Discrimination of Redox-Responsible Biomolecules by a Single Molecular Sensor

A new application of a fluorescent sensor (PyDPA) for the discrimination of redox-responsible molecules is reported. Nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate (NAD⁺/NADP⁺) and flavin mononucleotide/flavin adenine dinucleotide (FMN/FAD) were differentiated by means of ratiometric fluorescence change from excimer–monomer equilibrium and time-dependent fluorescence change, respectively

MOESM1 of Detection of bacterial sulfatase activity through liquid- and solid-phase colony-based assays

Additional file 1. Supplementary information

Enhancement of Thermoelectric Performance of Single-Walled Carbon Nanotubes/Small Organic Molecule Hybrids by Fine-Tuning of the Alkyl Chain Length

We investigated the alkyl chain length effect of small organic molecules (SOMs) on the thermoelectric (TE) efficiency and transport properties of single-walled carbon nanotubes (SWCNTs)/SOM hybrids. The SWCNTs/DBOBI with an octyl tethering chain exhibited the greatest Seebeck coefficient (91.6 ± 5.3 μV/K) and power factor (182.6 ± 15.1 μW/mK2), revealing semiconducting-dominant carrier transport. The FeCl3-doped SWCNTs/DBOBI exhibited a significantly enhanced power factor of 236.2 ± 12.3 μW/mK2 and a ZT of 0.021 at room temperature. Our study provides clear guidelines for enhancing the TE efficiency of SWCNT-based hybrid materials by systematically varying the alkyl chain length of SOMs

Phosphorescent Sensor for Phosphorylated Peptides Based on an Iridium Complex

A bis­[(4,6-difluorophenyl)­pyridinato-<i>N</i>,<i>C</i>^2′]­iridium­(III) picolinate (FIrpic) derivative coupled with bis­(Zn²⁺–dipicolylamine) (ZnDPA) was developed as a sensor (<b>1</b>) for phosphorylated peptides, which are related to many cellular mechanisms. As a control, a fluorescent sensor (<b>2</b>) based on anthracene coupled to ZnDPA was also prepared. When the total negative charge on the phosphorylated peptides was changed to −2, −4, and −6, the emission intensity of sensor <b>1</b> gradually increased by factors of up to 7, 11, and 16, respectively. In contrast, there was little change in the emission intensity of sensor <b>1</b> upon the addition of a neutral phosphorylated peptide, non-phosphorylated peptides, or various anions such as CO₃^2–, NO₃^–, SO₄^2–, phosphate, azide, and pyrophosphate. Furthermore, sensor <b>1</b> could be used to visually discriminate between phosphorylated peptides and adenosine triphosphate in aqueous solution under a UV–vis lamp, unlike fluorescent sensor <b>2</b>. This enhanced luminance of phosphorescent sensor <b>1</b> upon binding to a phosphorylated peptide is attributed to a reduction in the repulsion between the Zn²⁺ ions due to the phenoxy anion, its strong metal-to-ligand charge transfer character, and a reduction in self-quenching

Focused Fluorescent Probe Library for Metal Cations and Biological Anions

A focused fluorescent probe library for metal cations was developed by combining metal chelators and picolinium/quinolinium moieties as combinatorial blocks connected through a styryl group. Furthermore, metal complexes derived from metal chelators having high binding affinities for metal cations were used to construct a focused probe library for phosphorylated biomolecules. More than 250 fluorescent probes were screened for identifying an ultraselective probe for dTTP

Correction to Focused Fluorescent Probe Library for Metal Cations and Biological Anions

Correction to Focused Fluorescent Probe Library for Metal Cations and Biological Anion

Correlations of Optical Absorption, Charge Trapping, and Surface Roughness of TiO₂ Photoanode Layer Loaded with Neat Ag-NPs for Efficient Perovskite Solar Cells

We systematically investigated the effect of silver nanoparticles (Ag-NPs) on the power conversion efficiency (PCE) of perovskite solar cells (PSCs). Neat, spherical Ag-NPs at loading levels of 0.0, 0.5, 1.0, and 2.0 wt % were embedded into the titanium dioxide (TiO₂) photoanode layer. The plasmonic effect of the Ag-NPs strongly enhanced the incident light absorption over a wide range of the visible wavelength region in addition to the inherent absorbance of the perovskite sensitizer. The low conduction energy level of the Ag-NPs compared to that of TiO₂ provides trap sites for free charge carriers. Thus, the correlation between the enhancement of the optical absorption and the number of charge traps provided by the Ag-NPs is critical to determine the device performance, especially current density (<i>J</i>_sc) and PCE. This is confirmed by the quantitative comparison of the incident light absorption and the time-resolved photoluminescence decay according to the loading levels of the Ag-NPs in the TiO₂ layer. The absorption enhancement from 380 to 750 nm in the UV–visible spectrum is proportional to the increase in the loading levels of the Ag-NPs. However, the <i>J</i>_sc increases with the device with 0.5 wt % Ag-NPs and gradually decreases with increases in the loading level above 0.5 wt % because of the different contributions to the absorbance and the charge trapping by different Ag-NP loading levels. In addition, the suppression of the surface roughness with dense packing by the Ag-NPs helps to improve the <i>J</i>_sc and the following PCE. Consequently, the PCE of the PSC with 0.5 wt % Ag-NPs is increased to 11.96%. These results are attributed to the balance between increased absorbance by the localized surface plasmon resonance and the decreased charge trapping as well as the decreased surface roughness of the TiO₂ layer with the Ag-NPs

Efficient Fluorescence “Turn-On” Sensing of Dissolved Oxygen by Electrochemical Switching

We report on a novel method for sensing oxygen that is based on the use of a perylene diimide dye (<b>1</b>) which is electrochemically reduced to its nonfluorescent dianion form (<b>1</b>^2–). In the presence of oxygen, the dianion is oxidized to its initial form via an electron-transfer reaction with oxygen upon which fluorescence is recovered. As a result, the fluorescence intensity of the dianion solution increases upon the addition of oxygen gas. Results demonstrate that high sensitivity is obtained, and the emission intensity shows a linear correlation with oxygen content (0.0–4.0% v/v) at ambient barometric pressure. In addition, using electrochemical reduction, oxygen determination becomes regenerative, and no significant degradation is observed over several turnovers. The limit of detection is 0.4% oxygen in argon gas

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

Wearable Electrocardiogram Monitor Using Carbon Nanotube Electronics and Color-Tunable Organic Light-Emitting Diodes

With the rapid advances in wearable electronics, the research on carbon-based and/or organic materials and devices has become increasingly important, owing to their advantages in terms of cost, weight, and mechanical deformability. Here, we report an effective material and device design for an integrative wearable cardiac monitor based on carbon nanotube (CNT) electronics and voltage-dependent color-tunable organic light-emitting diodes (CTOLEDs). A p-MOS inverter based on four CNT transistors allows high amplification and thereby successful acquisition of the electrocardiogram (ECG) signals. In the CTOLEDs, an ultrathin exciton block layer of bis­[2-(diphenylphosphino)­phenyl]­ether oxide is used to manipulate the balance of charges between two adjacent emission layers, bis­[2-(4,6-difluorophenyl)­pyridinato-<i>C</i>²,<i>N</i>]­(picolinato)­iridium­(III) and bis­(2-phenylquinolyl-<i>N</i>,<i>C</i>(2′))­iridium­(acetylacetonate), which thereby produces different colors with respect to applied voltages. The ultrathin nature of the fabricated devices supports extreme wearability and conformal integration of the sensor on human skin. The wearable CTOLEDs integrated with CNT electronics are used to display human ECG changes in real-time using tunable colors. These materials and device strategies provide opportunities for next generation wearable health indicators