Simultaneous Detection of Single Attoliter Droplet Collisions by Electrochemical and Electrogenerated Chemiluminescent Responses

We provide evidence of single attoliter oil droplet collisions at the surface of an ultra‐microelectrode (UME) by the observation of simultaneous electrochemical current transients (i–t curves) and electrogenerated chemiluminescent (ECL) transients in an oil/water emulsion. An emulsion system based on droplets of toluene and tri‐n‐propylamine (2:1 v/v) emulsified with an ionic liquid and suspended in an aqueous continuous phase was formed by ultrasonification. When an ECL luminophore, such as rubrene, is added to the emulsion droplet, stochastic events can be tracked by observing both the current blips from oxidation at the electrode surface and the ECL blips from the follow‐up ECL reaction, which produces light. This report provides a means of studying fundamental aspects of electrochemistry using the attoliter oil droplet and offers complementary analytical techniques for analyzing discrete collision events, size distribution of emulsion systems, and individual droplet electroactivity.     

Surface-Plasmonic-Field-Induced Photoredox Catalysis and Mediated Electron Transfer for Washing-Free DNA Detection

Distance-dependent electromagnetic radiation and electron transfer have been commonly employed in washing-free fluorescence and electrochemical bioassays, respectively. In this study, we combined the two distance-dependent phenomena for sensitive washing-free DNA detection. A distance-dependent surface plasmonic field induces rapid photoredox catalysis of surface-bound catalytic labels, and distance-dependent mediated electron transfer allows for rapid electron transfer from the surface-bound labels to the electrode. An optimal system consists of a chemically reversible acceptor (Ru(NH₃)₆³⁺), a chemically reversible photoredox catalyst (eosin Y), and a chemically irreversible donor (triethanolamine). Side reactions with O₂ do not significantly decrease the efficiency of photoredox catalysis. Energy transfer quenching between the electrode and the label can be lowered by increasing the distance between them. Washing-free DNA detection had a detection limit of approximately 0.3 nm in buffer and 0.4 nm in serum without a washing step.     

Whole-Cell Photoenzymatic Cascades to Synthesize Long-Chain Aliphatic Amines and Esters from Renewable Fatty Acids

Long-chain aliphatic amines such as (S,Z)-heptadec-9-en-7-amine and 9-aminoheptadecane were synthesized from ricinoleic acid and oleic acid, respectively, by whole-cell cascade reactions using the combination of an alcohol dehydrogenase (ADH) from Micrococcus luteus, an engineered amine transaminase from Vibrio fluvialis (Vf-ATA), and a photoactivated decarboxylase from Chlorella variabilis NC64A (Cv-FAP) in a one-pot process. In addition, long chain aliphatic esters such as 10-(heptanoyloxy)dec-8-ene and octylnonanoate were prepared from ricinoleic acid and oleic acid, respectively, by using the combination of the ADH, a Baeyer–Villiger monooxygenase variant from Pseudomonas putida KT2440, and the Cv-FAP. The target compounds were produced at rates of up to 37 U g⁻¹ dry cells with conversions up to 90 %. Therefore, this study contributes to the preparation of industrially relevant long-chain aliphatic chiral amines and esters from renewable fatty acid resources.     

Nanocatalosomes as Plasmonic Bilayer Shells with Interlayer Catalytic Nanospaces for Solar‐Light‐Induced Reactions

Interest and challenges remain in designing and synthesizing catalysts with nature‐like complexity at few‐nm scale to harness unprecedented functionalities by using sustainable solar light. We introduce “nanocatalosomes”—a bio‐inspired bilayer‐vesicular design of nanoreactor with metallic bilayer shell‐in‐shell structure, having numerous controllable confined cavities within few‐nm interlayer space, customizable with different noble metals. The intershell‐confined plasmonically coupled hot‐nanospaces within the few‐nm cavities play a pivotal role in harnessing catalytic effects for various organic transformations, as demonstrated by “acceptorless dehydrogenation”, “Suzuki–Miyaura cross‐coupling” and “alkynyl annulation” affording clean conversions and turnover frequencies (TOFs) at least one order of magnitude higher than state‐of‐the‐art Au‐nanorod‐based plasmonic catalysts. This work paves the way towards next‐generation nanoreactors for chemical transformations with solar energy.     

Highly Conducting and Flexible Radical Crystals

Together with high conductivity, high flexibility is an important property required for next generation organic electronic components. Both properties are difficult to achieve together especially when the components are crystalline because of the intrinsic high brittleness of organic molecular crystals. We report an organic radical crystal system that has both high flexibility and high conductivity. The crystal consists of 9,10‐bis(phenylethynyl)anthracene radical cation ( BPEA^.+ ) units, and shows flexibility under pressure with high conductivity in ambient condition exhibiting average conductivity of 2.68 S cm^?1 when normal linear shape, as well as 2.43 S cm^?1 when bent. The structural analysis reveals that both a short π–π distance (3.290 Å) between BPEA^.+ units that are aligned along the crystal length direction, and the presence of PF₆^? counter ions induce flexibility and high electrical conductivity.     

Regulation of Cytokines and Dihydrotestosterone Production in Human Hair Follicle Papilla Cells by Supercritical Extraction-Residues Extract of Ulmus davidiana

This study was conducted to examine the anti-hair loss mechanism of the supercritical fluid extraction-residues extract of Ulmus davidiana by the regulation of cytokine production and hormone function in human dermal follicle papilla cells (HDFPCs). To investigate the modulatory effects on H₂O₂-induced cytokines, we measured transforming growth factor-beta and insulin-like growth factor 1 secreted from HDFPCs. To investigate the regulatory effects of supercritical extraction-residues extract of Ulmus davidiana on dihydrotestosterone hormone production, cells were co-incubated with high concentrations of testosterone. The supercritical extraction-residues extract of Ulmus davidiana significantly inhibited the secretion of transforming growth factor-beta but rescued insulin-like growth factor 1 in a dose-dependent manner. The supercritical extraction-residues extract of Ulmus davidiana markedly reduced dihydrotestosterone production. These results suggest that the supercritical fluid extract residues of Ulmus davidiana and their functional molecules are candidates for preventing human hair loss.     

Application of QPLEXTM biomarkers in cognitively normal individuals across a broad age range and diverse regions with cerebral amyloid deposition

The deposition of beta-amyloid (Aβ) in the brain precedes the onset of symptoms such as cognitive impairment in Alzheimer’s disease (AD); therefore, the early detection of Aβ accumulation is crucial. We previously reported the applicability of the QPLEX^TM Alz plus assay kit for the prescreening of Aβ accumulation. Here, we tested the specific application of the kit in a large cohort of cognitively normal (CN) individuals of varying ages for the early detection of Aβ accumulation. We included a total of 221 CN participants with or without brain Aβ. The QPLEX^TM biomarkers were characterized based on age groups (1^st–3^rd tertile) and across various brain regions with cerebral amyloid deposition. The 3^rd tertile group (>65 years) was found to be the most suitable age group for the application of our assay kit. Receiver operating characteristic curve analysis showed that the area under the curve (AUC, discrimination power) was 0.878 with 69.7% sensitivity and 98.4% specificity in the 3^rd tertile group. Additionally, specific correlations between biomarkers and cerebral amyloid deposition in four different brain regions revealed an overall correlation with general amyloid deposition, consistent with previous findings. Furthermore, the combinational panel with plasma Aβ1–42 levels maximized the discrimination efficiency and achieved an AUC of 0.921 with 95.7% sensitivity and 67.3% specificity. Thus, we suggest that the QPLEX^TM Alz plus assay is useful for prescreening brain Aβ levels in CN individuals, especially those aged >65 years, to prevent disease progression via the early detection of disease initiation.Subject terms: Alzheimer''s disease, Neural ageing, ELISA     

Stimuli sensitive polymers for drug delivery systems

Temperature sensitive and electric field sensitive hydrogels were prepared for use in modulated drug release systems. Crosslinked poly(N-isopropyl-acrylamide) and its networks, modified with hydrophobic components by copolymerization or by interpenetrating polymer networks (IPNs) formation, were utilized as temperature sensitive hydrogels. Indomethacin (a model solute)-release from polymer matrix and permeation through polymer membrane demonstrated “on-off” regulation with temperature fluctuation. This was the result of polymer surface properties rather than bulk swelling, as temperature was changed past the swelling transition temperature range of the polymer. The on-off regulation in an electric field was also obtained with a positively charged solute (Edrophonium chloride) release in distilled-deionized water from a matrix of crosslinked poly(2-acrylamido-2-methylpropanesulfonic acid-co-butyl methacrylate). This was attributed to the ion exchange between Edrophonium ion and protons produced at the anode. The swelling changes produced by local pH or ionic strength changes affected non-charged solute release.