Multiresonant plasmonic nanostructure for ultrasensitive fluorescence biosensing

AbstractA novel metallic nanostructure for efficient plasmon-enhanced fluorescence readout of biomolecular binding events on the surface of a solid sensor chip is reported. It is based on gold multiperiod plasmonic grating (MPG) that supports spectrally narrow plasmonic resonances centered at multiple distinct wavelengths. They originate from diffraction coupling to propagating surface plasmons (SPs) forming a delocalized plasmonic hotspot associated with enhanced electromagnetic field intensity and local density of optical states at its surface. The supported SP resonances are tailored to couple with the excitation and emission transitions of fluorophores that are conjugated with the biomolecules and serve as labels. By the simultaneous coupling at both excitation and emission wavelengths, detected fluorescence intensity is enhanced by the factor of 300 at the MPG surface, which when applied for the readout of fluorescence immunoassays translates to a limit of detection of 6 fM within detection time of 20 min. The proposed approach is attractive for parallel monitoring of kinetics of surface reactions in microarray format arranged on a macroscopic footprint. The readout by epi-fluorescence geometry (that inherently relies on low numerical aperture optics for the imaging of the arrays) can particularly take advantage of the reported MPG. In addition, the proposed MPG nanostructure can be prepared in scaled up means by UV-nanoimprint lithography for future practical applications.

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Ion Beam Induced Interfacial Reactions in Molybdenum Thin Films on Silicon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100097466 ◽

1981 ◽

Vol 39 ◽

pp. 162-163

Author(s):

L. J. Chen ◽

L. S. Hung ◽

J. W. Mayer

Keyword(s):

Ion Beam ◽

Chemical Vapor ◽

Interfacial Reactions ◽

Practical Applications ◽

Microelectronic Devices ◽

Recent Emergence ◽

Chemical Vapor Deposited ◽

Atomic Mixing ◽

Silicon Interface ◽

Kinetics Of

When an energetic ion penetrates through an interface between a thin film (of species A) and a substrate (of species B), ion induced atomic mixing may result in an intermixed region (which contains A and B) near the interface. Most ion beam mixing experiments have been directed toward metal-silicon systems, silicide phases are generally obtained, and they are the same as those formed by thermal treatment.Recent emergence of silicide compound as contact material in silicon microelectronic devices is mainly due to the superiority of the silicide-silicon interface in terms of uniformity and thermal stability. It is of great interest to understand the kinetics of the interfacial reactions to provide insights into the nature of ion beam-solid interactions as well as to explore its practical applications in device technology.About 500 Å thick molybdenum was chemical vapor deposited in hydrogen ambient on (001) n-type silicon wafer with substrate temperature maintained at 650-700°C. Samples were supplied by D. M. Brown of General Electric Research & Development Laboratory, Schenectady, NY.

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Development of Quantitative Real-Time Polymerase Chain Reaction for Detection of and Discrimination between Erysipelothrix Rhusiopathiae and Other Erysipelothrix Species

Journal of Veterinary Diagnostic Investigation ◽

10.1177/104063870902100518 ◽

2009 ◽

Vol 21 (5) ◽

pp. 701-706 ◽

Cited By ~ 8

Author(s):

Ho To ◽

Tomohiro Koyama ◽

Shinya Nagai ◽

Kotaro Tuchiya ◽

Tetsuo Nunoya

Keyword(s):

Polymerase Chain Reaction ◽

Real Time ◽

Limit Of Detection ◽

Enrichment Culture ◽

Bacterial Species ◽

Erysipelothrix Rhusiopathiae ◽

Chain Reaction ◽

Tissue Samples ◽

Practical Applications ◽

Polymerase Chain

Quantitative real-time polymerase chain reaction (qPCR) assays were developed and validated in combination with enrichment culture for the detection and discrimination of Erysipelothrix rhusiopathiae and other Erysipelothrix species from tissue samples. The targets for SYBR green qPCR assays were the 16S ribosomal RNA gene for Erysipelothrix species and a gene involved in capsular formation for E. rhusiopathiae. The specificity of the assays was assessed with Erysipelothrix species and other related bacterial species. The limit of detection was found to be 5 colony-forming units per reaction. Amplification of DNA extracted from spleen and joint samples spiked with increasing quantities of Erysipelothrix cells was shown to be equally sensitive to DNA extracted from a pure bacterial culture. The assays were evaluated with 88 tissue samples from 3 experimentally infected pigs and 50 mice and with 36 tissue samples from 3 naturally infected pigs and 11 noninfected pigs. Results were compared with those of direct qPCR and conventional culture. The qPCR after enrichment increased the diagnostic sensitivity over that of culture and qPCR, thereby significantly reducing the total time taken for the detection of E. rhusiopathiae and other Erysipelothrix species. Therefore, this technique could be used for practical applications.

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A benzothiazole-based fluorescence turn-on sensor for copper(II)

10.21203/rs.3.rs-381861/v1 ◽

2021 ◽

Author(s):

Gyeongjin Kim ◽

Donghwan Choi ◽

Cheal Kim

Keyword(s):

Charge Transfer ◽

Limit Of Detection ◽

Theoretical Calculations ◽

Enhanced Fluorescence ◽

Turn On ◽

Fluorescent Response ◽

Chelation Enhanced Fluorescence ◽

Fluorescence Turn On ◽

Internal Charge Transfer ◽

Internal Charge

Abstract A new benzothiazole-based chemosensor BTN (1-((Z)-(((E)-3-methylbenzo[d]thiazol-2(3H)-ylidene)hydrazono)methyl)naphthalen-2-ol) was synthesized for the detection of Cu2+. BTN could detect Cu2+ with “off-on” fluorescent response from colorless to yellow irrespective of presence of other cations. Limit of detection for Cu2+ was determined to be 3.3 µM. Binding ratio of BTN and Cu2+ turned out to be a 1:1 with the analysis of Job plot and ESI-MS. Sensing feature of Cu2+ by BTN was explained with theoretical calculations, which might be owing to internal charge transfer and chelation-enhanced fluorescence processes.

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Enzyme Method-Based Microfluidic Chip for the Rapid Detection of Copper Ions

Micromachines ◽

10.3390/mi12111380 ◽

2021 ◽

Vol 12 (11) ◽

pp. 1380

Author(s):

Binfeng Yin ◽

Xinhua Wan ◽

Changcheng Qian ◽

A. S. M. Muhtasim Fuad Sohan ◽

Teng Zhou ◽

...

Keyword(s):

Metal Ions ◽

Microfluidic Chip ◽

Limit Of Detection ◽

Copper Ions ◽

Practical Applications ◽

Enzyme Method ◽

In Series ◽

High Concentrations ◽

Biochemical Detection ◽

Seawater Samples

Metal ions in high concentrations can pollute the marine environment. Human activities and industrial pollution are the causes of Cu2+ contamination. Here, we report our discovery of an enzyme method-based microfluidic that can be used to rapidly detect Cu2+ in seawater. In this method, Cu2+ is reduced to Cu+ to inhibit horseradish peroxidase (HRP) activity, which then results in the color distortion of the reaction solution. The chip provides both naked eye and spectrophotometer modalities. Cu2+ concentrations have an ideal linear relationship, with absorbance values ranging from 3.91 nM to 256 μM. The proposed enzyme method-based microfluidic chip detects Cu2+ with a limit of detection (LOD) of 0.87 nM. Other common metal ions do not affect the operation of the chip. The successful detection of Cu2+ was achieved using three real seawater samples, verifying the ability of the chip in practical applications. Furthermore, the chip realizes the functions of two AND gates in series and has potential practical implementations in biochemical detection and biological computing.

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Investigation of measurement data of low-coherence interferometry at tilted surfaces in the 3D spatial frequency domain

tm - Technisches Messen ◽

10.1515/teme-2021-0051 ◽

2021 ◽

Vol 88 (s1) ◽

pp. s65-s70

Author(s):

Marco Künne ◽

Sebastian Hagemeier ◽

Eireen Käkel ◽

Hartmut Hillmer ◽

Peter Lehmann

Keyword(s):

Spatial Frequency ◽

Frequency Domain ◽

Nanoimprint Lithography ◽

System Analysis ◽

Measurement Data ◽

Numerical Aperture ◽

Surface Slopes ◽

Ewald Sphere ◽

Interference Signals ◽

Spatial Frequency Domain

Abstract The 3D transfer characteristics of interference microscopes and their effect on the interference signals occurring at surface slopes are studied. The interference image stacks acquired during a depth scan are 3D Fourier transformed. This allows a comprehensive frequency domain analysis of the interferograms. The double foil model introduced in a previous publication enables the interpretation of the signal spectra and the underlying transfer behavior of the interferometer using the concept of the Ewald sphere, which is limited by the numerical aperture (NA) of the imaging system. Analysis in the 3D spatial frequency domain directly discloses that the lateral dimensions of the transfer function depend on the axial spatial frequency. In this contribution we investigate measuring objects produced by Nanoimprint-Lithography. The corresponding signal spectra bear information that can be utilized to optimize the subsequent signal processing algorithms. These include envelope and phase evaluation procedures of the interference signals. A narrow bandpass filter is used to actively select certain frequency components in order to improve the robustness of the estimation of the envelope position. Although the shape and width of the envelope are affected, this procedure increases the reliability of the evaluation process and improves the accuracy of the measured topography especially at steeper surface slopes.

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Degradation of Fenoxaprop-p-Ethyl and Its Metabolite in Soil and Wheat Crops

Journal of Food Protection ◽

10.4315/0362-028x.jfp-19-127 ◽

2019 ◽

Vol 82 (11) ◽

pp. 1959-1964

Author(s):

SHISHIR TANDON

Keyword(s):

Limit Of Detection ◽

Field Conditions ◽

The European Union ◽

Uv Detector ◽

Wheat Field ◽

First Order Kinetics ◽

Application Rates ◽

Solid Liquid ◽

Kinetics Of ◽

Soil Wheat

ABSTRACT The dissipation kinetics of fenoxaprop-p-ethyl and its metabolite (fenoxaprop acid) at two application rates under wheat field conditions for two seasons was investigated. Herbicides were extracted by solid liquid extraction, cleaned up, and analyzed by a liquid chromatography–UV detector. Dissipation followed first-order kinetics; in soil, fenoxaprop-p-ethyl dissipated rapidly with an average half-life of 1.45 to 2.30 days, while fenoxaprop acid persisted for more than 30 days. The method was validated in terms of accuracy, linearity, specificity, and precision. Linearity was in the range of 5 to 5,000 ng, with a limit of detection (LOD) of 2 and 1 ng for fenoxaprop-p-ethyl and fenoxaprop acid, respectively. The quantitation limits in soil, grain, and straw were 5, 8, and 10 ng g−1 for fenoxaprop-p-ethyl and 5, 10, and 10 ng g−1 for fenoxaprop acid, respectively. Recovery in soil, grains, and straw ranged from 85.1 to 91.25%, 72.5 to 84.66%, and 77.64 to 82.24% for fenoxaprop-p-ethyl and 80.56 to 86.5%, 78 to 81.88%, and 75.2 to 79.68% for fenoxaprop acid, respectively. At harvest, no detectable residues of fenoxaprop-p-ethyl or acid were observed in soil, wheat grain, and straw samples. Owing to the short persistence under field conditions, fenoxaprop-p-ethyl is safe for use because parent and metabolite residues were below the European Union maximum residue limit and would not pose an adverse effect on the environment and human or animal foods.

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Ultrasensitive antibody-aptamer plasmonic biosensor for malaria biomarker detection in whole blood

Nature Communications ◽

10.1038/s41467-020-19755-0 ◽

2020 ◽

Vol 11 (1) ◽

Cited By ~ 1

Author(s):

Antonio Minopoli ◽

Bartolomeo Della Ventura ◽

Bohdan Lenyk ◽

Francesco Gentile ◽

Julian A. Tanner ◽

...

Keyword(s):

Whole Blood ◽

Limit Of Detection ◽

Sample Pretreatment ◽

High Specificity ◽

Ease Of Use ◽

Enhanced Fluorescence ◽

High Throughput Analysis ◽

Malaria Rapid Diagnostic Tests ◽

Copolymer Micelle ◽

Very High

AbstractDevelopment of plasmonic biosensors combining reliability and ease of use is still a challenge. Gold nanoparticle arrays made by block copolymer micelle nanolithography (BCMN) stand out for their scalability, cost-effectiveness and tunable plasmonic properties, making them ideal substrates for fluorescence enhancement. Here, we describe a plasmon-enhanced fluorescence immunosensor for the specific and ultrasensitive detection of Plasmodium falciparum lactate dehydrogenase (PfLDH)—a malaria marker—in whole blood. Analyte recognition is realized by oriented antibodies immobilized in a close-packed configuration via the photochemical immobilization technique (PIT), with a top bioreceptor of nucleic acid aptamers recognizing a different surface of PfLDH in a sandwich conformation. The combination of BCMN and PIT enabled maximum control over the nanoparticle size and lattice constant as well as the distance of the fluorophore from the sensing surface. The device achieved a limit of detection smaller than 1 pg/mL (<30 fM) with very high specificity without any sample pretreatment. This limit of detection is several orders of magnitude lower than that found in malaria rapid diagnostic tests or even commercial ELISA kits. Thanks to its overall dimensions, ease of use and high-throughput analysis, the device can be used as a substrate in automated multi-well plate readers and improve the efficiency of conventional fluorescence immunoassays.

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Hydrolysis Kinetics of Cornstalk in Formic Acid Solution

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.535-537.2438 ◽

2012 ◽

Vol 535-537 ◽

pp. 2438-2441

Author(s):

Jun Ping Zhuang ◽

Xue Ping Li

Keyword(s):

Activation Energy ◽

Acid Solution ◽

Formic Acid ◽

Wood Fiber ◽

Hydrolysis Kinetics ◽

Practical Applications ◽

And Performance ◽

Promising Source ◽

Kinetics Of ◽

Hydrolysis Of

Cornstalk, among the agricultural residues and other non-wood fiber, is a more promising source of lignocellulosic materials for bioethanol production. Pretreatment is an essential step in the enzymatic hydrolysis of biomass and subsequent production of bioethanol. Kinetic models can have practical applications for the optimization of the process and performance analysis, or economic estimations, so investigate the cornstalk hydrolysis kinetics is necessary. In this paper, effects of temperature and time on cornstalk hydrolysis in saturated formic acid with 4% hydrochloric acid solution reaction kinetics have been investigated. The results showed that the hydrolysis velocities of cornstalk were 0.021 h−1 at 60 °C, 0.0302 h−1 at 65 °C and 0.060 h−1 at 70 °C, the degradation velocities of glucose were 0.061 h−1 at 60 °C, 0.0845 h−1 at 65 °C, and 0.24 h−1 at 70 °C, the activation energy of cornstalk hydrolysis was 99.60 kJ/mol, and the activation energy of glucose degradation was130.94 kJ/mol.

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