The Experts below are selected from a list of 3132 Experts worldwide ranked by ideXlab platform
Lorico D S Lapitan - One of the best experts on this subject based on the ideXlab platform.
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A simple magnetic nanoparticle-poly-enzyme Nanobead sandwich assay for direct, ultrasensitive DNA detection.
Methods in Enzymology, 2019Co-Authors: Lorico D S Lapitan, Dejian ZhouAbstract:Abstract A simple magnetic nanoparticle (MNP)-poly-enzyme Nanobead sandwich assay for direct detection of ultralow levels of unlabeled target-DNA is developed. This approach uses a capture-DNA covalently linked to a dense PEGylated polymer encapsulated MNP and a biotinylated signal-DNA to sandwich the target-DNA. A DNA ligation is then followed to offer high discrimination between the perfect-match and single-base mismatch target-DNAs. Only the presence of a perfect-match target can covalently link the biotinylated signal-DNA onto the MNP surface for subsequent binding to a polymer Nanobead tagged with thousands of copies of high-activity neutravidin-horseradish peroxidase (NAV-HRP) for great enzymatic signal amplification. Combining the advantages of the dense MNP surface PEGylation to reduce non-specific adsorption (assay background) and the powerful signal amplification of poly-enzyme Nanobead, this assay can directly quantify the target-DNA down to single digit attomolar with a large linear dynamic range of 5 orders of magnitude (from 10− 18 to 10− 13 M).
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combining magnetic nanoparticle capture and poly enzyme Nanobead amplification for ultrasensitive detection and discrimination of dna single nucleotide polymorphisms
Nanoscale, 2019Co-Authors: Lorico D S Lapitan, Yuan Guo, Dejian ZhouAbstract:The development of ultrasensitive methods for detecting specific genes and discriminating single nucleotide polymorphisms (SNPs) is important for biomedical research and clinical disease diagnosis. Herein, we report an ultrasensitive approach for label-free detection and discrimination of a full-match target-DNA from its cancer related SNPs by combining magnetic nanoparticle (MNP) capture and poly-enzyme Nanobead signal amplification. It uses a MNP linked capture-DNA and a biotinylated signal-DNA to sandwich the target followed by ligation to offer high SNP discrimination: only the perfect-match target-DNA yields a covalently linked biotinylated signal-DNA on the MNP surface for subsequent binding to a neutravidin–horseradish peroxidase conjugate (NAV–HRP) for signal amplification. The use of polymer Nanobeads each tagged with thousands of copies of HRPs greatly improves the signal amplification power, allowing for direct, amplification-free quantification of low aM target-DNA over 6 orders of magnitude (0.001–1000 fM). Moreover, this sensor also offers excellent discrimination between the perfect-match gene and its cancer-related SNPs and can positively detect 1 fM perfect-match target-DNA in the presence of 100 fold excess of co-existing single-base mismatch targets. Furthermore, it works robustly in clinically relevant media (e.g. 10% human serum) and gives even higher SNP discrimination than that in clean buffers. This ultrasensitive DNA sensor appears to have excellent potential for rapid detection and diagnosis of genetic diseases.
Dejian Zhou - One of the best experts on this subject based on the ideXlab platform.
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A simple magnetic nanoparticle-poly-enzyme Nanobead sandwich assay for direct, ultrasensitive DNA detection.
Methods in Enzymology, 2019Co-Authors: Lorico D S Lapitan, Dejian ZhouAbstract:Abstract A simple magnetic nanoparticle (MNP)-poly-enzyme Nanobead sandwich assay for direct detection of ultralow levels of unlabeled target-DNA is developed. This approach uses a capture-DNA covalently linked to a dense PEGylated polymer encapsulated MNP and a biotinylated signal-DNA to sandwich the target-DNA. A DNA ligation is then followed to offer high discrimination between the perfect-match and single-base mismatch target-DNAs. Only the presence of a perfect-match target can covalently link the biotinylated signal-DNA onto the MNP surface for subsequent binding to a polymer Nanobead tagged with thousands of copies of high-activity neutravidin-horseradish peroxidase (NAV-HRP) for great enzymatic signal amplification. Combining the advantages of the dense MNP surface PEGylation to reduce non-specific adsorption (assay background) and the powerful signal amplification of poly-enzyme Nanobead, this assay can directly quantify the target-DNA down to single digit attomolar with a large linear dynamic range of 5 orders of magnitude (from 10− 18 to 10− 13 M).
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combining magnetic nanoparticle capture and poly enzyme Nanobead amplification for ultrasensitive detection and discrimination of dna single nucleotide polymorphisms
Nanoscale, 2019Co-Authors: Lorico D S Lapitan, Yuan Guo, Dejian ZhouAbstract:The development of ultrasensitive methods for detecting specific genes and discriminating single nucleotide polymorphisms (SNPs) is important for biomedical research and clinical disease diagnosis. Herein, we report an ultrasensitive approach for label-free detection and discrimination of a full-match target-DNA from its cancer related SNPs by combining magnetic nanoparticle (MNP) capture and poly-enzyme Nanobead signal amplification. It uses a MNP linked capture-DNA and a biotinylated signal-DNA to sandwich the target followed by ligation to offer high SNP discrimination: only the perfect-match target-DNA yields a covalently linked biotinylated signal-DNA on the MNP surface for subsequent binding to a neutravidin–horseradish peroxidase conjugate (NAV–HRP) for signal amplification. The use of polymer Nanobeads each tagged with thousands of copies of HRPs greatly improves the signal amplification power, allowing for direct, amplification-free quantification of low aM target-DNA over 6 orders of magnitude (0.001–1000 fM). Moreover, this sensor also offers excellent discrimination between the perfect-match gene and its cancer-related SNPs and can positively detect 1 fM perfect-match target-DNA in the presence of 100 fold excess of co-existing single-base mismatch targets. Furthermore, it works robustly in clinically relevant media (e.g. 10% human serum) and gives even higher SNP discrimination than that in clean buffers. This ultrasensitive DNA sensor appears to have excellent potential for rapid detection and diagnosis of genetic diseases.
Hiroyuki Fujita - One of the best experts on this subject based on the ideXlab platform.
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MICROMACHINED LINEAR BROWNIAN MOTOR: NET-UNIDIRECTIONAL TRANSPORT OF NanobeadS BY TAMED BROWNIAN MOTION WITH
2007Co-Authors: Electrostatic Rectification, Ersin Altintas, Karl F. Böhringer, Hiroyuki FujitaAbstract:This paper reports for the first time on net-unidirectional transport of Nanobeads by Brownian motion using a periodic 3-phase electrostatic rectification. The transportation of beads is performed in 1 µm deep, 2 or 3 µm wide PDMS microchannels, which constrain three dimensional random motion of Nanobeads into 1D fluctuation, so-called tamed Brownian motion. 3 µm wide and 2µm separated ITO electrodes are fabricated by lift-off process on a 24x36 mm 2 coverglass, and a previously fabricated PDMS sheet with microchannels and processed for inlets is aligned and sealed with the electrodes. Diluted fluorescent Nanobead, 500 nm in diameter, solution is introduced and equilibrium of the flow is awaited. Electrostatic rectification observations are performed by an inverted microscope. Rectified netunidirectional transport of Nanobeads is achieved at 200 mVpp and 400 mVpp at 1 MHz. 2 different beads are transported along the channel over 20 and 10 µm, respectively, in about 100 seconds, while other bead just wandered around in the same microchannel.
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Micromachined linear brownian motor: Net-unidirectional transport of Nanobeads by tamed brownian motion with electrostatic rectification
2007 IEEE 20th International Conference on Micro Electro Mechanical Systems (MEMS), 2007Co-Authors: Ersin Altintas, Karl F. Böhringer, Hiroyuki FujitaAbstract:This paper reports for the first time on net-unidirectional transport of Nanobeads by Brownian motion using a periodic 3-phase electrostatic rectification. The transportation of beads is performed in 1 mum deep, 2 or 3 mum wide PDMS microchannels, which constrain three dimensional random motion of Nanobeads into ID fluctuation, so-called tamed Brownian motion. 3 mum wide and 2 mum separated ITO electrodes are fabricated by lift-off process on a 24 x 36 mm2 coverglass, and a previously fabricated PDMS sheet with microchannels and processed for inlets is aligned and sealed with the electrodes. Diluted fluorescent Nanobead, 500 nm in diameter, solution is introduced and equilibrium of the flow is awaited. Electrostatic rectification observations are performed by an inverted microscope. Rectified net- unidirectional transport of Nanobeads is achieved at 200 mVpp and 400 mVpp at 1 MHz. 2 different beads are transported along the channel over 20 and 10 mum, respectively, in about 100 seconds, while other bead just wandered around in the same microchannel.
Horn-jiunn Sheen - One of the best experts on this subject based on the ideXlab platform.
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A Smartphone-based Diffusometric Immunoassay for Detecting C-Reactive Protein
Scientific Reports, 2019Co-Authors: Chih-shen Chuang, Chih-zong Deng, Yi-fan Fang, Hong-ren Jiang, Pao-wei Tseng, Horn-jiunn SheenAbstract:In this study, we developed a portable smartphone-based diffusometry for analyzing the C-reactive protein (CRP) concentration. An optimized fluorescence microscopic add-on system for a smartphone was used to image the 300 nm fluorescent beads. Sequential Nanobead images were recorded for a period and the image data were used for fluorescence correlation spectrometric (FCS) analysis. Through the analysis, the Nanobeads’ diffusion coefficient was obtained. Further, the diffusion coefficients of the anti-CRP-coated Nanobeads, which were suspended in the samples with various CRP concentrations, were estimated using smartphone-based diffusometry. After 10 min of reaction, the anti-CRP-coated Nanobeads in a higher CRP concentration solution led to a lower diffusion coefficient. Based on the experiments, a linear sensing range of 1~8 µg/mL was found.
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TIRF-enhanced Nanobeads’ Brownian diffusion measurements for detecting CRP in human serum
Microfluidics and Nanofluidics, 2015Co-Authors: Yu-jui Fan, Horn-jiunn Sheen, Zheng-yu Chen, Yi-hsing Liu, Jing-fa TsaiAbstract:This paper reports the in situ detection of C-reactive protein (CRP) and antibody-coated Nanobead interaction by measuring the variation of the Brownian diffusion of the Nanobeads. The measurements are carried out by using total internal reflective fluorescence-enhanced (TIRF-enhanced) micro-particle-tracking velocimetry (micro-PTV), which is highly sensitive for analyzing Nanobead movements in the near-wall region. The characteristics of evanescent wave penetration of various liquid samples, which have different refractive indices, are investigated for Nanobead illumination. The Brownian velocities of the Nanobeads in various concentrations of CRPs within glycerol solution and serum are measured in real time. The detectable CRP concentration range of 1–6 mg/ml in human serum is found, and the detecting process can be finished in 10 min. From the results, the dissociation constant of CRP and anti-CRP in various viscosity solutions can be determined through the developed kinetic analysis.
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A quantitative immunosensing technique based on the measurement of Nanobeads' Brownian motion
Biosensors and Bioelectronics, 2009Co-Authors: Yu-jui Fan, Horn-jiunn Sheen, Hsu Chia-jui, Cheng Pang Liu, Shiming LinAbstract:A novel bio-sensing technique based on the measurement of Nanobeads’ Brownian motion using a microparticle tracking velocimetry (micro-PTV) has been successfully developed to detect antigen–antibody interactions. The rapid interaction between antigens (C-reactive proteins, CRPs) and Nanobeads with conjugated antibodies (anti-CRPs) has enabled real-time detection of CRPs to be easily carried out. During the binding process of CRPs to Nanobeads, the mean value of the beads’ diameters increases so that the Brownian velocity decreases with the increase of time. Moreover, higher CRP concentration leads to a lower Brownian velocity of the Nanobeads in the equilibrium state. From the results, the limit of detection 0.1g/ml was observed and could be further improved by using smaller Nanobeads. Moreover, based on kinetic analysis, the average dissociation constant KD = (6.48 ± 1.43) × 10 −7 found by this technique for anti-CRP was shown to be in close agreement with the literature values obtained by dual-polarization interferometry (DPI) and indirect competition enzyme-linked immunosorbent assay (ELISA). This simple sensing method can further be used to detect other bio-molecules and viruses. © 2009 Elsevier B.V. All rights reserved.
Hiroshi Handa - One of the best experts on this subject based on the ideXlab platform.
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Application of high-performance magnetic Nanobeads to biological sensing devices
Analytical and Bioanalytical Chemistry, 2019Co-Authors: Yasuaki Kabe, Satoshi Sakamoto, Mamoru Hatakeyama, Yuki Yamaguchi, Makoto Suematsu, Makoto Itonaga, Hiroshi HandaAbstract:Nanomaterials have extensive applications in the life sciences and in clinical diagnosis. We have developed magnetic nanoparticles with high dispersibility and extremely low nonspecific binding to biomolecules and have demonstrated their application in chemical biology (e.g., for the screening of drug receptor proteins). Recently, the excellent properties of Nanobeads have made possible the development of novel rapid immunoassay systems and high-precision technologies for exosome detection. For immunoassays, we developed a technology to encapsulate a fluorescent substance in magnetic Nanobeads. The fluorescent Nanobeads allow the rapid detection of a specific antigen in solution or in tissue specimens. Exosomes, which are released into the blood, are expected to become markers for several diseases, including cancer, but techniques for measuring the absolute quantity of exosomes in biological fluids are lacking. By integrating magnetic Nanobead technology with an optical disc system, we developed a novel method for precisely quantifying exosomes in human serum with high sensitivity and high linearity without requiring enrichment procedures. This review focuses on the properties of our magnetic Nanobeads, the development of novel biosensors using these Nanobeads, and their broad practical applications. Graphical abstract
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Application of high-performance magnetic Nanobeads to biological sensing devices.
Analytical and Bioanalytical Chemistry, 2019Co-Authors: Yasuaki Kabe, Satoshi Sakamoto, Mamoru Hatakeyama, Yuki Yamaguchi, Makoto Suematsu, Itonaga Makoto, Hiroshi HandaAbstract:Nanomaterials have extensive applications in the life sciences and in clinical diagnosis. We have developed magnetic nanoparticles with high dispersibility and extremely low nonspecific binding to biomolecules and have demonstrated their application in chemical biology (e.g., for the screening of drug receptor proteins). Recently, the excellent properties of Nanobeads have made possible the development of novel rapid immunoassay systems and high-precision technologies for exosome detection. For immunoassays, we developed a technology to encapsulate a fluorescent substance in magnetic Nanobeads. The fluorescent Nanobeads allow the rapid detection of a specific antigen in solution or in tissue specimens. Exosomes, which are released into the blood, are expected to become markers for several diseases, including cancer, but techniques for measuring the absolute quantity of exosomes in biological fluids are lacking. By integrating magnetic Nanobead technology with an optical disc system, we developed a novel method for precisely quantifying exosomes in human serum with high sensitivity and high linearity without requiring enrichment procedures. This review focuses on the properties of our magnetic Nanobeads, the development of novel biosensors using these Nanobeads, and their broad practical applications. Open in a separate window Graphical abstract
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Ultrahigh-Sensitivity Biomarker Sensing System Based on the Combination of Optical Disc Technologies and Nanobead Technologies
Japanese Journal of Applied Physics, 2013Co-Authors: Koji Tsujita, Satoshi Sakamoto, Mamoru Hatakeyama, Itonaga Makoto, Hasegawa Yuichi, Masayuki Ono, Hiroshi HandaAbstract:The detection of biomarkers in body fluids is useful for the early detection of diseases or preventive medical care. Various types of equipment that detect biomarkers have been developed and used for various occasions. It is expected that further improvement of the detection sensitivity of biomarkers will enable the extension for their applications to various diseases. In this paper, we propose a new biomarker sensing system with higher sensitivity. In the system, by combining optical disc technologies and Nanobead technologies, we developed a new sensing method. Target biomarkers are specifically immobilized onto the optical disc surface through an antigen-antibody reaction, then the Nanobeads are immobilized on top of the biomarkers. Since the biomarkers and beads bind to each other one-on-one, the number of target biomarkers can be measured by counting the number of Nanobeads using an optical pickup. The most significant advantage of this method is that measurement can be carried out in a fully digital scheme, in contrast to current sensing systems which measure light intensity in an analog scheme.
