Publications by authors named "Sunho Joh"

This study investigates the applicability of six transition metal dichalcogenides to efficient therapeutic drug monitoring of ten antiepileptic drugs using laser desorption/ionization-mass spectrometry. We found that molybdenum ditelluride and tungsten ditelluride are suitable for the sensitive quantification of therapeutic drugs. The contribution of tellurium to the enhanced efficiency of laser desorption ionization was validated through theoretical calculations utilizing an integrated model that incorporates transition-metal dichalcogenides and antiepileptic drugs.

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Lipid alterations in the brain are well-documented in disease and aging, but our understanding of their pathogenic implications remains incomplete. Recent technological advances in assessing lipid profiles have enabled us to intricately examine the spatiotemporal variations in lipid compositions within the complex brain characterized by diverse cell types and intricate neural networks. In this study, we coupled time-of-flight secondary ion mass spectrometry (ToF-SIMS) to an amyotrophic lateral sclerosis (ALS) model, for the first time, to elucidate changes in the lipid landscape and investigate their potential role in the disease process, serving as a methodological and analytical complement to our prior approach that utilized matrix-assisted laser desorption/ionization mass spectrometry.

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Article Synopsis
  • * The study introduces a new method using laser desorption ionization mass spectrometry (LDI-MS) combined with tungsten disulfide nanosheets, which improves sensitivity and reproducibility for drug monitoring.
  • * This innovative approach enables high-throughput analysis of blood samples, successfully tested on 80 patient cases, showing promise to replace existing methods and improve drug management for organ transplant patients.
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MicroRNAs (miRNAs) are important post-transcriptional gene regulators and can serve as potential biomarkers for many diseases. Most of the current miRNA detection techniques require purification from biological samples, amplification, labeling, or tagging, which makes quantitative analysis of clinically relevant samples challenging. Here we present a new strategy for the detection of miRNAs with uniformity over a large area based on signal amplification using enzymatic reactions and measurements using time-of-flight secondary ion mass spectrometry (ToF-SIMS), a sensitive surface analysis tool.

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Nanomaterials form a complex called "protein corona" by contacting with protein-containing biological fluids such as serum when they are exposed to physiological environments. The characteristics of these proteins, which are one of the substantial factors in cellular response, are affected by the interactions between the nanomaterials and the biological systems. Many studies have investigated the biological behaviors of nanomaterials by conducting experiments in vitro and in vivo; however, the origin of the biological materials used is rather inconsistent.

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Nanoparticles (NPs) are substances between 1 and 100 nm in size. They have been the subject of numerous studies because of their potential applications in a wide range of fields such as cosmetics, electronics, medicine, and food. For biological applications of nanoparticles, they are usually coated with a substance capable of preventing agglomeration of the nanoparticles and nonspecific binding and exhibiting water-solubility characteristics with specific immobilized (bio)molecules.

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Since Ar-gas cluster ion beams (Ar-GCIBs) have been introduced into time-of-flight secondary ion mass spectrometry (ToF-SIMS), there have been various attempts to analyze organic materials and biomolecules that require low-damage analysis and high sensitivity, because Ar-GCIBs allow soft ionization of large molecules such as peptides and proteins due to the low energy per atom. Here, the authors adopted the Ar-GCIB as a primary beam to detect proteins including human insulin, ubiquitin, and cytochrome C (molecular weights are 5808, 8564, and 12 327 Da, respectively). They have confirmed that the detection of the intact proteins was possible when the Ar-GCIB was used as a primary ion beam.

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Synopsis of recent research by authors named "Sunho Joh"

  • - Sunho Joh's research focuses on the development and optimization of advanced mass spectrometry techniques, particularly laser desorption/ionization (LDI) and time-of-flight secondary ion mass spectrometry (ToF-SIMS), for sensitive detection and monitoring of therapeutic drugs and biomolecules in biological systems.
  • - Recent findings include the successful identification of transition metal dichalcogenides, such as molybdenum ditelluride and tungsten ditelluride, as effective materials for enhancing drug quantification, as well as insights into lipid alterations in amyotrophic lateral sclerosis models, contributing to a better understanding of disease mechanisms.
  • - Additionally, Joh has investigated the formation of protein coronas around nanomaterials, the quantitative analysis of immunosuppressive drugs through innovative methodologies, and strategies for the detection of microRNAs, demonstrating the versatility and applicability of mass spectrometry in various biochemical and medical fields.