Phase Equilibrium Measurements

Research Interests:

Design and Development of Point-of-care Microsystems for Diagnosis of Neurodegenerative Diseases

1) Diagnosis of neurodegenerative diseases by analyzing biomarkers from tear fluids

2) Design and development of microfluidic-based high-throughput mi-RNA analysis system for point-of-care (POC) analytics and diagnosis

3) Eye-on-a-chip

Ocular disease influences human vision and life quality. Worldwide, there are 285 million people who have a visual impairment, and the number of the people increases approximately 7 million every year. Glaucoma and age-related macular degeneration (AMD) are progressive optic neuropathies and are leading causes of blindness in the industrialized countries. Alzheimer’s diseases (AD) is a representative neurodegenerative disease causing dementia and eventual death, and 20% of people by the age of 85 are suffering from AD. Aging is known as one of primary factors of those neurodegenerative diseases, and interestingly, those diseases (glaucoma, AMD, and AD) share similar pathological pathway involved with amyloid beta (Aβ) accumulation in the brain and in the retina. Indeed, retinal disorders have been observed in patients who have other neurodegenerative diseases (i.e. Parkinson disease and AD) since the eye is a part of central nervous system. Although diverse pharmaceuticals have been developed, people are still suffering from those diseases because it is difficult to diagnose those diseases at early stage due to the unrecognizable symptoms. The diagnosis of AD at present can be made by physicians when the patients already exhibit early cognitive losses, the irreversible state causing dementia. Even if they have the chance to diagnose the diseases, it requires expensive diagnostic instrumentations such as a fundus camera, OCT (optical coherence tomography), and advanced imaging system. Thus, to overcome those limitations, development of an early diagnostic system which can detect the neurodegenerative diseases with high speed, sensitivity, and cost-effective manner is of paramount importance. In addition, development of point-of-care (POC) system for neurodegenerative disease detection at an early stage is important to demonstrate the self-diagnostic system at home or office. Furthermore, since the pathogenesis of the glaucoma, AMD, and AD is not fully discovered yet, the research investigating pathological pathway of the diseases should be performed simultaneously.

1) Diagnosis of neurodegenerative diseases by analyzing biomarkers from tear fluids

Objective: Early diagnosis of progressive neurodegenerative diseases using tear fluids

As the advance of the genetic and proteomic assay, tear fluid has been grown its interest as a source of biomarker analysis to diagnose the diseases. Tear fluid including various biomarkers such as proteins, lipids, and oligonucleotides, is less complex body fluid than serum or plasma and can be obtained without invasive method. Recently, as it has been known that tear fluid contains a high concentration of microRNA (miRNA), a non-coding and small RNA with approximately 20-22 nucleotides, which has been reported as biomarkers of neurodegenerative diseases. Since conventional diagnosis of neurodegenerative diseases requires expensive instrumentations, thus, miRNA based diagnosis is essential and can provide simple, inexpensive, sensitive, non-invasive method at an early stage of diseases. However, since the roles and pathogenesis of mi-RNAs and the data library among target mi-RNAs and the diseases was not fully investigated, it is paramount of importance to be investigated more quickly and widely.

I have been experienced detecting diverse biomarkers such as DNA/RNA, bacteria, and virus using immune/genetic analytical method. Since my Ph.D. thesis was involved in pathogen detection based on genetic and immune assay, I had obtained knowledge about genetic analysis technique; DNA/RNA amplification (i.e. single/multiplex PCR, isothermal amplification; LAMP, RPA), DNA/RNA purification from human samples. In addition, I have performed immune analysis using diverse antibodies, which were conjugated to graphene oxide, gold/iron oxide nanoparticles, and silica beads using conjugate chemistry, and ELISA reaction. I have knowledge of not only glaucoma and AMD but also ocular anatomy and pharmaceuticals, since I am working on ocular drug delivery in Georgia Tech. Thus, I believe I can successfully investigate miRNAs in the tear fluid based on my comprehensive experience.

2) Design and development of microfluidic-based high-throughput mi-RNA analysis system for point-of-care (POC) analytics and diagnosis

Objective: Design and development of (Aim #1) rapid, sensitive, portable and high-throughput mi-RNA diagnostic system based on microfluidics, and (Aim #2) POC testing device for self-diagnosis of neurodegenerative diseases at early stage

Diagnosis of neurodegenerative diseases using mi-RNAs in tear would be interesting research. However, tens of down-regulated mi-RNA can be derived from one target mi-RNA from the patients, and moreover, one mi-RNA can be also found in other neurodegenerative diseases. In the end, hundreds of mi-RNA samples should be analyzed to identify and detect target mi-RNA with high sensitivity and reproducibility. Since, the mi-RNA analysis in lab-scale (conventional method) requires much samples and reagents, labor-intensive process, long analysis time with low reproducibility, thus, I would like to exploit ‘Lab-on-a-Chip’ (LOC) technology to overcome the limitations mentioned above. My objective of this project is that design and development of high-throughput analysis system using on the LOC technology enabling hundreds of reactions simultaneously with high sensitivity and accuracy.

The second objective of this project is demonstrating POC testing device for neurodegenerative diseases for early self-diagnosis. People living in rural area and developing countries are vulnerable to diseases because they have economic and geographical difficulties in getting a medical diagnosis with physicians. In addition, there are some people miss the opportunity to find their disease at an early stage because they are annoyed or afraid of to go to the hospital to be examined. If we could develop a miniaturized portable diagnostic system to solve the above problems, it will contribute to diagnose and treat diseases of people who are not examined with doctors due to economical, geographical, temporal problems or individual’s will. Thus, this project aims to develop a portable diagnostic system that can diagnose the diseases more rapidly and accurately based on LOC technology by selecting one to three target mi-RNA that can represent each disease.

Since I fabricated diverse microchips made by glass, silicone, quartz, polycarbonate, and polydimethylsiloxane (PDMS), I have learned various fabrication methods (i.e. photo/soft lithography, by using a CO2 laser cutting, milling machine cutting). According to the target and detection methods, diagnostic microsystem can be optimized to maximize the detection sensitivity and specificity. In particular, I have mainly demonstrated centrifugal diagnosis microsystems, which do not require external valves or pumps for fluid flow, but fluid transfer can be controlled only by the structure and surface properties of microchannels, and spinning rate of the microchip. By using advantages of the centrifugal microsystems, I am going to develop high-throughput and POC testing diagnostic centrifugal microsystems.

3) Eye-on-a-Chip

Objective: Investigation of pathogenesis of progressive neurodegenerative diseases/ Drug screening for treatment of retinal disorders/ Demonstration of ocular organs on microfluidic devices

Various organs have been mimicked in the microchip, organ-on-a-chip, to investigate various pathological disease mechanisms in the body and to develop effective treatment methods using drugs, but the eyes rarely have been investigated on the microchip. Recently, eye research on the microchip has been started, but more intensive studies are needed and various applications are possible because the research has not been done sufficiently yet. By mimicking the retina on the microchip, “Retina-on-a-chip”, time and cost savings can be achieved by replacing some clinical trials in animals and humans, and real-time monitoring can be performed to observe the response and metabolism of retinal cells in a variety of physical, chemical, and biological conditions. Thus, it is effective in identifying pathological mechanisms of onset. In particular, the retina is located inside the eye, so expensive imaging equipment is needed for observation, while a retina-on-a-chip can be observed with a simple microscope. In addition, patient’s retinal cells can be cultured on a microchip to allow theragnosis to be diagnosed and treated according to the characteristics of the patient. Moreover, neurodegenerative diseases such as Alzheimer's disease, glaucoma, or age-related macular degeneration are highly related to retinal degeneration, and pathological pathways of the above diseases has not been clearly elucidated. Therefore, by using the retina-on-a-chip, the relationship between the pathogenesis and biomarkers can be identified. In addition, a drug delivery model based on the retina-on-a-chip can be demonstrated, which can be extended to various fields.

The first step is optimization of stem cell differentiation because it is strict to differentiate from stem cell to retinal cells like retinal pigment endothelium. Then, microchip materials capable of stem cell culture is chosen, and design and fabrication of microchips based on the actual structure of the retina is performed. Then, retinal or stem cells are cultured on the microchip by investigating conditions such as temperature, humidity, and pH that the retina cells can grow. The next step is to study the environment of the retina related to various neurodegenerative diseases, then, to demonstrate those conditions that can simulate the disease on the retina-on-a-chip. The factors that can treat the simulated retinal disease are summarized and flowed on the retina-on-a-chip to observe the reaction and denaturation of the cells by real time confirmation. Then, by analyzing the metabolites generated under various conditions, the relationship with the biomarker and diseases can be identified. Furthermore, the optimum conditions of the metabolism and the treatment can be investigated by controlling drugs, dose, and other conditions in the retina-on-a-chip.

Since I have worked on a drug delivery to the posterior eye through a suprachoroidal space (SCS) using a microneedle, thus, I also can mimic the SCS on a microchip, “SCS-on-a-chip”, and implement a SCS delivery model on the microchip. Based on my knowledge of microdevice fabrication and ocular drug delivery, SCS can be mimicked not only mechanically but also biologically. By using the SCS-on-a-chip, the pharmacokinetics model of ocular drugs which are injected by a microneedle can be optimized and compared to clinical trials with animals and humans to determine the feasibility of the SCS-on-a-chip.

Research Interests
1. Ocular and dermal drug delivery using microneedles
2. Diagnosis of neurodegenerative diseases by analyzing biomarkers from body fluids
3. Design and development of microfluidic based high-throughput mi-RNA analysis system and point-of-care (POC) system
4. Eye-on-a-chip: Suprachoroidal space-on-a-chip, Retina-on-a-chip

PhD Dissertation

“Development of a Total Integrated Rotary Genetic Analysis Microsystem for Rapid and Multiplex Pathogen Detection.”

Under supervision of Dr. Tae Seok Seo, School of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST).

Selected Publications

J.H. Jung, P. Desit and M.R. Prausnitz, 2018. “Targeted drug delivery in the suprachoroidal space by swollen hydrogel pushing”, Invest. Ophthalmol. Vis. Sci. 59, 20469-1079.

J.H. Jung, B. Chiang and Mark R. Prausnitz, 2018. “Ocular drug delivery targeted by iontophoresis in the suprachoroidal space using a microneedle”, J. Control. Release 227, 14-22 (2018).

J.H. Jung, B.H. Park, S.J. Oh, G. Choi and T.S. Seo, 2015. “Integrated centrifugal reverse transcriptase loop-mediated isothermal amplification microdevice for influenza A virus detection”. Biosens. Bioelectron., 68, 218-224.

J.H. Jung, B.H. Park, S.J. Oh, G. Choi and T.S. Seo, 2015. “Integration of reverse transcriptase loop-mediated isothermal amplification with an immunochromatographic strip on a centrifugal microdevice for influenza A virus identification”. Lab Chip, 15, 718-725.

J.H. Jung, T.J. Park, S.Y. Lee and T.S. Seo, 2012. “Homogeneous Biogenic Paramagnetic Nanoparticle Synthesis Based on a Microfluidic Droplet Generator”. Angew. Chem. Int. Ed. 51, 5634-5637.

J.H. Jung, D.S. Cheon, F. Liu, K.B. Lee and T.S. Seo, 2010. “A Graphene Oxide Based Immuno-Biosensor for Pathogen Detection”, Angew. Chem. Int. Ed. 49, 5708-5711.

Teaching Interests:

Aside from my research career, I have extensive teaching experience as a TA and RA. During graduate student, I TAed Chemical and Biomolecular Engineering (CBE) Laboratory, Organic Chemistry, and DNA chemistry in School of Chemical and Biomolecular Engineering in KAIST, Korea as a part of government fellowship. All classes were performed in English. I had worked as an RA of undergraduate research program (URP) in KAIST and the research class for undergraduates in CBE during graduate school. Also, I mentored graduate students in my group. In the Georgia Institute of Technology, I have performed ocular drug delivery projects with three undergraduates for 2 year.

Since I have immersed diverse research field I believe those experiences obviously will be helpful to my teaching. My research experiences are focused in the fields including Molecular Biology, Molecular Diagnostics, Bio Engineering. Thus, my teaching interests are also there in the same field. I also have interest in teaching of microfluidics, recent topics in chemical and biomolecular engineering.

In particularly, I would like to develop the class, ‘Point-of-care (POC) system design and development’. In my opinion, students should have wide insights in their fields. Thus, I would like to let student develop POC system from design to demonstration in this class. Although pre-requisites, basic classes, will be required to take this class, students can widely comprehend recent technology trends in their fields by literature survey and will understand how to design POC system. Actual development will be limited, but students will learn how to use their knowledge which earned in the class. I also would like to include importance of patents in the system development.