Search

Clustered regularly interspaced short palindromic repeats (CRISPR)-based diagnostics have emerged as next-generation molecular diagnostics. In CRISPR-based diagnostics, Cas12 and Cas13 proteins have been widely employed to detect DNA and RNA, respectively. Herein, we developed a novel hybrid Cas protein capable of detecting universal nucleic acids (DNA and RNA). The CRISPR/hybrid Cas system simultaneously recognizes both DNA and RNA, enabling the dual detection of pathogenic viruses in a single tube. Using wild-type (WT) and N501Y mutant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as detection models, we successfully detected both virus strains with a detection limit of 10 viral copies per reaction without cross-reactivity. Furthermore, it is demonstrated the detection of WT SARS-CoV-2 and N501Y mutant variants in clinical samples by using the CRISPR/hybrid Cas system. The hybrid Cas protein is expected to be utilized in a molecular diagnostic method for infectious diseases, tissue and liquid biopsies, and other nucleic acid biomarkers.

Heart disease is the leading cause of mortality in the U.S. with approximately 610,000 people dying every year. Effective therapies for many cardiac diseases are lacking, largely due to an incomplete understanding of their genetic basis and underlying molecular mechanisms. Zebrafish (Danio rerio) are an excellent model system for studying heart disease as they enable a forward genetic approach to tackle this unmet medical need. In recent years, our team has been employing electrocardiogram (ECG) as an efficient tool to study the zebrafish heart along with conventional approaches, such as immunohistochemistry, DNA and protein analyses. We have overcome various challenges in the small size and aquatic environment of zebrafish in order to obtain ECG signals with favorable signal-to-noise ratio (SNR), and high spatial and temporal resolution. In this paper, we highlight our recent efforts in zebrafish ECG acquisition with a cost-effective simplified microelectrode array (MEA) membrane providing multi-channel recording, a novel multi-chamber apparatus for simultaneous screening, and a LabVIEW program to facilitate recording and processing. We also demonstrate the use of machine learning-based programs to recognize specific ECG patterns, yielding promising results with our current limited amount of zebrafish data. Our solutions hold promise to carry out numerous studies of heart diseases, drug screening, stem cell-based therapy validation, and regenerative medicine.

In this work, we report polyimide-based biocompatible and flexible pH micro-probes. The sensing electrodes were based on iridium oxide (IrOx) thin film, electrodeposited by a cyclic voltammetry process onto a base sputtered gold (Au) layer. Square electrode configurations with sizes of 1 mm2, 500 μm2, 300 μm2, and 200 μm2 were designed, fabricated and tested; these yielded sensitivities of ∼71 mV/pH, ∼62 mV/pH, ∼52 mV/pH and ∼51 mV/pH, as well as limit of detection (LOD) values of 0.04 pH, 0.047 pH, 0.065 pH and 0.075 pH, respectively. Reference electrodes (REs) were developed by applying AgCl paste onto Au electrodes, followed by a curing process; demonstrating a comparable performance to commercial REs. Our pH micro-sensors hold promise for various applications, from analyses of chemical processes, to in-vitro and in-vivo experiments, to environmental or food safety monitoring.

In this study, we analyze the economic effects from the Korean Astronaut Program (KAP) and the subsequent Science Culture Diffusion Activity (SCDA). Korea has had a huge practical effect on the development of science and technology and has increased international awareness of Korea by producing Korea's first astronaut. There has also been a large, ripple effect on space related industries. In addition, the KAP has exercised a far-reaching influence on Korean society and culture by boosting all science and engineering and inspiring national pride. After the KAP, astronauts' outreach activities, such as lectures for the general public; interviews on television, newspapers and magazines; participating in children's science camps; and distributing publications and DVDs about astronaut program for general public, were instituted for diffusing science culture. Thus, positive effects such as the promotion of Korea's level of technology, student interest in science and engineering fields, and the expansion of the industrial base were reinforced after the KAP. This study is aimed at evaluating the economic significance and the value of return through analyzing the effects of the KAP and the subsequent Science Culture Diffusion Activity.

In this study, we simulated space flight of the nematode, Caenorhabditis elegans, on the ground and examined how it is affected by space radiation and G-forces. We simulated G-forces during launch in a gravity acceleration laboratory device in order to identify and isolate the effects of the G-forces. Following this, we irradiated C. elegans with accelerated protons (MC-50 Cyclotron) and gamma rays (iR 222 machine) at the same physical dose. We calculated the expected radiation dose according to Reitz [1] and simulation programs (NASA AP8MIN [2], NASA AE8MAX [2], and CREAM86 [3]) for 1 month (dose rate: 6 × 10-3 Gy; 2.8 × 10-2 Gy), 6 months (dose rate: 36 × 10-3 Gy; 16.8 × 10-2 Gy), and 2 years (dose rate: 144 × 10-3 Gy; 67.2 × 10-2 Gy) of space flight. There have been several trials that aimed to take C. elegans into orbit on US space shuttle missions including a mission on the shuttle Columbia. In this study, we simulated longer duration space flights and performed a whole-genome microarray analysis to observe phenotype variations whereas most such experiments were carried out during short duration space flights and focused on mutations and genotypic variations. We expect that the results of this study will be useful to predict the effects of long-term exposure of space radiation on living organisms.

PURPOSE This study was designed to evaluate the effect of microgravity on the diurnal variation of intraocular pressure (IOP). METHODS IOPs were measured with the pressure phosphene tonometer in 1 subject (the first Korean astronaut) during spaceflight. IOPs were measured every 3 hours during day time (6 times per day) at 2 separate days in space with 3 repeated measurements at each time on both eyes. A total of 72 measurements were obtained during spaceflight. To obtain control IOP data, IOP was measured using the same protocol on ground before spaceflight. RESULTS Mean IOP increased by 26.3% during spaceflight compared with that on ground [16.47 ± 0.60 (SD) mm Hg vs. 13.04 ± 0.74 mm Hg, P

The paper presents an overview of the scientific space experiments in the Korean Astronaut Program (KAP) that were conducted on the International Space Station (ISS), beginning with launch of the Soyuz TMA-12 spacecraft with the first Korean astronaut and two Russian astronauts on April 8, 2008 and returning to Earth on April 19, 2008. During the 10 days aboard the ISS, the Korean astronaut successfully completed thirteen scientific experiments in biology, life science, material science, earth science, and system engineering, five educational space experiments, and three kinds of international collaboration experiments. These experiments were the first Korean manned space experiments and these missions were the first steps toward the manned space exploration by Korea. In this paper, we briefly discuss the descriptions, conduct, and results of the space experiments and discuss future plans. In addition, the lessons learned with respect to the performing of these manned space experiments on the ISS are presented.

We analyzed the result of sensory evaluation for the 10 items of Korean Space Foods performed by Korean astronaut in ISS. Although there were low score items because of the individual preference difference, Most items received the high score. Also, we can confirm the possibility of the internationalization of the Korean Space Foods because international astronauts gave the high valuation. we should develop the various space foods and food package which are easy to use in space for the human exploration in the future.

We present the experimental study to realize a DNA separation chip using asymmetrically-switched nonuniform electric fields. The DNA separation chip redistributes DNA molecules within a specific area based on the size- and field-dependent nonlinearity of DNA drift velocity. The present chip is composed of a width variable channel to distribute nonuniform electric field, a DNA loading slit and a pair of electrodes to apply electric field. We focus on the design of DNA separation chips with identifying the nonlinearity of DNA drift velocity using three different DNA molecules (11.1kbp, 15.6kbp, and 48.5kbp) in the chips. It is demonstrated that different size of DNA shows different net migration in different direction under the asymmetrically-switched n onuniform electric field.기호설명 E 전기장 T 전기장 인가 주기 M DNA 분자의 크기 1. 서론 본 연구은 DNA 분리소자에 관한 것으로, 채널 내에 형성된 불균일한 전기장의 방향이 변함에 따라, DNA는 그 6cm크기에 따라 알짜이동 방향과 속도가 달라지게 된다. 본 논문에서는 이론적으로 제시된 바 있는 (1)이러한 래칫(ratchet) 효과를 실험적으로 검증하였다. 제안한 DNA분리소자(Fig. 1)에서는 비대칭 교차전기장(Fig. 2) 6mm미소유로을 양단에 인가하고 미소유로의 폭을 변화시켜 불균일 전기장을 형성하였다. 기존의 전기영동 소자

We present a novel method of measuring cell concentration using two electrical cell counters across a fixed control volume. Our device counts cells at the inlet and outlet of a fixed control volume and then measures the cell concentration by calculating the number of cells in the fixed control volume. Previous methods of measuring cell concentration (such as a Coulter counter and a flow cytometer) have attempted to count cells in a given fluid volume or at a known flow rate. Thus, in spite of the miniature nature of previous devices, the accuracy of their results depends on the performance of external mechanisms such as delicate pumps and flow sensors. Our prototype, however, does not depend on accurate fluid measurement or precise control of the flow rate because it measures the number of cells in a fixed control volume. In the experimental study, we measured cell concentrations ranging from 5.8 times 105 to 11.5 times 105 cells/mL without measuring or controlling the flow rate. For measuring the cell concentration, our prototype shows a maximum cell concentration measurement error of 10.3%, which is within the error range of a hemacytometer.

This paper presents the experimental study to realize a DNA separation chip based on the self-focusing effect in a micropillar array. The present self-focusing chip redistributes DNA molecules within a specific area of micropillar arrays based on the size- and field-dependent nonlinearity of DNA drift velocity. Compared to conventional electrophoresis chips, the present self-focusing chip reduces a substantial amount of the separation channel length, the influence of sample starting location, and the necessity of time-consuming continuous monitoring process. We focus on the design of DNA self-focusing chips, with identifying the nonlinearity of DNA drift velocity using three different DNA molecules including λ DNA(48.5 kbp), micrococcus DNA(115 kbp), and T4 DNA(169.8 kbp) in microfabricated test chips. It is demonstrated that the present DNA self-focusing chips have potentials not only for the miniaturization of DNA analysis systems, but also for the tunable capability of the target DNA size to be separated, trapped and extracted.

We present a novel flow-rate independent cell concentration sensor using a fixed control volume between double electrical sensing zones. Compared to Hemacytometer [L.M. Prescott, J.P. Harley, D.A. Klein, Microbiology, McGraw-Hill, New York, 2002.] and Coulter Counter [M. Koch, A.G.R. Evans, A. Brunnschweiler, Design and fabrication of a micromachined coulter counter, J. Micromech. Microeng. 9 (1999) 159–161] requiring an accurate fluid volume measurement or precision flow-rate control, the present cell concentration sensor offers the flow-rate independent method for the cell concentration measurement with counting cells in a fixed control volume of 0.423 μl. In the experimental study, we have used the RBC samples of three different concentrations and compared the results obtained from the present device with those from Hemacytometer. Using the fabricated devices, we have made two different cell concentration measurements: (1) with single electrical sensing at a fixed flow-rate of 1.2 μl/min; (2) with double electrical sensing with a known control volume of 0.423 ± 0.01 μl. Compared to Hemacytometer, the single and double sensing methods show the maximum concentration errors of 8.7% and 10.3%, which are in the measurement error range of Hemacytometer. We also measure the cell concentration within the maximum concentration errors of 10.3% in two cases: (1) two different flow-rates of 5 and 0.5 μl/min, (2) the varying flow-rates from 2 to 1 μl/min, respectively. Therefore, we verify the flow-rate independent measurement capability of the present device. Finally, we conclude that the present sensor can measure cell concentration without the accurate control and measurement of flow-rate.

We present a novel flow-rate independent cell counter using a fixed control volume between double electrical sensing zones. The previous device based on the single electrical cell sensing in a given flow-rate requires an accurate fluid volume measurement or precision flow rate control. The present cell counter, however, offers the flow-rate independent method for the cell concentration measurement with counting cells in a fixed control volume of . In the experimental study, using the RBC (Red Blood Cell), we have compared the measured RBC concentrations from the fabricated devices with those from Hemacytometer. The previous and present devices show the maximum errors of , which are in the measurement error range of Hemacytometer (about ). The present device also shows the flow-rate independent performance at the constant flow-rates ( and ) and the varying flow-rate (4, 2, and ). Therefore, we demonstrate that the present cell counter is a simple and automated method for the cell concentration measurement without requiring an accurate fluid measurement and precision flow-rate control.

This paper presents an integrated deoxyribose nucleic acid (DNA) trapping and extraction microchip based on the electrophoresis using periodically crossed electric fields in the micropillar array. The extraction microchip, integrated with a micropillar array, microchannels, nano-gap entropic barriers, loading and unloading windows, has been fabricated by a 3-mask microfabrication process. Using the electric field crossed at 120°, the microchip is designed to trap the DNA molecules, whose reorientation time is longer than the period of the crossed field, within the micropillars distributed at 60° direction. In the fabricated extraction microchip, three different DNA molecules, including λ DNA (48.5 kbp), micrococcus DNA (115 kbp) and T4 DNA (168.9 kbp) show the reorientation times of 4.80 ± 0.44 s, 7.12 ± 0.75 s and 9.71 ± 0.30 s, respectively, at the crossed electric field of 6.25 V/cm. Among three DNA molecules, T4 DNA could not come out of the micropillar array for the electric field of 6.25 V/cm crossed at the period of 10 s. We have demonstrated that the present DNA extraction microchip separates DNA molecules larger than a critical value, which can be adjusted by the period of the electric field across the micropillar array.

This paper presents the experimental study to realize a DNA separation chip based on the self-focusing effect in a microfabricated PDMS chip. The present self-focusing chip redistributes DNA molecules within a specific area based on the size- and field-dependent nonlinearity of DNA drift velocity. Compared to conventional electrophoresis chips, the present self-focusing chip offers the advantages of simple structure, short separation channel length, and starting-point independent DNA separation. We focus on the design of DNA self-focusing chips, with identifying the nonlinearity of DNA drift velocity using three different DNA molecules (11.1kbp, 15.6kbp, and 48.5kbp) in test chips. It is demonstrated that the present DNA self-focusing chips have potentials not only for the miniaturization of DNA analysis systems, but also for the tunable capability of the target DNA size to be separated, trapped and extracted.

This paper presents the first experimental study to realize a DNA separation chip based on the self-focusing effect in a micropillar array. The present self-focusing chip redistributes DNA molecules within a specific area of micropillar arrays based on the size- and field-dependent nonlinearity of DNA drift velocity. Compared to conventional electrophoresis chips, the present self-focusing chip reduces a substantial amount of the separation channel length, the influence of sample starting location, and the necessity of time-consuming continuous monitoring process. We focus on the design of DNA self-focusing chips, with identifying the nonlinearity of DNA drift velocity using three different DNA molecules including /spl lambda/ DNA (48.5 kbp), micrococcus DNA (115 kbp), and T4 DNA (169.8 kbp) in microfabricated test chips. It is demonstrated that the present DNA self-focusing chips have potentials not only for the miniaturization of DNA analysis systems, but also for the tunable capability of the target DNA size to be separated, trapped and extracted.

We present a novel cell counter using a fixed control volume and double electrical sensing zones at the inlet and outlet of the control volume. The present cell counter measures cell concentration based on the difference of the counted cell numbers from the double electrical sensing zones at inlet and outlet of the fixed control volume. In the experimental study, we use the RBC samples of three different concentrations and compare the results from the fabricated device with those from hemacytometer. Using the fabricated devices, we make two different measurements: 1) Cell concentration measurement using single electrical sensing at a fixed flow-rate of 10 /spl mu/l/min.; 2) Cell concentration measurement using double electrical sensing with the fixed control volume of 22.9/spl plusmn/0.98 /spl mu/l. Compared to hemacytometer, the single and double electrical sensing methods show the maximum errors of 20.3% and 16.1%, respectively, which are in the measurement error range of hemacytometer. We also observe that the present cell counter has an immunity for flow-rate change.

This paper presents a DNA (Deoxyribose Nucleic Acid) extractor based on an electrophoresis using periodically crossed electric fields in a micropillar array. The DNA extractor, having nanometer entropic barriers and micropillar array, was fabricated by micromachining processes. Under the crossed electric field, the DNA molecules, whose reorientation time is longer than the period of the crossed field, are trapped in the micropillar array. We applied the electric fields, crossed at 120/spl deg/, to the DNA molecules in the micropillar array distributed in 120/spl deg/ direction. Three different DNA, including /spl lambda/, micrococcus and T4 show reorientation times of 4.80 /spl plusmn/ 0.44sec, 7.12 /spl plusmn/ 0.75sec, and 9.71 /spl plusmn/ 0.30sec for /spl lambda/ DNA(48.5 kbp), micrococcus DNA (115 kbp), and T4 DNA (169.8 kbp), respectively at E=5V/0.8cm. In the fabricated DNA extractor, T4 DNA cannot come out of the micropillar array for the crossed electric field of 5V/0.8cm at a 10 second interval. We have demonstrated that the present DNA extractor separates DNA molecules longer than a critical value, which can be adjusted by the magnitude and the period of the electric field across the micropillar array.

Different photocurable acrylates, including two hyperbranched monomers, are compared with an epoxy negative-tone photoresist (SU-8) with respect to their suitability for the fabrication of ultra-thick polymer microstructures in a photolithographic process. To this end, a resolution pattern was used and key parameters, such as the maximum attainable thickness and aspect ratio, the minimum resolution and the processing time were determined. Compared to SU-8, all acrylate materials allowed the fabrication of thicker layers with a fast single layer fabrication procedure. Microstructures with thicknesses of up to 850 µm, an aspect ratio of up to 7.7, a 5.5-fold reduction in internal stress and a 6-fold reduction in processing time compared to SU-8 were demonstrated using an acrylated hyperbranched polyether. The specific development process of the hyperbranched polymer combined with channel design moreover enabled us to produce a high-performance valve for micro-battery devices.