Ultrafluorogenic Monochromophore-Type BODIPY-Tetrazine Series for Dual-Color Bioorthogonal Imaging with a Single Probe.

Various fluorogenic probes utilizing tetrazine (Tz) as a fluorescence quencher and bioorthogonal reaction partner have been extensively studied over the past few decades. Herein, we synthesized a series of boron-dipyrromethene (BODIPY)-Tz probes using monochromophoric design strategy for bioorthogonal cellular imaging. The BODIPY-Tz probes exhibited excellent bicyclo[6.1.0]nonyne (BCN)-selective fluorogenicity with three- to four-digit-fold enhancements in fluorescence over a wide range of emission wavelengths, including the far-red region. Furthermore, we demonstrated the applicability of BODIPY-Tz probes in bioorthogonal fluorescence imaging of cellular organelles without washing steps. We also elucidated the aromatized pyridazine moiety as the origin of BCN-selective fluorogenic behavior. Additionally, we discovered that the fluorescence of the trans-cyclooctene (TCO) adducts was quenched in aqueous media via photoinduced electron transfer (PeT) process. Interestingly, we observed a distinctive recovery of the initially quenched fluorescence of BODIPY-Tz-TCO upon exposure to hydrophobic media, accompanied by a significant bathochromic shift of its emission wavelength relative to that exhibited by the corresponding BODIPY-Tz-BCN. Leveraging this finding, for the first time, we achieved dual-color bioorthogonal cellular imaging with a single BODIPY-Tz probe.

Hierarchical Transformer for Motor Imagery-Based Brain Computer Interface.

In this paper, we propose a novel transformer-based classification algorithm for the brain computer interface (BCI) using a motor imagery (MI) electroencephalogram (EEG) signal. To design the MI classification algorithm, we apply an up-to-date deep learning model, the transformer, that has revolutionized the natural language processing (NLP) and successfully widened its application to many other domains such as the computer vision. Within a long MI trial spanning a few seconds, the classification algorithm should give more attention to the time periods during which the intended motor task is imagined by the subject without any artifact. To achieve this goal, we propose a hierarchical transformer architecture that consists of a high-level transformer (HLT) and a low-level transformer (LLT). We break down a long MI trial into a number of short-term intervals. The LLT extracts a feature from each short-term interval, and the HLT pays more attention to the features from more relevant short-term intervals by using the self-attention mechanism of the transformer. We have done extensive tests of the proposed scheme on four open MI datasets, and shown that the proposed hierarchical transformer excels in both the subject-dependent and subject-independent tests.

Synthesis and characterization of regioregular alkyl-substituted poly(3,4-ethylenedioxythiophenes).

In order to increase the solubility of PEDOT, we introduced an alkyl chain into polymer backbone. Depending on the position of the alkyl bond, the steric hindrance between the alkyl chains can also leads to regioregularity in the polymer. The regioregular polymers can easily occur self-assembly, both in solution and in the solid state, resulting in highly ordered two- and three-dimensional polymer architectures. A series of soluble regioregular alkyl-substituted PEDOTs were synthesized using the Grignard Metathesis (GRIM) for the purpose of study on regiorandom and regioregular PEDOT. The ethylene proton adjacent to the oxygen atom of regioregular methoxydodecyl-PEDOT appears at 3.51 ppm, whereas the corresponding peak of regiorandom methoxydodecyl-PEDOT appears at 3.42 ppm.

Synthesis, characterization, and electrical properties of regioregular alkyl-substituted PEDOTt.

The regioregular hexyl-substituted poly(3,4-ethylenedioxy-2-thiophenylthiophene) (PEDOTt), structurally alternating copolymer of EDOT and thiophene, was synthesized via the Grignard Metathesis (GRIM) using catalytic amounts of Ni(dppp)Cl2. The products were characterized by 1H NMR spectroscopy, UV-vis spectroscopy and XRD. The alkyl-substituted conjugated polymer showed an enhancement of solubility in common organic solvents. Based on XRD data, the regioregular hexyl-substituted poly(3,4-ethylenedioxy-2-thiophenylthiophene) (PEDOTt) shows better crystallinity than the regiorandom hexyl-substituted PEDOTt owing to self-ordering. In addition, regioregular hexyl-PEDOTt has a conductivity of 0.788 S/cm by iodine doping.

Oriented immobilization of antibodies by a self-assembled monolayer of 2-(biotinamido)ethanethiol for immunoarray preparation.

Orientation of antibodies is very important in the preparation of immunoarrays to keep the activity of antibodies on solid surfaces. Thus, we synthesized a new bifunctional compound, 2-(biotinamido)ethanethiol, and investigated whether the thiol compound is useful to analyze antibody-antigen interactions on immunoarrays with a spectral SPR biosensor. The synthesized organic thiol was characterized by nuclear magnetic resonance spectroscopy and mass spectrometry. 2-(Biotinamido)ethanethiol formed a monolayer on a gold surface and properly immobilized antibodies via streptavidin and biotinylated protein G. Optimal molar ratio of 2-(biotinamido)ethanethiol and mercaptohexanol for antigen-antibody interactions was 1:2. Thus, 2-(biotinamido)ethanethiol is an useful bifunctional linker in the preparation of immunoarrays on gold surfaces.