This paper reports for the first time the application of sol-gel microarrays for immobilizing non... more This paper reports for the first time the application of sol-gel microarrays for immobilizing nonsoluble small chemicals (Bisphenol-A; BPA). Also, known problems of sol-gel adhesion to conventional microtiter well plate substrates are circumvented by anchoring the sol-gel microspots to a porous silion surface so-called, PS-SG chips. We confirmed low molecular weight chemical immobilization inside a sol-gel network using fluorescein. BPA and the BPA specific aptamer were utilized as a model pair to verify the affinity specific interaction in the PS-SG selection system. The aptamer interacted specifically with BPA in the sol-gel spots, as shown in microarrays forming the letters "L", "U", "N", and "D". Moreover, the bound aptamer was released by heat, recovered, and verified by gel electrophoresis. The developed PS-SG chip platform will be used for screening aptamers against numerous small molecules such as toxins, metabolites, or pesticide residues.
This paper determined the optimal periodic mechanical stimulation of live bone cells from the int... more This paper determined the optimal periodic mechanical stimulation of live bone cells from the intracellular calcium oscillation induced by shear stress. The shear stress-induced intracellular calcium responses of cells on a micro-cell chip were measured to study the mechanotransduction of bone cells. From the measured static and dynamic characteristics of the internal cellular signaling in cells, the optimum duration of the mechanical stimulation is determined.
Proceedings 2006 IEEE International Conference on Robotics and Automation, 2006. ICRA 2006.
This paper reports the pneumatic PDMS micro hand as an endeffector of robot and miniaturized para... more This paper reports the pneumatic PDMS micro hand as an endeffector of robot and miniaturized parallel link robot (guide robot) for manipulating a tiny and delicate object. Micro finger structure for the micro hand consists of bonded two films having different stiffness. Balloon structures are designed between the two films. Swelling of the balloon structure by applied pressure generates bending motion of the micro finger. This combination of the micro hand is based on the human being's finger and/or hand. The guide robot has several design specifications such as multi degrees of freedom joint as a human, small size, highly accurate directional control and water/ sterilization proof. Micro Manipulation Robot System is developed by assembling the micro finger with two or three degree of freedom, the guide robot and VR (Virtual Realty) interface device. The hybrid motion and the manipulation of a single egg (1mm) of fish and a hair (100μm) in macro world is successfully realized.
2017 International Symposium on Micro-NanoMechatronics and Human Science (MHS)
This paper presents the fabrication of the micro fluidic platform for microfluidic encapsulation ... more This paper presents the fabrication of the micro fluidic platform for microfluidic encapsulation in Ca-Alginate microspheres toward the whole-cell neutralizing system for PEDV. This system has become a valuable antigen surface exposing tool for a broad spectrum of vaccine development and therapeutic applications. PED viral epitope regions (ER-1 and ER-2) were successfully expressed on the surface of yeast and their fluorescent activity was observed. Ca-alginate microspheres with encapsulated yeast were successfully produced using the fabricated micro fluidic platform and verified through the microscopic observation of the fluorescent-stained yeast cells in the microsphere.
Here, we report a simple and effective method for capturing and displacement of gram-negative bac... more Here, we report a simple and effective method for capturing and displacement of gram-negative bacteria using aptamer-modified microbeads and acoustophoresis. As acoustophoresis allows for simultaneous washing and size-dependent separation in continuous flow mode, we efficiently obtained gram-negative bacteria that showed high affinity without any additional washing steps. The proposed device has a simple and efficient channel design, utilizing a long, square-shaped microchannel that shows excellent separation performance in terms of the purity, recovery, and concentration factor. Microbeads (10 µm) coated with the GN6 aptamer can specifically bind gram-negative bacteria. After incubation of bacteria culture sample with aptamer affinity bead, gram-negative bacteria-bound microbeads, and other unbound/contaminants can be separated by size with high purity and recovery. The device demonstrated excellent separation performance, with high recovery (up to 98%), high purity (up to 99%), an...
Apple Scar Skin Viroid (ASSVd), a nonprotein coding, circular RNA pathogen is relatively difficul... more Apple Scar Skin Viroid (ASSVd), a nonprotein coding, circular RNA pathogen is relatively difficult to detect by immunoassay. We report here a one-step reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay to improve selectivity for diagnostic use in detecting ASSVd in plants. ASSVd RT-LAMP was accelerated using loop primers and was found to be highly sensitive with a detection limit of 10 copies of cDNA-ASSVd within 30 min. Real-time LAMP and melting curve analysis could differentiate between the true-positive LAMP amplicons and false-positive nonspecific primer amplification products. The optimized RT-LAMP was then followed by the addition of nonthiolated AuNP:poly-adenine (A10)-ASSVd LAMP barcodes, showing a high authentication capacity with colorimetric changes. This type of barcoding assay is a potential alternative for rapid and multiple viroid diagnosis, providing for visible sensing in the field that can be applied to viroid-free planting.
Analytical sciences : the international journal of the Japan Society for Analytical Chemistry, 2018
Here, we report a sol-gel integrated affinity microarray for on-chip matrix-assisted laser desorp... more Here, we report a sol-gel integrated affinity microarray for on-chip matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) that enables capture and identification of prostate?specific antigen (PSA) in samples. An anti-PSA antibody (H117) was mixed with a sol?gel, and the mixture was spotted onto a porous silicon (pSi) surface without additional surface modifications. The antibody easily penetrates the sol-gel macropore fluidic network structure, making possible high affinities. To assess the capture affinity of the platform, we performed a direct assay using fluorescein isothiocyanate-labeled PSA. Pure PSA was subjected to on-chip MALDI-TOF-MS analysis, yielding three clear mass peptide peaks (m/z = 1272, 1407, and 1872). The sol-gel microarray platform enables dual readout of PSA both fluorometric and MALDI-TOF MS analysis in biological samples. Here we report a useful method for a means for discovery of biomarkers in complex body fluids.
AbstractThe authors have developed a porous silicon (P-Si) based duplex antibody microarray platf... more AbstractThe authors have developed a porous silicon (P-Si) based duplex antibody microarray platform for simultaneous quantitation of the biomarkers prostate-specific antigen (PSA) and human glandular kallikrein 2 (hK2) in serum. Pore size-controlled P-Si surfaces have an extremely enlarged surface area that enables high-density immobilization of fluorescently labeled antibodies by physical adsorption. Automated microarraying of the antibodies provides a fast and reproducible duplex format of antibody arrays on the P-Si chips placed in the wells of a microtiter plate. The assay platform showed a 100 fg·mL−1 limit of detection for both PSA and hK2, and a dynamic range that extends over five orders of magnitude. After optimization of the density of both capture antibodies, neither the PSA nor the hK2 array showed cross-sensitivity to non-target proteins or other plasma proteins. The microarray was evaluated by titration of PSA and hK2, respectively, in the same serum samples. In our perception, this highly sensitive and selective platform holds promise for improved detection of tumor markers in an early diagnostic stage, but also to monitor the recurrence of prostate cancer. Graphical AbstractA porous silicon microarray platform is presented for simultaneous detection of biomarkers prostate specific antigen and human glandular kallikrein 2 in human blood sample. The platform shows highly sensitive and selective biomarker detection features.
Escherichia coli are important indicator organisms, used routinely for the monitoring of water an... more Escherichia coli are important indicator organisms, used routinely for the monitoring of water and food safety. For quick, sensitive and real-time detection of E. coli we developed a 2'F modified RNA aptamer Ec3, by Cell-SELEX. The 31 nucleotide truncated Ec3 demonstrated improved binding and low nano-molar affinity to E. coli. The aptamer developed by us out-performs the commercial antibody and aptamer used for E. coli detection. Ec3(31) aptamer based E. coli detection was done using three different detection formats and the assay sensitivities were determined. Conventional Ec3(31)-biotin-streptavidin magnetic separation could detect E. coli with a limit of detection of 1.3 × 10(6) CFU/ml. Although, optical analytic technique, biolayer interferometry, did not improve the sensitivity of detection for whole cells, a very significant improvement in the detection was seen with the E. coli cell lysate (5 × 10(4) CFU/ml). Finally we developed Electrochemical Impedance Spectroscopy (E...
We fabricated droplet-based microfluidic platform for copolymerizable microspheres with acrydite ... more We fabricated droplet-based microfluidic platform for copolymerizable microspheres with acrydite modified DNA probe. The copolymerizable 3-D polyacrylamide microspheres were successfully produced from microcontinuous-flow synthesis with on-channel solidification. DNA copolymerization activity, surface presentation and thermostability were assessed by using fluorescent labeled complementary probe. The binding performance was only visible on the surface area of oligo-microspheres. We show that the resulting oligo-microspheres can be directly integrated into a streamlined microsphere-PCR protocol for amplifying ssDNA. Our microspheres could be utilized as a potential material for ssDNA analysis such as DNA microarray and automatic DNA SELEX process.
IEEE International Symposium on Micro-NanoMechatronics and Human Science, 2005, 2005
This paper presents fabrication and drive test of a peristaltic PDMS micropump actuated by the pn... more This paper presents fabrication and drive test of a peristaltic PDMS micropump actuated by the pneumatic force. The micropump consists of the three peristaltic-type actuators and a microchannel connecting the chambers and the inlet/outlet port. The micropump is fabricated by silicon mold process and the two-step curing process for irreversible bonding of PDMS layers. The diameter and the thickness of the actuator diaphragm are 3 mm and 37 mum, respectively. The dynamic valve action of the cascade three actuators is confirmed by using video camera. The meniscus motion of the red-ink in the micro channel is also observed and its volume speed is estimated through the frame analysis of the recorded a video data. The square-wave input pressure of 37.5 kPa is applied to micro actuator for pumping test of the micro pump. The maximum tap-water suction volume speed from inlet port to micro pump is about 0.48 muL/sec at 0.3 Hz while the hydraulic pressure difference is 7 CmH2O. Suction volume speed due to capillary effect is about 0.09 muL/sec. The maximum meniscus speed of red-ink is about 0.83 mm/sec at 5 Hz
A pneumatically driven cell trap device with individually controllable vibrators was fabricated a... more A pneumatically driven cell trap device with individually controllable vibrators was fabricated and the effect of mechanical stimuli on a trapped live cell was examined. The device consisted of two polydimethylsiloxane (PDMS) layers that formed pneumatic vibrators and a trap chamber connected to a fluid channel for introducing the cell. When the vibrators were supplied with compressed air, the flexible diaphragms in the vibrators were deformed and exerted pressure on the fluid film in the trap chamber. If a cell was present in the trap chamber, drag force generated by the fluid flow affected the cell. By using a symmetrical arrangement of four vibrators, the cell could be manipulated and trapped in region at the center of the four vibrators. In order to verify this working principle, the ability of the device to trap solid particles and live cells was tested. Intracellular calcium levels were measured to investigate the influence of mechanical stimuli produced via the fluid film, which was induced by pneumatic actuation, on a single cell within the trap chamber. Once the vibrators were actuated, the intracellular calcium level of the cell at rest increased rapidly as it responded to the external mechanical stimulation induced by deformation of the vibrator. When considering the typical increases in calcium induced by shear stress, the measured peak value was very small. As the duration of trapping was prolonged, the calcium levels decreased. The calcium level was comparable to that of a cell at rest, with some fluctuations. In short, the influence of mechanical stimuli on a live cell induced by the pneumatic cell trap appeared to be negligible during trapping.
This paper reports for the first time the application of sol-gel microarrays for immobilizing non... more This paper reports for the first time the application of sol-gel microarrays for immobilizing nonsoluble small chemicals (Bisphenol-A; BPA). Also, known problems of sol-gel adhesion to conventional microtiter well plate substrates are circumvented by anchoring the sol-gel microspots to a porous silion surface so-called, PS-SG chips. We confirmed low molecular weight chemical immobilization inside a sol-gel network using fluorescein. BPA and the BPA specific aptamer were utilized as a model pair to verify the affinity specific interaction in the PS-SG selection system. The aptamer interacted specifically with BPA in the sol-gel spots, as shown in microarrays forming the letters "L", "U", "N", and "D". Moreover, the bound aptamer was released by heat, recovered, and verified by gel electrophoresis. The developed PS-SG chip platform will be used for screening aptamers against numerous small molecules such as toxins, metabolites, or pesticide residues.
This paper determined the optimal periodic mechanical stimulation of live bone cells from the int... more This paper determined the optimal periodic mechanical stimulation of live bone cells from the intracellular calcium oscillation induced by shear stress. The shear stress-induced intracellular calcium responses of cells on a micro-cell chip were measured to study the mechanotransduction of bone cells. From the measured static and dynamic characteristics of the internal cellular signaling in cells, the optimum duration of the mechanical stimulation is determined.
Proceedings 2006 IEEE International Conference on Robotics and Automation, 2006. ICRA 2006.
This paper reports the pneumatic PDMS micro hand as an endeffector of robot and miniaturized para... more This paper reports the pneumatic PDMS micro hand as an endeffector of robot and miniaturized parallel link robot (guide robot) for manipulating a tiny and delicate object. Micro finger structure for the micro hand consists of bonded two films having different stiffness. Balloon structures are designed between the two films. Swelling of the balloon structure by applied pressure generates bending motion of the micro finger. This combination of the micro hand is based on the human being's finger and/or hand. The guide robot has several design specifications such as multi degrees of freedom joint as a human, small size, highly accurate directional control and water/ sterilization proof. Micro Manipulation Robot System is developed by assembling the micro finger with two or three degree of freedom, the guide robot and VR (Virtual Realty) interface device. The hybrid motion and the manipulation of a single egg (1mm) of fish and a hair (100μm) in macro world is successfully realized.
2017 International Symposium on Micro-NanoMechatronics and Human Science (MHS)
This paper presents the fabrication of the micro fluidic platform for microfluidic encapsulation ... more This paper presents the fabrication of the micro fluidic platform for microfluidic encapsulation in Ca-Alginate microspheres toward the whole-cell neutralizing system for PEDV. This system has become a valuable antigen surface exposing tool for a broad spectrum of vaccine development and therapeutic applications. PED viral epitope regions (ER-1 and ER-2) were successfully expressed on the surface of yeast and their fluorescent activity was observed. Ca-alginate microspheres with encapsulated yeast were successfully produced using the fabricated micro fluidic platform and verified through the microscopic observation of the fluorescent-stained yeast cells in the microsphere.
Here, we report a simple and effective method for capturing and displacement of gram-negative bac... more Here, we report a simple and effective method for capturing and displacement of gram-negative bacteria using aptamer-modified microbeads and acoustophoresis. As acoustophoresis allows for simultaneous washing and size-dependent separation in continuous flow mode, we efficiently obtained gram-negative bacteria that showed high affinity without any additional washing steps. The proposed device has a simple and efficient channel design, utilizing a long, square-shaped microchannel that shows excellent separation performance in terms of the purity, recovery, and concentration factor. Microbeads (10 µm) coated with the GN6 aptamer can specifically bind gram-negative bacteria. After incubation of bacteria culture sample with aptamer affinity bead, gram-negative bacteria-bound microbeads, and other unbound/contaminants can be separated by size with high purity and recovery. The device demonstrated excellent separation performance, with high recovery (up to 98%), high purity (up to 99%), an...
Apple Scar Skin Viroid (ASSVd), a nonprotein coding, circular RNA pathogen is relatively difficul... more Apple Scar Skin Viroid (ASSVd), a nonprotein coding, circular RNA pathogen is relatively difficult to detect by immunoassay. We report here a one-step reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay to improve selectivity for diagnostic use in detecting ASSVd in plants. ASSVd RT-LAMP was accelerated using loop primers and was found to be highly sensitive with a detection limit of 10 copies of cDNA-ASSVd within 30 min. Real-time LAMP and melting curve analysis could differentiate between the true-positive LAMP amplicons and false-positive nonspecific primer amplification products. The optimized RT-LAMP was then followed by the addition of nonthiolated AuNP:poly-adenine (A10)-ASSVd LAMP barcodes, showing a high authentication capacity with colorimetric changes. This type of barcoding assay is a potential alternative for rapid and multiple viroid diagnosis, providing for visible sensing in the field that can be applied to viroid-free planting.
Analytical sciences : the international journal of the Japan Society for Analytical Chemistry, 2018
Here, we report a sol-gel integrated affinity microarray for on-chip matrix-assisted laser desorp... more Here, we report a sol-gel integrated affinity microarray for on-chip matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) that enables capture and identification of prostate?specific antigen (PSA) in samples. An anti-PSA antibody (H117) was mixed with a sol?gel, and the mixture was spotted onto a porous silicon (pSi) surface without additional surface modifications. The antibody easily penetrates the sol-gel macropore fluidic network structure, making possible high affinities. To assess the capture affinity of the platform, we performed a direct assay using fluorescein isothiocyanate-labeled PSA. Pure PSA was subjected to on-chip MALDI-TOF-MS analysis, yielding three clear mass peptide peaks (m/z = 1272, 1407, and 1872). The sol-gel microarray platform enables dual readout of PSA both fluorometric and MALDI-TOF MS analysis in biological samples. Here we report a useful method for a means for discovery of biomarkers in complex body fluids.
AbstractThe authors have developed a porous silicon (P-Si) based duplex antibody microarray platf... more AbstractThe authors have developed a porous silicon (P-Si) based duplex antibody microarray platform for simultaneous quantitation of the biomarkers prostate-specific antigen (PSA) and human glandular kallikrein 2 (hK2) in serum. Pore size-controlled P-Si surfaces have an extremely enlarged surface area that enables high-density immobilization of fluorescently labeled antibodies by physical adsorption. Automated microarraying of the antibodies provides a fast and reproducible duplex format of antibody arrays on the P-Si chips placed in the wells of a microtiter plate. The assay platform showed a 100 fg·mL−1 limit of detection for both PSA and hK2, and a dynamic range that extends over five orders of magnitude. After optimization of the density of both capture antibodies, neither the PSA nor the hK2 array showed cross-sensitivity to non-target proteins or other plasma proteins. The microarray was evaluated by titration of PSA and hK2, respectively, in the same serum samples. In our perception, this highly sensitive and selective platform holds promise for improved detection of tumor markers in an early diagnostic stage, but also to monitor the recurrence of prostate cancer. Graphical AbstractA porous silicon microarray platform is presented for simultaneous detection of biomarkers prostate specific antigen and human glandular kallikrein 2 in human blood sample. The platform shows highly sensitive and selective biomarker detection features.
Escherichia coli are important indicator organisms, used routinely for the monitoring of water an... more Escherichia coli are important indicator organisms, used routinely for the monitoring of water and food safety. For quick, sensitive and real-time detection of E. coli we developed a 2'F modified RNA aptamer Ec3, by Cell-SELEX. The 31 nucleotide truncated Ec3 demonstrated improved binding and low nano-molar affinity to E. coli. The aptamer developed by us out-performs the commercial antibody and aptamer used for E. coli detection. Ec3(31) aptamer based E. coli detection was done using three different detection formats and the assay sensitivities were determined. Conventional Ec3(31)-biotin-streptavidin magnetic separation could detect E. coli with a limit of detection of 1.3 × 10(6) CFU/ml. Although, optical analytic technique, biolayer interferometry, did not improve the sensitivity of detection for whole cells, a very significant improvement in the detection was seen with the E. coli cell lysate (5 × 10(4) CFU/ml). Finally we developed Electrochemical Impedance Spectroscopy (E...
We fabricated droplet-based microfluidic platform for copolymerizable microspheres with acrydite ... more We fabricated droplet-based microfluidic platform for copolymerizable microspheres with acrydite modified DNA probe. The copolymerizable 3-D polyacrylamide microspheres were successfully produced from microcontinuous-flow synthesis with on-channel solidification. DNA copolymerization activity, surface presentation and thermostability were assessed by using fluorescent labeled complementary probe. The binding performance was only visible on the surface area of oligo-microspheres. We show that the resulting oligo-microspheres can be directly integrated into a streamlined microsphere-PCR protocol for amplifying ssDNA. Our microspheres could be utilized as a potential material for ssDNA analysis such as DNA microarray and automatic DNA SELEX process.
IEEE International Symposium on Micro-NanoMechatronics and Human Science, 2005, 2005
This paper presents fabrication and drive test of a peristaltic PDMS micropump actuated by the pn... more This paper presents fabrication and drive test of a peristaltic PDMS micropump actuated by the pneumatic force. The micropump consists of the three peristaltic-type actuators and a microchannel connecting the chambers and the inlet/outlet port. The micropump is fabricated by silicon mold process and the two-step curing process for irreversible bonding of PDMS layers. The diameter and the thickness of the actuator diaphragm are 3 mm and 37 mum, respectively. The dynamic valve action of the cascade three actuators is confirmed by using video camera. The meniscus motion of the red-ink in the micro channel is also observed and its volume speed is estimated through the frame analysis of the recorded a video data. The square-wave input pressure of 37.5 kPa is applied to micro actuator for pumping test of the micro pump. The maximum tap-water suction volume speed from inlet port to micro pump is about 0.48 muL/sec at 0.3 Hz while the hydraulic pressure difference is 7 CmH2O. Suction volume speed due to capillary effect is about 0.09 muL/sec. The maximum meniscus speed of red-ink is about 0.83 mm/sec at 5 Hz
A pneumatically driven cell trap device with individually controllable vibrators was fabricated a... more A pneumatically driven cell trap device with individually controllable vibrators was fabricated and the effect of mechanical stimuli on a trapped live cell was examined. The device consisted of two polydimethylsiloxane (PDMS) layers that formed pneumatic vibrators and a trap chamber connected to a fluid channel for introducing the cell. When the vibrators were supplied with compressed air, the flexible diaphragms in the vibrators were deformed and exerted pressure on the fluid film in the trap chamber. If a cell was present in the trap chamber, drag force generated by the fluid flow affected the cell. By using a symmetrical arrangement of four vibrators, the cell could be manipulated and trapped in region at the center of the four vibrators. In order to verify this working principle, the ability of the device to trap solid particles and live cells was tested. Intracellular calcium levels were measured to investigate the influence of mechanical stimuli produced via the fluid film, which was induced by pneumatic actuation, on a single cell within the trap chamber. Once the vibrators were actuated, the intracellular calcium level of the cell at rest increased rapidly as it responded to the external mechanical stimulation induced by deformation of the vibrator. When considering the typical increases in calcium induced by shear stress, the measured peak value was very small. As the duration of trapping was prolonged, the calcium levels decreased. The calcium level was comparable to that of a cell at rest, with some fluctuations. In short, the influence of mechanical stimuli on a live cell induced by the pneumatic cell trap appeared to be negligible during trapping.
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Papers by Ok Chan Jeong