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Joon-Ho Maeng

Bio: Joon-Ho Maeng is an academic researcher from Hanyang University. The author has contributed to research in topics: Sperm & Colloidal gold. The author has an hindex of 6, co-authored 9 publications receiving 209 citations.

Papers
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Journal ArticleDOI
TL;DR: The results of this study showed that the time required for a complete assay was reduced by 1h and a detection limit as low as 1 ng/mL was attained when this system used, which indicates that similar bead-based electrical detection systems could be used for the diagnosis of many forms of cancer.

61 citations

Journal ArticleDOI
TL;DR: The development of a microchip‐based multiplex electro‐immunosensing system for simultaneous detection of cancer biomarkers using gold nanoparticles and silver enhancer is described.
Abstract: Microfluidic-based microchips have become the focus of research interest for immunoassays and biomarker diagnostics. This is due to their aptitude for high-throughput processing, small sample volume, and short analysis times. In this paper, we describe the development of a microchip-based multiplex electro-immunosensing system for simultaneous detection of cancer biomarkers using gold nanoparticles and silver enhancer. Our microchip is composed of biocompatible poly(PDMS) and glass substrates. To fix the antibody-immobilized microbeads, we used pillar-type microfilters within a reaction chamber. An immunogold silver staining (IGSS) method was used to amplify the electrical signal that corresponded to the immunecomplex. To demonstrate this approach, we simultaneously assayed three cancer biomarkers, alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), and prostate-specific antigen (PSA) on the microchip. The electrical signal generated from the result of the immunoreaction was measured and monitored by a PC-based system. The overall assay time was reduced from 3–8 h to about 55 min when compared to conventional immunoassays. The working range of the proposed microchip was from 10−3 to 10−1 μg/mL of the target antigen.

56 citations

Journal ArticleDOI
TL;DR: This device provides a convenient, disposable, and high-throughput platform that could function as a progressive motile sperm sorter for potential use in intracytoplasmic sperm injection.
Abstract: We present a novel method for the separation of progressive motile sperm from non-progressive motile and immotile sperm. This separation was accomplished by inducing chemotaxis along a longitudinal chemical gradient in a microchip composed of a biocompatible polydimethysiloxane layer and a glass substrate. In a preliminary experiment using fluorescent rhodamine B as a marker, we verified that a chemical gradient was generated by diffusion within the microchannel. We used acetylcholine as a chemoattractant to evaluate the chemotactic response of sperm. We tested the response to a 1/2 to 1/64 dilution series of acetylcholine. The results of a mouse sperm chemotaxis assay showed that progressive motile sperm swam predominantly toward the outlet at an optimal chemical gradient of 0.625 (mg/ml)/mm of acetylcholine. This device provides a convenient, disposable, and high-throughput platform that could function as a progressive motile sperm sorter for potential use in intracytoplasmic sperm injection.

41 citations

Journal ArticleDOI
27 Jun 2018
TL;DR: Experimental results show that motile mouse sperm are attracted more sensitively under integrated conditions of chemotaxis and thermotaxis rather than individual conditions ofChemoattractant and thermOTaxis.
Abstract: Infertile couples needing assisted reproduction are increasing, so a fundamental understanding of motile sperm migration is required. This paper presents an advanced microfluidic device for sperm motion analysis utilizing chemotaxis and thermotaxis simultaneously for the first time. The proposed device is a transparent polydimethylsiloxane- and glass-based microfluidic chip system providing a low-cost, useful, and disposable platform for sperm analysis. The concentration gradient of the chemoattractant (acetylcholine) and the temperature difference are formed along the microchannel. The temperature gradient is generated and controlled by a microheater and microsensor. Thermotactic and chemotactic responses of mouse sperm were examined using the proposed device. Experimental results show that motile mouse sperm are attracted more sensitively under integrated conditions of chemotaxis and thermotaxis rather than individual conditions of chemotaxis and thermotaxis. This sperm analysis device is expected to be a useful tool for the study of mammalian sperm migration and the improvement of artificial insemination techniques.

29 citations

Journal ArticleDOI
TL;DR: In this article, a PDMS and glass-based microfluidic device consisting of a micromixer and a microreactor for DNA ligation is described, which shows a good mixing efficiency of 87.7% at a 500μL/min flow rate.
Abstract: A novel PDMS and glass-based microfluidic device consisting of a micromixer and microreactor for DNA ligation is described in this article. The new passive type planar micromixer is 10.33 mm long and composed of a straight channel integrated with nozzles and pillars, and the microreactor is composed of a serpentine channel. Mixing was enhanced by convective diffusion facilitated by the nozzles and pillars. The performance of the micromixer was analytically simulated and experimentally evaluated. The micromixer showed a good mixing efficiency of 87.7% at a 500 μL/min flow rate ( Re = 66.5). DNA ligation was successfully performed using the new microfluidic device, and ligation time was shortened from 4 h to 5 min. When used for on-chip ligation, this new micromixer offers advantages of disposability and portability.

21 citations


Cited by
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Journal ArticleDOI
TL;DR: This chapter discusses the development of personalized medicine and home testing in the developing world, and some of the strategies used to achieve this goal have not yet been developed.
Abstract: Introduction A Why POC Diagnostics? B Time B Patient Responsibility and Compliance B Cost B Diagnostic Targets C Proteins C Metabolites and Other Small Molecules C Nucleic Acids C Human Cells D Microbes/Pathogens D Drugs and Food Safety D Current Context of POC Assays E POC Glucose Assays E Lateral Flow Assays E Limitations of “Traditional” POC Approaches F Enabling Technologies G Printing and Laminating G Microfluidic Technologies and Approaches: “Unit Operations” for POC Devices G Pumping and Valving H Mixing I Separation I Reagent Storage J Sample Preparation K Surface Chemistry and Device Substrates L Physical Adsorption L Bioaffinity Attachment L Covalent Attachment M Substrate Materials M Detection M Electrochemical Detection N Optical Detection N Magnetic Detection N Label-Free Methods O Enabling Multiplexed Assays O Recent Innovation O Lateral Flow Assay Technologies O Proteins P Antibodies P Protein Expression and Purification Q Nucleic Acids Q Aptamers R Infectious Diseases and Food/Water Safety R Blood Chemistry S Coagulation Markers S Whole Cells S Trends, Unmet Needs, Perspectives T Glucose T Global Health and the Developing World T Personalized Medicine and Home Testing U Technology Trends U Multiplexing V Author Information V Biographies V Acknowledgment W References W

983 citations

Journal ArticleDOI
TL;DR: This work comprehensively review the present diagnostic systems and techniques for xPOCT applications, and critically summarize the in-field applicability and the future perspectives of the presented approaches.

360 citations

Journal ArticleDOI
TL;DR: This review, which summarizes developments in microfluidics-based immunoassays since 2000, includes four sections, focusing on the configurations of immuno ASSays that have been implemented in micro fluidics, the main fluid handling modalities that have be used for microfluidity immunoASSays, multiplexed immunoAssays in micro fluididic platforms, and the emergence of label-free detection techniques.
Abstract: Immunoassays have greatly benefited from miniaturization in microfluidic systems. This review, which summarizes developments in microfluidics-based immunoassays since 2000, includes four sections, focusing on the configurations of immunoassays that have been implemented in microfluidics, the main fluid handling modalities that have been used for microfluidic immunoassays, multiplexed immunoassays in microfluidic platforms, and the emergence of label-free detection techniques. The field of microfluidic immunoassays is continuously improving and has great promise for the future.

316 citations

Journal ArticleDOI
TL;DR: This tutorial review surveys the latest achievements in the use of nanoparticles to detect cancer biomarkers and cancer cells with a focus on optical and electrochemical techniques.
Abstract: This tutorial review surveys the latest achievements in the use of nanoparticles to detect cancer biomarkers and cancer cells with a focus on optical and electrochemical techniques. Nanoparticle based cancer diagnostics are becoming an increasingly relevant alternative to traditional techniques. Although some drawbacks exist in relation to the obtained sensitivity the use of nanoparticle-based sensors in biomarker detection or cancer cell detection offers some advantages in comparison to conventional methods. The developed techniques can be interesting and relevant for their use in point-of-care of cancer diagnostics. The methods can be of low cost and in addition easy to be incorporated into user-friendly sensing platforms.

302 citations