Publications by authors named "Juhun Park"

23 Publications

  • Page 1 of 1

Magnetically-focusing biochip structures for high-speed active biosensing with improved selectivity.

Nanotechnology 2018 Jun 6;29(26):265501. Epub 2018 Apr 6.

Department of Physics and Astronomy, and Institute of Applied Physics, Seoul national University, Seoul 08826, Republic of Korea.

We report a magnetically-focusing biochip structure enabling a single layered magnetic trap-and-release cycle for biosensors with an improved detection speed and selectivity. Here, magnetic beads functionalized with specific receptor molecules were utilized to trap target molecules in a solution and transport actively to and away from the sensor surfaces to enhance the detection speed and reduce the non-specific bindings, respectively. Using our method, we demonstrated the high speed detection of IL-13 antigens with the improved detection speed by more than an order of magnitude. Furthermore, the release step in our method was found to reduce the non-specific bindings and improve the selectivity and sensitivity of biosensors. This method is a simple but powerful strategy and should open up various applications such as ultra-fast biosensors for point-of-care services.
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http://dx.doi.org/10.1088/1361-6528/aabc4dDOI Listing
June 2018

Magnetically-refreshable receptor platform structures for reusable nano-biosensor chips.

Nanotechnology 2016 Jan 14;27(4):045502. Epub 2015 Dec 14.

Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 151-747, Korea.

We developed a magnetically-refreshable receptor platform structure which can be integrated with quite versatile nano-biosensor structures to build reusable nano-biosensor chips. This structure allows one to easily remove used receptor molecules from a biosensor surface and reuse the biosensor for repeated sensing operations. Using this structure, we demonstrated reusable immunofluorescence biosensors. Significantly, since our method allows one to place receptor molecules very close to a nano-biosensor surface, it can be utilized to build reusable carbon nanotube transistor-based biosensors which require receptor molecules within a Debye length from the sensor surface. Furthermore, we also show that a single sensor chip can be utilized to detect two different target molecules simply by replacing receptor molecules using our method. Since this method does not rely on any chemical reaction to refresh sensor chips, it can be utilized for versatile biosensor structures and virtually-general receptor molecular species.
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http://dx.doi.org/10.1088/0957-4484/27/4/045502DOI Listing
January 2016

Real-time monitoring of geosmin and 2-methylisoborneol, representative odor compounds in water pollution using bioelectronic nose with human-like performance.

Biosens Bioelectron 2015 Dec 25;74:199-206. Epub 2015 Jun 25.

Interdisciplinary Program for Bioengineering, Seoul National University, Seoul 151-742, Republic of Korea; School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, Republic of Korea; Advanced Institutes of Convergence Technology, Suwon 433-270, Republic of Korea. Electronic address:

A bioelectronic nose for the real-time assessment of water quality was constructed with human olfactory receptor (hOR) and single-walled carbon nanotube field-effect transistor (swCNT-FET). Geosmin (GSM) and 2-methylisoborneol (MIB), mainly produced by bacteria, are representative odor compounds and also indicators of contamination in the water supply system. For the screening of hORs which respond to these compounds, we performed CRE-luciferase assays of the two odorants in heterologous cell system. Human OR51S1 for GSM and OR3A4 for MIB were selected, and nanovesicles expressing the hORs on surface were produced from HEK-293 cell. Carbon nanotube field-effect transistor was functionalized with the nanovesicles. The bioelectronic nose was able to selectively detect GSM and MIB at concentrations as low as a 10 ng L(-1). Furthermore, detection of these compounds from the real samples such as tap water, bottled water and river water was available without any pretreatment processes.
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http://dx.doi.org/10.1016/j.bios.2015.06.053DOI Listing
December 2015

Bioelectronic nose combined with a microfluidic system for the detection of gaseous trimethylamine.

Biosens Bioelectron 2015 Sep 14;71:179-185. Epub 2015 Apr 14.

School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, Republic of Korea; Bio-MAX Institute, Seoul National University, Seoul 151-742, Republic of Korea; Advanced Institutes of Convergence Technology, Suwon, Gyeonggi-do 443-270, Republic of Korea. Electronic address:

A bioelectronic nose based on a novel microfluidic system (μBN) was fabricated to detect gaseous trimethylamine (TMA) in real-time. Single-walled carbon nanotube-field effect transistors (SWNT-FETs) were functionalized with olfactory receptor-derived peptides (ORPs) that can recognize the TMA molecules. The ORP-coated SWNT-FETs were assembled with a microfluidic channel and were sealed with top and bottom frames. This simple process was used to complete the μBNs, and a well-defined condition was achieved to detect the gaseous molecules. The μBNs allowed us to detect gaseous TMA molecules down to 10 parts per trillion (ppt) in real-time and showed high selectivity when distinguishing gaseous TMA from other gaseous odorants. The sensor was used to determine the quality of seafood (oysters), and spoiled seafood and other types of spoiled foods were also successfully discriminated without any pretreatment processes. These results indicate that portable-scale platforms can be manufactured by using μBNs and can be applicable for real-time on-site gas analysis.
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http://dx.doi.org/10.1016/j.bios.2015.04.033DOI Listing
September 2015

Surface passivation of a photonic crystal band-edge laser by atomic layer deposition of SiO2 and its application for biosensing.

Nanoscale 2015 Feb;7(8):3565-71

Department of Biophysics and Chemical Biology, Seoul National University, Seoul 151-747, Republic of Korea.

We report on the conformal surface passivation of photonic crystal (PC) laser devices with an ultrathin dielectric layer. Air-bridge-type Γ-point band-edge lasers (BELs) are fabricated by forming a honeycomb lattice two-dimensional PC structure into an InGaAsP multiple-quantum-well epilayer. Atomic layer deposition (ALD) is employed for conformal deposition of a few-nanometer-thick SiO2 layer over the entire device surface, not only on the top and bottom surfaces of the air-bridge membrane but also on the air-hole sidewalls. Despite its extreme thinness, the ALD passivation layer is found to protect the InGaAsP BEL devices from harsh chemicals. In addition, the ALD-SiO2 is compatible with the silane-based surface chemistry, which allows us to use ALD-passivated BEL devices as label-free biosensors. The standard streptavidin-biotin interaction shifts the BEL lasing wavelength by ∼1 nm for the dipole-like Γ-point band-edge mode. A sharp lasing line (<0.2 nm, full width at half-maximum) and a large refractive index sensitivity (∼163 nm per RIU) produce a figure of merit as high as ∼800 for our BEL biosensor, which is at least an order of magnitude higher than those of more common biosensors that rely on a broad resonance peak, showing that our nanolaser structures are suitable for highly sensitive biosensor applications.
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http://dx.doi.org/10.1039/c4nr07552hDOI Listing
February 2015

Ion-channel-coupled receptor-based platform for a real-time measurement of G-protein-coupled receptor activities.

ACS Nano 2015 Feb 30;9(2):1699-706. Epub 2015 Jan 30.

School of Chemical and Biological Engineering, ‡Interdisciplinary Program for Bioengineering, §Department of Physics and Astronomy, and ⊥Department of Biophysics and Chemical Biology, Seoul National University , Seoul 151-744, Republic of Korea.

A simple but efficient measurement platform based on ion-channel-coupled receptors and nanovesicles was developed for monitoring the real-time activity of G-protein-coupled receptors (GPCRs). In this work, an olfactory receptor (OR), the most common class A GPCR, was covalently fused with a Kir6.2 channel so that the GPCR action directly induced the opening of the ion channels and changes in the electrical membrane potential without complex cellular signaling processes. This strategy reduced the measurement errors caused by instability of various cellular components. In addition, rather than using whole cells, a cell-surface-derived nanovesicle was used to preserve the membrane-integrated structure of GPCRs and to exclude case-dependent cellular conditions. Another merit of using the nanovesicle is that nanovesicles can be easily combined with nanomaterial-based field-effect transistors (FETs) to build a sensitive and stable measurement platform to monitor GPCR activities with high sensitivity in real-time. Using a platform based on carbon nanotube FETs and nanovesicles carrying Kir6.2-channel-coupled ORs, we monitored the real-time response of ORs to their ligand molecules. Significantly, since this platform does not rely on rather unstable cell signaling pathways, our platform could be utilized for a rather long time period without losing its functionality. This system can be utilized extensively for simple and sensitive analysis of the activities of various GPCRs and should enable various academic and practical applications.
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http://dx.doi.org/10.1021/nn506494eDOI Listing
February 2015

Olfactory receptor screening assay using nanovesicle-immobilized carbon nanotube transistor.

Methods Mol Biol 2015 ;1272:189-98

School of Chemical and Biological Engineering, Seoul National University, Seoul, 151-744, Republic of Korea.

Olfactory receptor (OR) genes are considered to be the largest superfamily of the mammalian genome, and in the case of humans, approximately 390 kinds of functional ORs play a role in perceiving odors. In spite of their significance in olfaction, the function of all ORs has not yet been fully revealed. In order to efficiently identify specific ligands of orphan ORs, methods that can generate olfactory signals in a reliable manner and that can convert the cellular signals into measurable responses are required. Here, we describe an OR screening assay method using olfactory sensors that are based on cell-derived nanovesicles combined with single-walled carbon nanotube field-effect transistors (SWNT-FETs). The nanovesicles contain ORs on their surface membrane and induce influx of calcium ions similar to olfactory signal transduction. This ion influx causes an electrical current change along the carbon nanotube, and then this change is measured by the SWNT-FET sensor. This technique facilitates the simple and rapid screening of OR functions.
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http://dx.doi.org/10.1007/978-1-4939-2336-6_13DOI Listing
September 2015

Nanovesicle-based platform for the electrophysiological monitoring of aquaporin-4 and the real-time detection of its antibody.

Biosens Bioelectron 2014 Nov 13;61:140-6. Epub 2014 May 13.

Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 151-747, Republic of Korea; Department of Biophysics and Chemical Biology, Seoul National University, Seoul 151-747, Republic of Korea. Electronic address:

Aquaporin-4 (AQP4) water channel protein transports water molecules across cell membranes bidirectionally and involves in a neurological disorder, neuromyelitis optica (NMO) caused by anti-AQP4 antibodies. Here, we developed a platform based on nanovesicle-carbon nanotube hybrid nanostructures for the real-time detection of anti-AQP4 antibodies and the electrophysiological monitoring of AQP4 activities. Using the hybrid device, we could detect anti-AQP4 antibodies with a high sensitivity and estimate the binding constants under different osmotic conditions. The results show AQP4 had a better affinity to anti-AQP4 antibodies under hyper-osmotic conditions than normal conditions. Furthermore, our device can be utilized to study the real-time cellular responses related with AQP4 such as those to different osmotic stresses. This nanovesicle-based platform can be a simple but versatile tool for basic research about AQP4 and related biomedical applications such as disease diagnostics.
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http://dx.doi.org/10.1016/j.bios.2014.05.003DOI Listing
November 2014

Gate-bias stress-dependent photoconductive characteristics of multi-layer MoS2 field-effect transistors.

Nanotechnology 2014 Apr 18;25(15):155201. Epub 2014 Mar 18.

Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 151-747, Korea.

We investigated the photoconductive characteristics of molybdenum disulfide (MoS2) field-effect transistors (FETs) that were fabricated with mechanically exfoliated multi-layer MoS2 flakes. Upon exposure to UV light, we observed an increase in the MoS2 FET current because of electron-hole pair generation. The MoS2 FET current decayed after the UV light was turned off. The current decay processes were fitted using exponential functions with different decay characteristics. Specifically, a fast decay was used at the early stages immediately after turning off the light to account for the exciton relaxation, and a slow decay was used at later stages long after turning off the light due to charge trapping at the oxygen-related defect sites on the MoS2 surface. This photocurrent decay phenomenon of the MoS2 FET was influenced by the measurement environment (i.e., vacuum or oxygen environment) and the electrical gate-bias stress conditions (positive or negative gate biases). The results of this study will enhance the understanding of the influence of environmental and measurement conditions on the optical and electrical properties of MoS2 FETs.
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http://dx.doi.org/10.1088/0957-4484/25/15/155201DOI Listing
April 2014

Irradiation effects of high-energy proton beams on MoS2 field effect transistors.

ACS Nano 2014 Mar 25;8(3):2774-81. Epub 2014 Feb 25.

Department of Physics and Astronomy and Institute of Applied Physics , Seoul National University , Seoul 151-747, Korea.

We investigated the effect of irradiation on molybdenum disulfide (MoS2) field effect transistors with 10 MeV high-energy proton beams. The electrical characteristics of the devices were measured before and after proton irradiation with fluence conditions of 10(12), 10(13), and 10(14) cm(-2). For a low proton beam fluence condition of 10(12) cm(-2), the electrical properties of the devices were nearly unchanged in response to proton irradiation. In contrast, for proton beam fluence conditions of 10(13) or 10(14) cm(-2), the current level and conductance of the devices significantly decreased following proton irradiation. The electrical changes originated from proton-irradiation-induced traps, including positive oxide-charge traps in the SiO2 layer and trap states at the interface between the MoS2 channel and the SiO2 layer. Our study will enhance the understanding of the influence of high-energy particles on MoS2-based nanoelectronic devices.
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http://dx.doi.org/10.1021/nn4064924DOI Listing
March 2014

Reusable floating-electrode sensor for the quantitative electrophysiological monitoring of a nonadherent cell.

ACS Nano 2014 Mar 7;8(3):2206-13. Epub 2014 Feb 7.

Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University , Seoul 151-747, Korea.

We report a reusable floating-electrode sensor based on aligned semiconducting single-walled carbon nanotubes for the quantitative monitoring of the electrophysiological responses from a nonadherent cell. This method allowed us to monitor and distinguish the real-time responses from normal and small-cell lung cancer (SCLC) cells to the addition of nicotine. The difference was attributed to the overexpressed nicotinic acetylcholine receptors (nAChRs) in the SCLC cells. The sensor was also utilized to monitor the effect of various drugs on the cells. The treatment with inhibitors such as genistin or daidzein was found to reduce Ca(2+) influx in SCLC cells. Moreover, tamoxifen, though known as the antiestrogen compound, was found to only partly block the binding of daidzein to nAChRs. Significantly, the activities of multiple individual cells could be measured repeatedly using a single sensor device, enabling statistically meaningful measurements without errors from the device-to-device variations of the sensor characteristics. This capability of the quantitative monitoring of nonadherent cells should be a major breakthrough for electrophysiology research and various biomedical applications such as drug screening and therapeutic monitoring.
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http://dx.doi.org/10.1021/nn4053155DOI Listing
March 2014

Sub-diffraction limit imaging of inorganic nanowire networks interfacing cells.

Small 2014 Feb 3;10(3):462-8. Epub 2013 Sep 3.

Department of Physics and Astronomy, Seoul National University, Seoul, 151-747, Korea.

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http://dx.doi.org/10.1002/smll.201301214DOI Listing
February 2014

Electric stress-induced threshold voltage instability of multilayer MoS2 field effect transistors.

ACS Nano 2013 Sep 12;7(9):7751-8. Epub 2013 Aug 12.

Department of Physics and Astronomy, Seoul National University , Gwanak-ro, Gwanak-gu, Seoul 151-744, Korea.

We investigated the gate bias stress effects of multilayered MoS2 field effect transistors (FETs) with a back-gated configuration. The electrical stability of the MoS2 FETs can be significantly influenced by the electrical stress type, relative sweep rate, and stress time in an ambient environment. Specifically, when a positive gate bias stress was applied to the MoS2 FET, the current of the device decreased and its threshold shifted in the positive gate bias direction. In contrast, with a negative gate bias stress, the current of the device increased and the threshold shifted in the negative gate bias direction. The gate bias stress effects were enhanced when a gate bias was applied for a longer time or when a slower sweep rate was used. These phenomena can be explained by the charge trapping due to the adsorption or desorption of oxygen and/or water on the MoS2 surface with a positive or negative gate bias, respectively, under an ambient environment. This study will be helpful in understanding the electrical-stress-induced instability of the MoS2-based electronic devices and will also give insight into the design of desirable devices for electronics applications.
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http://dx.doi.org/10.1021/nn402348rDOI Listing
September 2013

Multilayered nano-prism vertex tips for tip-enhanced Raman spectroscopy and imaging.

Analyst 2013 Oct;138(19):5588-93

Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea.

We presented a scalable fabrication method for the preparation of multilayered nano-prism vertex (NV)-tips whose dimensions can be controlled for tip-enhanced Raman spectroscopy (TERS). The NV-tip had sharp vertices (diameter ~20 nm) originated from the chemical lift-off process after the angle-grinding process, enabling high resolution imaging. TERS measurements were performed on brilliant cresyl blue (BCB) molecules using a Ag/Au NV-tip, revealing the enhanced field localization at the vertices of the NV-tip. Furthermore, we could observe the polarization effect of the NV-tip. Our NV-tips should be a powerful tool for basic research on TERS experiments and SPM applications.
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http://dx.doi.org/10.1039/c3an00808hDOI Listing
October 2013

Nanovesicle-based bioelectronic nose for the diagnosis of lung cancer from human blood.

Adv Healthc Mater 2014 Mar 18;3(3):360-6. Epub 2013 Jul 18.

School of Chemical and Biological Engineering, Bio-MAX Institute, Seoul National University, Seoul, 151-742, Korea.

A human nose-mimetic diagnosis system that can distinguish the odor of a lung cancer biomarker, heptanal, from human blood is presented. Selective recognition of the biomarker is mimicked in the human olfactory system. A specific olfactory receptor recognizing the chemical biomarker is first selected through screening a library of human olfactory receptors (hORs). The selected hOR is expressed on the membrane of human embryonic kidney (HEK)-293 cells. Nanovesicles containing the hOR on the membrane are produced from these cells, and are then used for the functionalization of single-walled carbon nanotubes. This strategy allows the development of a sensitive and selective nanovesicle-based bioelectronic nose (NvBN). The NvBN is able to selectively detect heptanal at a concentration as low as 1 × 10(-14) m, a sufficient level to distinguish the blood of a lung cancer patient from the blood of a healthy person. In actual experiments, NvBN could detect an extremely small increase in the amount of heptanal from human blood plasma without any pretreatment processes. This result offers a rapid and easy method to analyze chemical biomarkers from human blood in real-time and to diagnose lung cancer.
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http://dx.doi.org/10.1002/adhm.201300174DOI Listing
March 2014

Nano-storage wires.

ACS Nano 2013 Aug 19;7(8):6906-13. Epub 2013 Jul 19.

Department of Biophysics and Chemical Biology, Seoul National University, Seoul 151-747, Korea.

We report the development of "nano-storage wires" (NSWs), which can store chemical species and release them at a desired moment via external electrical stimuli. Here, using the electrodeposition process through an anodized aluminum oxide template, we fabricated multisegmented nanowires composed of a polypyrrole segment containing adenosine triphosphate (ATP) molecules, a ferromagnetic nickel segment, and a conductive gold segment. Upon the application of a negative bias voltage, the NSWs released ATP molecules for the control of motor protein activities. Furthermore, NSWs can be printed onto various substrates including flexible or three-dimensional structured substrates by direct writing or magnetic manipulation strategies to build versatile chemical storage devices. Since our strategy provides a means to store and release chemical species in a controlled manner, it should open up various applications such as drug delivery systems and biochips for the controlled release of chemicals.
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http://dx.doi.org/10.1021/nn402082vDOI Listing
August 2013

"Chemical-pain sensor" based on nanovesicle-carbon nanotube hybrid structures.

Biosens Bioelectron 2013 Nov 9;49:86-91. Epub 2013 May 9.

Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Republic of Korea.

We developed a "chemical-pain sensor" that could recognize chemical pain stimuli such as capsaicin and resiniferatoxin just like mammalian chemical pain sensory systems. Here, we first prepared nanovesicles containing rat pain sensory receptor, rat transient receptor potential vanilloid 1 (rTRPV1), which is activated by noxious heat and capsaicin. And the nanovesicles were immobilized on a single-walled carbon nanotube-based field effect transistor. The chemical-pain sensor could selectively detect chemical pain stimuli with a high sensitivity of a 1 pM detection limit. It also responded to different chemical pain stimuli in a manner similar as to that of mammalian chemical pain sensory systems. This sensor platform can be utilized for various practical applications such as food screening tools and artificial somesthetic sensors. Moreover, TRP families have been suggested as potential drug targets related to nerve and circulation disorders. Thus, the capability of monitoring TRP responses using our sensor platforms should provide a powerful means for the development of new drugs as well as the basic research about nerve and circulation systems.
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http://dx.doi.org/10.1016/j.bios.2013.04.045DOI Listing
November 2013

Oxygen environmental and passivation effects on molybdenum disulfide field effect transistors.

Nanotechnology 2013 Mar 12;24(9):095202. Epub 2013 Feb 12.

Department of Physics and Astronomy, Seoul National University, Gwanak-ro, Gwanak-gu, Seoul 151-747, Korea.

We investigated the effects of passivation on the electrical characteristics of molybdenum disulfide (MoS(2)) field effect transistors (FETs) under nitrogen, vacuum, and oxygen environments. When the MoS(2) FETs were exposed to oxygen, the on-current decreased and the threshold voltage shifted in the positive gate bias direction as a result of electrons being trapped by the adsorbed oxygen at the MoS(2) surface. In contrast, the electrical properties of the MoS(2) FETs changed only slightly in the different environments when a passivation layer was created using polymethyl methacrylate (PMMA). Specifically, the carrier concentration of unpassivated devices was reduced to 6.5 × 10(15) cm(-2) in oxygen from 16.3 × 10(15) cm(-2) in nitrogen environment. However, in PMMA-passivated devices, the carrier concentration remained nearly unchanged in the range of 1-3 × 10(15) cm(-2) regardless of the environment. Our study suggests that surface passivation is important for MoS(2)-based electronic devices.
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http://dx.doi.org/10.1088/0957-4484/24/9/095202DOI Listing
March 2013

A peptide receptor-based bioelectronic nose for the real-time determination of seafood quality.

Biosens Bioelectron 2013 Jan 3;39(1):244-9. Epub 2012 Aug 3.

School of Chemical and Biological Engineering, Seoul National University, Seoul, 151-742, Korea.

We herein report a peptide receptor-based bioelectronic nose (PRBN) that can determine the quality of seafood in real-time through measuring the amount of trimethylamine (TMA) generated from spoiled seafood. The PRBN was developed using single walled-carbon nanotube field-effect transistors (SWNT-FETs) functionalized with olfactory receptor-derived peptides (ORPs) which can recognize TMA and it allowed us to sensitively and selectively detect TMA in real-time at concentrations as low as 10fM. Utilizing these properties, we were able to not only determine the quality of three kinds of seafood (oyster, shrimp, and lobster), but were also able to distinguish spoiled seafood from other types of spoiled foods without any pretreatment processes. Especially, the use of small synthetic peptide rather than the whole protein allowed PRBNs to be simply manufactured through a single-step process and to be reused with high reproducibility due to no requirement of lipid bilayers. Furthermore, the PRBN was produced on a portable scale making it effectively useful for the food industry where the on-site measurement of seafood quality is required.
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http://dx.doi.org/10.1016/j.bios.2012.07.054DOI Listing
January 2013

A bioelectronic sensor based on canine olfactory nanovesicle-carbon nanotube hybrid structures for the fast assessment of food quality.

Analyst 2012 Jul 12;137(14):3249-54. Epub 2012 Apr 12.

Department of Physics and Astronomy, Seoul National University, Seoul, 151-742, Korea.

We developed an olfactory-nanovesicle-fused carbon-nanotube-transistor biosensor (OCB) that mimics the responses of a canine nose for the sensitive and selective detection of hexanal, an indicator of the oxidation of food. OCBs allowed us to detect hexanal down to 1 fM concentration in real-time. Significantly, we demonstrated the detection of hexanal with an excellent selectivity capable of discriminating hexanal from analogous compounds such as pentanal, heptanal, and octanal. Furthermore, we successfully detected hexanal in spoiled milk without any pretreatment processes. Considering these results, our sensor platform should offer a new method for the assessment of food quality and contribute to the development of portable sensing devices.
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http://dx.doi.org/10.1039/c2an16274aDOI Listing
July 2012

Nanovesicle-based bioelectronic nose platform mimicking human olfactory signal transduction.

Biosens Bioelectron 2012 May 17;35(1):335-341. Epub 2012 Mar 17.

Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Republic of Korea; Department of Biophysics and Chemical Biology, Seoul National University, Seoul 151-747, Republic of Korea. Electronic address:

We developed a nanovesicle-based bioelectronic nose (NBN) that could recognize a specific odorant and mimic the receptor-mediated signal transmission of human olfactory systems. To build an NBN, we combined a single-walled carbon nanotube-based field effect transistor with cell-derived nanovesicles containing human olfactory receptors and calcium ion signal pathways. Importantly, the NBN took advantages of cell signal pathways for sensing signal amplification, enabling ≈ 100 times better sensitivity than that of previous bioelectronic noses based on only olfactory receptor protein and carbon nanotube transistors. The NBN sensors exhibited a human-like selectivity with single-carbon-atomic resolution and a high sensitivity of 1 fM detection limit. Moreover, this sensor platform could mimic a receptor-meditated cellular signal transmission in live cells. This sensor platform can be utilized for the study of molecular recognition and biological processes occurring at cell membranes and also for various practical applications such as food screening and medical diagnostics.
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http://dx.doi.org/10.1016/j.bios.2012.03.012DOI Listing
May 2012

Controlling the growth and differentiation of human mesenchymal stem cells by the arrangement of individual carbon nanotubes.

ACS Nano 2011 Sep 10;5(9):7383-90. Epub 2011 Aug 10.

Department of Physics and Astronomy, Seoul National University, Seoul, 151-747, Korea.

Carbon nanotube (CNT) networks on solid substrates have recently drawn attention as a means to direct the growth and differentiation of stem cells. However, it is still not clear whether cells can recognize individual CNTs with a sub-2 nm diameter, and directional nanostructured substrates such as aligned CNT networks have not been utilized to control cell behaviors. Herein, we report that human mesenchymal stem cells (hMSCs) grown on CNT networks could recognize the arrangement of individual CNTs in the CNT networks, which allowed us to control the growth direction and differentiation of the hMSCs. We achieved the directional growth of hMSCs following the alignment direction of the individual CNTs. Furthermore, hMSCs on aligned CNT networks exhibited enhanced proliferation and osteogenic differentiation compared to those on randomly oriented CNT networks. As a plausible explanation for the enhanced proliferation and osteogenic differentiation, we proposed mechanotransduction pathways triggered by high cytoskeletal tension in the aligned hMSCs. Our findings provide new insights regarding the capability of cells to recognize nanostructures smaller than proteins and indicate their potential applications for regenerative tissue engineering.
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http://dx.doi.org/10.1021/nn2023057DOI Listing
September 2011

Polarization-controlled differentiation of human neural stem cells using synergistic cues from the patterns of carbon nanotube monolayer coating.

ACS Nano 2011 Jun 13;5(6):4704-11. Epub 2011 May 13.

Interdisciplinary Program in Nano-Science and Technology, Seoul National University, Seoul 151-747, Korea.

We report a method for selective growth and structural-polarization-controlled neuronal differentiation of human neural stem cells (hNSCs) into neurons using carbon nanotube network patterns. The CNT patterns provide synergistic cues for the differentiation of hNSCs in physiological solution and an optimal nanotopography at the same time with good biocompatibility. We demonstrated a polarization-controlled neuronal differentiation at the level of individual NSCs. This result should provide a stable and versatile platform for controlling the hNSC growth because CNT patterns are known to be stable in time unlike commonly used organic molecular patterns.
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http://dx.doi.org/10.1021/nn2006128DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3125501PMC
June 2011