Jin-young Kim

Convenient Genetic Diagnosis of Virion Captured (VC)/RT-PCR for Rice Viruses (RSV, RBSDV) and Small Brown Plant Hopper

Genetic diagnosis method of Virion Captured (VC)/RT-PCR for Rice stripe virus (RSV) and Rice black-streaked dwarf virus (RBSDV), Korean major rice viruses transmitted by small brown plant hopper, Laodelphax striatellus, was developed. Virion extraction buffer for rice plant was 0.01M potassium phosphate buffer, pH 7.0, containing 0.5% sodium sulfite. However, the extraction buffer for L. striatellus was 0.01M potassium phosphate buffer, pH 7.0, containing 0.5% sodium sulfite and 2% polyvinylpyrrolidone wt 40,000 (PVP-40). Specific primers for detection of RSV and RBSDV were selected for VC/RT-PCR method. The specific primers were used as a duplex primer to detect viruliferous small brown plant hopper collected from Gimpo, Pyeongtaek and Siheung areas in Gyeonggi province. The genetic diagnosis methods of single and duplex VC/RT-PCR for RSV and RBSDV could be used easily and economically, especially on the diagnosis of L. striatellus. The rate of viruliferous insect (RVI) for RSV was compared with ELISA and VC/RT-PCR for L. striatellus collected from fields. RVI by ELISA was same as 9.2% with RVI by VC/RT-PCR. However, there were some different detection results between the methods. It could be suggested that there is a possibility of serological and/or genomic differences among RSV isolates. The portion of RVI detected simultaneously by ELISA and VC/RT-PCR was 71.0%, and the detection rate from VC/RT-PCR was higher as 3.2% than that from ELISA, which had a reason of simultaneous detection ability both RSV and RBSDV of VC/RT-PCR.

Occurrence and Symptoms of Tomato spotted wilt virus on Egg Plant, Whole Radish and Sugar Loaf in Korea

Tomato spotted wilt virus (TSWV) was occurred on the three vegetables of egg plant (Solanum melongena), whole radish (Raphanus acanthiformis) and sugar loaf (Cichorium intybus) at Anyang area infested with TSWV. Whole radish was produced the symptoms of necrotic spots on the leaves, and necrosis and malformation on the roots by TSWV. Egg plant was induced the symptoms of typical multiple ring spots on the leaves and necrotic rings on the fruits. Sugar loaf was infected severely with the typical symptoms of ring spots on the leaves and stunt. The three isolates of TSWV could infect locally on the indicator plants of Chenopodium amaranticolor, C. quinoa and Nicotiana debney, and systemically on N. glutinosa, N. benthamiana and Datura stramonium. Two TSWV isolates from egg plant and sugar loaf were very similar in virulence. However, the virulence of TSWV from whole radish was very different as local infection on 5 Nicotiana species including N. tabacum `Xanthi NC`.

A Capsule-Type Microrobot with Pick-and-Drop Motion for Targeted Drug and Cell Delivery

A capsule-type microrobot exhibits pick-and-drop (P&D) motion to hold a particle within a confined volume and transports it via a corkscrewing motion. The P&D motion is possible because the capsule-type microrobot has two parts: a plunger and a cap. The fabricated microrobots are wirelessly controlled by a magnetic manipulator. Drugs or cells can be encapsulated in the container of the capsule-type microrobot by the P&D motion or attached to the surface of the cap, which can be used as a supporting structure. Therefore, the capsule-type microrobot can deliver suspended or adherent cells. The drug or cells are minimally exposed or not completely exposed to the surrounding fluid and do not experience shear force when encapsulated in the container. As a proof-of-concept, secure transportation of microparticles in the confined volume of the capsule via P&D motion is demonstrated. In addition, the cap is used as a scaffold for neuronal cell culture on a rat brain slice to demonstrate its biocompatibility and feasibility for targeted cell delivery. The proposed capsule-type microrobot is suitable for diverse applications, as it protects the encapsulated materials.

A Magnetically Controlled Soft Microrobot Steering a Guidewire in a Three-Dimensional Phantom Vascular Network

Abstract Magnetically actuated soft robots may improve the treatment of disseminated intravascular coagulation. Significant progress has been made in the development of soft robotic systems that steer catheters. A more challenging task, however, is the development of systems that steer sub-millimeter-diameter guidewires during intravascular treatments; a novel microrobotic approach is required for steering. In this article, we develop a novel, magnetically actuated, soft microrobotic system, increasing the steerability of a conventional guidewire. The soft microrobot is attached to the tip of the guidewire, and it is magnetically steered by changing the direction and intensity of an external magnetic field. The microrobot is fabricated via replica molding and features a soft body made of polydimethylsiloxane, two permanent magnets, and a microspring. We developed a mathematical model mapping deformation of the soft microrobot using a feed-forward approach toward steering. Then, we used the model to steer a guidewire. The angulation of the microrobot can be controlled from 21.1° to 132.7° by using a magnetic field of an intensity of 15 mT. Steerability was confirmed by two-dimensional in vitro tracking. Finally, a guidewire with the soft microrobot was tested by using a three-dimensional (3D) phantom of the coronary artery to verify steerability in 3D space.

Fabrication and Characterization of a Magnetic Drilling Actuator for Navigation in a Three-dimensional Phantom Vascular Network

Intravascular microrobots have emerged as a promising tool for vascular diseases. They can be wirelessly and precisely manipulated with a high degree of freedom. Previous studies have evaluated their drilling performance and locomotion, and showed the feasibility of using microrobots for biomedical applications in two-dimensional space. However, it is critical to validate micro-drillers in a three-dimensional (3D) environment because gravity plays an important role in a 3D environment and significantly affects the performance of the micro-drillers in vascular networks. In this work, we fabricated magnetic drilling actuators (MDAs) and characterized their locomotion and drilling performance in vascular network-mimicking fluidic channels. The MDAs were precisely manipulated in the fluidic channel network in both horizontal and vertical planes, selecting and moving through the desired path via the junctions of multiple channels. The MDAs also accurately navigated an artificial thrombosis in an artificial 3D vascular network and successfully drilled through it. The results obtained here confirmed the precise manipulation and drilling performance of the developed MDAs in 3D. We think that the MDAs presented in this paper have great potential as intravascular drillers for precise thrombus treatment.

Monolithic nano-porous polymer in microfluidic channels for lab-chip liquid chromatography

In this paper, a nano-porous polymer has been integrated into the microfluidics device as on-chip monolithic liquid chromatography column for separation of chemical and biological samples. Monolithic nano-porous polymer (MNP) was formed and firmly grafted on the surface of the microfluidic channel. Neurotransmitters, 5-hydroxyindole-3-acetic acid (5-HIAA) and 5-hydroxytryptamine (serotonin, 5-HT), were successfully separated with the developed on-chip MNP column.

Characterization of a mm-scale swimming microrobot for 3D manipulation

Microrobots have proven to be a promising approach for minimally invasive treatment in the biomedical field. The microdriller with wireless magnetic manipulation has great potential for vascular disease such as thrombosis. It is required to remotely navigate the microdriller in three-dimensional (3D) because the vascular network in a body is complicated and formed in 3D. In this study, the helical microdriller with different number of helix was fabricated using 3D printing and then a permanent magnet was inserted. Translational velocity of the microdriller was investigated, manipulating in the horizontal (XY) and vertical (XZ) axes for 3D manipulation. The developed microdriller was able to successfully overcome gravity, operate vertically and horizontally and horizontally. Translational velocity was inversely proportional to the number of helix. The results addressed that the microdriller can be manipulated in 3D, which shows the potential as a targeted thrombus treatment.