Publications by authors named "Jonghyun Oh"

Microwell technology is crucial in biological applications due to its ability to handle small sample sizes and perform numerous assays efficiently. This study aimed to develop a novel technique for microwell fabrication using pressure-assisted steam technology, offering lower cost, simplicity, and high reproducibility. Mechanical properties of microwell surfaces were successfully controlled and characterized, making them suitable for DNA capture.

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The application of cell sheet technology for wound healing preserves dense cell tissue and the natural extracellular matrix (ECM), contributing to disease prevention. Despite the effectiveness of autologous and allograft cell sheets for wound healing, conventional cell sheets, although stable, may experience necrosis in their middle layers due to a lack of nutrients or oxygen. To address these issues, a novel approach is proposed to create cell sheets using mechanical and electrical stimulation.

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Researchers have developed in vitro small intestine models of biomimicking microvilli, such as gut-on-a-chip devices. However, fabrication methods developed to date for 2D and 3D in vitro gut still have unsolved limitations. In this study, an innovative fabrication method of a 3D in vitro gut model is introduced for effective drug screening.

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Glaucoma is a group of ocular diseases that cause irreversible blindness. It is characterized by multifactorial degeneration of the optic nerve axons and retinal ganglion cells (RGCs), resulting in the loss of vision. Major components of glaucoma pathogenesis include glia-driven neuroinflammation and impairment of mitochondrial dynamics and bioenergetics, leading to retinal neurodegeneration.

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Traditional goal of microfabrication was to limitedly construct nano- and micro-geometries on silicon or quartz wafers using various semiconductor manufacturing technologies, such as photolithography, soft lithography, etching, deposition, and so on. However, recent integration with biotechnologies has led to a wide expansion of microfabrication. In particular, many researchers studying pharmacology and pathology are very interested in producing in vitro models that mimic the actual intestine to study the effectiveness of new drug testing and interactions between organs.

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Polydimethylsiloxane (PDMS) membranes can allow the precise control of well-defined micropore generation. A PDMS solution was mixed with a Rushton impeller to generate a large number of microbubbles. The mixed solution was spin-coated on silicon wafer to control the membrane thickness.

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In the field of biology, dark field microscopy provides superior insight into cells and subcellular structures. However, most dark field microscopes are equipped with a dark field filter and a light source on a 2D-based specimen, so only a flat sample can be observed in a limited space. We propose a compact cell monitoring system with built-in dark field filter with an optimized incident angle of the light source to provide real-time cell imaging and spatial cell monitoring for long-term free from phototoxicity.

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Article Synopsis
  • The viscosity of prepolymer fluids like hydrogels significantly impacts the mechanical properties of the extracellular matrix (ECM) and cell viability.
  • A new method utilizing a flow-focused microdroplet generator allows for measuring the viscosity of fluids with small amounts of prepolymers, showing promising results with alginates and gelatin methacryloyl (GelMA).
  • An empirical formula derived from experiments accurately predicts viscosity based on the break-up length of the disperse phase, offering potential advancements in hydrogel applications for biomedical and tissue regeneration.
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Objectives: We sought to identify the consecutive changes and predictive features for exudation recurrence in macular neovascularization (MNV) using optical coherence tomography angiography (OCTA) in type 1 neovascular age-related macular degeneration (NVAMD).

Methods: A total of 291 OCTA images in consecutive visit of 45 patients newly diagnosed with type 1 NMV and treated with three loading intravitreal anti-vascular endothelial growth factor injections (IVIs) and a pro-re-nata (PRN) therapy regimen were analysed. Quantitative features of OCTA included the MNV area, MNV length, total number of endpoints (open-ended vessels) and junctions (internal branching) using AngioTool.

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Purpose: The purpose of this study was to present normative data of optical coherence tomography (OCT), electrophysiological, and ocular biometry parameters and their correlation in minipigs.

Methods: Eighty-eight eyes of 44 minipigs underwent full-field electroretinogram (ERG) recording and ocular biometry. However, 10 eyes of 6 minipigs were excluded because of poor OCT image quality.

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It is necessary to investigate effective energy storage devices that can fulfill the requirements of short-term and long-term durable energy outputs. Here, we report a simple one-pot hydrothermal technique through which to fabricate the MoS/Te nanocomposite to be used as an effective electrode material for high-performance supercapacitors. Comprehensive characterization of the as-fabricated nanomaterial was performed using FESEM, HRTEM, XRD, FTIR, XPS, etc.

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Purpose: To investigate the effect of the foveal Müller cell cone structure on the anatomical and functional response to intravitreal bevacizumab treatment in patients with diabetic macular edema.

Methods: In 93 treatment-naive eyes with center-involved cystic type diabetic macular edema, spectral-domain optical coherence tomography scans of baseline were retrospectively evaluated to determine the foveal Müller cell cone structure and prognostic features including length of disorganization in the retinal inner layers and ellipsoid zone disruption. The area and circularity of the foveal avascular zone of the superficial and deep capillary plexus 1 month after intravitreal bevacizumab treatment were evaluated using optical coherence tomography angiography.

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This review highlights current developments, challenges, and future directions for the use of invasive and noninvasive biosample-based small biosensors for early diagnosis of Alzheimer's disease (AD) with biomarkers to incite a conceptual idea from a broad number of readers in this field. We provide the most promising concept about biosensors on the basis of detection scale (from femto to micro) using invasive and noninvasive biosamples such as cerebrospinal fluid (CSF), blood, urine, sweat, and tear. It also summarizes sensor types and detailed analyzing techniques for ultrasensitive detection of multiple target biomarkers (i.

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Most elderly patients after orthopedic and dental implant surgeries are exposed to cardiostimulants to reduce potential blood pressure-related risks of cardiovascular diseases. Such treatments lead to deconditioning of platelet function, which is an important factor in wound healing treatments. We introduced an innovative parylene-C coated microporous PDMS structure that can prevent the functional deconditioning of platelets caused by certain cardiostimulants.

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The three-dimensional volumetric application of conductive poly (3,4-ethylenedioxythiophene)/poly (4-styrenesulfonate) (PEDOT:PSS) to multiwalled carbon nanotubes (MWCNTs) has not been widely reported. In this study, the applicability of the 3D PEDOT:PSS-MWCNT composite for a gas sensor was investigated with different PEDOT:PSS concentrations. The gas-sensing performance of the 3D PEDOT:PSS-MWCNT composites was investigated using ethanol and carbon monoxide (CO) gas.

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We present multiple-bent multi-walled carbon nanotubes (MWCNTs) that enable the picomolar detection of C-reactive protein (CRP), which is considered to be a promising biomarker for various diseases. The MWCNTs were grown via chemical vapor deposition repeating the asymmetric catalytic CNT growth on atypical carbon nanoparticles that were generated by carbon coating on a silicon substrate. The multiple-bent MWCNTs with the carbon film (CF) possessed abundant hydrophilic functional groups (-COOH and -OH) at their bending sites, resulting in enhanced bioadhesion to collagen and platelets, compared to MWCNTs grown without a CF layer.

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In this study, we propose a microchip that is sequentially capable of fluorescently staining and washing DNAs. The main advantage of this microchip is that it allows for one-step preparation of small amounts of solution without degrading microscopic bio-objects such as the DNAs, cells, and biomolecules to be stained. The microchip consists of two inlets, the main channel, staining zone, washing zone, and one outlet, and was processed using a femtosecond laser system.

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Polydimethylsiloxane (PDMS)-based elastomers have become the de facto platform for various biomedical applications. But the stable attachment of biomolecules to PDMS for more robust and long-term performance of the PDMS-based devices has been a significant challenge, owing to its unique physical properties (e.g.

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Techniques that manipulate DNA, a biomolecule with electrical properties, are in demand in various medical fields. This study fabricated a nanochannel with a conductive/semi-conductive interface using focused ion beams (FIBs) and introduced a nanochip technology to freely align, attach, and detach lambda DNAs in the interface via electrophoresis. Two-step fabrication process of nanochannels was quantitatively characterized according to the different conditions of the FIB dose (1~30 nC/μm) and current (1~500 pA).

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In situ near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and density functional theory calculations were conducted to demonstrate the decomposition mechanism of propylene glycol methyl ether acetate (PGMEA) on a MnO-CuO catalyst. The catalytic activity of MnO-CuO was higher than that of MnO at low temperatures, although the pore properties of MnO were similar to those of MnO-CuO. In addition, whereas the chemical state of MnO remained constant following PGMEA dosing at 150 °C, MnO-CuO was reduced under identical conditions, as confirmed by in situ NEXAFS spectroscopy.

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Purpose: To investigate the effects of bevacizumab on endoplasmic reticulum (ER) stress in human retinal pigment epithelial (RPE) cells cultured under hypoxic conditions.

Methods: RPE cells (ARPE-19) were cultured under hypoxic conditions (1% O2) with or without bevacizumab (0.3125 mg/mL) for 24 and 48 h.

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Purpose: To report the presence of hyper-reflective dots in the vitreous cavity using spectral-domain optical coherence tomography (SD-OCT) in patients with acute symptomatic posterior vitreous detachment (PVD) and investigate their association with the presence of retinal tear.

Methods: The medical records of 77 patients with acute symptomatic PVD, who were examined between March 2013 and February 2015, were reviewed. The severity of vitreous hyper-reflective dots (VHDs) was graded using SD-OCT images, and the presence of retinal tear was assessed.

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Background: Dry eye disease (DED) is a multifactorial disease of the tears and ocular surface. No epidemiologic reports have yet been published about the relationship between DED and allergic rhinitis or sensitization to allergens.

Objective: To investigate the association between DED and allergic conditions in the general adult Korean population.

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Background: To investigate the alleviation effect of Vaccinium uliginosum extract (DA9301) on tablet computer-induced asthenopia.

Methods: This was a randomized, placebo-controlled, double-blind and parallel study (Trial registration number: 2013-95). A total 60 volunteers were randomized into DA9301 (n = 30) and control (n = 30) groups.

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