Application of Thio-Ugi Adducts for the Preparation of Benzo[<i>b</i>]thiophene and S‑Heterocycle Library via Copper Catalyzed Intramolecular C–S Bond Formation

Fused heterocycles, such as benzo­[<i>b</i>]­thiophene, thiochroman, benzo­[<i>b</i>]­[1,4]­thiazine, and 1,4-benzothiazepine were generated from thio-Ugi adducts containing a thioamide group through copper-catalyzed intramolecular C–S bond formation under microwave irradiation

Effect of Back-Channel Surface on Reliability of Solution-Processed In_0.51Ga_0.15Zn_0.34O Thin-Film Transistors with Thin Active Layer

We have investigated the degradation mechanism of solution-processed indium–gallium–zinc-oxide (IGZO) thin-film transistors. The threshold voltage shift (ΔVth) followed a linear function under negative gate bias stress (NBS), while it showed a stretched-exponential behavior under positive gate bias stress. The slope of ΔVth for stress time was rarely changed with variations below 0.3 mV/s. The thickness of the fabricated IGZO layer (In0.51Ga0.15Zn0.34O) was approximately 10 nm. The Debye length (LD) was larger than IGZO thickness (tIGZO) due to the fully depleted active layer under NBS. Therefore, the degradation phenomenon under NBS was related to the adsorption at back-channel surface. The back-channel surface could be affected by the gate bias under NBS, and the molecules adsorbed at the IGZO layer were positively charged and induced extra electrons by NBS. We verified that the number of positively charged adsorbates had a proportional relationship with the ΔVth based on the two-dimensional technology computer-aided design (TCAD) simulation. Furthermore, we investigated the degradation phenomenon with the ΔVth equation regarding the adsorbates, and the result confirmed that the adsorption process could cause the linear ΔVth. We experimentally confirmed the effect of back-channel surface by comparing the ΔVth between different atmospheric conditions and LD. Consequently, the reaction at the back-channel surface should be considered to develop the metal-oxide semiconductor devices

Mechanism of Label-Free DNA Detection Using the Floating Electrode on Pentacene Thin Film Transistor

The analysis of DNA in the posthuman genome project era has become an ever-expanding branch of research and is thus routinely employed in the majority of biochemical laboratories. This work discusses the mechanism and label-free detection of DNA using a pentacene thin film transistor with a gold floating electrode on the active layer. Thiolated polynucleotide probes were used, which form self-aligned monolayers on the floating electrode over the pentacene active layer. The immobilization of the DNA on floating electrode increased the work function and raised the Schottky barrier of the device, resulting in a charge screening effect. Hence, the negative charge of the DNA caused a positive shift in the threshold voltage of the transistor. Based on the change in the electrical output, synthesized DNA and the viral DNA were detected

Homogeneous Electrochemical Assay for Protein Kinase Activity

Herein, we report a homogeneous assay for protein kinase activity using an electrochemistry-based probe. The approach involves a peptide substrate conjugated with a redox tag and the phosphate-specific receptor immobilized on an electrode surface. The peptide substrate phosphorylated by a protein kinase binds to the receptor site of the probe, which results in a redox current under voltammetric measurement. Our method was successfully applied even in the presence of citrated human blood and modified to enable a single-use, chip-based electrochemical assay for kinase activity