Junhong Min

Chung-Ang University, Sŏul, Seoul, South Korea

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Publications (90)254.63 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The films organized with biomolecules and organic materials are important elements for developing bioelectronic devices according to their electron transfer property. Until now, several concepts of techniques have been accomplished to be used for developing biomemory devices. However it is difficult to detect the current signal from the electron transfer between biomolecules and the substrate in these fabricated films. To enhance the current signal, the silver nanoparticle was introduced to the cytochrome c in this present study. The surface morphology of the fabricated film was investigated by atomic force microscopy. The current signal enhancement was investigated by cyclic voltammetry. As a result, we could obtain the redox potentials. Moreover, by chronoamperometry, we validated that this proposed layer showed the signal-enhanced memory property for biomemory devices. This new film composed of the cytochrome c and the silver nanoparticle showed the signal enhancement. Using chronoamperometry, the areas under the graphs between 0 s and 50 ms were calculated. The calculated result showed that the areas under the cytochrome c/SNP graph and cytochrome c graph were 6.93 x 10(-7) C and 4.54 x 10(-7) C, respectively. This numerical value verified that the cytochrome c/silver nanoparticle hetero-layer film showed better electron charged biomemory performance compared to the cytochrome c monolayer. This signal-enhanced film can be applied to the bioelectronic devices which are able to replace existing electronic devices in the near future.
    Journal of Nanoscience and Nanotechnology 03/2014; 14(3):2466-71. · 1.15 Impact Factor
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    ABSTRACT: A subnanometer gap-separated linear chain gold nanoparticle (AuNP) silica nanotube peapod (SNTP) was fabricated by self-assembly. The geometrical configurations of the AuNPs inside the SNTPs were managed in order to pose either a single-line or a double-line nanostructure by controlling the diameters of the AuNPs and the orifice in the silica nanotubes (SNTs). The AuNPs were internalized and self-assembled linearly inside the SNTs by capillary force using a repeated wet-dry process on a rocking plate. Transmission electron microscopy (TEM) images clearly indicated that numerous nanogap junctions with sub-1-nm distances were formed among AuNPs inside SNTs. Finite-dimension time domain (FDTD) calculations were performed to estimate the electric field enhancements. Polarization-dependent SERS spectra of bifunctional aromatic linker p-mercaptobenzoic acid (p-MBA)-coated AuNP-embedded SNTs supported the linearly aligned nanogaps. We could demonstrate a silica wall-protected nanopeapod sensor with single nanotube sensitivity. SNTPs have potential application to intracellular pH sensors after endocytosis in mammalian cells for practical purposes. The TEM images indicated that the nanogaps were preserved inside the cellular constituents. SNTPs exhibited superior quality surface-enhanced Raman scattering (SERS) spectra in vivo due to well-sustained nanogap junctions inside the SNTs, when compared to simply using AuNPs without any silica encapsulation. By using these SNTPs, a robust intracellular optical pH sensor could be developed with the advantage of the sustained nanogaps, due to silica wall-protection.
    Journal of the American Chemical Society 02/2014; · 10.68 Impact Factor
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    ABSTRACT: Rare-earth doped nanoparticle (RE), termed upconversion nanoparticle (UCNP), is a new generation of phosphorescence which has recently attracted significant research interest. Due to the unique upconversion properties, UCNP has been considered to be an excellent alternative for conventional fluorescence. Since its first emergence in mid-1960s, UCNPs have been studied in a wide range of fields, including those in biological applications. Owing to its suitable size distribution and biocompatibility, UCNP could be conjugated with various kinds of biomolecules, resulting in the development of numerous biological platforms such as biodetection assays and therapeutic modalities. The unique optical properties of UCNP such as prominent luminescence, deep penetration to biological tissues without damaging the cells, low background and high resistance to photo-bleaching enhance UCNP prospects as an excellent contrast agent in both in vitro and in vivo. In this review, we discuss the recent developments of UCNP in bioassays, optical imaging, and therapy, also the prospects and challenges of UCNP-based detection in the development of biomedical science.
    Journal of Nanoscience and Nanotechnology 01/2014; 14(1):157-74. · 1.15 Impact Factor
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    ABSTRACT: Biomolecular computing devices that are based on the properties of biomolecular activities offer a unique possibility for constructing new computing structures. A new concept of using various biomolecules has been proposed in order to develop a protein-based memory device that is capable of switching physical properties when electrical input signals are applied to perform memory switching. To clarify the proposed concept, redox protein is immobilized on Au nanoelectrodes to catalyze reversible reactions of redox-active molecules, which is controlled electrochemically and reversibly converted between its ON/OFF states. In this review, we summarize recent research towards developing nanoscale biomemory devices including design, synthesis, fabrication, and functionalization based on the proposed concept. At first we analyze the memory function properties of the proposed device at bulk material level and then explain the WORM (write-once-read-many times) nature of the device, later we extend the analysis to multi-bit and multi-level storage functions, and then we focus the developments in nanoscale biomemory devices based on the electron transport of redox molecules to the underlying Au patterned surface. The developed device operates at very low voltages and has good stability and excellent reversibility, proving to be a promising platform for future memory devices.
    Journal of Nanoscience and Nanotechnology 01/2014; 14(1):433-46. · 1.15 Impact Factor
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    ABSTRACT: Recently, the fabrication of protein bilayer has been required for the development of protein or enzyme complex formation. In the present study, we fabricated a fusion protein bilayer composed of recombinant azurin-cytochrome P450, which was synthesized by a site-specific sortase-mediated ligation method. The Pseudomonas aeruginosa azurin was modified by DNA recombinant technique, for enzymatic ligation and immobilization. The Pseudomonas putida cytochrome P450 was also modified for enzymatic ligation. The recombinant metalloproteins were conjugated via the sortase A. The conjugation was confirmed by SDS-PAGE and UV-vis. Then, the prepared fusion protein was immobilized on Au substrate, by the self-assembly method. The Azu-P450 (recombinant azurin-cytochrome P450) fusion protein layer was confirmed by AFM (Atomic Force Microscopy) and SERS (Surface-enhanced Raman Spectroscopy), to confirm the fusion protein bilayer orientation. Moreover, the electrochemical property of Azu-P450 was observed by cyclic voltammetry (CV). As a result, the Azu-P450 fusion protein bilayer shows good orientation on the Au substrate. Also, the original redox property of this fusion protein bilayer has been well maintained. The proposed fusion protein bilayer can.
    Colloids and surfaces B: Biointerfaces 01/2014; · 3.55 Impact Factor
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    ABSTRACT: This study describes a simple but effective combinatory effect of magnetic silica nanotubes (MSNTs) in bacterial separation and impedimetric signal enhancement for the label-free detection of Salmonella typhimurium. The outer surface of MSNTs was functionalized with positive charges for the successful concentration and the isolation of bacteria from a high-volume sample. Scanning electron microscopy (SEM) was used to confirm the bacterial adsorption on MSNT. Antibody specific to S. typhimurium was immobilized on the interdigitated microelectrode of an impedimetric sensor. Bacteria binding MSNT (bacteria–MSNT complex) was successfully conjugated with antibody immobilized impedimetric sensor. The decrease of the impedance response was automatically shown due to the antigen–antibody recognition between bacteria and antibody immobilized impedimetric microelectrodes. The presence of MSNT significantly enhanced the impedimetric sensor performance by generating highly discriminated impedance signals in correspond with different bacterial concentrations 103–107 CFU. The total detection time from bacteria isolation to measurement was completed within roughly 30 min with low cost and an ease of operation. This study shows the potential use of MSNT in antibody-free bio-separation and in impedimetric signal enhancement with the effort to develop a label-free, automatic pathogenic detection system.
    Sensors and Actuators B Chemical 01/2014; 197:314–320. · 3.54 Impact Factor
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    ABSTRACT: In the present study, we investigated the simultaneous detection of multilevel electrochemical signals from various metalloprotein heterolayers for the bioelectronic devices. A layer-by-layer assembly method based on simple electrostatic interaction was introduced to form protein bilayers. The gold substrate was modified with poly (ethylene glycol) thiol acid as the precursor, which introduced negative charges to the surface. Based on the isoelectric point, net-charge controlled metalloproteins by pH adjustment were sequentially immobilized on this negatively charged substrate. The degree of protein immobilization on the gold substrate was confirmed by surface plasmon resonance spectroscopy, and the surface topology changes due to the protein immobilization were confirmed by atomic force microscopy. Redox signals in the protein layers were measured by cyclic voltammetry. As a result, various redox signals generated from different metalloproteins on a single electrode were monitored. This proposed method for the detection of multi-level electrochemical signals can be directly applied to bioelectronic devices that store multi-information in a single electrode.
    Thin Solid Films 01/2014; 551:174–180. · 1.60 Impact Factor
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    ABSTRACT: Major challenges in molecular electronics include miniaturization, and the realization of a simple function to alter silicon-based electronics. It has been hard to develop a single molecular-based computing system, since such systems need complex functionality to be developed at the single-molecular level. To develop a molecular-based biocomputing system, a bioprocessing device is demonstrated that consists of recombinant azurin/DNA/inorganic material hybrid to perform the various functions in a device. A metalloprotein which exhibits redox behavior is used as a biomemory source. The redox property could be controlled with command materials (conducting nanoparticles, heavy metal ions, and semiconducting nanoparticles) to perform ‘information reinforcement,’ ‘information regulation,’ and ‘information amplification’ functions, respectively. This bioprocessing device could be a foundation to develop single-biomolecular-based computing systems.
    Advanced Functional Materials 12/2013; · 9.77 Impact Factor
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    ABSTRACT: In the present study, an nano-platform composed of Au nanodot arrays on which biomolecules could be self-assembled was developed and investigated for a stable bioelectronic device platform. Au nanodot pattern was fabricated using a nanoporous alumina template. Two different biomolecules, a cytochrome c and a single strand DNA (ssDNA), were immobilized on the Au nanodot arrays. Cytochorme c and single stranded DNA could be immobilized on the Au nanodot using the chemical linker 11-MUA and thiol-modification by covalent bonding, respectively. The atomic structure of the fabricated nano-platform device was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The electrical conductivity of biomolecules immobilized on the Au nanodot arrays was confirmed by scanning tunneling spectroscopy (STS). To investigate the activity of biomolecule-immobilized Au-nano dot array, the cyclic voltammetry was carried out. This proposed nano-platform device, which is composed of biomolecules, can be used for the construction of a novel bioelectronic device.
    Journal of Nanoscience and Nanotechnology 09/2013; 13(9):6020-6. · 1.15 Impact Factor
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    ABSTRACT: A protein based electrochemical sensor for the detection of hydrogen peroxide based on Myoglobin immobilized on gold nano structures patterned on Indium tin oxide electrode was developed. A uniformly distributed nanometer sized Au-array on ITO electrode surface was obtained by optimizing electro deposition conditions. The morphology of Mb molecules and Au-nanostructures on ITO was investigated by scanning electron microscopy. A Cyclic voltammetry technique was employed to study electrochemical behavior of immobilized Mb on Au/ITO electrode. From CV, a pair of quasi-reversible redox peaks of Mb obtained in 10 mM PBS buffer solution at 0.28 and 0.11 V respectively. From the electrochemical experiments, it is observed that Mb/Au/ITO electrode provides a facile electron transfer between Mb and modified ITO electrode and it also catalyzes the reduction of H2O2. A linear increase in amperometric current with increase in H2O2 concentration was also observed. The stability, reusability and selectivity of the biosensor were also evaluated. The proposed biosensor exhibits an effective and fast catalytic response to reduction of H2O2 which can be used in future biosensor applications.
    Journal of Nanoscience and Nanotechnology 09/2013; 13(9):6424-8. · 1.15 Impact Factor
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    ABSTRACT: We fabricate a nanoscale biomemory device composed of recombinant azurin on nanogap electrodes. For this, size-controllable nanogap electrodes are fabricated by photolithography, electron beam lithography, and surface catalyzed chemical deposition. Moreover, we investigate the effect of gap distance to optimize the size of electrodes for a biomemory device and explore the mechanism of electron transfer from immobilized protein to a nanogap counter-electrode. As the distance of the nanogap electrode is decreased in the nanoscale, the absolute current intensity decreases according to the distance decrement between the electrodes due to direct electron transfer, in contrast with the diffusion phenomenon of a micro-electrode. The biomemory function is achieved on the optimized nanogap electrode. These results demonstrate that the fabricated nanodevice composed of a nanogap electrode and biomaterials provides various advantages such as quantitative control of signals and exclusion of environmental effects such as noise. The proposed bioelectronics device, which could be mass-produced easily, could be applied to construct a nanoscale bioelectronics system composed of a single biomolecule.
    Nanotechnology 08/2013; 24(36):365301. · 3.84 Impact Factor
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    ABSTRACT: In this study, we have provided a novel analytical integration between hydrogel-based cell chip and Electric Cell-substrate Impedance Sensing (ECIS) technique to apply to a high-throughput, real-time cell viability assay and drug screening. For simulating the drug diffusion model, we have developed a hydrogel-based tissue-mimicking structure with microfluidic channel, without unwanted flow, to generate a gradient concentration with long-term stability. Along the gradient line, four individual micro-electrodes were installed to record the impedance signal changes, which result from the cell viability under drug effects. By watching for cellular impedance changes, we successfully estimated the cytotoxicity of the treatment corresponding to the various concentration values of stimuli, generated by the diffusion process along the channel. Reliable IC50 values and time-dose relationships were also achieved. With the feature of real-time monitoring capability, the advantages of non-invasion, label-free detection, time saving and simple manipulation, our integrative device has become a promising high throughput cell-based on-chip platform for cell viability assay and drug screening.
    Biosensors & bioelectronics 07/2013; 50C:453-459. · 5.43 Impact Factor
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    ABSTRACT: In this study, we developed a simple and fast isolation tool of Escherichia coli O157:H7 (E. coli O157:H7) using a magnet nanoparticle embedded silica nanotube (MNSNT) for the detection of E. coli O157:H7 in the sample with nucleic acid based amplification. This method does not require chaotropic salt and sophisticated equipment to isolate bacteria. The E. coli O157:H7 in the sample was effectively bound to the hydrophilic surface of MNSNT in low pH binding buffer containing divalent ions and PEG without the need for expensive biological reagents such as antibodies. This E. coli O157:H7 bound MNSNT was simply isolated by a magnet, prior to adding an amplification mixture to the same micro tube without transferring the sample to another tube. Using this novel method, the detection sensitivities of E. coli O157:H7 (102 cfu/1 g of seed sprout and 102 cfu/5 mL of water) were 80% and 100%, respectively, whereas that was 0% using the commercial method.
    Journal of Biomedical Nanotechnology 05/2013; 9(5):886-90. · 5.26 Impact Factor
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    ABSTRACT: We fabricated and analyzed a nanoscale biofilm of human lactoferrin making use of 11-mercapto-undecanoic acid (11-MUA) as chemical linker. The fabrication of the bimolecular/organic hetero monolayer (lactoferrin/11-MUA) on gold substrate was confirmed with Raman spectroscopy. Cyclic voltammetry (CV) was carried out to observe the electrochemical properties of the nanoscaled biofilm under various pH conditions and at different time intervals. The well-defined redox properties were observed, even in certain harsh pH conditions and after a long time, proving the stabilities of this biofilm. Atomic force microscopy (AFM) was further employed to confirm the retention time by investigating the morphology variety of the biofilm over time. All these results proved that, the proposed nanoscaled thin film composed of lactoferrin and 11-MUA is a powerful alternative for making bioelectronics devices.
    Journal of Biomedical Nanotechnology 05/2013; 9(5):849-55. · 5.26 Impact Factor
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    ABSTRACT: In this study, an enzymatic biosensor for amperometric detection of hydrogen peroxide was developed based on the direct electrochemistry of myoglobin (Mb) on a porous cerium dioxide (CeO2) nanostructured film. The developed film accomplished with large surface area was electrodeposited on an indium tin oxide (ITO) substrate. Surface morphological studies revealed that the formed CeO2 film has a large specific surface area with a unique nanostructure on the ITO surface. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed to demonstrate the electrochemical behavior of Mb immobilized on the fabricated film, which exhibited facile, direct electrochemistry and good electrocatalytic performance without any electron mediator. The electrode displayed a pair of quasi-reversible reduction-oxidation peaks at -0.3 and -0.2V, respectively, due to the Mb [Fe(3+)/Fe(2+)] redox couple, which is a surface-controlled electrochemical process with one electron transfer. This reagent-less biosensor showed good stability and high sensitivity for detecting H2O2 without any influence of intermediate compounds. This protein-based biosensor was capable of detecting H2O2 as low as 0.6μM with linearity up to 3mM and a response time of ~8s, compared to those of other modified electrodes. Hence, porous CeO2 is a possible candidate material for fabricating enzymatic sensors or devices.
    Biosensors & bioelectronics 03/2013; 47C:385-390. · 5.43 Impact Factor
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    ABSTRACT: Intracellular glutathione-triggered doxorubicin release from silica nanotubes with hydrophobic labile cap was demonstrated for the drug-resistant cancer cell treatment.
    Chemical Communications 02/2013; · 6.38 Impact Factor
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    ABSTRACT: An electrical measurement known as Electric Cell-substrate Impedance Sensing (ECIS) has become increasingly applied to the study of cellular viability, proliferation and cytotoxicity with the advantages of label-free, non-invasion and real-time monitoring capability in comparison with other conventional methods (MTS, MTT). With this technique, cells are grown on the micro-sized gold electrodes where the micro-ampere alternative current is applied to measure the impedance changes due to the physiological changes caused by internal or external stimuli. In another field, Silica Nanotubes (SNTs) are a novel class of inorganic structures with promising potentials in bio-separation, drug delivery, imaging and other biomedical applications. In this study, by using ECIS-based self-fabricated cell chip, Cells were cultured on the working electrodes and separately exposure to the 0, 2 microm, 2 microm and 10 microm long at the varying concentrations of SNTs to evaluate the cellular responses such as viability, multiplication time and cytotoxicity. Final results were additionally compared with the MTS method as a reference to review the reliability
    Journal of Biomedical Nanotechnology 02/2013; 9(2):286-90. · 5.26 Impact Factor
  • Jae Hwan Ahn, Sang Jun Son, Junhong Min
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    ABSTRACT: We investigated the effect of arrayed nanostructures on the cell adhesion rate by forming nanopillars on a PMMA polymer surface, and demonstrated cell patterning tools for the polymer surface without biological or chemical reagents. Nanopillar arrayed structures with various heights (0, 50, 100, 150, and 200nm with 50nm of pitch size and 60nm of diameter) were formed on a PMMA surface by using nano-molding techniques with nanoporous AAO (Anodic Aluminum Oxide) as a template. The nanopillar arrayed structures providenegative effects on the cell adhesion on the non-treated PMMA (moderate hydrophobic, ≥ 80(o) of contact angle), whereas slightly positive and no effects were shown by nanopillar structures on plasma (hydrophilic, ≤ 20(o)) and silane-treated PMMA (moderate, 40(o)∼70(o)), respectively.The microstructure on the polymer surface showed a 20% positive effect on the cell adhesion rate. As a result, nano or micro patterning structures could control the cell adhesion rate (15 to 120%) and it enabled the formation of closed cell patterns on the PMMA surface without chemical or biological surface treatments.
    Journal of Biotechnology 01/2013; · 3.18 Impact Factor
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    ABSTRACT: We developed a nanoscale memory device consisting of signal-responsive biomaterial, which is capable of switching physical properties (such as electrical/electrochemical, optical, and magnetic) upon application of appropriate electrical signals to perform memory switching. Here, we propose a highly robust surface-confined switch composed of an electroactive cysteine-modified azurin immobilized on an Au hexagonal pattern formed on indium tin oxide (ITO) substrates that can be controlled electrochemically and reversibly converted between its redox states. The memory effect is based on conductance switching, which leads to the occurrence of bistable states and behaves as an extremely robust redox switch in which an electrochemical input is transduced into optical and magnetic outputs under ambient conditions. The fact that this molecular surface switch, operating at very low voltages, can be patterned and addressed locally, and also has good stability and excellent reversibility, makes it a promising platform for nonvolatile memory devices.
    Biosensors & bioelectronics 08/2012; · 5.43 Impact Factor
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    ABSTRACT: We demonstrated a new QIHC (Quantitative Immunohistochemistry) microfluidic PDMS (Polydimethylsiloxane) platform by the introduction of the aptamer specific to the Fc region of the IgG antibody as a reporting probe. The aptamer was designed and synthesized. Various breast cancer cell lines were prepared as paraffin block slides, which were covered by a microfluidic PDMS platform to form a micro-reaction chamber. Primary antibodies specific to marker proteins (HER2, ER, PR, and ki-67) for breast cancer characterization were loaded in the micro-fluidic chip prior to the introduction of the aptamer. A master mixture of QNASBA (Quantitative Nucleic Acid Sequence Based Amplification) was used to quantify marker proteins by real time amplification of the aptamers. The quantitative results of aptamer amplification were linearly proportional to the concentrations of 4 different primary antibodies. The characterization results of the aptamer-assisted IHC using the microfluidic platform were well-correlated with those of conventional IHC for breast cancer cell lines (SK-BR-3, MCF-7, MDA-MB-231). Objective quantitative evaluations were carried out and compared with conventional results for real clinical samples.
    Biosensors & bioelectronics 07/2012; · 5.43 Impact Factor

Publication Stats

242 Citations
254.63 Total Impact Points

Institutions

  • 2012–2014
    • Chung-Ang University
      • School of Integrative Engineering
      Sŏul, Seoul, South Korea
  • 2007–2013
    • Gachon University
      • • Department of BioNano Technology
      • • College of BioNano Technology
      Seongnam, Gyeonggi, South Korea
  • 1997–2013
    • Sogang University
      • Department of Chemical and Biomolecular Engineering
      Seoul, Seoul, South Korea
  • 2011
    • Kyung Hee University
      • Department of Dentistry
      Seoul, Seoul, South Korea
  • 2000
    • Korea University
      Sŏul, Seoul, South Korea