having 75 and 90 {mu}m pitches, a novel continuous photodiode structure was found to provide fill factors that approach the theoretical maximum of 100%. Both sets of novel designs achieved large fill factors by employing architectures in which some, or all of the photodiode structure was elevated above the plane of the pixel addressing transistor. Generally, enhancement of the fill factor in either discrete or

  20. An investigation of signal performance enhancements achieved through innovative pixel design across several generations of indirect detection, active matrix, flat-panel arrays

    PubMed Central

    Antonuk, Larry E.; Zhao, Qihua; El-Mohri, Youcef; Du, Hong; Wang, Yi; Street, Robert A.; Ho, Jackson; Weisfield, Richard; Yao, William

    2009-01-01

    Active matrix flat-panel imager (AMFPI) technology is being employed for an increasing variety of imaging applications. An important element in the adoption of this technology has been significant ongoing improvements in optical signal collection achieved through innovations in indirect detection array pixel design. Such improvements have a particularly beneficial effect on performance in applications involving low exposures and∕or high spatial frequencies, where detective quantum efficiency is strongly reduced due to the relatively high level of additive electronic noise compared to signal levels of AMFPI devices. In this article, an examination of various signal properties, as determined through measurements and calculations related to novel array designs, is reported in the context of the evolution of AMFPI pixel design. For these studies, dark, optical, and radiation signal measurements were performed on prototype imagers incorporating a variety of increasingly sophisticated array designs, with pixel pitches ranging from 75 to 127 μm. For each design, detailed measurements of fundamental pixel-level properties conducted under radiographic and fluoroscopic operating conditions are reported and the results are compared. A series of 127 μm pitch arrays employing discrete photodiodes culminated in a novel design providing an optical fill factor of ∼80% (thereby assuring improved x-ray sensitivity), and demonstrating low dark current, very low charge trapping and charge release, and a large range of linear signal response. In two of the designs having 75 and 90 μm pitches, a novel continuous photodiode structure was found to provide fill factors that approach the theoretical maximum of 100%. Both sets of novel designs achieved large fill factors by employing architectures in which some, or all of the photodiode structure was elevated above the plane of the pixel addressing transistor. Generally, enhancement of the fill factor in either discrete or continuous

  1. Ultrabroadband noncollinear optical parametric amplification with LBO crystal.

    PubMed

    Zhao, Baozhen; Jiang, Yongliang; Sueda, Keiich; Miyanaga, Noriaki; Kobayashi, Takayoshi

    2008-11-10

    Ultrabroadband visible noncollinear optical parametric amplification (NOPA) was achieved in an LBO crystal, with a continuum seed pulse generated from a sapphire plate. The spectral bandwidth of the amplified visible pulse was about 200 nm, which can support sub-5 fs pulse amplification. An amplified output of 0.21 microJ with an average gain of about 210 was achieved. This provides, to the best of our knowledge, the first-time demonstration of such broadband amplification with a biaxial nonlinear optical crystal. Both the simulation and experimental results indicate that the LBO has a great potential as nonlinear medium in power amplifier for TW to PW noncollinear optical parametric chirped pulse amplification (NOPCPA) systems. PMID:19581976

  2. Coherent white light amplification

    DOEpatents

    Jovanovic, Igor; Barty, Christopher P.

    2004-05-25

    A system for coherent simultaneous amplification of a broad spectral range of light that includes an optical parametric amplifier and a source of a seed pulse is described. A first angular dispersive element is operatively connected to the source of a seed pulse. A first imaging telescope is operatively connected to the first angular dispersive element and operatively connected to the optical parametric amplifier. A source of a pump pulse is operatively connected to the optical parametric amplifier. A second imaging telescope is operatively connected to the optical parametric amplifier and a second angular dispersive element is operatively connected to the second imaging telescope.

  3. Evidence of high-elevation amplification versus Arctic amplification

    NASA Astrophysics Data System (ADS)

    Wang, Qixiang; Fan, Xiaohui; Wang, Mengben

    2016-01-01

    Elevation-dependent warming in high-elevation regions and Arctic amplification are of tremendous interest to many scientists who are engaged in studies in climate change. Here, using annual mean temperatures from 2781 global stations for the 1961-2010 period, we find that the warming for the world’s high-elevation stations (>500 m above sea level) is clearly stronger than their low-elevation counterparts; and the high-elevation amplification consists of not only an altitudinal amplification but also a latitudinal amplification. The warming for the high-elevation stations is linearly proportional to the temperature lapse rates along altitudinal and latitudinal gradients, as a result of the functional shape of Stefan-Boltzmann law in both vertical and latitudinal directions. In contrast, neither altitudinal amplification nor latitudinal amplification is found within the Arctic region despite its greater warming than lower latitudes. Further analysis shows that the Arctic amplification is an integrated part of the latitudinal amplification trend for the low-elevation stations (≤500 m above sea level) across the entire low- to high-latitude Northern Hemisphere, also a result of the mathematical shape of Stefan-Boltzmann law but only in latitudinal direction.

  4. Evidence of high-elevation amplification versus Arctic amplification

    PubMed Central

    Wang, Qixiang; Fan, Xiaohui; Wang, Mengben

    2016-01-01

    Elevation-dependent warming in high-elevation regions and Arctic amplification are of tremendous interest to many scientists who are engaged in studies in climate change. Here, using annual mean temperatures from 2781 global stations for the 1961–2010 period, we find that the warming for the world’s high-elevation stations (>500 m above sea level) is clearly stronger than their low-elevation counterparts; and the high-elevation amplification consists of not only an altitudinal amplification but also a latitudinal amplification. The warming for the high-elevation stations is linearly proportional to the temperature lapse rates along altitudinal and latitudinal gradients, as a result of the functional shape of Stefan-Boltzmann law in both vertical and latitudinal directions. In contrast, neither altitudinal amplification nor latitudinal amplification is found within the Arctic region despite its greater warming than lower latitudes. Further analysis shows that the Arctic amplification is an integrated part of the latitudinal amplification trend for the low-elevation stations (≤500 m above sea level) across the entire low- to high-latitude Northern Hemisphere, also a result of the mathematical shape of Stefan-Boltzmann law but only in latitudinal direction. PMID:26753547

  5. Evidence of high-elevation amplification versus Arctic amplification.

    PubMed

    Wang, Qixiang; Fan, Xiaohui; Wang, Mengben

    2016-01-01

    Elevation-dependent warming in high-elevation regions and Arctic amplification are of tremendous interest to many scientists who are engaged in studies in climate change. Here, using annual mean temperatures from 2781 global stations for the 1961-2010 period, we find that the warming for the world's high-elevation stations (>500 m above sea level) is clearly stronger than their low-elevation counterparts; and the high-elevation amplification consists of not only an altitudinal amplification but also a latitudinal amplification. The warming for the high-elevation stations is linearly proportional to the temperature lapse rates along altitudinal and latitudinal gradients, as a result of the functional shape of Stefan-Boltzmann law in both vertical and latitudinal directions. In contrast, neither altitudinal amplification nor latitudinal amplification is found within the Arctic region despite its greater warming than lower latitudes. Further analysis shows that the Arctic amplification is an integrated part of the latitudinal amplification trend for the low-elevation stations (≤500 m above sea level) across the entire low- to high-latitude Northern Hemisphere, also a result of the mathematical shape of Stefan-Boltzmann law but only in latitudinal direction. PMID:26753547

  6. Flexible operability and amplification of gray pulses.

    PubMed

    Li, Xingliang; Zhang, Shumin; Han, Mengmeng; Zhang, Huaxing; Wen, Fang; Yang, Zhenjun

    2014-07-15

    We have investigated experimentally the flexible production and amplification of gray pulses for the first time to our knowledge. Switchable wavelengths, tunable pulse-widths, and adjustable contrasts have all been obtained in a fiber laser. Amplification of gray pulses was also experimentally investigated in detail. The contrast of the pulses could also be increased in an amplifier. The robust stability that results from the interactions between adjacent harmonic mode locking counterparts of gray pulses was found to last for up to ten hours. To the best of our knowledge, the gray pulses trains we have generated are the most stable achieved to date in an all-fiber laser system. This finding can be used as a guide for the establishment of robust gray pulses as laser sources. PMID:25121665

  7. Gene amplification during myogenic differentiation

    PubMed Central

    Fischer, Ulrike; Ludwig, Nicole; Raslan, Abdulrahman; Meier, Carola; Meese, Eckart

    2016-01-01

    Gene amplifications are mostly an attribute of tumor cells and drug resistant cells. Recently, we provided evidence for gene amplifications during differentiation of human and mouse neural progenitor cells. Here, we report gene amplifications in differentiating mouse myoblasts (C2C12 cells) covering a period of 7 days including pre-fusion, fusion and post-fusion stages. After differentiation induction we found an increase in copy numbers of CDK4 gene at day 3, of NUP133 at days 4 and 7, and of MYO18B at day 4. The amplification process was accompanied by gamma-H2AX foci that are indicative of double stand breaks. Amplifications during the differentiating process were also found in primary human myoblasts with the gene CDK4 and NUP133 amplified both in human and mouse myoblasts. Amplifications of NUP133 and CDK4 were also identified in vivo on mouse transversal cryosections at stage E11.5. In the course of myoblast differentiation, we found amplifications in cytoplasm indicative of removal of amplified sequences from the nucleus. The data provide further evidence that amplification is a fundamental mechanism contributing to the differentiation process in mammalians. PMID:26760505

  8. Isothermal Amplification of Nucleic Acids.

    PubMed

    Zhao, Yongxi; Chen, Feng; Li, Qian; Wang, Lihua; Fan, Chunhai

    2015-11-25

    Isothermal amplification of nucleic acids is a simple process that rapidly and efficiently accumulates nucleic acid sequences at constant temperature. Since the early 1990s, various isothermal amplification techniques have been developed as alternatives to polymerase chain reaction (PCR). These isothermal amplification methods have been used for biosensing targets such as DNA, RNA, cells, proteins, small molecules, and ions. The applications of these techniques for in situ or intracellular bioimaging and sequencing have been amply demonstrated. Amplicons produced by isothermal amplification methods have also been utilized to construct versatile nucleic acid nanomaterials for promising applications in biomedicine, bioimaging, and biosensing. The integration of isothermal amplification into microsystems or portable devices improves nucleic acid-based on-site assays and confers high sensitivity. Single-cell and single-molecule analyses have also been implemented based on integrated microfluidic systems. In this review, we provide a comprehensive overview of the isothermal amplification of nucleic acids encompassing work published in the past two decades. First, different isothermal amplification techniques are classified into three types based on reaction kinetics. Then, we summarize the applications of isothermal amplification in bioanalysis, diagnostics, nanotechnology, materials science, and device integration. Finally, several challenges and perspectives in the field are discussed. PMID:26551336

  9. Graphene fluorescence switch-based cooperative amplification: a sensitive and accurate method to detection microRNA.

    PubMed

    Liu, Haiyun; Li, Lu; Wang, Qian; Duan, Lili; Tang, Bo

    2014-06-01

    MicroRNAs (miRNAs) play significant roles in a diverse range of biological progress and have been regarded as biomarkers and therapeutic targets in cancer treatment. Sensitive and accurate detection of miRNAs is crucial for better understanding their roles in cancer cells and further validating their function in clinical diagnosis. Here, we developed a stable, sensitive, and specific miRNAs detection method on the basis of cooperative amplification combining with the graphene oxide (GO) fluorescence switch-based circular exponential amplification and the multimolecules labeling of SYBR Green I (SG). First, the target miRNA is adsorbed on the surface of GO, which can protect the miRNA from enzyme digest. Next, the miRNA hybridizes with a partial hairpin probe and then acts as a primer to initiate a strand displacement reaction to form a complete duplex. Finally, under the action of nicking enzyme, universal DNA fragments are released and used as triggers to initiate next reaction cycle, constituting a new circular exponential amplification. In the proposed strategy, a small amount of target miRNA can be converted to a large number of stable DNA triggers, leading to a remarkable amplification for the target. Moreover, compared with labeling with a 1:1 stoichiometric ratio, multimolecules binding of intercalating dye SG to double-stranded DNA (dsDNA) can induce significant enhancement of fluorescence signal and further improve the detection sensitivity. The extraordinary fluorescence quenching of GO used here guarantees the high signal-to-noise ratio. Due to the protection for target miRNA by GO, the cooperative amplification, and low fluorescence background, sensitive and accurate detection of miRNAs has been achieved. The strategy proposed here will offer a new approach for reliable quantification of miRNAs in medical research and early clinical diagnostics. PMID:24823448

  10. Solid state Raman image amplification

    NASA Astrophysics Data System (ADS)

    Calmes, Lonnie K.; Murray, James T.; Austin, William L.; Powell, Richard C.

    1998-07-01

    Lite Cycles has developed a new type of eye-safe, range-gated, lidar sensing element based on Solid-state Raman Image Amplification (SSRIA) in a solid-state optical crystal. SSRIA can amplify low-level infrared images with gains greater than 106 with the addition of only quantum-limited noise. The high gains from SSRIA can compensate for low quantum efficiency detectors and can reduce the need for detector cooling. The range-gate of SSRIA is controlled by the pulsewidth of the pump laser and can be as short as 30 - 100 cm for nanosecond pulses and less than 5 mm if picosecond pulses are used. SSRIA results in higher SNR images throughout a broad range of incident light levels, in contrast to the increasing noise factor with reduced gain in image intensified CCDs. A theoretical framework for the optical resolution of SSRIA is presented and it is shown that SSRIA can produce higher resolution than ICCDs. SSRIA is also superior in rejecting unwanted sunlight background, further increasing image SNR, and can be used for real-time optical signal processing. Applications for military use include eye-safe imaging lidars that can be used for autonomous vehicle identification and targeting.

  11. Mismatch extension of DNA polymerases and high-accuracy single nucleotide polymorphism diagnostics by gold nanoparticle-improved isothermal amplification.

    PubMed

    Chen, Feng; Zhao, Yue; Fan, Chunhai; Zhao, Yongxi

    2015-09-01

    Sequence mismatches may induce nonspecific extension reaction, causing false results for SNP diagnostics. Herein, we systematically investigated the impact of various 3'-terminal mismatches on isothermal amplification catalyzed by representative DNA polymerases. Despite their diverse efficiencies depending on types of mismatch and kinds of DNA polymerase, all 12 kinds of single 3'-terminal mismatches induced the extension reaction. Generally, only several mismatches (primer-template, C-C, G-A, A-G, and A-A) present an observable inhibitory effect on the amplification reaction, whereas other mismatches trigger amplified signals as high as those of Watson-Crick pairs. The related mechanism was deeply discussed, and a primer-design guideline for specific SNP analysis was summarized. Furthermore, we found that the addition of appropriate gold nanoparticles (AuNPs) can significantly inhibit mismatch extension and enhance the amplification specificity. Also the high-accuracy SNP analysis of human blood genomic DNA has been demonstrated by AuNPs-improved isothermal amplification, the result of which was verified by sequencing (the gold standard method for SNP assay). Collectively, this work provides mechanistic insight into mismatch behavior and achieves accurate SNP diagnostics, holding great potential for the application in molecular diagnostics and personalized medicine. PMID:26249366

  12. Self-induced parametric amplification arising from nonlinear elastic coupling in a micromechanical resonating disk gyroscope.

    PubMed

    Nitzan, Sarah H; Zega, Valentina; Li, Mo; Ahn, Chae H; Corigliano, Alberto; Kenny, Thomas W; Horsley, David A

    2015-01-01

    Parametric amplification, resulting from intentionally varying a parameter in a resonator at twice its resonant frequency, has been successfully employed to increase the sensitivity of many micro- and nano-scale sensors. Here, we introduce the concept of self-induced parametric amplification, which arises naturally from nonlinear elastic coupling between the degenerate vibration modes in a micromechanical disk-resonator, and is not externally applied. The device functions as a gyroscope wherein angular rotation is detected from Coriolis coupling of elastic vibration energy from a driven vibration mode into a second degenerate sensing mode. While nonlinear elasticity in silicon resonators is extremely weak, in this high quality-factor device, ppm-level nonlinear elastic effects result in an order-of-magnitude increase in the observed sensitivity to Coriolis force relative to linear theory. Perfect degeneracy of the primary and secondary vibration modes is achieved through electrostatic frequency tuning, which also enables the phase and frequency of the parametric coupling to be varied, and we show that the resulting phase and frequency dependence of the amplification follow the theory of parametric resonance. We expect that this phenomenon will be useful for both fundamental studies of dynamic systems with low dissipation and for increasing signal-to-noise ratio in practical applications such as gyroscopes. PMID:25762243

  13. Self-induced parametric amplification arising from nonlinear elastic coupling in a micromechanical resonating disk gyroscope

    NASA Astrophysics Data System (ADS)

    Nitzan, Sarah H.; Zega, Valentina; Li, Mo; Ahn, Chae H.; Corigliano, Alberto; Kenny, Thomas W.; Horsley, David A.

    2015-03-01

    Parametric amplification, resulting from intentionally varying a parameter in a resonator at twice its resonant frequency, has been successfully employed to increase the sensitivity of many micro- and nano-scale sensors. Here, we introduce the concept of self-induced parametric amplification, which arises naturally from nonlinear elastic coupling between the degenerate vibration modes in a micromechanical disk-resonator, and is not externally applied. The device functions as a gyroscope wherein angular rotation is detected from Coriolis coupling of elastic vibration energy from a driven vibration mode into a second degenerate sensing mode. While nonlinear elasticity in silicon resonators is extremely weak, in this high quality-factor device, ppm-level nonlinear elastic effects result in an order-of-magnitude increase in the observed sensitivity to Coriolis force relative to linear theory. Perfect degeneracy of the primary and secondary vibration modes is achieved through electrostatic frequency tuning, which also enables the phase and frequency of the parametric coupling to be varied, and we show that the resulting phase and frequency dependence of the amplification follow the theory of parametric resonance. We expect that this phenomenon will be useful for both fundamental studies of dynamic systems with low dissipation and for increasing signal-to-noise ratio in practical applications such as gyroscopes.

  14. Measurement-based noiseless linear amplification for quantum communication

    NASA Astrophysics Data System (ADS)

    Chrzanowski, H. M.; Walk, N.; Haw, J. Y.; Thearle, O.; Assad, S. M.; Janousek, J.; Hosseini, S.; Ralph, T. C.; Symul, T.; Lam, P. K.

    2014-11-01

    Entanglement distillation is an indispensable ingredient in extended quantum communication networks. Distillation protocols are necessarily non-deterministic and require non-trivial experimental techniques such as noiseless amplification. We show that noiseless amplification could be achieved by performing a post-selective filtering of measurement outcomes. We termed this protocol measurement-based noiseless linear amplification (MBNLA). We apply this protocol to entanglement that suffers transmission loss of up to the equivalent of 100km of optical fibre and show that it is capable of distilling entanglement to a level stronger than that achievable by transmitting a maximally entangled state through the same channel. We also provide a proof-of-principle demonstration of secret key extraction from an otherwise insecure regime via MBNLA. Compared to its physical counterpart, MBNLA not only is easier in term of implementation, but also allows one to achieve near optimal probability of success.

  15. An aptamer assay using rolling circle amplification coupled with thrombin catalysis for protein detection.

    PubMed

    Guo, Limin; Hao, Lihua; Zhao, Qiang

    2016-07-01

    We describe a sensitive aptamer-based sandwich assay for protein detection on microplate by using rolling circle amplification (RCA) coupled with thrombin catalysis. This assay takes advantage of RCA generating long DNA oligonucleotides with repeat thrombin-binding aptamer sequence, specific aptamer affinity binding to achieve multiple thrombin labeling, and enzyme activity of thrombin for signal generation. Protein target is specifically captured by antibody-coated microplate. Then, an oligonucleotide containing an aptamer for protein and a primer sequence is added to form a typical sandwich structure. Following a template encoded with complementary sequence of aptamer for thrombin, RCA reaction extends the primer sequence into a long oligonucleotide. Many thrombin molecules bind with the RCA product. Thrombin catalyzes the conversion of its chromogenic or fluorogenic peptide substrates into detectable products for final quantification of protein targets. We applied this strategy to the detection of a model protein target, platelet-derived growth factor-BB (PDGF-BB). Due to double signal amplifications from RCA and thrombin catalysis, this assay enabled the detection of PDGF-BB as low as 3.1 pM when a fluorogenic peptide substrate was used. This assay provides a new way for signal generation in RCA-involved assay through direct thrombin labeling, circumventing time-consuming preparation of enzyme-conjugate and affinity probes. This method has promise for a variety of analytical applications. PMID:27108282

  16. Laser light triggers increased Raman amplification in the regime of nonlinear Landau damping.

    PubMed

    Depierreux, S; Yahia, V; Goyon, C; Loisel, G; Masson-Laborde, P-E; Borisenko, N; Orekhov, A; Rosmej, O; Rienecker, T; Labaune, C

    2014-01-01

    Stimulated Raman backscattering (SRS) has many unwanted effects in megajoule-scale inertially confined fusion (ICF) plasmas. Moreover, attempts to harness SRS to amplify short laser pulses through backward Raman amplification have achieved limited success. In high-temperature fusion plasmas, SRS usually occurs in a kinetic regime where the nonlinear response of the Langmuir wave to the laser drive and its host of complicating factors make it difficult to predict the degree of amplification that can be achieved under given experimental conditions. Here we present experimental evidence of reduced Landau damping with increasing Langmuir wave amplitude and determine its effects on Raman amplification. The threshold for trapping effects to influence the amplification is shown to be very low. Above threshold, the complex SRS dynamics results in increased amplification factors, which partly explains previous ICF experiments. These insights could aid the development of more efficient backward Raman amplification schemes in this regime. PMID:24938756

  17. Laser light triggers increased Raman amplification in the regime of nonlinear Landau damping

    PubMed Central

    Depierreux, S.; Yahia, V.; Goyon, C.; Loisel, G.; Masson-Laborde, P. -E.; Borisenko, N.; Orekhov, A.; Rosmej, O.; Rienecker, T.; Labaune, C.

    2014-01-01

    Stimulated Raman backscattering (SRS) has many unwanted effects in megajoule-scale inertially confined fusion (ICF) plasmas. Moreover, attempts to harness SRS to amplify short laser pulses through backward Raman amplification have achieved limited success. In high-temperature fusion plasmas, SRS usually occurs in a kinetic regime where the nonlinear response of the Langmuir wave to the laser drive and its host of complicating factors make it difficult to predict the degree of amplification that can be achieved under given experimental conditions. Here we present experimental evidence of reduced Landau damping with increasing Langmuir wave amplitude and determine its effects on Raman amplification. The threshold for trapping effects to influence the amplification is shown to be very low. Above threshold, the complex SRS dynamics results in increased amplification factors, which partly explains previous ICF experiments. These insights could aid the development of more efficient backward Raman amplification schemes in this regime. PMID:24938756

  18. Nonlinear inverse synthesis technique for optical links with lumped amplification.

    PubMed

    Le, Son Thai; Prilepsky, Jaroslaw E; Turitsyn, Sergei K

    2015-04-01

    The nonlinear inverse synthesis (NIS) method, in which information is encoded directly onto the continuous part of the nonlinear signal spectrum, has been proposed recently as a promising digital signal processing technique for combating fiber nonlinearity impairments. However, because the NIS method is based on the integrability property of the lossless nonlinear Schrödinger equation, the original approach can only be applied directly to optical links with ideal distributed Raman amplification. In this paper, we propose and assess a modified scheme of the NIS method, which can be used effectively in standard optical links with lumped amplifiers, such as, erbium-doped fiber amplifiers (EDFAs). The proposed scheme takes into account the average effect of the fiber loss to obtain an integrable model (lossless path-averaged model) to which the NIS technique is applicable. We found that the error between lossless path-averaged and lossy models increases linearly with transmission distance and input power (measured in dB). We numerically demonstrate the feasibility of the proposed NIS scheme in a burst mode with orthogonal frequency division multiplexing (OFDM) transmission scheme with advanced modulation formats (e.g., QPSK, 16QAM, and 64QAM), showing a performance improvement up to 3.5 dB; these results are comparable to those achievable with multi-step per span digital back-propagation. PMID:25968670

  19. Nonlinearities and Parametric Amplification of Superconducting Coplanar Waveguide Resonators

    NASA Astrophysics Data System (ADS)

    Haviland, David; Tholén, Erik; Ergul, Adem

    2008-03-01

    We have experimentally studied the nonlinear properties of superconducting coplanar stripline resonators fabricated from Al and Nb films with small transverse dimensions (gap size 1μm). Magnetic field penetration into the superconductor causes a current-dependant kinetic inductance, which gives an ideal Kerr nonlinearity. When the nonlinear oscillator is pumped very near its dynamic instability, it can be used to realize parametric amplification. We have achieved a gain of +22.4dB in a 5.8 GHz resonator cooled to 450 mK [E. Thol'en et. al. Appl. Phys. Lett. 90, 253509 (2007)]. Parametric deamplification or squeezing of a signal has also been verified with squeezing of 30 dB. The later effect is interesting because it can be used to generate squeezed vacuum states of the electromagnetic field. We have modeled the data using a theory developed by Yurke and Buks [J. Lightwave Technol. 24, 5054 (2006)]. Excellent fit of the model to the measured data can be achieved over a wide range of pump power, and the strength of the nonlinear terms can be obtained with high accuracy.

  20. ELECTRON AMPLIFICATION IN DIAMOND.

    SciTech Connect

    SMEDLEY, J.; BEN-ZVI, I.; BURRILL, A.; CHANG, X.; GRIMES, J.; RAO, T.; SEGALOV, Z.; WU, Q.

    2006-07-10

    We report on recent progress toward development of secondary emission ''amplifiers'' for photocathodes. Secondary emission gain of over 300 has been achieved in transmission mode and emission mode for a variety of diamond samples. Techniques of sample preparation, including hydrogenation to achieve negative electron affinity (NEA), have been adapted to this application.

  1. An Intrinsically Digital Amplification Scheme for Hearing Aids

    NASA Astrophysics Data System (ADS)

    Blamey, Peter J.; Macfarlane, David S.; Steele, Brenton R.

    2005-12-01

    Results for linear and wide-dynamic range compression were compared with a new 64-channel digital amplification strategy in three separate studies. The new strategy addresses the requirements of the hearing aid user with efficient computations on an open-platform digital signal processor (DSP). The new amplification strategy is not modeled on prior analog strategies like compression and linear amplification, but uses statistical analysis of the signal to optimize the output dynamic range in each frequency band independently. Using the open-platform DSP processor also provided the opportunity for blind trial comparisons of the different processing schemes in BTE and ITE devices of a high commercial standard. The speech perception scores and questionnaire results show that it is possible to provide improved audibility for sound in many narrow frequency bands while simultaneously improving comfort, speech intelligibility in noise, and sound quality.

  2. Complement amplification revisited.

    PubMed

    Lutz, Hans U; Jelezarova, Emiliana

    2006-01-01

    Complement amplification in blood takes place not only on activating surfaces, but in plasma as well, where it is maintained primarily by C3b2-IgG complexes. Regular products of C3 activation in serum, these complexes are inherently very efficient precursors of the alternative pathway C3 convertase. Moreover, they can bind properdin bivalently, thus creating preferred sites for convertase formation. C3b2-IgG complexes have a half-life that is substantially longer than that of free C3b, since both C3b molecules are partially protected from inactivation by factor H and I. These complexes are preferentially generated on certain naturally occurring and induced antibodies that exhibit a paratope-independent affinity for C3/C3b. Such antibodies are known to stimulate alternative complement pathway activation. We have assembled the evidence for the generation and the functional potency of the C3b2-IgG complexes, which have been studied during the last two decades. We illustrate their roles in immune complex solubilization, phagocytosis, immune response, and their ability to initiate devastating effects in ischemia/reperfusion and in aggravating inflammation. PMID:16023211

  3. Enhanced acoustic sensing through wave compression and pressure amplification in anisotropic metamaterials

    NASA Astrophysics Data System (ADS)

    Chen, Yongyao; Liu, Haijun; Reilly, Michael; Bae, Hyungdae; Yu, Miao

    2014-10-01

    Acoustic sensors play an important role in many areas, such as homeland security, navigation, communication, health care and industry. However, the fundamental pressure detection limit hinders the performance of current acoustic sensing technologies. Here, through analytical, numerical and experimental studies, we show that anisotropic acoustic metamaterials can be designed to have strong wave compression effect that renders direct amplification of pressure fields in metamaterials. This enables a sensing mechanism that can help overcome the detection limit of conventional acoustic sensing systems. We further demonstrate a metamaterial-enhanced acoustic sensing system that achieves more than 20 dB signal-to-noise enhancement (over an order of magnitude enhancement in detection limit). With this system, weak acoustic pulse signals overwhelmed by the noise are successfully recovered. This work opens up new vistas for the development of metamaterial-based acoustic sensors with improved performance and functionalities that are highly desirable for many applications.

  4. High-energy infrared femtosecond pulses generated by dual-chirped optical parametric amplification.

    PubMed

    Fu, Yuxi; Takahashi, Eiji J; Midorikawa, Katsumi

    2015-11-01

    We demonstrate high-energy infrared femtosecond pulse generation by a dual-chirped optical parametric amplification (DC-OPA) scheme [Opt. Express19, 7190 (2011)]. By employing a 100 mJ pump laser, a signal pulse energy exceeding 20 mJ at a wavelength of 1.4 μm was achieved before dispersion compensation. A total output energy of 33 mJ was recorded. Under a further energy scaling condition, the signal pulse was compressed to an almost transform-limited duration of 27 fs using a fused silica prism compressor. Since the DC-OPA scheme is efficient and energy scalable, design parameters for obtaining 100 mJ level infrared pulses are presented, which are suitable as driver lasers for the energy scaling of high-order harmonic generation with sub-keV photon energy. PMID:26512524

  5. Why ring regenerative amplification (regen)?

    NASA Astrophysics Data System (ADS)

    Yanovsky, V.; Felix, C.; Mourou, G.

    2002-06-01

    We show that ring cavity regenerative amplifiers (regens) have distinct advantages over the linear ones for applications in chirped pulse amplification. Larger energy, better contrast and better isolation from the oscillator are experimentally demonstrated.

  6. Why ring regenerative amplification (regen)?

    NASA Astrophysics Data System (ADS)

    Yanovsky, V.; Felix, C.; Mourou, G.

    We show that ring cavity regenerative amplifiers (regens) have distinct advantages over the linear ones for applications in chirped pulse amplification. Larger energy, better contrast and better isolation from the oscillator are experimentally demonstrated.

  7. Regulation of ribosomal DNA amplification by the TOR pathway

    PubMed Central

    Jack, Carmen V.; Cruz, Cristina; Hull, Ryan M.; Keller, Markus A.; Ralser, Markus; Houseley, Jonathan

    2015-01-01

    Repeated regions are widespread in eukaryotic genomes, and key functional elements such as the ribosomal DNA tend to be formed of high copy repeated sequences organized in tandem arrays. In general, high copy repeats are remarkably stable, but a number of organisms display rapid ribosomal DNA amplification at specific times or under specific conditions. Here we demonstrate that target of rapamycin (TOR) signaling stimulates ribosomal DNA amplification in budding yeast, linking external nutrient availability to ribosomal DNA copy number. We show that ribosomal DNA amplification is regulated by three histone deacetylases: Sir2, Hst3, and Hst4. These enzymes control homologous recombination-dependent and nonhomologous recombination-dependent amplification pathways that act in concert to mediate rapid, directional ribosomal DNA copy number change. Amplification is completely repressed by rapamycin, an inhibitor of the nutrient-responsive TOR pathway; this effect is separable from growth rate and is mediated directly through Sir2, Hst3, and Hst4. Caloric restriction is known to up-regulate expression of nicotinamidase Pnc1, an enzyme that enhances Sir2, Hst3, and Hst4 activity. In contrast, normal glucose concentrations stretch the ribosome synthesis capacity of cells with low ribosomal DNA copy number, and we find that these cells show a previously unrecognized transcriptional response to caloric excess by reducing PNC1 expression. PNC1 down-regulation forms a key element in the control of ribosomal DNA amplification as overexpression of PNC1 substantially reduces ribosomal DNA amplification rate. Our results reveal how a signaling pathway can orchestrate specific genome changes and demonstrate that the copy number of repetitive DNA can be altered to suit environmental conditions. PMID:26195783

  8. Differential transimpedance amplifier circuit for correlated differential amplification

    DOEpatents

    Gresham, Christopher A.; Denton, M. Bonner; Sperline, Roger P.

    2008-07-22

    A differential transimpedance amplifier circuit for correlated differential amplification. The amplifier circuit increase electronic signal-to-noise ratios in charge detection circuits designed for the detection of very small quantities of electrical charge and/or very weak electromagnetic waves. A differential, integrating capacitive transimpedance amplifier integrated circuit comprising capacitor feedback loops performs time-correlated subtraction of noise.

  9. New Technologies in Amplification: Applications to the Pediatric Population.

    ERIC Educational Resources Information Center

    Kopun, Judy

    1995-01-01

    Discussion of technological advances in amplification for children with hearing impairments focuses on the advantages and limitations of fitting children with devices that have features such as dynamic-range compression, multiband signal processing, multimemory capability, digital feedback reduction, and frequency transposition. (Author/DB)

  10. Photonic microwave amplification for radio-over-fiber links using period-one nonlinear dynamics of semiconductor lasers.

    PubMed

    Hung, Yu-Han; Hwang, Sheng-Kwang

    2013-09-01

    For radio-over-fiber links, microwave-modulated optical carriers with high optical modulation depth are preferred because high optical modulation depth allows generation of high microwave power after photodetection, leading to high detection sensitivity, long transmission distance, and large link gain. This study investigates the period-one nonlinear dynamics of semiconductor lasers for optical modulation depth improvement to achieve photonic microwave amplification through modulation sideband enhancement. In our scheme, only typical semiconductor lasers are required as the amplification unit. The amplification is achieved for a broad microwave range, from less than 25 GHz to more than 60 GHz, and for a wide gain range, from less than 10 dB to more than 30 dB. The microwave phase quality is mainly preserved while the microwave power is largely amplified, improving the signal-to-noise ratio up to at least 25 dB. The bit-error ratio at 1.25 Gbits/s is better than 10(-9), and a sensitivity improvement of up to at least 15 dB is feasible. PMID:23988956

  11. Spin noise amplification and giant noise in optical microcavity

    SciTech Connect

    Ryzhov, I. I.; Poltavtsev, S. V.; Kozlov, G. G.; Zapasskii, V. S.; Kavokin, A. V.; Lagoudakis, P. V.

    2015-06-14

    When studying the spin-noise-induced fluctuations of Kerr rotation in a quantum-well microcavity, we have found a dramatic increase of the noise signal (by more than two orders of magnitude) in the vicinity of anti-crossing of the polariton branches. The effect is explained by nonlinear optical instability of the microcavity giving rise to the light-power-controlled amplification of the polarization noise signal. In the framework of the developed model of built-in amplifier, we also interpret the nontrivial spectral and intensity-related properties of the observed noise signal below the region of anti-crossing of polariton branches. The discovered effect of optically controllable amplification of broadband polarization signals in microcavities in the regime of optical instability may be of interest for detecting weak oscillations of optical anisotropy in fundamental research and for other applications in optical information processing.

  12. Space Optical Communications Using Laser Beam Amplification

    NASA Technical Reports Server (NTRS)

    Agrawal, Govind

    2015-01-01

    The Space Optical Communications Using Laser Beam Amplification (SOCLBA) project will provide a capability to amplify a laser beam that is received in a modulating retro-reflector (MRR) located in a satellite in low Earth orbit. It will also improve the pointing procedure between Earth and spacecraft terminals. The technology uses laser arrays to strengthen the reflected laser beam from the spacecraft. The results of first year's work (2014) show amplification factors of 60 times the power of the signal beam. MMRs are mirrors that reflect light beams back to the source. In space optical communications, a high-powered laser interrogator beam is directed from the ground to a satellite. Within the satellite, the beam is redirected back to ground using the MMR. In the MMR, the beam passes through modulators, which encode a data signal onto the returning beam. MMRs can be used in small spacecraft for optical communications. The SOCLBA project is significant to NASA and small spacecraft due to its application to CubeSats for optical data transmission to ground stations, as well as possible application to spacecraft for optical data transmission.

  13. Brillouin amplification in phase coherent transfer of optical frequencies over 480 km fiber.

    PubMed

    Terra, O; Grosche, G; Schnatz, H

    2010-07-19

    We describe the use of fiber Brillouin amplification (FBA) for the coherent transmission of optical frequencies over a 480 km long optical fiber link. FBA uses the transmission fiber itself for efficient, bi-directional coherent amplification of weak signals with pump powers around 30 mW. In a test setup we measured the gain and the achievable signal-to-noise ratio (SNR) of FBA and compared it to that of the widely used uni-directional Erbium doped fiber amplifiers (EDFA) and to our recently built bi-directional EDFA. We measured also the phase noise introduced by the FBA and used a new and simple technique to stabilize the frequency of the FBA pump laser. We then transferred a stabilized laser frequency over a wide area network with a total fiber length of 480 km using only one intermediate FBA station. After compensating the noise induced by the fiber, the frequency is delivered to the user end with an uncertainty below 2 x 10(-18) and an instability sigma y(tau) = 2 x 10(-14) /(tau/s). PMID:20720995

  14. Chirped-pulse amplification of 100-fsec pulses.

    PubMed

    Pessot, M; Squier, J; Mourou, G; Harter, D J

    1989-08-01

    Chirped-pulse amplification is used to generate 2-mJ pulses of 106-fsec duration in an alexandrite amplifier. Compression of the optical pulse is achieved by using a sequence of intracavity prisms in conjunction with diffraction gratings. This allows for the compensation of both linear and quadratic contributions to the dispersion from the amplifier. PMID:19752971

  15. Influence of environmental noise on the weak value amplification

    NASA Astrophysics Data System (ADS)

    Zhu, Xuannmin; Zhang, Yu-Xiang

    2016-05-01

    Quantum systems are always disturbed by environmental noise. We have investigated the influence of the environmental noise on the amplification in weak measurements. Three typical quantum noise processes are discussed in this article. The maximum expectation values of the observables of the measuring device decrease sharply with the strength of the depolarizing and phase damping channels, while the amplification effect of weak measurement is immune to the amplitude damping noise. To obtain significantly amplified signals, we must ensure that the preselection quantum systems are kept away from the depolarizing and phase damping processes.

  16. Ultra-broad bandwidth parametric amplification at degeneracy.

    PubMed

    Limpert, J; Aguergaray, C; Montant, S; Manek-Hönninger, I; Petit, S; Descamps, D; Cormier, E; Salin, F

    2005-09-19

    We report on a novel approach of ultra-broad bandwidth parametric amplification around degeneracy. A bandwidth of up to 400 nm centered around 800 nm is amplified in a BBO crystal by using chirped pump pulses with a bandwitdth as broad as 10 nm. A supercontinuum signal is generated in a microstructured fiber, having to first order a quadratic chirp, which is necessary to ensure temporal overlap of the interacting waves over this broad bandwidth. Furthermore, we discuss the potential of this approach for an octave-spanning parametric amplification. PMID:19498762

  17. Influence of environmental noise on the weak value amplification

    NASA Astrophysics Data System (ADS)

    Zhu, Xuannmin; Zhang, Yu-Xiang

    2016-08-01

    Quantum systems are always disturbed by environmental noise. We have investigated the influence of the environmental noise on the amplification in weak measurements. Three typical quantum noise processes are discussed in this article. The maximum expectation values of the observables of the measuring device decrease sharply with the strength of the depolarizing and phase damping channels, while the amplification effect of weak measurement is immune to the amplitude damping noise. To obtain significantly amplified signals, we must ensure that the preselection quantum systems are kept away from the depolarizing and phase damping processes.

  18. Efficient S-Band Amplification Using Depressed-Cladding Erbium-Doped Silica Fibers

    NASA Astrophysics Data System (ADS)

    Rosolem, J. B.; Romero, M. A.

    2008-10-01

    In this paper we review our work to achieve S-band amplification using only erbium doped silica fibers. To this end, double-pass and single pass erbium doped depressed cladding fiber amplifier designed for S band operation are evaluated under changes of the input optical power, pumping power and fiber bending radius. The double pass configuration employs the usual combination of a circulator and a Faraday rotator mirror while the single pass is based on the co-propagating scheme. The amplifiers were characterized in terms of gain and noise figure. It is demonstrated that the double pass topology shows much improved gain performance compared to the single pass configuration although the noise figure is slightly degraded by counter-propagating ASE. Next, the amplifier double pass topology is properly modified to achieve signal amplification simultaneously over S, C and L bands. An embedded dispersion compensating fiber is included and the experimental characterization is carried out in terms gain and noise figure over the CWDM wavelength grid. By providing optical gain to seven CWDM channels spectrally located between 1490 and 1610 nm, the amplifier can extend the reach of a 16-channel CWDM optical bus well beyond the 100 km limit. The system results are then compared to those obtained by using a SOA (semiconductor optical amplifier), under the same experimental conditions.

  19. Kinase signaling in the spindle checkpoint.

    PubMed

    Kang, Jungseog; Yu, Hongtao

    2009-06-01

    The spindle checkpoint is a cell cycle surveillance system that ensures the fidelity of chromosome segregation. In mitosis, it elicits the "wait anaphase" signal to inhibit the anaphase-promoting complex or cyclosome until all chromosomes achieve bipolar microtubule attachment and align at the metaphase plate. Because a single kinetochore unattached to microtubules activates the checkpoint, the wait anaphase signal is thought to be generated by this kinetochore and is then amplified and distributed throughout the cell to inhibit the anaphase-promoting complex/cyclosome. Several spindle checkpoint kinases participate in the generation and amplification of this signal. Recent studies have begun to reveal the activation mechanisms of these checkpoint kinases. Increasing evidence also indicates that the checkpoint kinases not only help to generate the wait anaphase signal but also actively correct kinetochore-microtubule attachment defects. PMID:19228686

  20. Chromosomal destabilization during gene amplification.

    PubMed Central

    Ruiz, J C; Wahl, G M

    1990-01-01

    Acentric extrachromosomal elements, such as submicroscopic autonomously replicating circular molecules (episomes) and double minute chromosomes, are common early, and in some cases initial, intermediates of gene amplification in many drug-resistant and tumor cell lines. In order to gain a more complete understanding of the amplification process, we investigated the molecular mechanisms by which such extrachromosomal elements are generated and we traced the fate of these amplification intermediates over time. The model system consists of a Chinese hamster cell line (L46) created by gene transfer in which the initial amplification product was shown previously to be an unstable extrachromosomal element containing an inverted duplication spanning more than 160 kilobases (J. C. Ruiz and G. M. Wahl, Mol. Cell. Biol. 8:4302-4313, 1988). In this study, we show that these molecules were formed by a process involving chromosomal deletion. Fluorescence in situ hybridization was performed at multiple time points on cells with amplified sequences. These studies reveal that the extrachromosomal molecules rapidly integrate into chromosomes, often near or at telomeres, and once integrated, the amplified sequences are themselves unstable. These data provide a molecular and cytogenetic chronology for gene amplification in this model system; an early event involves deletion to generate extrachromosomal elements, and subsequent integration of these elements precipitates a cascade of chromosome instability. Images PMID:2188107

  1. Optimizing biased semiconductor superlattices for terahertz amplification

    SciTech Connect

    Lei, Xiaoli; Wang, Dawei; Wu, Zhaoxin; Dignam, M. M.

    2014-08-11

    Over the past 15 yr or more, researchers have been trying to achieve gain for electromagnetic fields in the terahertz frequency region using biased semiconductor superlattices, but with little success. In this work, we employ our model of the excitonic states in biased GaAs/Al{sub 0.3}Ga{sub 0.7}As semiconductor superlattices to find the optimal structures for amplification of terahertz radiation. In particular, we determine the optimum well width, barrier width, and bias field for terahertz fields with frequencies ranging from 1 to 4 terahertz. We find that gain coefficients on the order of 40 cm{sup −1} should be achievable over most of this frequency range.

  2. Discovery of a photoresponse amplification mechanism in compensated PN junctions

    SciTech Connect

    Zhou, Yuchun; Rahman, Samia N.; Hall, David; Lo, Yu-Hwa; Liu, Yu-Hsin; Sham, L. J.

    2015-01-19

    We report the experimental evidence of uncovering a photoresponse amplification mechanism in heavily doped, partially compensated silicon p-n junctions under very low bias voltage. We show that the observed photocurrent gain occurs at a bias that is more than an order of magnitude below the threshold voltage for conventional impact ionization. Moreover, contrary to the case of avalanche detectors and p-i-n diodes, the amplified photoresponse is enhanced rather than suppressed with increasing temperature. These distinctive characteristics lead us to hypothesize that the inelastic scattering between energetic electrons (holes) and the ionized impurities in the depletion and charge neutral regions of the p-n junction in a cyclic manner plays a significant role in the amplification process. Such an internal signal amplification mechanism, which occurs at much lower bias than impact ionization and favors room temperature over cryogenic temperature, makes it promising for practical device applications.

  3. Quantum phase amplification for temporal pulse shaping and super-resolution in remote sensing

    NASA Astrophysics Data System (ADS)

    Yin, Yanchun

    QPA in the spatial domain has also been studied as a method to enhance the spatial resolution of imaging systems. A detailed model has been developed for achieving both super-resolution and detection of phase-amplified light. The imaging resolution problem considered here is treated as a binary hypotheses testing problem. Resolution enhancement is achieved by magnification of the angular separation of two targets in the sub-Rayleigh regime. The detection model includes optimization of detector segmentation, detector noise, and detection in both the spatial and the spatial frequency domain, which provide strategies for the optimization of the signal-to-noise ratio that take advantage of both the change of the field distribution and the change of energy of the signal in the QPA process. Proof-of-principle experiments have been conducted in the spatial domain. For the first time, beam angular amplification has been demonstrated, and the experimental result is in good agreement with simulations. The experimental demonstration has been achieved by observing the correlation of amplitude and angular phase in the phase-sensitive three-wave mixing process using ultrashort laser pulses and utilizing a type I three-wave mixing process. Several diagnostics have been developed and employed in the experimental measurements, including the near-field diagnostic, the far-field diagnostic, and the interferometry diagnostic. They have all been used to confirm the existence and study the properties of the QPA process on a shot-to-shot basis. Specifically, amplitude was measured in the near-field diagnostic, while the angular phase was indirectly measured in the far-field diagnostic by determining the position of the beam centroid. Interferometric measurements have been found to be of insufficient accuracy for this measurement in the way they were implemented. The demonstration of beam angular amplification by use of QPA lays the foundation for future integrated demonstration of imaging

  4. Sequence independent amplification of DNA

    DOEpatents

    Bohlander, S.K.

    1998-03-24

    The present invention is a rapid sequence-independent amplification procedure (SIA). Even minute amounts of DNA from various sources can be amplified independent of any sequence requirements of the DNA or any a priori knowledge of any sequence characteristics of the DNA to be amplified. This method allows, for example, the sequence independent amplification of microdissected chromosomal material and the reliable construction of high quality fluorescent in situ hybridization (FISH) probes from YACs or from other sources. These probes can be used to localize YACs on metaphase chromosomes but also--with high efficiency--in interphase nuclei. 25 figs.

  5. Sequence independent amplification of DNA

    DOEpatents

    Bohlander, Stefan K.

    1998-01-01

    The present invention is a rapid sequence-independent amplification procedure (SIA). Even minute amounts of DNA from various sources can be amplified independent of any sequence requirements of the DNA or any a priori knowledge of any sequence characteristics of the DNA to be amplified. This method allows, for example the sequence independent amplification of microdissected chromosomal material and the reliable construction of high quality fluorescent in situ hybridization (FISH) probes from YACs or from other sources. These probes can be used to localize YACs on metaphase chromosomes but also--with high efficiency--in interphase nuclei.

  6. Optimization of noncollinear optical parametric amplification

    NASA Astrophysics Data System (ADS)

    Schimpf, D. N.; Rothardt, J.; Limpert, J.; Tünnermann, A.

    2007-02-01

    Noncollinearly phase-matched optical parametric amplifiers (NOPAs) - pumped with the green light of a frequency doubled Yb-doped fiber-amplifier system 1, 2 - permit convenient generation of ultrashort pulses in the visible (VIS) and near infrared (NIR) 3. The broad bandwidth of the parametric gain via the noncollinear pump configuration allows amplification of few-cycle optical pulses when seeded with a spectrally flat, re-compressible signal. The short pulses tunable over a wide region in the visible permit transcend of frontiers in physics and lifescience. For instance, the resulting high temporal resolution is of significance for many spectroscopic techniques. Furthermore, the high magnitudes of the peak-powers of the produced pulses allow research in high-field physics. To understand the demands of noncollinear optical parametric amplification using a fiber pump source, it is important to investigate this configuration in detail 4. An analysis provides not only insight into the parametric process but also determines an optimal choice of experimental parameters for the objective. Here, the intention is to design a configuration which yields the shortest possible temporal pulse. As a consequence of this analysis, the experimental setup could be optimized. A number of aspects of optical parametric amplifier performance have been treated analytically and computationally 5, but these do not fully cover the situation under consideration here.

  7. Horseradish peroxidase and aptamer dual-functionalized nanoprobe for the amplification detection of alpha-methylacyl-CoA racemase.

    PubMed

    Zeng, Yongyi; Zheng, Aixian; Wu, Jing; Cai, Zhixiong; Huang, Aimin; Liu, Xiaolong

    2015-10-29

    Alpha-methylacyl-CoA racemase (AMACR) is over-expressed in many cancer types and can serve as a novel diagnostic biomarker. Development of convenient and sensitive detection methods of AMACR is of particular importance for cancer diagnosis. Aptamers are a type of recognition elements, which possess many advantages over antibody, making them suitable for applications in biosensing and biotechnology. In this work, we use the efficient surface modification of gold nanoparticles (AuNPs) to prepare the horseradish peroxidase (HRP) and aptamer dual-functionalized nanoprobe. The immobilization of HRP and thiol-terminated aptamer on the surface of AuNPs can be achieved through electrostatic interaction and the formation of Au-S bond, respectively. This nanoprobe, which is used as discriminating and catalytic probe, can be combined with enzyme immunoassay method to increase the detection sensitivity of AMACR. The detection limit can reach as low as 4.6 pg mL(-1) due to the dual signal amplification from enzymatic cycling and the high loading of enzymes on AuNPs. This sensitivity is about three orders of magnitude higher than that of AMACR aptamer based fluorescence method, which is also comparable to or one order of magnitude higher than that of ELISA. Furthermore, this method is more simple and effective, which not only avoids the conjugation between recognition element and the catalytic enzyme, but also achieves greater signal amplification. This assay could be used as a sensitive and selective platform for the detection of target protein. PMID:26547498

  8. Chronic centrosome amplification without tumorigenesis

    PubMed Central

    Vitre, Benjamin; Holland, Andrew J.; Kulukian, Anita; Shoshani, Ofer; Hirai, Maretoshi; Wang, Yin; Maldonado, Marcus; Cho, Thomas; Boubaker, Jihane; Swing, Deborah A.; Tessarollo, Lino; Evans, Sylvia M.; Fuchs, Elaine; Cleveland, Don W.

    2015-01-01

    Centrosomes are microtubule-organizing centers that facilitate bipolar mitotic spindle assembly and chromosome segregation. Recognizing that centrosome amplification is a common feature of aneuploid cancer cells, we tested whether supernumerary centrosomes are sufficient to drive tumor development. To do this, we constructed and analyzed mice in which centrosome amplification can be induced by a Cre-recombinase–mediated increase in expression of Polo-like kinase 4 (Plk4). Elevated Plk4 in mouse fibroblasts produced supernumerary centrosomes and enhanced the expected mitotic errors, but proliferation continued only after inactivation of the p53 tumor suppressor. Increasing Plk4 levels in mice with functional p53 produced centrosome amplification in liver and skin, but this did not promote spontaneous tumor development in these tissues or enhance the growth of chemically induced skin tumors. In the absence of p53, Plk4 overexpression generated widespread centrosome amplification, but did not drive additional tumors or affect development of the fatal thymic lymphomas that arise in animals lacking p53. We conclude that, independent of p53 status, supernumerary centrosomes are not sufficient to drive tumor formation. PMID:26578792

  9. Isothermal amplification of insect DNA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The loop-mediated isothermal amplification of DNA (LAMP) method can amplify a target DNA sequence at a constant temperature in about 1 hour. LAMP has broad application in agriculture and medicine because of the need for rapid and inexpensive diagnoses. The power of LAMP is being used by researchers ...

  10. Isothermal Amplification of Insect DNA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The loop-mediated isothermal amplification of DNA (LAMP) method can amplify a target DNA sequence at a constant temperature in about one hour. LAMP has broad application in agriculture and medicine because of the need for rapid and inexpensive diagnoses. LAMP eliminates the need for temperature cycl...

  11. Boosting riboswitch efficiency by RNA amplification

    PubMed Central

    Emadpour, Masoumeh; Karcher, Daniel; Bock, Ralph

    2015-01-01

    Riboswitches are RNA sensors that regulate gene expression in response to binding of small molecules. Although they conceptually represent simple on/off switches and, therefore, hold great promise for biotechnology and future synthetic biology applications, the induction of gene expression by natural riboswitches after ligand addition or removal is often only moderate and, consequently, the achievable expression levels are not very high. Here, we have designed an RNA amplification-based system that strongly improves the efficiency of riboswitches. We have successfully implemented the method in a biological system for which currently no efficient endogenous tools for inducible (trans)gene expression are available: the chloroplasts of higher plants. We further show that an HIV antigen whose constitutive expression from the chloroplast genome is deleterious to the plant can be inducibly expressed under the control of the RNA amplification-enhanced riboswitch (RAmpER) without causing a mutant phenotype, demonstrating the potential of the method for the production of proteins and metabolites that are toxic to the host cell. PMID:25824954

  12. Optical chirped beam amplification and propagation

    DOEpatents

    Barty, Christopher P.

    2004-10-12

    A short pulse laser system uses dispersive optics in a chirped-beam amplification architecture to produce high peak power pulses and high peak intensities without the potential for intensity dependent damage to downstream optical components after amplification.

  13. Amplification sans bruit d'images optiques

    NASA Astrophysics Data System (ADS)

    Gigan, S.; Delaubert, V.; Lopez, L.; Treps, N.; Maitre, A.; Fabre, C.

    2004-11-01

    Nous utilisons un Oscillateur Paramétrique Optique (OPO) pompé sous le seuil dans le but d'amplifier une image multimode transverse sans dégradation du rapport signal à bruit. Le dispositif expérimental met en œuvre un OPO de type II triplement résonant et semi-confocal pour le faisceau amplifié. L'existence d'effets quantiques lors de l'amplification multimode dans un tel dispositif a été montrée expérimentalement. Plus généralement, ceci nous a amené à étudier les propriétés quantiques transverses des faisceaux lumineux amplifiés. Une telle étude peut trouver des applications non seulement en imagerie, mais également dans le traitement quantique de l'information.

  14. Parametric amplification by coupled flux qubits

    SciTech Connect

    Rehák, M.; Neilinger, P.; Grajcar, M.; Oelsner, G.; Hübner, U.; Meyer, H.-G.; Il'ichev, E.

    2014-04-21

    We report parametric amplification of a microwave signal in a Kerr medium formed from superconducting qubits. Two mutually coupled flux qubits, embedded in the current antinode of a superconducting coplanar waveguide resonator, are used as a nonlinear element. Shared Josephson junctions provide the qubit-resonator coupling, resulting in a device with a tunable Kerr constant (up to 3 × 10{sup −3}) and a measured gain of about 20 dB. This arrangement represents a unit cell which can be straightforwardly extended to a quasi one-dimensional quantum metamaterial with large tunable Kerr nonlinearity, providing a basis for implementation of wide-band travelling wave parametric amplifiers.

  15. Tm3+-doped ion-exchanged aluminum germanate glass waveguide for S-band amplification

    NASA Astrophysics Data System (ADS)

    Yang, D. L.; Pun, E. Y. B.; Lin, H.

    2009-10-01

    K+-Na+ ion-exchanged channel waveguide amplifiers have been fabricated in Tm3+-doped acid-resistant aluminum germanate glasses. The optical and relative gains of a 3.15-cm-long waveguide channel were achieved to be 4.05 and 2.29 dB at 1.482 μm wavelength under 110 mW 793 nm laser excitation, respectively. After compensating the propagation loss, an internal gain of 1.50 dB and a remarkable gain coefficient of 0.48 dB/cm were obtained, which reveals a definite S-band signal amplification in the low phonon energy glass waveguide. As an expectation, UV-radiation-sensitive glass waveguide should promote the developments of gain-flatten S-band waveguide amplifiers, infrared UV-writing grating waveguide lasers, and compact multifunctional integrated optical devices.

  16. Amplification and noise properties of an erbium-doped multicore fiber amplifier

    NASA Astrophysics Data System (ADS)

    Abedin, K. S.; Taunay, T. F.; Fishteyn, M.; Yan, M. F.; Zhu, B.; Fini, J. M.; Monberg, E. M.; Dimarcello, F. V.; Wisk, P. W.

    2011-08-01

    A multicore erbium-doped fiber (MC-EDF) amplifier for simultaneous amplification in the 7-cores has been developed, and the gain and noise properties of individual cores have been studied. The pump and signal radiation were coupled to individual cores of MC-EDF using two tapered fiber bundled (TFB) couplers with low insertion loss. For a pump power of 146 mW, the average gain achieved in the MC-EDF fiber was 30 dB, and noise figure was less than 4 dB. The net useful gain from the multicore-amplifier, after taking into consideration of all the passive losses, was about 23-27 dB. Pump induced ASE noise transfer between the neighboring channel was negligible.

  17. Highly efficient sample stacking by enhanced field amplification on a simple paper device.

    PubMed

    Ma, Biao; Song, Yi-Zhen; Niu, Ji-Cheng; Wu, Zhi-Yong

    2016-09-21

    We present a novel electrokinetic stacking (ES) method based on field amplification on a simple paper device for sample preconcentration. With voltage application, charged probe ions in a solution of lower conductivity stack and form a narrow band at the boundary between the sample and the background electrolyte of higher conductivity. The stacking band appears quickly and stabilizes in a few minutes. With this ES method, three orders of magnitude signal improvement was successfully achieved for both a fluorescein probe and a double-stranded DNA within 300 s. This enhanced stacking efficiency is attributed to a focusing effect due to the balance between electromigration and counter electroosmotic flow. We also applied this ES method to other low-cost fiber substrates such as cloth and thread. Such a simple and highly efficient ES method will find wide applications in the development of sensitive paper-based analytical devices (PADs), especially for low-cost point-of-care testing (POCT). PMID:27528399

  18. Intrapulse x-ray parametric amplification in high-order-harmonic generation

    NASA Astrophysics Data System (ADS)

    Serrat, Carles

    2016-06-01

    We demonstrate strong-field-driven impulsive XUV-x-ray parametric amplification (IXPA) processes in high-order harmonic generation at the single-atom level by using ab initio calculations. We consider the example of Li+ ions exposed simultaneously to an intense IR pulse and a weak 200-as XUV-x-ray pulse with central photon energies varying from 90 to 400 eV. We determine optimal parameter ranges and the precise delays between the IR and the XUV-x-ray pulses for IXPA to occur. The present results might be a guide to achieve exponential growth of the XUV-x-ray signal in tabletop XUV-x-ray lasers.

  19. Amplification and noise properties of an erbium-doped multicore fiber amplifier.

    PubMed

    Abedin, K S; Taunay, T F; Fishteyn, M; Yan, M F; Zhu, B; Fini, J M; Monberg, E M; Dimarcello, F V; Wisk, P W

    2011-08-15

    A multicore erbium-doped fiber (MC-EDF) amplifier for simultaneous amplification in the 7-cores has been developed, and the gain and noise properties of individual cores have been studied. The pump and signal radiation were coupled to individual cores of MC-EDF using two tapered fiber bundled (TFB) couplers with low insertion loss. For a pump power of 146 mW, the average gain achieved in the MC-EDF fiber was 30 dB, and noise figure was less than 4 dB. The net useful gain from the multicore-amplifier, after taking into consideration of all the passive losses, was about 23-27 dB. Pump induced ASE noise transfer between the neighboring channel was negligible. PMID:21935033

  20. Double regenerative amplification of picosecond pulses

    NASA Astrophysics Data System (ADS)

    Bai, Zhen-ao; Chen, Li-yuan; Bai, Zhen-xu; Chen, Meng; Li, Gang

    2012-04-01

    An double Nd:YAG regenerative amplification picosecond pulse laser is demonstrated under the semiconductor saturable absorption mirror(SESAM) mode-locking technology and regenerative amplification technology, using BBO crystal as PC electro-optic crystal. The laser obtained is 20.71ps pulse width at 10 KHz repetition rate, and the energy power is up to 4W which is much larger than the system without pre-amplification. This result will lay a foundation for the following amplification.

  1. The Quantum Theory of Optical Parametric Amplification

    NASA Astrophysics Data System (ADS)

    Hussain, N. A.

    Available from UMI in association with The British Library. Requires signed TDF. The aim of this thesis is to investigate the effect of parametric amplification on various forms of light. In particular we shall consider number and coherent states, but many of the calculations hold for those states whose operators satisfy the properties, < {a}^+{a}^+ >=<{a}{a }> = < {a}^+>=<{a }>=0 e.g. chaotic light. The first chapter lays down the fundamental preliminaries necessary for our calculations and reviews linear amplifier theory. We consider the phase sensitive and insensitive forms of amplifiers modelling the former on the degenerate parametric amplifier and the latter on the non-degenerate and inverted population amplifiers. Chapter 2 deals with balanced homodyne detection of a narrow band coherent state before and after degenerate parametric amplification. In chapter 3 we consider a continuous mode number state produced by atomic emission and parametrically amplified using the formalism of Collett and Gardiner. We give general results for the output flux intensity and also consider the simpler case where the atomic decay rate is much smaller than the parametric cavity decay rate. Also we consider the degree of second order coherence using this simplified theory. Chapters 4 and 5 consider the double amplifier interferometer, using single and continuous mode theories, and enable us to determine the form of amplifier which produces the best visibility and hence lowest noise figures. The travelling-wave parametric amplifier is discussed in chapter 6 and is contrasted with the cavity parametric amplifier discussed in chapters 1 and 2. Finally we consider the much contemplated idea of using amplifiers to boost signals in fibre optic transmission lines using our model of the parametric amplifier and examining the degradation of the signal-to-noise ratio. We consider both coherent and squeezed inputs and our results hold for both cavity and travelling -wave amplifiers.

  2. Fibroblast growth factor receptor 1 gene amplification is associated with poor survival in patients with resected esophageal squamous cell carcinoma

    PubMed Central

    Kim, Dae Joon; Lee, Chang-Geol; Hur, Jin; Chung, Hyunsoo; Park, Jun Chul; Jung, Da Hyun; Shin, Sung Kwan; Lee, Sang Kil; Lee, Yong Chan; Kim, Hye Ryun; Moon, Yong Wha; Kim, Joo Hang; Shim, Young Mog; Jewell, Susan S.; Kim, Hyunki; Choi, Yoon-La; Cho, Byoung Chul

    2015-01-01

    To investigate the frequency and the prognostic impact of fibroblast growth factor receptor 1 (FGFR1) gene amplification in 526 curatively resected esophageal squamous cell carcinoma (ESCC). Using fluorescent in situ hybridization, high amplification was defined by an FGFR1/centromer 8 ratio is ≥ 2.0, or average number of FGFR1 signals/tumor cell nucleus ≥ 6.0, or percentage of tumor cells containing ≥ 15 FGFR1 signals or large cluster in ≥ 10%. Low amplification was defined by ≥ 5 FGFR1 signals in ≥ 50%. FGFR2 and FGFR3 mutations were assessed by direct sequencing in 388 cases and no mutation was detected. High and low amplification were detected in 8.6% and 1.1%, respectively. High FGFR1 amplification had significantly shorter disease-free survival (34.0 vs 158.5 months P=0.019) and overall survival (52.2 vs not reached P=0.022) than low/no amplification group. After adjusting for sex, smoking, stage, histology, and adjuvant treatment, high FGFR1 amplification had a greater risk of recurrence (adjusted hazard ratio [AHR], 1.6; P=0.029) and death (AHR, 1.53; P=0.050). High amplification was significantly higher in current smokers than former and never-smokers (Ptrend<0.001) and increased proportional to smoking dosage. High FGFR1 amplification is a frequent oncogenic alteration and an independent poor prognostic factor in resected ESCC. PMID:25537505

  3. Deterministic amplification of Schrödinger cat states in circuit quantum electrodynamics

    NASA Astrophysics Data System (ADS)

    Joo, Jaewoo; Elliott, Matthew; Oi, Daniel K. L.; Ginossar, Eran; Spiller, Timothy P.

    2016-02-01

    Perfect deterministic amplification of arbitrary quantum states is prohibited by quantum mechanics, but determinism can be achieved by compromising between fidelity and amplification power. We propose a dynamical scheme for deterministically amplifying photonic Schrödinger cat states, which show great promise as a tool for quantum information processing. Our protocol is designed for strongly coupled circuit quantum electrodynamics and utilizes artificial atomic states and external microwave controls to engineer a set of optimal state transfers and achieve high fidelity amplification. We compare analytical results with full simulations of the open, driven Jaynes-Cummings model, using realistic device parameters for state of the art superconducting circuits. Amplification with a fidelity of 0.9 can be achieved for sizable cat states in the presence of cavity and atomic-level decoherence. This tool could be applied to practical continuous-variable information processing for the purification and stabilization of cat states in the presence of photon losses.

  4. Field-Applicable Recombinase Polymerase Amplification Assay for Rapid Detection of Mycoplasma capricolum subsp. capripneumoniae

    PubMed Central

    Yu, Mingyan; O'Brien, Elizabeth; Heller, Martin; Nepper, Julia F.; Weibel, Douglas B.; Gluecks, Ilona; Younan, Mario; Frey, Joachim; Falquet, Laurent; Jores, Joerg

    2015-01-01

    Contagious caprine pleuropneumonia (CCPP) is a highly contagious disease caused by Mycoplasma capricolum subsp. capripneumoniae that affects goats in Africa and Asia. Current available methods for the diagnosis of Mycoplasma infection, including cultivation, serological assays, and PCR, are time-consuming and require fully equipped stationary laboratories, which make them incompatible with testing in the resource-poor settings that are most relevant to this disease. We report a rapid, specific, and sensitive assay employing isothermal DNA amplification using recombinase polymerase amplification (RPA) for the detection of M. capricolum subsp. capripneumoniae. We developed the assay using a specific target sequence in M. capricolum subsp. capripneumoniae, as found in the genome sequence of the field strain ILRI181 and the type strain F38 and that was further evidenced in 10 field strains from different geographical regions. Detection limits corresponding to 5 × 103 and 5 × 104 cells/ml were obtained using genomic DNA and bacterial culture from M. capricolum subsp. capripneumoniae strain ILRI181, while no amplification was obtained from 71 related Mycoplasma isolates or from the Acholeplasma or the Pasteurella isolates, demonstrating a high degree of specificity. The assay produces a fluorescent signal within 15 to 20 min and worked well using pleural fluid obtained directly from CCPP-positive animals without prior DNA extraction. We demonstrate that the diagnosis of CCPP can be achieved, with a short sample preparation time and a simple read-out device that can be powered by a car battery, in <45 min in a simulated field setting. PMID:26085615

  5. Field-Applicable Recombinase Polymerase Amplification Assay for Rapid Detection of Mycoplasma capricolum subsp. capripneumoniae.

    PubMed

    Liljander, Anne; Yu, Mingyan; O'Brien, Elizabeth; Heller, Martin; Nepper, Julia F; Weibel, Douglas B; Gluecks, Ilona; Younan, Mario; Frey, Joachim; Falquet, Laurent; Jores, Joerg

    2015-09-01

    Contagious caprine pleuropneumonia (CCPP) is a highly contagious disease caused by Mycoplasma capricolum subsp. capripneumoniae that affects goats in Africa and Asia. Current available methods for the diagnosis of Mycoplasma infection, including cultivation, serological assays, and PCR, are time-consuming and require fully equipped stationary laboratories, which make them incompatible with testing in the resource-poor settings that are most relevant to this disease. We report a rapid, specific, and sensitive assay employing isothermal DNA amplification using recombinase polymerase amplification (RPA) for the detection of M. capricolum subsp. capripneumoniae. We developed the assay using a specific target sequence in M. capricolum subsp. capripneumoniae, as found in the genome sequence of the field strain ILRI181 and the type strain F38 and that was further evidenced in 10 field strains from different geographical regions. Detection limits corresponding to 5 × 10(3) and 5 × 10(4) cells/ml were obtained using genomic DNA and bacterial culture from M. capricolum subsp. capripneumoniae strain ILRI181, while no amplification was obtained from 71 related Mycoplasma isolates or from the Acholeplasma or the Pasteurella isolates, demonstrating a high degree of specificity. The assay produces a fluorescent signal within 15 to 20 min and worked well using pleural fluid obtained directly from CCPP-positive animals without prior DNA extraction. We demonstrate that the diagnosis of CCPP can be achieved, with a short sample preparation time and a simple read-out device that can be powered by a car battery, in <45 min in a simulated field setting. PMID:26085615

  6. Separate TRP channels mediate amplification and transduction in drosophila

    NASA Astrophysics Data System (ADS)

    Lehnert, Brendan P.; Baker, Allison E.; Wilson, Rachel I.

    2015-12-01

    Auditory receptor cells rely on mechanically-gated channels to transform sound stimuli into neural activity. Several TRP channels have been implicated in Drosophila auditory transduction, but mechanistic studies have been hampered by the inability to record subthreshold signals from receptor neurons. We developed a non-invasive method for measuring these signals by recording from a central neuron that is electrically coupled to a genetically-defined population of auditory receptors. We find that the TRPN family member NompC, which is necessary for the active amplification of motion by the auditory organ, is not required for transduction. Instead, NompC sensitizes the transduction complex to movement and precisely regulates the static forces on the complex. In contrast, the TRPV channels Nanchung and Inactive are required for responses to sound, suggesting they are components of the transduction complex. Thus, transduction and active amplification are genetically separable processes in Drosophila hearing.

  7. A geostatistical approach to mapping site response spectral amplifications

    USGS Publications Warehouse

    Thompson, E.M.; Baise, L.G.; Kayen, R.E.; Tanaka, Y.; Tanaka, H.

    2010-01-01

    If quantitative estimates of the seismic properties do not exist at a location of interest then the site response spectral amplifications must be estimated from data collected at other locations. Currently, the most common approach employs correlations of site class with maps of surficial geology. Analogously, correlations of site class with topographic slope can be employed where the surficial geology is unknown. Our goal is to identify and validate a method to estimate site response with greater spatial resolution and accuracy for regions where additional effort is warranted. This method consists of three components: region-specific data collection, a spatial model for interpolating seismic properties, and a theoretical method for computing spectral amplifications from the interpolated seismic properties. We consider three spatial interpolation schemes: correlations with surficial geology, termed the geologic trend (GT), ordinary kriging (OK), and kriging with a trend (KT). We estimate the spectral amplifications from seismic properties using the square root of impedance method, thereby linking the frequency-dependent spectral amplifications to the depth-dependent seismic properties. Thus, the range of periods for which this method is applicable is limited by the depth of exploration. A dense survey of near-surface S-wave slowness (Ss) throughout Kobe, Japan shows that the geostatistical methods give more accurate estimates of Ss than the topographic slope and GT methods, and the OK and KT methods perform equally well. We prefer the KT model because it can be seamlessly integrated with geologic maps that cover larger regions. Empirical spectral amplifications show that the region-specific data achieve more accurate estimates of observed median short-period amplifications than the topographic slope method. ?? 2010 Elsevier B.V.

  8. Characterization of Gas Amplification in Varied Gas Mixtures for Stacked Gas Electron Multiplier and Micromegas Detectors

    NASA Astrophysics Data System (ADS)

    Ehlers, Raymond

    2015-04-01

    Micropattern Gas Detectors (MPGDs) represent a promising group of gas amplification technologies. Utilizing large electric fields over geometries on the order of tens of micrometers, these elements can achieve large gas amplification while minimizing field distortions by minimizing the number of ions escaping from the amplification stage. Such properties are extremely useful for readout in gaseous detectors such as Time Projection Chambers. Two types of MPGDs are of particular interest, Gas Electron Multipliers (GEMs) and Micro-mesh Gaseous Structure (Micromegas) detectors. These elements may be stacked, which allows for the utilization of the best properties of both, further improving the amplification performance. We report here on the characterization of 2 GEMs stacked on top of a Micromegas. In particular, I will present the dependence of gas amplification on Micromegas voltage in various gas mixtures, as well as an investigation into stability of the elements against sparking.

  9. Frequency domain optical parametric amplification

    PubMed Central

    Schmidt, Bruno E.; Thiré, Nicolas; Boivin, Maxime; Laramée, Antoine; Poitras, François; Lebrun, Guy; Ozaki, Tsuneyuki; Ibrahim, Heide; Légaré, François

    2014-01-01

    Today’s ultrafast lasers operate at the physical limits of optical materials to reach extreme performances. Amplification of single-cycle laser pulses with their corresponding octave-spanning spectra still remains a formidable challenge since the universal dilemma of gain narrowing sets limits for both real level pumped amplifiers as well as parametric amplifiers. We demonstrate that employing parametric amplification in the frequency domain rather than in time domain opens up new design opportunities for ultrafast laser science, with the potential to generate single-cycle multi-terawatt pulses. Fundamental restrictions arising from phase mismatch and damage threshold of nonlinear laser crystals are not only circumvented but also exploited to produce a synergy between increased seed spectrum and increased pump energy. This concept was successfully demonstrated by generating carrier envelope phase stable, 1.43 mJ two-cycle pulses at 1.8 μm wavelength. PMID:24805968

  10. Cross-triggered and cascaded recycling amplification for ultrasensitive electrochemical sensing of the mutant human p53 gene.

    PubMed

    Yang, Cuiyun; Dou, Baoting; Yang, Jianmei; Yuan, Ruo; Xiang, Yun

    2016-07-01

    Based on an endonuclease-assisted, cross-triggered and cascaded recycling amplification strategy, the construction of a simple electrochemical sensing platform for the ultrasensitive detection of the mutant p53 gene in human serum is described. Using this new signal amplification approach, the sub-femtomolar level of the mutant p53 gene can be selectively detected. PMID:27331773

  11. PCR-free and label-free fluorescent detection of telomerase activity at single-cell level based on triple amplification.

    PubMed

    Gao, Yanfang; Xu, Jing; Li, Baoxin; Jin, Yan

    2016-07-15

    As a universal biomarker for cancer diagnostics and cancer therapeutics, telomerase has attracted extensive attention concerning its detection and discovery of its inhibitors. Herein, we developed a PCR-free and label-free fluorescent strategy for facile, reliable and highly sensitive assay of human telomerase activity from crude cancer cell extracts. A G-quadruplex-selective fluorescent dye, N-methyl mesoporphyrin IX (NMM), was utilized as signal probe. Two hairpin probes with hidden G-quadruplex strand in their stem were designed as assembly components of strand displacement reaction (SDR). In this strategy, one telomerase elongation product contains several hexamer repeats which can hybridize with numerous assistant DNA to release a lot of trigger DNA (T-DNA) of SDR for achieving first step amplification. Then, strand displacement reaction led to the formation of G-quadruplex at the both end of two hairpin DNA probes for realizing second step amplification. Finally, the re-released T-DNA initiated another cycle of SDR, resulting in a significant increase in the fluorescence intensity of NMM. By taking advantage of triple signal amplification, the telomerase activity in the HeLa extracts equivalent to 1-3000 cells was detected in homogeneous solution. Telomerase activities of different cell lines, including cancer cells and normal cell, were also successfully evaluated. Meanwhile, the inhibition effect of 3'-azido-3'-deoxythymidine (AZT) was also investigated. Therefore, it offers a simple and reliable method for detecting telomerase activity at single-cell level without complex pre-modification of probe and enzyme auxiliary signal amplification, which has the merits of simplicity, rapid response, low cost and high reliability. PMID:26999622

  12. Unidirectional Mechanical Amplification as a Design Principle for an Active Microphone

    NASA Astrophysics Data System (ADS)

    Reichenbach, Tobias; Hudspeth, A. J.

    2011-04-01

    Amplification underlies the operation of many biological and engineering systems. Simple electrical, optical, and mechanical amplifiers are reciprocal: the backward coupling of the output to the input equals the forward coupling of the input to the output. Unidirectional amplifiers that occur often in electrical and optical systems are special nonreciprocal devices in which the output does not couple back to the input even though the forward coupling persists. Here we propose a scheme for unidirectional mechanical amplification that we utilize to construct an active microphone. We show that amplification improves the microphone’s threshold for detecting weak signals and that unidirectionality prevents distortion.

  13. Theory of energy gain in a laser-amplifier based on a photon-branched chain reaction: Auto-wave amplification mode under the condition of input signal focusing

    NASA Astrophysics Data System (ADS)

    Letfullin, Renat R.; George, Thomas F.

    2000-10-01

    Huge energy gain is detected theoretically in a pulsed chemical laser amplifier based on a photon-branched chain reaction initiating in a gaseous disperse medium composed of H2-F2-O2-He and Al particles by focused external infrared radiation. It is shown that this effect is observed due to the possibility of the ignition of the laser-chemical reaction into an initial small focal volume of an active medium. It then spreads out of this minimal volume spontaneously in the auto-wave regime without external power sources and subsequently fills the whole volume of the laser cavity with a high intensive electromagnetic field as self-supporting cylindrical photon-branching zones formed by the paths of the rays inside the unstable telescopic cavity. Calculations show that the ignition of an auto-wave photon-branched chain reaction under the condition of external signal focusing strongly reduces the input pulse energy necessary for initiation up to ˜10-8 J, and thereby allows a huge value of the energy gain of ˜1011. The observed effect of this huge laser energy gain makes it possible to construct a self-contained laser with kilojoule output energy, which can be initiated by a very weak source signal.

  14. Parametric amplification in AgGaSe2

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Gettemy, Donald J.; Hietanen, Jack R.; Iannini, Rebecca A.

    1989-01-01

    AgGaSe2 has been grown, annealed, and characterized for the mid-IR. Characterization includes measurement of the average power-limiting factors including absorption and the variation of the refractive indices with temperature. Using specially annealed crystals 20 mm long and a Ho:YAG pump, parametric amplification at 3.39 microns has achieved a gain of 2.9 with a peak power input of only 8 MW/sq cm.

  15. Methods and devices based on brillouin selective sideband amplification

    NASA Technical Reports Server (NTRS)

    Yao, X. Steve (Inventor)

    2003-01-01

    Opto-electronic devices and techniques using Brillouin scattering to select a sideband in a modulated optical carrier signal for amplification. Two lasers respectively provide a carrier signal beam and a Brillouin pump beam which are fed into an Brillouin optical medium in opposite directions. The relative frequency separation between the lasers is adjusted to align the frequency of the backscattered Brillouin signal with a desired sideband in the carrier signal to effect a Brillouin gain on the sideband. This effect can be used to implement photonic RF signal mixing and conversion with gain, conversion from phase modulation to amplitude modulation, photonic RF frequency multiplication, optical and RF pulse generation and manipulation, and frequency-locking of lasers.

  16. Brillouin Amplification--A Powerful New Scheme for Microwave Photonic Communications

    NASA Technical Reports Server (NTRS)

    Yao, S.; Maleki, L.

    1997-01-01

    We introduce the Brillouin selective sideband amplification technique and demonstrate many important applications of this technique in photonic microwave systems, including efficient phase modulation to amplitude modulation conversion, photonic frequency multiplication, photonic signal mixing with gain, and frequency multiplied signal up conversion.

  17. High peak-power kilohertz laser system employing single-stage multi-pass amplification

    DOEpatents

    Shan, Bing; Wang, Chun; Chang, Zenghu

    2006-05-23

    The present invention describes a technique for achieving high peak power output in a laser employing single-stage, multi-pass amplification. High gain is achieved by employing a very small "seed" beam diameter in gain medium, and maintaining the small beam diameter for multiple high-gain pre-amplification passes through a pumped gain medium, then leading the beam out of the amplifier cavity, changing the beam diameter and sending it back to the amplifier cavity for additional, high-power amplification passes through the gain medium. In these power amplification passes, the beam diameter in gain medium is increased and carefully matched to the pump laser's beam diameter for high efficiency extraction of energy from the pumped gain medium. A method of "grooming" the beam by means of a far-field spatial filter in the process of changing the beam size within the single-stage amplifier is also described.

  18. Envelope matching for enhanced backward Raman amplification by using self-ionizing plasmas

    SciTech Connect

    Zhang, Z. M.; Zhang, B.; Hong, W.; Teng, J.; He, S. K.; Gu, Y. Q.; Yu, M. Y.

    2014-12-15

    Backward Raman amplification (BRA) in plasmas has been promoted as a means for generating ultrapowerful laser pulses. For the purpose of achieving the maximum intensities over the shortest distances, an envelope matching between the seed pulse and the amplification gain is required, i.e., the seed pulse propagates at the same velocity with the gain such that the peak of the seed pulse can always enjoy the maximum gain. However, such an envelope matching is absent in traditional BRA because in the latter the amplification gain propagates at superluminous velocity while the seed pulse propagates at the group velocity, which is less than the speed of light. It is shown here that, by using self-ionizing plasmas, the speed of the amplification gain can be well reduced to reach the envelope matching regime. This results in a favorable BRA process, in which higher saturated intensity, shorter interaction length and higher energy-transfer efficiency are achieved.

  19. SOLITONS AND OPTICAL FIBERS: On the problem of ideal amplification of optical solitons

    NASA Astrophysics Data System (ADS)

    Melo Melchor, G.; Agüero Granados, M.; Corro, G. H.

    2002-11-01

    The new possibilities of almost ideal amplification of optical solitons during the incoherent interaction of light pulses with a resonantly amplifying medium are considered. The mechanism of two-photon amplification of optical solitons with an optimal frequency-modulation law is proposed. It is shown that the entirely ideal amplification of solitons cannot be achieved because the law of phase modulation of radiation differs from a parabolic law. The possibility of using the phase cross modulation to produce the required initial phase of amplified solitons is studied.

  20. Telomerase Repeated Amplification Protocol (TRAP)

    PubMed Central

    Mender, Ilgen; Shay, Jerry W.

    2016-01-01

    Telomeres are found at the end of eukaryotic linear chromosomes, and proteins that bind to telomeres protect DNA from being recognized as double-strand breaks thus preventing end-to-end fusions (Griffith et al., 1999). However, due to the end replication problem and other factors such as oxidative damage, the limited life span of cultured cells (Hayflick limit) results in progressive shortening of these protective structures (Hayflick and Moorhead, 1961; Olovnikov, 1973). The ribonucleoprotein enzyme complex telomerase-consisting of a protein catalytic component hTERT and a functional RNA component hTR or hTERC- counteracts telomere shortening by adding telomeric repeats to the end of chromosomes in ~90% of primary human tumors and in some transiently proliferating stem-like cells (Shay and Wright, 1996; Shay and Wright, 2001). This results in continuous proliferation of cells which is a hallmark of cancer. Therefore, telomere biology has a central role in aging, cancer progression/metastasis as well as targeted cancer therapies. There are commonly used methods in telomere biology such as Telomere Restriction Fragment (TRF) (Mender and Shay, 2015b), Telomere Repeat Amplification Protocol (TRAP) and Telomere dysfunction Induced Foci (TIF) analysis (Mender and Shay, 2015a). In this detailed protocol we describe Telomere Repeat Amplification Protocol (TRAP). The TRAP assay is a popular method to determine telomerase activity in mammalian cells and tissue samples (Kim et al., 1994). The TRAP assay includes three steps: extension, amplification, and detection of telomerase products. In the extension step, telomeric repeats are added to the telomerase substrate (which is actually a non telomeric oligonucleotide, TS) by telomerase. In the amplification step, the extension products are amplified by the polymerase chain reaction (PCR) using specific primers (TS upstream primer and ACX downstream primer) and in the detection step, the presence or absence of telomerase is

  1. Resonant primordial gravitational waves amplification

    NASA Astrophysics Data System (ADS)

    Lin, Chunshan; Sasaki, Misao

    2016-01-01

    We propose a mechanism to evade the Lyth bound in models of inflation. We minimally extend the conventional single-field inflation model in general relativity (GR) to a theory with non-vanishing graviton mass in the very early universe. The modification primarily affects the tensor perturbation, while the scalar and vector perturbations are the same as the ones in GR with a single scalar field at least at the level of linear perturbation theory. During the reheating stage, the graviton mass oscillates coherently and leads to resonant amplification of the primordial tensor perturbation. After reheating the graviton mass vanishes and we recover GR.

  2. Heralded amplification of photonic qubits.

    PubMed

    Bruno, Natalia; Pini, Vittorio; Martin, Anthony; Verma, Varun B; Nam, Sae Woo; Mirin, Richard; Lita, Adriana; Marsili, Francesco; Korzh, Boris; Bussières, Félix; Sangouard, Nicolas; Zbinden, Hugo; Gisin, Nicolas; Thew, Rob

    2016-01-11

    We demonstrate postselection free heralded qubit amplification for Time-Bin qubits and single photon states in an all-fibre, telecom-wavelength, scheme that highlights the simplicity, stability and potential for fully integrated photonic solutions. Exploiting high-efficiency superconducting detectors, the gain, fidelity and the performance of the amplifier are studied as a function of loss. We also demonstrate the first heralded single photon amplifier with independent sources. This provides a significant advance towards demonstrating device-independent quantum key distribution as well as fundamental tests of quantum mechanics over extended distances. PMID:26832244

  3. Chemical Amplification with Encapsulated Reagents

    NASA Technical Reports Server (NTRS)

    Chen, Jian; Koemer, Steffi; Craig, Stephen; Lin, Shirley; Rudkevich, Dmitry M.; Rebek, Julius, Jr.

    2002-01-01

    Autocatalysis and chemical amplification are characteristic properties of living systems, and they give rise to behaviors such as increased sensitivity, responsiveness, and self-replication. Here we report a synthetic system in which a unique form of compartmentalization leads to nonlinear, autocatalytic behavior. The compartment is a reversibly formed capsule in which a reagent is sequestered. Reaction products displace the reagent from the capsule into solution and the reaction rate is accelerated. The resulting self-regulation is sensitive to the highly selective molecular recognition properties of the capsule.

  4. Label-free electrochemical nucleic acid biosensing by tandem polymerization and cleavage-mediated cascade target recycling and DNAzyme amplification.

    PubMed

    Liu, Shufeng; Gong, Hongwei; Wang, Yanqun; Wang, Li

    2016-03-15

    Owing to the intrinsic importance of nucleic acid as bio-targets, the achievement of its simple and sensitive detection with high confidence is very essential for biological studies and diagnostic purposes. Herein, a label-free, isothermal, and ultrasensitive electrochemical detection of target DNA was developed by using a tandem polymerization and cleavage-mediated cascade target recycling and DNAzyme releasing amplification strategy. Upon sensing of the nucleic acid analyte for the assembled hairpin-like probe DNA on the electrode, the DNA polymerase guided the target recycling and simultaneously triggered the lambda exonuclease cleavage, accompanied by the cascade recycling of the released new complementary strand and the amplified liberation of the G-rich sequence of the HRP-mimicking DNAzyme. The electrocatalytic reduction of H2O2 by the generated hemin/G-quadruplex DNAzyme was used for the signal readout and further amplification toward target response. Such tandem functional operation by DNA polymerase, lambda exonuclease and DNAzyme endows the developed biosensor with a high sensitivity and also a high confidence. A low detection limit of 5 fM with an excellent selectivity toward target DNA could be achieved. It also exhibits the distinct advantages of simplicity in probe design and biosensor fabrication, and label-free electrochemical detection, thus may offer a promising avenue for the applications in disease diagnosis and clinical biomedicine. PMID:26513289

  5. Low noise, low heat dissipation, high gain AC-DC front end amplification for scanning probe microscopy.

    SciTech Connect

    Messina, P.; Fradin, F. Y.; Pittana, P.

    2009-01-01

    We report here on the design, construction and testing of a vacuum compatible AC-DC amplification system for low signal measurements with scanning probes. The most important feature of this new amplification system is incorporated within the head of a scanning tunneling microscope (STM). This is achieved with a very low thermal dissipation radio frequency amplifier at the STM head. The amplifier gain is higher than 40 dB and has a 50 dB maximum. Further, the AC noise figure is 0.7 dB between 100 and 1000 MHz. The noise induced in the DC amplifier is less than 2 pA RMS (root mean square), which enables the microscope to scan over soft insulating molecular layers. Thermal drift at the STM tip-sample interface is below 0.1 nm min{sup -1} both in air and in vacuum operation. Atomic resolution on highly oriented pyrolytic graphite surfaces is reliably achieved. Spin noise measurements are provided as an example of an application.

  6. Quantum-coherence-enhanced surface plasmon amplification by stimulated emission of radiation.

    PubMed

    Dorfman, Konstantin E; Jha, Pankaj K; Voronine, Dmitri V; Genevet, Patrice; Capasso, Federico; Scully, Marlan O

    2013-07-26

    We investigate surface plasmon amplification in a silver nanoparticle coupled to an externally driven three-level gain medium and show that quantum coherence significantly enhances the generation of surface plasmons. Surface plasmon amplification by stimulated emission of radiation is achieved in the absence of population inversion on the spasing transition, which reduces the pump requirements. The coherent drive allows us to control the dynamics and holds promise for quantum control of nanoplasmonic devices. PMID:23931365

  7. Brief review of monitoring methods for loop-mediated isothermal amplification (LAMP).

    PubMed

    Zhang, Xuzhi; Lowe, Stuart B; Gooding, John Justin

    2014-11-15

    The loop-mediated isothermal amplification (LAMP) technique has the potential to revolutionize molecular biology because it allows DNA amplification under isothermal conditions and is highly compatible with point-of-care analysis. To achieve efficient genetic analysis of samples, the method of real-time or endpoint determination selected to monitor the biochemical reaction is of great importance. In this paper we briefly review progress in the development of monitoring methods for LAMP. PMID:24949822

  8. Universal nucleic acid sequence-based amplification for simultaneous amplification of messengerRNAs and microRNAs.

    PubMed

    Mader, Andreas; Riehle, Ulrike; Brandstetter, Thomas; Stickeler, Elmar; Ruehe, Juergen

    2012-11-19

    A universal NASBA assay is presented for simultaneous amplification of multiple microRNA (miRNA) and messengerRNA (mRNA) sequences. First, miRNA and mRNA sequences are reverse transcribed using tailed reverse transcription primer pairs containing a gene-specific and an non-specific region. For reverse transcription of small miRNA molecules a non-specific region is incorporated into a structured stem-loop reverse transcription primer. Second, a universal NASBA primer pair that recognizes the tagged cDNA molecules enables a simultaneous, transcription-based amplification reaction (NASBA) of all different cDNA molecules in one reaction. The NASBA products (RNA copies) are detected by gene-specific DNA probes immobilized on a biochip. By using the multiplex reverse transcription combined with the universal NASBA amplification up to 14 different mRNA and miRNA sequences can be specifically amplified and detected in parallel. In comparison with standard multiplex NASBA assays this approach strongly enhances the multiplex capacity of NASBA-based amplification reactions. Furthermore simultaneous assaying of different RNA classes can be achieved that might be beneficial for studying miRNA-based regulation of gene expression or for RNA-based tumor diagnostics. PMID:23140948

  9. Bacteriophage Amplification-Coupled Detection and Identification of Bacterial Pathogens

    NASA Astrophysics Data System (ADS)

    Cox, Christopher R.; Voorhees, Kent J.

    Current methods of species-specific bacterial detection and identification are complex, time-consuming, and often require expensive specialized equipment and highly trained personnel. Numerous biochemical and genotypic identification methods have been applied to bacterial characterization, but all rely on tedious microbiological culturing practices and/or costly sequencing protocols which render them impractical for deployment as rapid, cost-effective point-of-care or field detection and identification methods. With a view towards addressing these shortcomings, we have exploited the evolutionarily conserved interactions between a bacteriophage (phage) and its bacterial host to develop species-specific detection methods. Phage amplification-coupled matrix assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS) was utilized to rapidly detect phage propagation resulting from species-specific in vitro bacterial infection. This novel signal amplification method allowed for bacterial detection and identification in as little as 2 h, and when combined with disulfide bond reduction methods developed in our laboratory to enhance MALDI-TOF-MS resolution, was observed to lower the limit of detection by several orders of magnitude over conventional spectroscopy and phage typing methods. Phage amplification has been combined with lateral flow immunochromatography (LFI) to develop rapid, easy-to-operate, portable, species-specific point-of-care (POC) detection devices. Prototype LFI detectors have been developed and characterized for Yersinia pestis and Bacillus anthracis, the etiologic agents of plague and anthrax, respectively. Comparable sensitivity and rapidity was observed when phage amplification was adapted to a species-specific handheld LFI detector, thus allowing for rapid, simple, POC bacterial detection and identification while eliminating the need for bacterial culturing or DNA isolation and amplification techniques.

  10. Amplification of ultra-short laser pulses via resonant backward Raman amplification in plasma

    NASA Astrophysics Data System (ADS)

    Mishra, S. K.; Andreev, A.

    2016-08-01

    In this paper, we have examined the possibility of using resonant backward Raman amplification (BRA) as an efficient mechanism in amplifying the low intensity ultra-short ( ≤ fs ) pulses using plasma as intermediate amplifying medium; such pulses are anticipated to get produced in the form of the secondary sources at ALPS (Attosecond Light Pulse Source) center of ELI (Extreme Light Infrastructure). In preliminary assessment of the scheme, the analytical expressions for the pump/seed laser pulses and plasma characteristic features are obtained which concisely describe the parameter regime of resonant BRA applicability in achieving significant amplification. The consistency of the scheme in the context of ELI-ALPS sources has been validated through particle in cell (PIC) simulations. The peak intensity of the amplified seed pulse predicted via simulation results is found in reasonable agreement with the analytical estimates. Utilizing these analytical expressions as a basis in perspective of ELI-ALPS parameter access, a specific example displaying the key plasma and laser parameters for amplifying weak seed pulse has been configured; the limitations and conceivable remedies in resonant BRA implementation have also been highlighted.

  11. Antigen receptor signaling: integration of protein tyrosine kinase functions.

    PubMed

    Tamir, I; Cambier, J C

    1998-09-17

    through these receptors are propagated and modified by accessory molecules, and discuss how signal amplification and diversification are achieved. PMID:9779983

  12. Dynamics and control of DNA sequence amplification

    SciTech Connect

    Marimuthu, Karthikeyan; Chakrabarti, Raj E-mail: rajc@andrew.cmu.edu

    2014-10-28

    DNA amplification is the process of replication of a specified DNA sequence in vitro through time-dependent manipulation of its external environment. A theoretical framework for determination of the optimal dynamic operating conditions of DNA amplification reactions, for any specified amplification objective, is presented based on first-principles biophysical modeling and control theory. Amplification of DNA is formulated as a problem in control theory with optimal solutions that can differ considerably from strategies typically used in practice. Using the Polymerase Chain Reaction as an example, sequence-dependent biophysical models for DNA amplification are cast as control systems, wherein the dynamics of the reaction are controlled by a manipulated input variable. Using these control systems, we demonstrate that there exists an optimal temperature cycling strategy for geometric amplification of any DNA sequence and formulate optimal control problems that can be used to derive the optimal temperature profile. Strategies for the optimal synthesis of the DNA amplification control trajectory are proposed. Analogous methods can be used to formulate control problems for more advanced amplification objectives corresponding to the design of new types of DNA amplification reactions.

  13. Dynamics and control of DNA sequence amplification

    NASA Astrophysics Data System (ADS)

    Marimuthu, Karthikeyan; Chakrabarti, Raj

    2014-10-01

    DNA amplification is the process of replication of a specified DNA sequence in vitro through time-dependent manipulation of its external environment. A theoretical framework for determination of the optimal dynamic operating conditions of DNA amplification reactions, for any specified amplification objective, is presented based on first-principles biophysical modeling and control theory. Amplification of DNA is formulated as a problem in control theory with optimal solutions that can differ considerably from strategies typically used in practice. Using the Polymerase Chain Reaction as an example, sequence-dependent biophysical models for DNA amplification are cast as control systems, wherein the dynamics of the reaction are controlled by a manipulated input variable. Using these control systems, we demonstrate that there exists an optimal temperature cycling strategy for geometric amplification of any DNA sequence and formulate optimal control problems that can be used to derive the optimal temperature profile. Strategies for the optimal synthesis of the DNA amplification control trajectory are proposed. Analogous methods can be used to formulate control problems for more advanced amplification objectives corresponding to the design of new types of DNA amplification reactions.

  14. An evaluation of direct PCR amplification

    PubMed Central

    Hall, Daniel E.; Roy, Reena

    2014-01-01

    Aim To generate complete DNA profiles from blood and saliva samples deposited on FTA® and non-FTA® paper substrates following a direct amplification protocol. Methods Saliva samples from living donors and blood samples from deceased individuals were deposited on ten different FTA® and non-FTA® substrates. These ten paper substrates containing body fluids were kept at room temperature for varying lengths of time ranging from one day to approximately one year. For all assays in this research, 1.2 mm punches were collected from each substrate containing one type of body fluid and amplified with reagents provided in the nine commercial polymerase chain reaction (PCR) amplification kits. The substrates were not subjected to purification reagent or extraction buffer prior to amplification. Results Success rates were calculated for all nine amplification kits and all ten substrates based on their ability to yield complete DNA profiles following a direct amplification protocol. Six out of the nine amplification kits, and four out of the ten paper substrates had the highest success rates overall. Conclusion The data show that it is possible to generate complete DNA profiles following a direct amplification protocol using both standard (non-direct) and direct PCR amplification kits. The generation of complete DNA profiles appears to depend more on the success of the amplification kit rather than the than the FTA®- or non-FTA®-based substrates. PMID:25559837

  15. Trophic amplification of climate warming

    PubMed Central

    Kirby, Richard R.; Beaugrand, Gregory

    2009-01-01

    Ecosystems can alternate suddenly between contrasting persistent states due to internal processes or external drivers. It is important to understand the mechanisms by which these shifts occur, especially in exploited ecosystems. There have been several abrupt marine ecosystem shifts attributed either to fishing, recent climate change or a combination of these two drivers. We show that temperature has been an important driver of the trophodynamics of the North Sea, a heavily fished marine ecosystem, for nearly 50 years and that a recent pronounced change in temperature established a new ecosystem dynamic regime through a series of internal mechanisms. Using an end-to-end ecosystem approach that included primary producers, primary, secondary and tertiary consumers, and detritivores, we found that temperature modified the relationships among species through nonlinearities in the ecosystem involving ecological thresholds and trophic amplifications. Trophic amplification provides an alternative mechanism to positive feedback to drive an ecosystem towards a new dynamic regime, which in this case favours jellyfish in the plankton and decapods and detritivores in the benthos. Although overfishing is often held responsible for marine ecosystem degeneration, temperature can clearly bring about similar effects. Our results are relevant to ecosystem-based fisheries management (EBFM), seen as the way forward to manage exploited marine ecosystems. PMID:19740882

  16. Nanoparticle amplification via photothermal unveiling of cryptic collagen binding sites

    PubMed Central

    Lo, Justin H.; von Maltzahn, Geoffrey; Douglass, Jacqueline; Park, Ji-Ho; Sailor, Michael J.; Ruoslahti, Erkki

    2013-01-01

    The success of nanoparticle-based cancer therapies ultimately depends on their ability to selectively and efficiently accumulate in regions of disease. Outfitting nanoparticles to actively target tumor-specific markers has improved specificity, yet it remains a challenge to amass adequate therapy in a selective manner. To help address this challenge, we have developed a mechanism of nanoparticle amplification based on stigmergic (environment-modifying) signalling, in which a “Signalling” population of gold nanorods induces localized unveiling of cryptic collagen epitopes, which are in turn targeted by “Responding” nanoparticles bearing gelatin-binding fibronectin fragments. We demonstrate that this two-particle system results in significantly increased, selective recruitment of responding particles. Such amplification strategies have the potential to overcome limitations associated with single-particle targeting by leveraging the capacity of nanoparticles to interact with their environment to create abundant new binding motifs. PMID:24177171

  17. Narrow band amplification of light carrying orbital angular momentum.

    PubMed

    Borba, G C; Barreiro, S; Pruvost, L; Felinto, D; Tabosa, J W R

    2016-05-01

    We report on the amplification of an optical vortex beam carrying orbital angular momentum via induced narrow Raman gain in an ensemble of cold cesium atoms. A 20% single-pass Raman gain of a weak vortex signal field is observed with a spectral width of order of 1 MHz, much smaller than the natural width, demonstrating that the amplification process preserves the phase structure of the vortex beam. The gain is observed in the degenerated two-level system associated with the hyperfine transition 6S1/2(F = 3) ↔ 6P3/2(F' = 2) of cesium. Our experimental observations are explained with a simple theoretical model based on a three-level Λ system interacting coherently with the weak Laguerre-Gauss field and a strong coupling field, including an incoherent pumping rate between the two degenerate ground-states. PMID:27137618

  18. Tsunami Amplification due to Focusing

    NASA Astrophysics Data System (ADS)

    Moore, C. W.; Kanoglu, U.; Titov, V. V.; Aydin, B.; Spillane, M. C.; Synolakis, C. E.

    2012-12-01

    Tsunami runup measurements over the periphery of the Pacific Ocean after the devastating Great Japan tsunami of 11 March 2011 showed considerable variation in far-field and near-field impact. This variation of tsunami impact have been attributed to either directivity of the source or by local topographic effects. Directivity arguments alone, however, cannot explain the complexity of the radiated patterns in oceans with trenches and seamounts. Berry (2007, Proc. R. Soc. Lond. A 463, 3055-3071) discovered how such underwater features may concentrate tsunamis into cusped caustics and thus cause large local amplifications at specific focal points. Here, we examine focusing and local amplification, not by considering the effects of underwater diffractive lenses, but by considering the details of the dipole nature of the initial profile, and propose that certain regions of coastline are more at-risk, not simply because of directivity but because typical tsunami deformations create focal regions where abnormal tsunami wave height can be registered (Marchuk and Titov, 1989, Proc. IUGG/IOC International Tsunami Symposium, Novosibirsk, USSR). In this work, we present a new general analytical solution of the linear shallow-water wave equation for the propagation of a finite-crest-length source over a constant depth without any restriction on the initial profile. Unlike the analytical solution of Carrier and Yeh (2005, Comp. Mod. Eng. & Sci. 10(2), 113-121) which was restricted to initial conditions with Gaussian profiles and involved approximation, our solution is not only exact, but also general and allows the use of realistic initial waveform such as N-waves as defined by Tadepalli and Synolakis (1994, Proc. R. Soc. Lond. A 445, 99-112). We then verify our analytical solution for several typical wave profiles, both with the NOAA tsunami forecast model MOST (Titov and Synolakis, 1998, J. Waterw. Port Coast. Ocean Eng. 124(4), 157-171) which is validated and verified through

  19. Raman amplification in plasma: Wavebreaking and heating effects

    SciTech Connect

    Farmer, J. P.; Ersfeld, B.; Jaroszynski, D. A.

    2010-11-15

    A three-wave model has been developed to investigate the influence of wavebreaking and thermal effects on the Raman amplification in plasma. This has been benchmarked against a particle-in-cell code with positive results. A new regime, the 'thermal chirp' regime, has been identified and illustrated. Here the shift in plasma resonance due to heating of the plasma by a monochromatic pump allows a probe pulse to be amplified and compressed without significant pump depletion. In regimes where damping dominates, it is found that inverse bremsstrahlung dominates at high densities, and improved growth rates may be achieved by preheating the plasma. At low densities or high pump intensities, wavebreaking acts to limit amplification. The inclusion of thermal effects can dramatically reduce the peak attainable intensity because of the reduced wavebreaking limit at finite temperatures.

  20. Measurement-based noiseless linear amplification for quantum communication

    NASA Astrophysics Data System (ADS)

    Chrzanowski, Helen M.; Walk, Nathan; Assad, Syed M.; Janousek, Jiri; Hosseini, Sara; Ralph, Timothy C.; Symul, Thomas; Lam, Ping Koy

    2014-04-01

    Entanglement distillation is an indispensable ingredient in extended quantum communication networks. Distillation protocols are necessarily non-deterministic and require advanced experimental techniques such as noiseless amplification. Recently, it was shown that the benefits of noiseless amplification could be extracted by performing a post-selective filtering of the measurement record to improve the performance of quantum key distribution. We apply this protocol to entanglement degraded by transmission loss of up to the equivalent of 100 km of optical fibre. We measure an effective entangled resource stronger than that achievable by even a maximally entangled resource passively transmitted through the same channel. We also provide a proof-of-principle demonstration of secret key extraction from an otherwise insecure regime. The measurement-based noiseless linear amplifier offers two advantages over its physical counterpart: ease of implementation and near-optimal probability of success. It should provide an effective and versatile tool for a broad class of entanglement-based quantum communication protocols.

  1. Divided-pulse nonlinear amplification and simultaneous compression

    SciTech Connect

    Hao, Qiang; Zhang, Qingshan; Sun, Tingting; Chen, Jie; Wang, Yuqing; Guo, Zhengru; Yang, Kangwen; Guo, Zhanhua; Zeng, Heping

    2015-03-09

    We report on a fiber laser system delivering 122 fs pulse duration and 600 mW average power at 1560 nm by the interplay between divided pulse amplification and nonlinear pulse compression. A small-core double-clad erbium-doped fiber with anomalous dispersion carries out the pulse amplification and simultaneously compresses the laser pulses such that a separate compressor is no longer necessary. A numeric simulation reveals the existence of an optimum fiber length for producing transform-limited pulses. Furthermore, frequency doubling to 780 nm with 240 mW average power and 98 fs pulse duration is achieved by using a periodically poled lithium niobate crystal at room temperature.

  2. Digital Droplet Multiple Displacement Amplification (ddMDA) for Whole Genome Sequencing of Limited DNA Samples

    PubMed Central

    Rhee, Minsoung; Light, Yooli K.; Meagher, Robert J.; Singh, Anup K.

    2016-01-01

    Multiple displacement amplification (MDA) is a widely used technique for amplification of DNA from samples containing limited amounts of DNA (e.g., uncultivable microbes or clinical samples) before whole genome sequencing. Despite its advantages of high yield and fidelity, it suffers from high amplification bias and non-specific amplification when amplifying sub-nanogram of template DNA. Here, we present a microfluidic digital droplet MDA (ddMDA) technique where partitioning of the template DNA into thousands of sub-nanoliter droplets, each containing a small number of DNA fragments, greatly reduces the competition among DNA fragments for primers and polymerase thereby greatly reducing amplification bias. Consequently, the ddMDA approach enabled a more uniform coverage of amplification over the entire length of the genome, with significantly lower bias and non-specific amplification than conventional MDA. For a sample containing 0.1 pg/μL of E. coli DNA (equivalent of ~3/1000 of an E. coli genome per droplet), ddMDA achieves a 65-fold increase in coverage in de novo assembly, and more than 20-fold increase in specificity (percentage of reads mapping to E. coli) compared to the conventional tube MDA. ddMDA offers a powerful method useful for many applications including medical diagnostics, forensics, and environmental microbiology. PMID:27144304

  3. Digital Droplet Multiple Displacement Amplification (ddMDA) for Whole Genome Sequencing of Limited DNA Samples.

    PubMed

    Rhee, Minsoung; Light, Yooli K; Meagher, Robert J; Singh, Anup K

    2016-01-01

    Multiple displacement amplification (MDA) is a widely used technique for amplification of DNA from samples containing limited amounts of DNA (e.g., uncultivable microbes or clinical samples) before whole genome sequencing. Despite its advantages of high yield and fidelity, it suffers from high amplification bias and non-specific amplification when amplifying sub-nanogram of template DNA. Here, we present a microfluidic digital droplet MDA (ddMDA) technique where partitioning of the template DNA into thousands of sub-nanoliter droplets, each containing a small number of DNA fragments, greatly reduces the competition among DNA fragments for primers and polymerase thereby greatly reducing amplification bias. Consequently, the ddMDA approach enabled a more uniform coverage of amplification over the entire length of the genome, with significantly lower bias and non-specific amplification than conventional MDA. For a sample containing 0.1 pg/μL of E. coli DNA (equivalent of ~3/1000 of an E. coli genome per droplet), ddMDA achieves a 65-fold increase in coverage in de novo assembly, and more than 20-fold increase in specificity (percentage of reads mapping to E. coli) compared to the conventional tube MDA. ddMDA offers a powerful method useful for many applications including medical diagnostics, forensics, and environmental microbiology. PMID:27144304

  4. Digital droplet multiple displacement amplification (ddMDA) for whole genome sequencing of limited DNA samples

    DOE PAGESBeta

    Rhee, Minsoung; Light, Yooli K.; Meagher, Robert J.; Singh, Anup K.; Kumar-Sinha, Chandan

    2016-05-04

    Here, multiple displacement amplification (MDA) is a widely used technique for amplification of DNA from samples containing limited amounts of DNA (e.g., uncultivable microbes or clinical samples) before whole genome sequencing. Despite its advantages of high yield and fidelity, it suffers from high amplification bias and non-specific amplification when amplifying sub-nanogram of template DNA. Here, we present a microfluidic digital droplet MDA (ddMDA) technique where partitioning of the template DNA into thousands of sub-nanoliter droplets, each containing a small number of DNA fragments, greatly reduces the competition among DNA fragments for primers and polymerase thereby greatly reducing amplification bias. Consequently,more » the ddMDA approach enabled a more uniform coverage of amplification over the entire length of the genome, with significantly lower bias and non-specific amplification than conventional MDA. For a sample containing 0.1 pg/μL of E. coli DNA (equivalent of ~3/1000 of an E. coli genome per droplet), ddMDA achieves a 65-fold increase in coverage in de novo assembly, and more than 20-fold increase in specificity (percentage of reads mapping to E. coli) compared to the conventional tube MDA. ddMDA offers a powerful method useful for many applications including medical diagnostics, forensics, and environmental microbiology.« less

  5. Amplification without instability: applying fluid dynamical insights in chemistry and biology

    NASA Astrophysics Data System (ADS)

    McCoy, Jonathan H.

    2013-11-01

    While amplification of small perturbations often arises from instability, transient amplification is possible locally even in asymptotically stable systems. That is, knowledge of a system's stability properties can mislead one's intuition for its transient behaviors. This insight, which has an interesting history in fluid dynamics, has more recently been rediscovered in ecology. Surprisingly, many nonlinear fluid dynamical and ecological systems share linear features associated with transient amplification of noise. This paper aims to establish that these features are widespread in many other disciplines concerned with noisy systems, especially chemistry, cell biology and molecular biology. Here, using classic nonlinear systems and the graphical language of network science, we explore how the noise amplification problem can be reframed in terms of activatory and inhibitory interactions between dynamical variables. The interaction patterns considered here are found in a great variety of systems, ranging from autocatalytic reactions and activator-inhibitor systems to influential models of nerve conduction, glycolysis, cell signaling and circadian rhythms.

  6. Multiscale image contrast amplification (MUSICA)

    NASA Astrophysics Data System (ADS)

    Vuylsteke, Pieter; Schoeters, Emile P.

    1994-05-01

    This article presents a novel approach to the problem of detail contrast enhancement, based on multiresolution representation of the original image. The image is decomposed into a weighted sum of smooth, localized, 2D basis functions at multiple scales. Each transform coefficient represents the amount of local detail at some specific scale and at a specific position in the image. Detail contrast is enhanced by non-linear amplification of the transform coefficients. An inverse transform is then applied to the modified coefficients. This yields a uniformly contrast- enhanced image without artefacts. The MUSICA-algorithm is being applied routinely to computed radiography images of chest, skull, spine, shoulder, pelvis, extremities, and abdomen examinations, with excellent acceptance. It is useful for a wide range of applications in the medical, graphical, and industrial area.

  7. Measuring the amplification of attention.

    PubMed

    Blaser, E; Sperling, G; Lu, Z L

    1999-09-28

    An ambiguous motion paradigm, in which the direction of apparent motion is determined by salience (i.e., the extent to which an area is perceived as figure versus ground), is used to assay the amplification of color by attention to color. In the red-green colored gratings used in these experiments, without attention instructions, salience depends on the chromaticity difference between colored stripes embedded in the motion sequence and the yellow background. Selective attention to red (or to green) alters the perceived direction of motion and is found to be equivalent to increasing the physical redness (or greenness) by 25-117%, depending on the observer and color. Whereas attention to a color drastically alters the salience of that color, it leaves color appearance unchanged. A computational model, which embodies separate, parallel pathways for object perception and for salience, accounts for 99% of the variance of the experimental data. PMID:10500237

  8. Mechanisms of Metal-Induced Centrosome Amplification

    PubMed Central

    Holmes, Amie L.; Wise, John Pierce

    2014-01-01

    Exposure to toxic and carcinogenic metals is widespread; however, their mechanisms of action remain largely unknown. One potential mechanism for metal-induced carcinogenicity and toxicity is centrosome amplification. Here, we review the mechanisms for metal-induced centrosome amplification, including arsenic, chromium, mercury and nano-titanium dioxide. PMID:21118148

  9. Active amplification by critical oscillators in hearing

    NASA Astrophysics Data System (ADS)

    Julicher, Frank

    2004-03-01

    The ear posesses exquisit abilities to detect sounds over a wide range of frequencies with an extraordinary dynamic range. From the faintest sounds that we hear to the loudest noises, the sound pressure varies over twelve orders of magnitude. It has been first proposed by Thomas Gold in 1948 that passive resonating elements alone cannot explain these abilities of the ear. The observation, that the ears of seemingly all vertebrates exhibit spontaneous sound emissions, so called oto-acoustic emissions, adds evidence to the idea that hearing is based on active mechanisms for signal amplification and detection which for different species are based on the same principles. It has been suggested that the active properties and the observed nonlinearities in the ear's response can be explained by assuming that the cochlea contains dynamical systems operating in the vicinity of the critical point of an oscillating instability. A sound stimulus excites deformations of the basilar membrane which travel along the choclea towards the apex. The combination of this travelling wave with properties of critical oscillators leads to a scenario where sound excites nonlinear waves in the cochlea. The large dynamic range of hearing then results from compressive power law responses of these nonlinear excitations.

  10. Influence of interfacial Dzyaloshinskii-Moriya interaction on the parametric amplification of spin waves

    SciTech Connect

    Verba, Roman; Tiberkevich, Vasil; Slavin, Andrei

    2015-09-14

    The influence of the interfacial Dzyaloshinskii-Moriya interaction (IDMI) on the parametric amplification of spin waves propagating in ultrathin ferromagnetic film is considered theoretically. It is shown that the IDMI changes the relation between the group velocities of the signal and idler spin waves in a parametric amplifier, which may result in the complete vanishing of the reversed idler wave. In the optimized case, the idler spin wave does not propagate from the pumping region at all, which increases the efficiency of the amplification of the signal wave and suppresses the spurious impact of the idler waves on neighboring spin-wave processing devices.

  11. Ultrasensitive electrochemical detection of nucleic acid by coupling an autonomous cascade target replication and enzyme/gold nanoparticle-based post-amplification.

    PubMed

    Liu, Shufeng; Wei, Wenji; Wang, Yanqun; Fang, Li; Wang, Li; Li, Feng

    2016-06-15

    Owing to the intrinsic importance of nucleic acid as bio-targets, the development of isothermal and ultrasensitive electrochemical DNA biosensor is very essential for biological studies and medical diagnostics. Herein, the autonomous cascade DNA replication strategy was effectively married with the enzyme/gold nanoparticle-based post-amplification strategy to promote the detection performance toward target DNA. A hairpin DNA probe (HP) is designed that consists of an overhang at 3'-end as the recognition unit for target DNA, a recognition site for nicking endonuclease, and an alkane spacer to terminate polymerization reaction. The autonomous DNA replication-scission-displacement reaction operated by the nicking endonuclease/KF polymerase induced the autocatalytic opening of HP, which was then specifically bound by the enzyme/gold nanoparticles for further dual-signal amplification toward target-related sensing events. A low detection limit of 0.065fM with an excellent selectivity toward target DNA could be achieved. The proposed biosensor could be also easily regenerated for target detection. The developed biosensor creates an opportunity for the effective coupling of the target replication with post-amplification strategies and thus opens a promising avenue for the detection of nucleic acid with low abundance in bioanalysis and clinical biomedicine. PMID:26849348

  12. Isothermal solid-phase amplification system for detection of Yersinia pestis.

    PubMed

    Mayboroda, Olena; Gonzalez Benito, Angel; Sabaté del Rio, Jonathan; Svobodova, Marketa; Julich, Sandra; Tomaso, Herbert; O'Sullivan, Ciara K; Katakis, Ioanis

    2016-01-01

    DNA amplification is required for most molecular diagnostic applications, but conventional polymerase chain reaction (PCR) has disadvantages for field testing. Isothermal amplification techniques are being developed to respond to this problem. One of them is the recombinase polymerase amplification (RPA) that operates at isothermal conditions without sacrificing specificity and sensitivity in easy-to-use formats. In this work, RPA was used for the optical detection of solid-phase amplification of the potential biowarfare agent Yersinia pestis. Thiolated forward primers were immobilized on the surface of maleimide-activated microtitre plates for the quantitative detection of synthetic and genomic DNA, with elongation occurring only in the presence of the specific template DNA and solution phase reverse primers. Quantitative detection was achieved via the use of biotinylated reverse primers and post-amplification addition of streptavidin-HRP conjugate. The overall time of amplification and detection was less than 1 h at a constant temperature of 37 °C. Single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) sequences were detected, achieving detection limits of 4.04*10(-13) and 3.14*10(-16) M, respectively. The system demonstrated high specificity with negligible responses to non-specific targets. PMID:26563112

  13. Technique for extending the range of a signal measuring circuit

    DOEpatents

    Chaprnka, Anthony G.; Sun, Shan C.; Vercellotti, Leonard C.

    1978-01-01

    An input signal supplied to a signal measuring circuit is either amplified or attenuated as necessary to establish the magnitude of the input signal within the defined dynamic range of the measuring circuit and the output signal developed by the measuring circuit is subsequently readjusted through amplification or attenuation to develop an output signal which corresponds to the magnitude of the initial input signal.

  14. Enhanced Amplification and Fan-Out Operation in an All-Magnetic Transistor.

    PubMed

    Barman, Saswati; Saha, Susmita; Mondal, Sucheta; Kumar, Dheeraj; Barman, Anjan

    2016-01-01

    Development of all-magnetic transistor with favorable properties is an important step towards a new paradigm of all-magnetic computation. Recently, we showed such possibility in a Magnetic Vortex Transistor (MVT). Here, we demonstrate enhanced amplification in MVT achieved by introducing geometrical asymmetry in a three vortex sequence. The resulting asymmetry in core to core distance in the three vortex sequence led to enhanced amplification of the MVT output. A cascade of antivortices travelling in different trajectories including a nearly elliptical trajectory through the dynamic stray field is found to be responsible for this amplification. This asymmetric vortex transistor is further used for a successful fan-out operation, which gives large and nearly equal gains in two output branches. This large amplification in magnetic vortex gyration in magnetic vortex transistor is proposed to be maintained for a network of vortex transistor. The above observations promote the magnetic vortex transistors to be used in complex circuits and logic operations. PMID:27624662

  15. Femtosecond Er-doped fiber laser based on divided-pulse nonlinear amplification

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Li, Wenxue; Li, Lang; Hao, Qiang; Zhao, Jian; Zeng, Heping

    2016-02-01

    A high-power erbium-doped fiber amplifier was realized by using a spatially and temporally divided pulse amplification technique. Pulse amplification and compression were simultaneously achieved in a double-clad Er-doped fiber by controlling the pulse gain and dispersion, generating a slope efficiency of 19.2% for the divided pulse amplification. The spectrum and pulse evolutions for nonlinear amplification and compression in the double-clad gain fiber were studied both in theory and experiment. Then 680 mW near-infrared femtosecond laser pulses were obtained by using 0.45 m single-mode fiber to compress amplified pulses. Frequency doubling was further carried out with a periodically poled lithium niobate (PPLN) crystal, generating 790 nm laser pulses with 110 mW average power and 95.7 fs pulse duration.

  16. Isolation and Amplification of mRNA within a Simple Microfluidic Lab on a Chip

    PubMed Central

    Reinholt, Sarah J.; Behrent, Arne; Greene, Cassandra; Kalfe, Ayten; Baeumner, Antje J.

    2014-01-01

    The major modules for realizing molecular biological assays in a micro total analysis system (μTAS) were developed for the detection of pathogenic organisms. The specific focus was the isolation and amplification of eukaryotic messenger RNA (mRNA) within a simple, single-channel device for very low RNA concentrations that could then be integrated with detection modules. The hsp70 mRNA from Cryptosporidium parvum was used as a model analyte. Important points of study were surface chemistries within poly(methyl methacrylate) (PMMA) microfluidic channels that enabled specific and sensitive mRNA isolation and amplification reactions for very low mRNA concentrations. Optimal conditions were achieved when the channel surface was carboxylated via UV/ozone treatment followed by the immobilization of polyamidoamine (PAMAM) dendrimers on the surface, thus increasing the immobilization efficiency of the thymidine oligonucleotide, oligo(dT)25, and providing a reliable surface for the amplification reaction, importantly, without the need for blocking agents. Additional chemical modifications of the remaining active surface groups were studied to avoid non-specific capturing of nucleic acids and hindering of the mRNA amplification at low RNA concentrations. Amplification of the mRNA was accomplished using nucleic acid sequence-based amplification (NASBA), an isothermal, primer-dependent technique. Positive controls consisting of previously generated NASBA amplicons could be diluted 1015 fold and still result in successful on-chip re-amplification. Finally, the successful isolation and amplification of mRNA from as few as 30 C. parvum oocysts was demonstrated directly on-chip and compared to bench-top devices. This is the first proof of successful mRNA isolation and NASBA-based amplification of mRNA within a simple microfluidic device in relevant analytical volumes. PMID:24328414

  17. Coupling of background reduction with rolling circle amplification for highly sensitive protein detection via terminal protection of small molecule-linked DNA.

    PubMed

    Wang, Qiong; Jiang, Bingying; Xie, Jiaqing; Xiang, Yun; Yuan, Ruo; Chai, Yaqin

    2013-10-01

    In this work, by coupling background current reduction with rolling circle amplification (RCA), we describe the development of an ultrasensitive electrochemical sensing method for protein detection based on a small molecule-linked DNA terminal protection strategy. Our detection platform employs a typical streptavidin (STV)-biotin interaction system. Biotin-linked single-stranded DNA (SH-ssDNA-biotin) is self-assembled on a gold electrode to capture the target protein, STV. The binding of STV with the biotin small molecule recognition element protects the SH-ssDNA-biotin against hydrolysis by exonuclease I (Exo I), while the unbound SH-ssDNA-biotin is effectively hydrolyzed and removed from the electrode surface. The bound STV further interacts with long, RCA-amplified biotin DNAs to facilitate the adsorption of numerous electroactive reporters, hexaammineruthenium(III) chloride (RuHex) via electrostatic interactions, which results in significantly amplified signals for the quantitative determination of STV. Moreover, the removal of the unbound SH-ssDNA-biotin probes from the sensing electrode obviates the accumulation of RuHex and leads to a highly minimized background current. The simultaneous RCA signal amplification and background current reduction is expected to significantly enhance the signal-to-noise ratio and to achieve ultrahigh sensitivity. The results reveal that the developed strategy provides a low detection limit of 0.4 pM with high selectivity. PMID:23907287

  18. Optical parametric chirped pulse amplification and spectral shaping of a continuum generated in a photonic band gap fiber.

    PubMed

    Hugonnot, E; Somekh, M; Villate, D; Salin, F; Freysz, E

    2004-05-31

    A chirped pulse, spectrally broadened in a photonic bandgap optical fiber by 120 fs Ti:Sapphire laser pulses, is parametrically amplified in a BBO crystal pumped by a frequency doubled nanosecond Nd:YAG laser pulse. Without changing the frequency of the Ti:Sapphire, a spectral tunability of the amplified pulses is demonstrated. The possibility to achieve broader spectral range amplification is confirmed for a non-collinear pump-signal interaction geometry. For optimal non-collinear interaction geometry, the pulse duration of the original and amplified pulse are similar. Finally, we demonstrate that the combination of two BBO crystals makes it possible to spectrally shape the amplified pulses. PMID:19475076

  19. Point-of-care multiplexed assays of nucleic acids using microcapillary-based loop-mediated isothermal amplification.

    PubMed

    Zhang, Yi; Zhang, Lu; Sun, Jiashu; Liu, Yulei; Ma, Xingjie; Cui, Shangjin; Ma, Liying; Xi, Jianzhong Jeff; Jiang, Xingyu

    2014-07-15

    This report demonstrates a straightforward, robust, multiplexed and point-of-care microcapillary-based loop-mediated isothermal amplification (cLAMP) for assaying nucleic acids. This assay integrates capillaries (glass or plastic) to introduce and house sample/reagents, segments of water droplets to prevent contamination, pocket warmers to provide heat, and a hand-held flashlight for a visual readout of the fluorescent signal. The cLAMP system allows the simultaneous detection of two RNA targets of human immunodeficiency virus (HIV) from multiple plasma samples, and achieves a high sensitivity of two copies of standard plasmid. As few nucleic acid detection methods can be wholly independent of external power supply and equipment, our cLAMP holds great promise for point-of-care applications in resource-poor settings. PMID:24937125

  20. Raman Amplification and Tunable Pulse Delays in Silicon Waveguides

    SciTech Connect

    Rukhlenko, Ivan D.; Premaratne, Malin; Garanovich, Ivan L.; Sukhorukov, Andrey A.; Agrawal, Govind P.

    2010-10-07

    The nonlinear process of stimulated Raman scattering is important for silicon photonics as it enables optical amplification and lasing. However, generally employed numerical approaches provide very little insight into the contribution of different silicon Raman amplifier (SRA) parameters. In this paper, we solve the coupled pump-signal equations analytically and derive an exact formula for the envelope of a signal pulse when picosecond optical pulses are amplified inside a SRA pumped by a continuous-wave laser beam. Our solution is valid for an arbitrary pulse shape and fully accounts for the Raman gain-dispersion effects, including temporal broadening and group-velocity reduction. Our results are useful for optimizing the performance of SRAs and for engineering controllable signal delays.

  1. Electrochemiluminescent Graphene Quantum Dots as a Sensing Platform: A Dual Amplification for MicroRNA Assay.

    PubMed

    Zhang, Pu; Zhuo, Ying; Chang, Yuanyuan; Yuan, Ruo; Chai, Yaqin

    2015-10-20

    Graphene quantum dots (GQDs) with an average diameter as small as 2.3 nm were synthesized to fabricate an electrochemiluminescence (ECL) biosensor based on T7 exonuclease-assisted cyclic amplification and three-dimensional (3D) DNA-mediated silver enhancement for microRNA (miRNA) analysis. Herein, to overcome the barrier in immobilizing GQDs, aminated 3,4,9,10-perylenetetracarboxylic acid (PTCA-NH2) was introduced to load GQDs through π-π stacking (GQDs/PTCA-NH2), realizing the solid-state GQDs application. Furthermore, Fe3O4-Au core-shell nanocomposite (Au@Fe3O4) was adopted as a probe anchor to form a novel electrochemiluminescent signal tag of GQDs/PTCA-NH2/Au@Fe3O4. The prepared ECL signal tag was decorated on the electrode surface, exhibiting excellent film-forming performance, good electronic conductivity, and favorable stability, all of which overcame the obstacle for applying GQDs in ECL biosensing and showed a satisfactory ECL response under the coreactant of S2O8(2-) (peroxydisulfate). Afterward, hairpin probe modified on the electrode was opened by helper DNA, followed by assembling target to hybridize with the exposed stem of the helper DNA. Significantly, T7 exonuclease was employed to digest the DNA/RNA duplex and trigger the target recycling without asking for a specific recognition site in the target sequence, realizing a series of RNA/DNA detections by changing the sequence of the complementary DNA. At last, the ECL signal was further enhanced by silver nanoparticles (AgNPs)-based 3D DNA networks. After the two amplifications, the ECL signal of GQDs was extraordinarily increased and the prepared biosensor achieved a high sensitivity with the detection limit of 0.83 fM. The biosensor was also explored in real samples, and the result was in good accordance with the performance of quantitative real-time polymerase chain reaction (qRT-PCR). Considering the excellent sensitivity and applicability, we believe that the proposed biosensor is a potential

  2. Quantitation of DNA methyltransferase activity via chronocoulometry in combination with rolling chain amplification.

    PubMed

    Ji, Jingjing; Liu, Yuanjian; Wei, Wei; Zhang, Yuanjian; Liu, Songqin

    2016-11-15

    In this paper, a rolling chain amplification (RCA) strategy was proposed for chronocoulometric detection of DNA methyltransferase (MTase) activity. Briefly, after the double DNA helix structure was assembled on the surface of gold electrode, it was first methylated by M. SssI MTase and then RCA was realized in the presence of E. coli and phi29 DNA polymerase. Successively, numerous hexaammineruthenium (III) chloride ([Ru(NH3)6)(3+), RuHex) were adsorbed on replicons by electrostatic interaction and generated a large electrochemical readout, the signal was "on". On the contrary, in the absence of M. SssI MTase, the methylated CpG site in the unmethylated double DNA helix structure could be specifically recognized and cleaved by HpaII, resulting in a disconnection of RCA from the electrode. This led seldom RuHex to be absorbed onto the surface of electrode, the signal was "off". Based on the proposed strategy, the activity of M. SssI MTase was assayed in the range of 0.5-60U/mL with a detection limit of 0.09U/mL (S/N=3). In addition, the inhibition of procaine and epicatechin on M. SssI MTase activity was evaluated. When the proposed method was applied in complex matrix such as human serum samples, acceptable accuracy, precision and high sensitivity were achieved. Therefore, the proposed method was a potential useful mean for clinical diagnosis and drug development. PMID:27155113

  3. Directional Amplification with a Josephson Circuit

    NASA Astrophysics Data System (ADS)

    Abdo, Baleegh; Sliwa, Katrina; Frunzio, Luigi; Devoret, Michel

    2013-07-01

    Nonreciprocal devices perform crucial functions in many low-noise quantum measurements, usually by exploiting magnetic effects. In the proof-of-principle device presented here, on the other hand, two on-chip coupled Josephson parametric converters (JPCs) achieve directionality by exploiting the nonreciprocal phase response of the JPC in the transmission-gain mode. The nonreciprocity of the device is controlled in situ by varying the amplitude and phase difference of two independent microwave pump tones feeding the system. At the desired working point and for a signal frequency of 8.453 GHz, the device achieves a forward power gain of 15 dB within a dynamical bandwidth of 9 MHz, a reverse gain of -6dB, and suppression of the reflected signal by 8 dB. We also find that the amplifier adds a noise equivalent to less than 1.5 photons at the signal frequency (referred back to the input). It can process up to 3 photons at the signal frequency per inverse dynamical bandwidth. With a directional amplifier operating along the principles of this device, qubit and readout preamplifier could be integrated on the same chip.

  4. Profiling In Situ Microbial Community Structure with an Amplification Microarray

    PubMed Central

    Knickerbocker, Christopher; Bryant, Lexi; Golova, Julia; Wiles, Cory; Williams, Kenneth H.; Peacock, Aaron D.; Long, Philip E.

    2013-01-01

    The objectives of this study were to unify amplification, labeling, and microarray hybridization chemistries within a single, closed microfluidic chamber (an amplification microarray) and verify technology performance on a series of groundwater samples from an in situ field experiment designed to compare U(VI) mobility under conditions of various alkalinities (as HCO3−) during stimulated microbial activity accompanying acetate amendment. Analytical limits of detection were between 2 and 200 cell equivalents of purified DNA. Amplification microarray signatures were well correlated with 16S rRNA-targeted quantitative PCR results and hybridization microarray signatures. The succession of the microbial community was evident with and consistent between the two microarray platforms. Amplification microarray analysis of acetate-treated groundwater showed elevated levels of iron-reducing bacteria (Flexibacter, Geobacter, Rhodoferax, and Shewanella) relative to the average background profile, as expected. Identical molecular signatures were evident in the transect treated with acetate plus NaHCO3, but at much lower signal intensities and with a much more rapid decline (to nondetection). Azoarcus, Thaurea, and Methylobacterium were responsive in the acetate-only transect but not in the presence of bicarbonate. Observed differences in microbial community composition or response to bicarbonate amendment likely had an effect on measured rates of U reduction, with higher rates probable in the part of the field experiment that was amended with bicarbonate. The simplification in microarray-based work flow is a significant technological advance toward entirely closed-amplicon microarray-based tests and is generally extensible to any number of environmental monitoring applications. PMID:23160129

  5. Highly efficient cascaded amplification using Pr(3+)-doped mid-infrared chalcogenide fiber amplifiers.

    PubMed

    Hu, Jonathan; Menyuk, Curtis R; Wei, Chengli; Brandon Shaw, L; Sanghera, Jasbinder S; Aggarwal, Ishwar D

    2015-08-15

    We computationally investigate cascaded amplification in a three-level mid-infrared (IR) Pr(3+)-doped chalcogenide fiber amplifier. The overlap of the cross-sections in the transitions (3)H(6)→(3)H(5) and (3)H(5)→(3)H(4) enable both transitions to simultaneously amplify a single wavelength in the range between 4.25 μm and 4.55 μm. High gain and low noise are achieved simultaneously if the signal is at 4.5 μm. We show that 45% of pump power that is injected at 2 μm can be shifted to 4.5 μm. The efficiency of using a mid-IR fiber amplifier is higher than what can be achieved by using mid-IR supercontinuum generation, which has been estimated at 25%. This mid-IR fiber amplifier can be used in conjunction with quantum cascade lasers to obtain a tunable, high-power mid-IR source. PMID:26274635

  6. Demonstrating a Multi-drug Resistant Mycobacterium tuberculosis Amplification Microarray

    PubMed Central

    Linger, Yvonne; Kukhtin, Alexander; Golova, Julia; Perov, Alexander; Qu, Peter; Knickerbocker, Christopher; Cooney, Christopher G.; Chandler, Darrell P.

    2014-01-01

    Simplifying microarray workflow is a necessary first step for creating MDR-TB microarray-based diagnostics that can be routinely used in lower-resource environments. An amplification microarray combines asymmetric PCR amplification, target size selection, target labeling, and microarray hybridization within a single solution and into a single microfluidic chamber. A batch processing method is demonstrated with a 9-plex asymmetric master mix and low-density gel element microarray for genotyping multi-drug resistant Mycobacterium tuberculosis (MDR-TB). The protocol described here can be completed in 6 hr and provide correct genotyping with at least 1,000 cell equivalents of genomic DNA. Incorporating on-chip wash steps is feasible, which will result in an entirely closed amplicon method and system. The extent of multiplexing with an amplification microarray is ultimately constrained by the number of primer pairs that can be combined into a single master mix and still achieve desired sensitivity and specificity performance metrics, rather than the number of probes that are immobilized on the array. Likewise, the total analysis time can be shortened or lengthened depending on the specific intended use, research question, and desired limits of detection. Nevertheless, the general approach significantly streamlines microarray workflow for the end user by reducing the number of manually intensive and time-consuming processing steps, and provides a simplified biochemical and microfluidic path for translating microarray-based diagnostics into routine clinical practice. PMID:24796567

  7. Parametric amplification and compression to ultrashort pulse duration of resonant linear waves

    NASA Astrophysics Data System (ADS)

    Aguergaray, C.; Andersen, T. V.; Schimpf, D. N.; Schmidt, O.; Rothhardt, J.; Schreiber, T.; Limpert, J.; Cormier, E.; Tünnermann, A.

    2007-04-01

    We report on an optical parametric amplification system which is pumped and seeded by fiber generated laser radiation. Due to its low broadening threshold, high spatial beam quality and high stability, the fiber based broad bandwidth signal generation is a promising alternative to white light generation in bulky glass or sapphire plates. We demonstrate a novel and successful signal engineering implemented in a setup for parametric amplification and subsequent recompression of resonant linear waves resulting from soliton fission in a highly nonlinear photonic crystal fiber. The applied pump source is a high repetition rate ytterbium-doped fiber chirped pulse amplification system. The presented approach results in the generation of ~50 fs pulses at MHz repetition rate. The potential of generating even shorter pulse duration and higher pulse energies will be discussed.

  8. Nanoparticle-bridge assay for amplification-free electrical detection of oligonucleotides

    NASA Astrophysics Data System (ADS)

    Teimouri, Manouchehr

    The aim of this research is to investigate a highly sensitive, fast, inexpensive, and field-applicable amplification-free nanoparticle-based oligonucleotide detection method which does not rely on any enzymatic or signal amplification process. In this approach, target oligonucleotide strands are detected through the formation of nanoparticle satellites which make an electrical path between two electrodes. This method enables an extremely sensitive oligonucleotide detection because even a few oligonucleotide strands can form a single nanoparticle satellite which can solely generates an electrical output signal. Results showed that this oligonucleotide detection method can detect oligonucleotide single strands at concentrations as low as 50 femtomolar without any amplification process. This detection method can be implemented in many fields such as biodefense, food safety, clinical research, and forensics.

  9. Transmission performance improvement using random DFB laser based Raman amplification and bidirectional second-order pumping.

    PubMed

    Tan, M; Rosa, P; Le, S T; Iqbal, Md A; Phillips, I D; Harper, P

    2016-02-01

    We demonstrate that a distributed Raman amplification scheme based on random distributed feedback (DFB) fiber laser enables bidirectional second-order Raman pumping without increasing relative intensity noise (RIN) of the signal. This extends the reach of 10 × 116 Gb/s DP-QPSK WDM transmission up to 7915 km, compared with conventional Raman amplification schemes. Moreover, this scheme gives the longest maximum transmission distance among all the Raman amplification schemes presented in this paper, whilst maintaining relatively uniform and symmetric signal power distribution, and is also adjustable in order to be highly compatible with different nonlinearity compensation techniques, including mid-link optical phase conjugation (OPC) and nonlinear Fourier transform (NFT). PMID:26906797

  10. Amplification of large artificial chromosomes.

    PubMed Central

    Smith, D R; Smyth, A P; Moir, D T

    1990-01-01

    Yeast artificial chromosome cloning is an attractive technology for genomic mapping studies because very large DNA segments can be readily propagated. However, detailed analyses often require the extensive application of blotting-hybridization techniques because artificial chromosomes are normally present at only one copy per haploid genome. We have developed a cloning vector and host strain that alleviate this problem by permitting copy number amplification of artificial chromosomes. The vector includes a conditional centromere that can be turned on or off by changing the carbon source. Strong selective pressure for extra copies of the artificial chromosome can be applied by selecting for the expression of a heterologous thymidine kinase gene. When this system was used, artificial chromosomes ranging from about 100 to 600 kilobases in size were readily amplified 10- to 20-fold. The selective conditions did not induce obvious rearrangements in any of the clones tested. Reactivation of the centromere in amplified artificial chromosome clones resulted in stable maintenance of an elevated copy number for 20 generations. Applications of copy number control to various aspects of artificial chromosome analysis are addressed. Images PMID:2236036

  11. A genome-wide study of preferential amplification/hybridization in microarray-based pooled DNA experiments

    PubMed Central

    Yang, H.-C.; Liang, Y.-J.; Huang, M.-C.; Li, L.-H.; Lin, C.-H.; Wu, J.-Y.; Chen, Y.-T.; Fann, C.S.J.

    2006-01-01

    Microarray-based pooled DNA methods overcome the cost bottleneck of simultaneously genotyping more than 100 000 markers for numerous study individuals. The success of such methods relies on the proper adjustment of preferential amplification/hybridization to ensure accurate and reliable allele frequency estimation. We performed a hybridization-based genome-wide single nucleotide polymorphisms (SNPs) genotyping analysis to dissect preferential amplification/hybridization. The majority of SNPs had less than 2-fold signal amplification or suppression, and the lognormal distributions adequately modeled preferential amplification/hybridization across the human genome. Comparative analyses suggested that the distributions of preferential amplification/hybridization differed among genotypes and the GC content. Patterns among different ethnic populations were similar; nevertheless, there were striking differences for a small proportion of SNPs, and a slight ethnic heterogeneity was observed. To fulfill appropriate and gratuitous adjustments, databases of preferential amplification/hybridization for African Americans, Caucasians and Asians were constructed based on the Affymetrix GeneChip Human Mapping 100 K Set. The robustness of allele frequency estimation using this database was validated by a pooled DNA experiment. This study provides a genome-wide investigation of preferential amplification/hybridization and suggests guidance for the reliable use of the database. Our results constitute an objective foundation for theoretical development of preferential amplification/hybridization and provide important information for future pooled DNA analyses. PMID:16931491

  12. Isothermal DNA amplification in vitro: the helicase-dependent amplification system.

    PubMed

    Jeong, Yong-Joo; Park, Kkothanahreum; Kim, Dong-Eun

    2009-10-01

    Since the development of polymerase chain reaction, amplification of nucleic acids has emerged as an elemental tool for molecular biology, genomics, and biotechnology. Amplification methods often use temperature cycling to exponentially amplify nucleic acids; however, isothermal amplification methods have also been developed, which do not require heating the double-stranded nucleic acid to dissociate the synthesized products from templates. Among the several methods used for isothermal DNA amplification, the helicase-dependent amplification (HDA) is discussed in this review with an emphasis on the reconstituted DNA replication system. Since DNA helicase can unwind the double-stranded DNA without the need for heating, the HDA system provides a very useful tool to amplify DNA in vitro under isothermal conditions with a simplified reaction scheme. This review describes components and detailed aspects of current HDA systems using Escherichia coli UvrD helicase and T7 bacteriophage gp4 helicase with consideration of the processivity and efficiency of DNA amplification. PMID:19629390

  13. AMPLIFICATION OF RIBOSOMAL RNA SEQUENCES - Book Chapter

    EPA Science Inventory

    This book chapter contains the following headings and subheadings: Introduction; Experimental Approach - Precautions, Template, Primers, Reaction Conditions, Enhancers, Post Amplification; Procedures - Template DNA, Basic PCR, Thermal Cycle Parameters, Enzyme Addition, Agarose Ge...

  14. Centrosome amplification and cancer: Branching out

    PubMed Central

    Godinho, Susana A

    2015-01-01

    Despite being a common feature of human cancer, the role of supernumerary centrosomes in tumourigenesis is still poorly understood. We have recently described a novel role for centrosome amplification in promoting cell invasion that could impact tumor progression.

  15. Coupled isothermal polynucleotide amplification and translation system

    NASA Technical Reports Server (NTRS)

    Joyce, Gerald F. (Inventor)

    1998-01-01

    A cell-free system for polynucleotide amplification and translation is disclosed. Also disclosed are methods for using the system and a composition which allows the various components of the system to function under a common set of reaction conditions.

  16. Chemical amplification based on fluid partitioning

    DOEpatents

    Anderson, Brian L.; Colston, Jr., Billy W.; Elkin, Chris

    2006-05-09

    A system for nucleic acid amplification of a sample comprises partitioning the sample into partitioned sections and performing PCR on the partitioned sections of the sample. Another embodiment of the invention provides a system for nucleic acid amplification and detection of a sample comprising partitioning the sample into partitioned sections, performing PCR on the partitioned sections of the sample, and detecting and analyzing the partitioned sections of the sample.

  17. Rolling circle amplification of metazoan mitochondrialgenomes

    SciTech Connect

    Simison, W. Brian; Lindberg, D.R.; Boore, J.L.

    2005-07-31

    Here we report the successful use of rolling circle amplification (RCA) for the amplification of complete metazoan mt genomes to make a product that is amenable to high-throughput genome sequencing techniques. The benefits of RCA over PCR are many and with further development and refinement of RCA, the sequencing of organellar genomics will require far less time and effort than current long PCR approaches.

  18. Amplification of chromosomal DNA in situ

    DOEpatents

    Christian, Allen T.; Coleman, Matthew A.; Tucker, James D.

    2002-01-01

    Amplification of chromosomal DNA in situ to increase the amount of DNA associated with a chromosome or chromosome region is described. The amplification of chromosomal DNA in situ provides for the synthesis of Fluorescence in situ Hybridization (FISH) painting probes from single dissected chromosome fragments, the production of cDNA libraries from low copy mRNAs and improved in Comparative Genomic Hybridization (CGH) procedures.

  19. Amplification of a seed pumped by a chirped laser in the strong coupling Brillouin regime

    SciTech Connect

    Schluck, F.; Lehmann, G.; Spatschek, K. H.

    2015-09-15

    Seed amplification via Brillouin backscattering of a long pump laser-pulse is considered. The interaction takes place in the so called strong coupling regime. Pump chirping is applied to mitigate spontaneous Raman backscattering of the pump before interacting with the seed. The strong coupling regime facilitates stronger exponential growth and narrower seeds compared to the so called weak coupling regime, although in the latter the scaling with pump amplitude is stronger. Strong coupling is achieved when the pump laser amplitude exceeds a certain threshold. It is shown how the chirp influences both the linear as well as the nonlinear amplification process. First, linear amplification as well as the seed profiles are determined in dependence of the chirping rate. In contrast to the weak coupling situation, the evolution is not symmetric with respect to the sign of the chirping rate. In the nonlinear stage of the amplification, we find an intrinsic chirp of the seed pulse even for an un-chirped pump. We show that chirping the pump may have a strong influence on the shape of the seed in the nonlinear amplification phase. Also, the influence of pump chirp on the efficiency of Brillouin seed amplification is discussed.

  20. OPTICAL SOLITONS: Fibreoptic communication lines with distributed Raman amplification: Numerical simulation

    NASA Astrophysics Data System (ADS)

    Nasieva, I. O.; Fedoruk, Mikhail P.

    2003-10-01

    The properties of optical solitons in variable-dispersion fibreoptic communication lines in which distributed Raman amplification of optical signals is used are studied by numerical simulation. It is shown that solitons can serve as carriers of information in communication systems with a data transmission rate exceeding 10 Gbit s-1.

  1. Measurement of the gain in a disk amplification stage with neodymium phosphate glass active elements

    SciTech Connect

    Voronich, Ivan N; Galakhov, I V; Garanin, Sergey G; Eroshenko, V A; Zaretskii, Aleksei I; Zimalin, B G; Ignat'ev, Ivan V; Kirdyashkin, M Yu; Kirillov, G A; Osin, Vladimir A; Rukavishnikov, N N; Sukharev, Stanislav A; Sharov, Oleg A; Charukhchev, Aleksandr V

    2003-06-30

    The measuring technique is described and time-resolved measurements of the small-signal gain as a function of the pump energy in a disk amplification stage with neodymium phosphate glass active elements in the 'Luch' facility are presented. The distribution of the gain over the amplifier aperture in the horizontal plane is measured. (lasers)

  2. A novel colorimetric sensor for Hg(2+) based on hybridization chain reaction and silver nanowire amplification.

    PubMed

    Tang, Shurong; Tong, Ping; Wang, Meili; Chen, Jinghua; Li, Guangwen; Zhang, Lan

    2015-10-18

    Through the silver ion catalysis to form colored KMnO4, and combined with the DNA hybridization chain reaction and silver nanowire for signal amplification, a highly sensitive and selective colorimetric sensor has been developed for the detection of Hg(2+). PMID:26313655

  3. Amplification uncertainty relation for probabilistic amplifiers

    NASA Astrophysics Data System (ADS)

    Namiki, Ryo

    2015-09-01

    Traditionally, quantum amplification limit refers to the property of inevitable noise addition on canonical variables when the field amplitude of an unknown state is linearly transformed through a quantum channel. Recent theoretical studies have determined amplification limits for cases of probabilistic quantum channels or general quantum operations by specifying a set of input states or a state ensemble. However, it remains open how much excess noise on canonical variables is unavoidable and whether there exists a fundamental trade-off relation between the canonical pair in a general amplification process. In this paper we present an uncertainty-product form of amplification limits for general quantum operations by assuming an input ensemble of Gaussian-distributed coherent states. It can be derived as a straightforward consequence of canonical uncertainty relations and retrieves basic properties of the traditional amplification limit. In addition, our amplification limit turns out to give a physical limitation on probabilistic reduction of an Einstein-Podolsky-Rosen uncertainty. In this regard, we find a condition that probabilistic amplifiers can be regarded as local filtering operations to distill entanglement. This condition establishes a clear benchmark to verify an advantage of non-Gaussian operations beyond Gaussian operations with a feasible input set of coherent states and standard homodyne measurements.

  4. Onshore seismic amplifications due to bathymetric features

    NASA Astrophysics Data System (ADS)

    Rodríguez-Castellanos, A.; Carbajal-Romero, M.; Flores-Guzmán, N.; Olivera-Villaseñor, E.; Kryvko, A.

    2016-08-01

    We perform numerical calculations for onshore seismic amplifications, taking into consideration the effect of bathymetric features on the propagation of seismic movements. To this end, the boundary element method is applied. Boundary elements are employed to irradiate waves and, consequently, force densities can be obtained for each boundary element. From this assumption, Huygens’ principle is applied, and since the diffracted waves are built at the boundary from which they are radiated, this idea is equivalent to Somigliana’s representation theorem. The application of boundary conditions leads to a linear system being obtained (Fredholm integral equations). Several numerical models are analyzed, with the first one being used to verify the proposed formulation, and the others being used to estimate onshore seismic amplifications due to the presence of bathymetric features. The results obtained show that compressional waves (P-waves) generate onshore seismic amplifications that can vary from 1.2 to 5.2 times the amplitude of the incident wave. On the other hand, the shear waves (S-waves) can cause seismic amplifications of up to 4.0 times the incident wave. Furthermore, an important result is that in most cases the highest seismic amplifications from an offshore earthquake are located on the shoreline and not offshore, despite the seafloor configuration. Moreover, the influence of the incident angle of seismic waves on the seismic amplifications is highlighted.

  5. Expression Enhancement in Trastuzumab Therapeutic Monoclonal Antibody Production using Genomic Amplification with Methotrexate

    PubMed Central

    Akbarzadeh-Sharbaf, Soudabeh; Yakhchali, Bagher; Minuchehr, Zarrin; Shokrgozar, Mohammad Ali; Zeinali, Sirous

    2013-01-01

    Background Trastuzumab (Herceptin) is a humanized monoclonal antibody (mAb) which is used for specific treatment of metastatic breast cancer in patients with overexpression of HER2/neu receptor. In this study, we have attempted to develop a biosimilar version of trastuzumab mAb. Methods According to in silico studies, the heavy and light chains of trastuzumab mAb were designed and constructed. The recombinant constructs were co-transfected in CHO DG44 cell line. Stable transformants were selected on a semi solid medium. Genomic amplification with methotrexate was achieved for heavy chain gene amplification. Biological activity of produced antibody in comparison with Herceptin was tested by flow cytometry method. Results Three folds of amplification were obtained after seven rounds of methotrexate treatments. The results indicated the equal expression level of heavy and light chains. The yield of purified mAb was between 50 to 60 mg/l /day. According to the results, the produced mAb had similar affinity to HER2+ tumor cells to that of Herceptin. Conclusion High-level recombinant protein expression can be achieved by amplification of the recombinant gene with a selectable marker, such as Dihydrofolate Reductase (DHFR). It is usually accepted that DHFR gene can be amplified in DHFR- CHO cells, which consequently leads to amplification of the co-linked target gene, and finally amplification of recombinant protein. In this research, with the aim of producing a biosimilar version of herceptin, the effect of genomic amplification was investigated on the increasing the gene copy number using quantitative real-time PCR. PMID:23799177

  6. Heat induces gene amplification in cancer cells

    SciTech Connect

    Yan, Bin; Ouyang, Ruoyun; Huang, Chenghui; Liu, Franklin; Neill, Daniel; Li, Chuanyuan; Dewhirst, Mark

    2012-10-26

    Highlights: Black-Right-Pointing-Pointer This study discovered that heat exposure (hyperthermia) results in gene amplification in cancer cells. Black-Right-Pointing-Pointer Hyperthermia induces DNA double strand breaks. Black-Right-Pointing-Pointer DNA double strand breaks are considered to be required for the initiation of gene amplification. Black-Right-Pointing-Pointer The underlying mechanism of heat-induced gene amplification is generation of DNA double strand breaks. -- Abstract: Background: Hyperthermia plays an important role in cancer therapy. However, as with radiation, it can cause DNA damage and therefore genetic instability. We studied whether hyperthermia can induce gene amplification in cancer cells and explored potential underlying molecular mechanisms. Materials and methods: (1) Hyperthermia: HCT116 colon cancer cells received water-submerged heating treatment at 42 or 44 Degree-Sign C for 30 min; (2) gene amplification assay using N-(phosphoacetyl)-L-aspartate (PALA) selection of cabamyl-P-synthetase, aspartate transcarbarmylase, dihydro-orotase (cad) gene amplified cells; (3) southern blotting for confirmation of increased cad gene copies in PALA-resistant cells; (4) {gamma}H2AX immunostaining to detect {gamma}H2AX foci as an indication for DNA double strand breaks. Results: (1) Heat exposure at 42 or 44 Degree-Sign C for 30 min induces gene amplification. The frequency of cad gene amplification increased by 2.8 and 6.5 folds respectively; (2) heat exposure at both 42 and 44 Degree-Sign C for 30 min induces DNA double strand breaks in HCT116 cells as shown by {gamma}H2AX immunostaining. Conclusion: This study shows that heat exposure can induce gene amplification in cancer cells, likely through the generation of DNA double strand breaks, which are believed to be required for the initiation of gene amplification. This process may be promoted by heat when cellular proteins that are responsible for checkpoints, DNA replication, DNA repair and

  7. Long-distance fiber Bragg grating sensor system with a high optical signal-to-noise ratio based on a tunable fiber ring laser configuration

    NASA Astrophysics Data System (ADS)

    Rao, Yun-Jiang; Ran, Zeng-Ling; Chen, Rong-Rui

    2006-09-01

    A novel tunable fiber ring laser configuration with a combination of bidirectional Raman amplification and dual erbium-doped fiber (EDF) amplification is proposed for realizing high optical signal-to-noise ratio (SNR), long-distance, quasi-distributed fiber Bragg grating (FBG) sensing systems with large capacities and low cost. The hybrid Raman-EDF amplification configuration arranged in the ring laser can enhance the optical SNR of FBG sensor signals significantly owing to the good combination of the high gain of the erbium-doped fiber amplifier (EDFA) and the low noise of the Raman amplification. Such a sensing system can support a large number of FBG sensors because of the use of a tunable fiber Fabry-Perot filter located within the ring laser and spatial division multiplexing for expansion of sensor channels. Experimental results show that an excellent optical SNR of ˜60 dB has been achieved for a 50 km transmission distance with a low Raman pump power of ˜170 mW at a wavelength of 1455 nm and a low EDFA pump power of ˜40 mW at a wavelength of 980 nm, which is the highest optical SNR achieved so far for a 50 km long FBG sensor system, to our knowledge.

  8. Long-distance fiber Bragg grating sensor system with a high optical signal-to-noise ratio based on a tunable fiber ring laser configuration.

    PubMed

    Rao, Yun-Jiang; Ran, Zeng-Ling; Chen, Rong-Rui

    2006-09-15

    A novel tunable fiber ring laser configuration with a combination of bidirectional Raman amplification and dual erbium-doped fiber (EDF) amplification is proposed for realizing high optical signal-to-noise ratio (SNR), long-distance, quasi-distributed fiber Bragg grating (FBG) sensing systems with large capacities and low cost. The hybrid Raman-EDF amplification configuration arranged in the ring laser can enhance the optical SNR of FBG sensor signals significantly owing to the good combination of the high gain of the erbium-doped fiber amplifier (EDFA) and the low noise of the Raman amplification. Such a sensing system can support a large number of FBG sensors because of the use of a tunable fiber Fabry-Perot filter located within the ring laser and spatial division multiplexing for expansion of sensor channels. Experimental results show that an excellent optical SNR of approximately 60 dB has been achieved for a 50 km transmission distance with a low Raman pump power of approximately 170 mW at a wavelength of 1455 nm and a low EDFA pump power of approximately 40 mW at a wavelength of 980 nm, which is the highest optical SNR achieved so far for a 50 km long FBG sensor system, to our knowledge. PMID:16936857

  9. Optimisation of geometrical ratchets for spin-current amplification

    NASA Astrophysics Data System (ADS)

    Abdullah, Ranjdar M.; Vick, Andrew J.; Murphy, Benedict A.; Hirohata, Atsufumi

    2015-05-01

    A two-dimensional model is used to study the geometrical effects of a nonmagnetic (NM) nanowire upon a spin-polarised electron current in a lateral spin-valve structure. We found that the implemented ratchet shapes at the centre of the NM have a crucial effect on the diffusive rate for up- and down-spin electrons along the wire, which leads to the amplification of non-local spin-current signals. By using our simple model, the geometries have been optimised. The calculated spin-current signals are in good qualitative agreement with our recent experimental results [Abdullah et al., J. Phys. D: Appl. Phys. 47, 482001(FTC) (2014)]. Our model may be very useful to evaluate such a geometrical effect on spin-polarised electron transport.

  10. Optimisation of geometrical ratchets for spin-current amplification

    SciTech Connect

    Abdullah, Ranjdar M.; Vick, Andrew J.; Murphy, Benedict A.; Hirohata, Atsufumi

    2015-05-07

    A two-dimensional model is used to study the geometrical effects of a nonmagnetic (NM) nanowire upon a spin-polarised electron current in a lateral spin-valve structure. We found that the implemented ratchet shapes at the centre of the NM have a crucial effect on the diffusive rate for up- and down-spin electrons along the wire, which leads to the amplification of non-local spin-current signals. By using our simple model, the geometries have been optimised. The calculated spin-current signals are in good qualitative agreement with our recent experimental results [Abdullah et al., J. Phys. D: Appl. Phys. 47, 482001(FTC) (2014)]. Our model may be very useful to evaluate such a geometrical effect on spin-polarised electron transport.

  11. Micropulse lidar for detection of backscatter amplification in the turbulent atmosphere

    NASA Astrophysics Data System (ADS)

    Banakh, Victor A.; Razenkov, Igor A.

    2015-11-01

    The design of a two-channel lidar with afocal transceiving telescope receiving the backscattered radiation at the axis of the probing beam and at some distance from the axis is described. The lidar with this design can detect the atmospheric backscatter amplification caused by turbulent fluctuations of the refractive index of air due to the correlation of the probing and scattered radiation. The power ratio of echo signals recorded in two different channels gives the value (coefficient) of backscatter amplification. The developed micropulse two-channel lidar can conduct unattended continuous measurements for a long time.

  12. Advanced unrepeatered systems using novel Raman amplification schemes

    NASA Astrophysics Data System (ADS)

    Chang, Do-il; Pelouch, Wayne; Burtsev, Sergey; Perrier, Philippe; Fevrier, Herve

    2015-01-01

    Unrepeatered transmission systems provide a cost-effective solution to transmit high capacity channels in submarine networks to communicate between coastal population centers or in terrestrial networks to connect remote areas where service access is difficult. The main goal of unrepeatered systems has traditionally been to achieve the longest reach, however, increasing traffic demands now require unrepeatered systems to support both longer reach and higher transport capacity. As a result, transmission rate of unrepeatered systems has quickly moved from 10 Gb/s to 40 Gb/s or 100 Gb/s. This paper reviews the key basic technologies, with a specific focus on Raman amplification, required for long-reach, high-capacity unrepeatered optical transmission systems. We will discuss novel Raman amplification schemes, enhanced remote optically pumped amplifiers (ROPA), ultra-low loss / large effective area fibers, and coherent transmission with advanced modulation format and high FEC coding gain. We will also report recent experimental demonstrations that show how these technologies have been combined to achieve industry's leading capacity and reach transmission.

  13. Efficient noncollinear parametric amplification of weak femtosecond pulses in the visible and near-infrared spectral range.

    PubMed

    Krylov, V; Ollikainen, O; Gallus, J; Wild, U; Rebane, A; Kalintsev, A

    1998-01-15

    We report measurement of efficient amplification of weak femtosecond supercontinuum seed pulses by use of a noncollinear optical parametric process in BBO crystal pumped with 150-fs pulses from a frequency-doubled regenerative-amplified Ti:sapphire laser at 390nm . The highest amplification factor, 10(8) , was achieved for 3x10(-16)J energy seed pulses at wavelength of 560nm. PMID:18084425

  14. Hairpin DNA-Templated Silver Nanoclusters as Novel Beacons in Strand Displacement Amplification for MicroRNA Detection.

    PubMed

    Zhang, Jingpu; Li, Chao; Zhi, Xiao; Ramón, Gabriel Alfranca; Liu, Yanlei; Zhang, Chunlei; Pan, Fei; Cui, Daxiang

    2016-01-19

    MicroRNA (miRNA) biomarkers display great potential for cancer diagnosis and prognosis. The development of rapid and specific methods for miRNA detection has become a hotspot. Herein, hairpin DNA-templated silver nanoclusters (AgNCs/HpDNA) were prepared and integrated into strand-displacement amplification (SDA) as a novel beacon for miRNA detection. The light-up platform was established based on guanine (G)-rich fluorescence enhancement that essentially converted the excitation/emission pair of AgNCs/HpDNAs from a shorter wavelength to a longer wavelength, and then achieved fluorescent enhancement at longer wavelength. On the basis of the validation of the method, the single and duplex detection were conducted in two plasma biomarkers (miR-16-5p and miR-19b-3p) for the diagnosis of gastric cancer. The probe (AgNCs/RED 16(7s)C) utilized for miR-16-5p detection adopted a better conformation with high specificity to recognize single-base mismatches by producing dramatically opposite signals (increase or decrease at 580 nm ex/640 nm em) while the probe (AgNCs/GRE 19b(5s)C) for miR-19b-3p generated dual signals (increase at 490 nm ex/570 nm em and decrease at 430 nm ex/530 nm em) with bright fluorescence in one reaction during the amplification, but unexpectedly was partially digested. This is for the first time to allow the generation of enhanced fluorescent AgNCs and the target recognition integrated into a single process, which offers great opportunity for specific miRNA detection in an easy and rapid way. PMID:26675240

  15. 2D dynamic studies combined with the surface curvature analysis to predict Arias Intensity amplification

    NASA Astrophysics Data System (ADS)

    Torgoev, Almaz; Havenith, Hans-Balder

    2016-01-01

    A 2D elasto-dynamic modelling of the pure topographic seismic response is performed for six models with a total length of around 23.0 km. These models are reconstructed from the real topographic settings of the landslide-prone slopes situated in the Mailuu-Suu River Valley, Southern Kyrgyzstan. The main studied parameter is the Arias Intensity (Ia, m/sec), which is applied in the GIS-based Newmark method to regionally map the seismically-induced landslide susceptibility. This method maps the Ia values via empirical attenuation laws and our studies investigate a potential to include topographic input into them. Numerical studies analyse several signals with varying shape and changing central frequency values. All tests demonstrate that the spectral amplification patterns directly affect the amplification of the Ia values. These results let to link the 2D distribution of the topographically amplified Ia values with the parameter called as smoothed curvature. The amplification values for the low-frequency signals are better correlated with the curvature smoothed over larger spatial extent, while those values for the high-frequency signals are more linked to the curvature with smaller smoothing extent. The best predictions are provided by the curvature smoothed over the extent calculated according to Geli's law. The sample equations predicting the Ia amplification based on the smoothed curvature are presented for the sinusoid-shape input signals. These laws cannot be directly implemented in the regional Newmark method, as 3D amplification of the Ia values addresses more problem complexities which are not studied here. Nevertheless, our 2D results prepare the theoretical framework which can potentially be applied to the 3D domain and, therefore, represent a robust basis for these future research targets.

  16. 2D dynamic studies combined with the surface curvature analysis to predict Arias Intensity amplification

    NASA Astrophysics Data System (ADS)

    Torgoev, Almaz; Havenith, Hans-Balder

    2016-07-01

    A 2D elasto-dynamic modelling of the pure topographic seismic response is performed for six models with a total length of around 23.0 km. These models are reconstructed from the real topographic settings of the landslide-prone slopes situated in the Mailuu-Suu River Valley, Southern Kyrgyzstan. The main studied parameter is the Arias Intensity (Ia, m/sec), which is applied in the GIS-based Newmark method to regionally map the seismically-induced landslide susceptibility. This method maps the Ia values via empirical attenuation laws and our studies investigate a potential to include topographic input into them. Numerical studies analyse several signals with varying shape and changing central frequency values. All tests demonstrate that the spectral amplification patterns directly affect the amplification of the Ia values. These results let to link the 2D distribution of the topographically amplified Ia values with the parameter called as smoothed curvature. The amplification values for the low-frequency signals are better correlated with the curvature smoothed over larger spatial extent, while those values for the high-frequency signals are more linked to the curvature with smaller smoothing extent. The best predictions are provided by the curvature smoothed over the extent calculated according to Geli's law. The sample equations predicting the Ia amplification based on the smoothed curvature are presented for the sinusoid-shape input signals. These laws cannot be directly implemented in the regional Newmark method, as 3D amplification of the Ia values addresses more problem complexities which are not studied here. Nevertheless, our 2D results prepare the theoretical framework which can potentially be applied to the 3D domain and, therefore, represent a robust basis for these future research targets.

  17. Highly sensitive homogeneous electrochemical aptasensor for antibiotic residues detection based on dual recycling amplification strategy.

    PubMed

    Wang, Xiuzhong; Dong, Shanshan; Gai, Panpan; Duan, Rui; Li, Feng

    2016-08-15

    The ubiquitous presence of antibiotic residues in foodstuff have serious health consequences for consumers from allergic reactions to the evolution of antibiotic-resistant bacteria. To address this problem, a novel homogeneous electrochemical aptasensor with high sensitivity and specificity is designed for antibiotic residues detection based on target-induced and T7 exonuclease-assisted dual recycling signal amplification strategy. It was realized by the remarkable diffusivity difference between hairpin probe and the mononucleotides towards the negatively charged indium tin oxide electrode. For the proof-of-concept experiment, ampicillin, was employed as a model analyte to examine the desirable properties of this assay. A low detection limit of 4.0pM toward ampicillin with an excellent selectivity could be achieved, which has been successfully applied to assay antibiotic in milk. What's more, compared with the immobilization-based electrochemical means, the proposed sensing system avoids the tedious and time-consuming steps of electrode modification, making the experimental processes much simpler and more convenient. With the advantages of high sensitivity, excellent selectivity and simple operation, it is believed that this strategy possesses great potential for the simple, easy and convenient detection of antibiotic residues in food safety field. PMID:27040941

  18. Amplification, redundancy, and quantum Chernoff information.

    PubMed

    Zwolak, Michael; Riedel, C Jess; Zurek, Wojciech H

    2014-04-11

    Amplification was regarded, since the early days of quantum theory, as a mysterious ingredient that endows quantum microstates with macroscopic consequences, key to the "collapse of the wave packet," and a way to avoid embarrassing problems exemplified by Schrödinger's cat. Such a bridge between the quantum microworld and the classical world of our experience was postulated ad hoc in the Copenhagen interpretation. Quantum Darwinism views amplification as replication, in many copies, of the information about quantum states. We show that such amplification is a natural consequence of a broad class of models of decoherence, including the photon environment we use to obtain most of our information. This leads to objective reality via the presence of robust and widely accessible records of selected quantum states. The resulting redundancy (the number of copies deposited in the environment) follows from the quantum Chernoff information that quantifies the information transmitted by a typical elementary subsystem of the environment. PMID:24765928

  19. Time varying arctic climate change amplification

    SciTech Connect

    Chylek, Petr; Dubey, Manvendra K; Lesins, Glen; Wang, Muyin

    2009-01-01

    During the past 130 years the global mean surface air temperature has risen by about 0.75 K. Due to feedbacks -- including the snow/ice albedo feedback -- the warming in the Arctic is expected to proceed at a faster rate than the global average. Climate model simulations suggest that this Arctic amplification produces warming that is two to three times larger than the global mean. Understanding the Arctic amplification is essential for projections of future Arctic climate including sea ice extent and melting of the Greenland ice sheet. We use the temperature records from the Arctic stations to show that (a) the Arctic amplification is larger at latitudes above 700 N compared to those within 64-70oN belt, and that, surprisingly; (b) the ratio of the Arctic to global rate of temperature change is not constant but varies on the decadal timescale. This time dependence will affect future projections of climate changes in the Arctic.

  20. Ultrahigh contrast from a frequency-doubled chirped-pulse-amplification beamline.

    PubMed

    Hillier, David; Danson, Colin; Duffield, Stuart; Egan, David; Elsmere, Stephen; Girling, Mark; Harvey, Ewan; Hopps, Nicholas; Norman, Michael; Parker, Stefan; Treadwell, Paul; Winter, David; Bett, Thomas

    2013-06-20

    This paper describes frequency-doubled operation of a high-energy chirped-pulse-amplification beamline. Efficient type-I second-harmonic generation was achieved using a 3 mm thick 320 mm aperture KDP crystal. Shots were fired at a range of energies achieving more than 100 J in a subpicosecond, 527 nm laser pulse with a power contrast of 10(14). PMID:23842168