Jungkyun Oh

Peripheral T‐cell lymphoma involving subcutaneous tissue

The peripheral T‐cell lymphomas, presumably derived from various immunocompetent peripheral T‐cell system components, form a heterogeneous group of non‐Hodgkins lymphomas. We describe two patients with peripheral T‐cell lymphoma primarily involving subcutaneous tissue. They presented with multiple subcutaneous nodules. Skin biopsy specimens in both patients demonstrated a lobular subcutaneous infiltrate. The infiltrate consisted of small and medium‐sized atypical lymphoid cells. Both patients had a protracted clinical course before they were diagnosed as having malignant lymphoma. We detected latent Epstein‐Barr virus infection in the skin lesions of case 2. Latent Epstein‐Barr virus infection might be related to the development of this variant of peripheral T‐cell lymphoma.

Wireless Hydrogen Smart Sensor Based on Pt/Graphene-Immobilized Radio-Frequency Identification Tag

Hydrogen, a clean-burning fuel, is of key importance to various industrial applications, including fuel cells and the aerospace and automotive industries. However, hydrogen gas is odorless, colorless, and highly flammable; thus, appropriate safety protocol implementation and monitoring are essential. Highly sensitive hydrogen-gas leak detection and surveillance systems are needed; additionally, the ability to monitor large areas (e.g., cities) via wireless networks is becoming increasingly important. In this report, we introduce a radio frequency identification (RFID)-based wireless smart-sensor system, composed of a Pt-decorated reduced graphene oxide (Pt_rGO)-immobilized RFID sensor tag and an RFID-reader antenna-connected network analyzer to detect hydrogen gas. The Pt_rGOs, produced using a simple chemical reduction process, were immobilized on an antenna pattern in the sensor tag through spin coating. The resulting Pt_rGO-based RFID sensor tag exhibited a high sensitivity to hydrogen gas at unprecedentedly low concentrations (1 ppm), with wireless communication between the sensor tag and RFID-reader antenna. The wireless sensor tag demonstrated flexibility and a long lifetime due to the strong immobilization of Pt_rGOs on the substrate and battery-independent operation during hydrogen sensing, respectively.

Highly Sensitive and Selective Field‐Effect‐Transistor NonEnzyme Dopamine Sensors Based on Pt/Conducting Polymer Hybrid Nanoparticles

Dopamine (DA), as one of catecholamine family of neurotransmitters, is crucially important in humans owing to various critical effects on biometric system such as brine circuitry, neuronal plasticity, organization of stress responses, and control of cardiovascular and renal organizations. Abnormal level of dopamine in the central nervous system causes several neurological diseases, e.g., schizophrenia, Parkinsons disease, and attention deficit hybperactivity disorder (ADHD)/attention deficit disorder (ADD). In this report, we suggest the fabrication of nonenzyme field effect transistor (FET) sensor composed of immobilized Pt particle decorated conducting-polymer (3-carboxylate polypyrrole) nanoparticles (Pt_CPPy) to detect dopamine. The hybrid nanoparticles (NPs) are produced by means of facile chemical reduction of pristine CPPyNP-contained Pt precursor (PtCl4 ) solution. The Pt_CPPys are then immobilized on an amine-functionalized (-NH2 ) interdigitated-array electrode substrate, through the formation of covalent bonds with amine groups (-CONH). The resulting Pt_CPPy-based FET sensors exhibit high sensitivity and selectivity toward DA at unprecedentedly low concentrations (100 × 10(-15) m) and among interfering biomolecules, respectively. Additionally, due to the covalent bonding involved in the immobilization process, a longer lifetime is expected for the FET sensor.

Platinum-decorated carbon nanoparticle/polyaniline hybrid paste for flexible wideband dipole tag-antenna application

Recently, tremendous effort has been devoted to the production of materials for flexible device systems due to the advancement of portable electronic devices. Solution-processed conducting polymers (CPs), as a promising approach, have been extensively studied owing to facile synthesis, high electrical conductivity, and various morphologies with diverse substrates. Here we report the demonstration of platinum decorated carbon nanoparticle embedded polyaniline:camphorsulfonic acid (Pt_C/PANI:CSA) hybrid paste for flexible electronic devices. First, platinum decorated carbon nanoparticles (Pt_C) were fabricated by chemical reduction of platinum cations following the carbonization step. The as-prepared Pt_C were added to the aniline monomer solution and then polymerization of aniline occurred to form the hybrid PANI:CSA based paste (Pt_C/PANI:CSA). The Pt_C/PANI:CSA was printed as a micro-pattern and exhibited a high electrical conductivity (792 S cm−1) with flexible stability. Furthermore, it was applied to dipole tag-antenna application which displayed a wide bandwidth (0.55 GHz) and a high transmitted power efficiency (99.6%).

Fabrication of a one-dimensional tube-in-tube polypyrrole/tin oxide structure for highly sensitive DMMP sensor applications

Detection of toxic gases is of great importance for protection against chemical weapons. In particular, organophosphates, such as sarin, damage nerve function and are fatal inhibitors of acetylcholinesterase. Therefore, simple and enhanced technologies for the detection of organophosphates are needed. Herein, we report the fabrication of a chemiresistive gas sensor based on a polypyrrole (PPy)-coated SnO2 tube-in-tube structure that was highly sensitive (0.05 ppb) and selective toward dimethyl methylphosphonate (DMMP), which is a simulant of organophosphates. The complex tube-in-tube structure was fabricated using a single-nozzle electrospinning method with two mixed solvents. Vapor deposition polymerization (VDP) was used to form a thin PPy layer on the surface of the SnO2 tube-in-tube structure without any aggregation. Our new synthetic methodology promises to be an effective approach for fabricating organic/inorganic complex tubular structures for future sensing technologies.

Fabrication of sinter-free conductive Cu paste using sub-10 nm copper nanoparticles

We herein describe the fabrication of sinter-free copper nanoparticle-based conductive paste (Cu NP paste). The copper nanoparticles with a size below 10 nm enable the formation of integrated structures even without heat treatment. Poly(vinylimidazole-co-vinyltrimethoxysilane) used in the synthesis grants the copper surface a high anti-oxidant ability over a temperature range of up to 300 °C under ambient conditions. Furthermore, the viscosity of the conductive paste could be arbitrarily adjusted while minimizing the change of resistivity. The pattern printed using Cu NP paste demonstrated an electrical resistivity of 1.2 × 10−2 Ω cm for un-sintered conductive paste. We confirmed the potential of the Cu NP paste through dipole tag antenna application.

Ultrasensitive and Selective Organic FET-type Non-enzymatic Dopamine Sensor Based on Platinum Nanoparticles Decorated Reduced Graphene Oxide

Dopamine (DA), a catecholamine hormone, is an important neurotransmitter that controls renal and cardiovascular organizations and regulates physiological activities. Abnormal concentrations of DA cause unfavorable neuronal illnesses such as Parkinsons disease, schizophrenia, and attention deficit hyperactivity disorder/attention deficit disorder. However, the DA concentration is exceedingly low in patients and difficult to detect with existing biosensors. In this study, we developed an organic field-effect-transistor-type (OFET) nonenzyme biosensor using platinum nanoparticle-decorated reduced graphene oxide (Pt_rGO) for ultrasensitive and selective DA detection. The Pt_rGOs were fabricated by reducing GO aqueous solution-containing Pt precursors (PtCl4) with a chemical reducing agent. The Pt_rGOs were immobilized on a graphene substrate by π-π interactions and a conducting-polymer source-drain electrode was patterned on the substrate to form the DA sensor. The resulting OFET sensor showed a high sensitivity to remarkably low DA concentrations (100 × 10-18 M) and selectivity among interfering molecules. Good stability was expected for the OFET sensor because it was fabricated without an enzymatic receptor, and π-π conjugation is a part of the immobilization process. Furthermore, the OFET sensors are flexible and offer the possibility of wide application as wearable and portable sensors.

Efficient and moisture-resistant hole transport layer for inverted perovskite solar cells using solution-processed polyaniline

Inverted-structure perovskite solar cells (PSCs), with low-temperature processed poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) and perovskite-passivating phenyl–C61–butyric acid methyl ester (PCBM) employed as charge transport layers, have great potential as efficient, flexible, and hysteresis-free solar cells. However, PEDOT:PSS processed from an aqueous solution has a hygroscopic nature, and can degrade the ambient stability of moisture-vulnerable perovskite electronics. Furthermore, excess insulating PSS in the PEDOT:PSS complex can deteriorate the hole extraction and photovoltaic performance of the solar cell. In this work, polyaniline doped with camphorsulfonic acid (PANI-CSA) is introduced as a hole transport layer (HTL) to promote hole extraction ability and improve the efficiency and stability of inverted PSCs. The device fabricated with PANI-CSA exhibited superior photovoltaic performance, with a maximum efficiency of 15.42%, compared to 14.11% efficiency for the device fabricated with PEDOT:PSS. Most notably, the stability of the device fabricated with PANI-CSA was greatly improved due to a stable HTL/perovskite interface against exposure to ambient moisture.

Multidimensional Conductive Nanofilm-Based Flexible Aptasensor for Ultrasensitive and Selective HBsAg Detection

Hepatitis B virus (HBV) infection is a major worldwide health issue causing serious liver diseases, including liver cirrhosis and hepatocellular carcinoma. Monitoring the serum hepatitis B surface antigen (HBsAg) level is pivotal to the diagnosis of HBV infection. In this study, we describe multidimensional conductive nanofilm (MCNF)-based field-effect transistor (FET) aptasensor for HBsAg detection. The MCNF, composed of vertically oriented carboxylic polypyrrole nanowires (CPPyNW) and graphene layer, is formed using electropolymerization of pyrrole on the graphene surface and following acid treatment. The amine-functionalized HBsAg-binding aptamers are then immobilized on the CPPyNW surface through covalent bonding formation (i.e., amide group). The prepared aptasensor presents highly sensitive to HBsAg as low as 10 aM among interfering biomolecules with various deformations. Moreover, the MCNF-based aptasensor has great potential for practical application in the noninvasive real-time diagnosis because of its improved sensing ability to the human serum and artificial saliva.