Histological and molecular analyses revealing excessive nitrite affected zebrafish heart valve development directly.

<p>Nitrite-exposed embryos were treated with 100 mg/l sodium nitrite from 10 hpf. (A–F) Histological sections showing defective valve development caused by nitrite exposure occurred from 48 hpf. At 36 hpf, the embryos exposed to nitrite exhibited similar histological heart structure (B) to that of control zebrafish, comprising one layer of myocardium and one layer of endocardium (A). At 48 hpf, endocardial cells of control embryos exhibited cuboidal shape in AVC between two chambers (C) but the exposed embryos did not have cuboidal endocardial cells in AVC (D). At 76 hpf, invagination of endocardial cells into cardiac jelly in AVC in control embryos formed superior primitive valve leaflet consisting of multilayer of cells (E); however, no superior primitive valve leaflet (no multilayer cells in the superior part of AVC) was formed in nitrite-exposed embryos (F). (G–N) Cardiac looping in zebrafish embryos shown by the expression of <i>cmlc2</i> revealing abnormal cardiac looping caused by nitrite exposure occurred as early as 43 hpf. The expression pattern of <i>cmlc2</i> was not affected by nitrite exposure at 36 hpf (G–H) and 40 hpf (I–J), but slightly abnormal (shown in white dotted curve) at 43 hpf (K–L) and obviously abnormal (shown in white dotted curve) at 48 hpf (M–N). (O–X) Nitrite exposures altered the expressions of molecular makers of valve progenitors at 48 hpf. <i>nppa</i> was not expressed in the AVC (rectangular box) of control embryos (O) but was ectopically expressed in the AVC of nitrite-exposed embryos (P). Compared to control embryos, nitrite exposure significantly decreased or abolished expressions of <i>bmp4</i> (Q, R), <i>vcana</i> (S, T), <i>notch1b</i> (U, V) and <i>has2</i> (W, X) in AVC. The number shown in the lower right-hand corner was the number of embryos exhibiting the typical phenotype shown in the panel to the number of embryos totally observed. Black arrow: position of cuboidal endocardial cells; Black arrowhead: position of superior primitive leaflet; White arrow: endocardium; White arrowhead: myocardium.</p

A scatter plot showing that sodium nitrite affected zebrafish heart development starting from 36 hpf.

<p>Nitrite-exposed embryos were treated with 100 mg/l sodium nitrite for different time window shown in X-axis. EI (shown in Y-axis) of each embryos was measured and shown in the plot. Average ± standard errors of EIs were shown in lines.</p

Sodium nitrite caused defective development of zebrafish heart in a dose dependent way.

<p>(A–C) Zebrafish embryos exposed to 100 mg/l sodium nitrite from 10 hpf exhibited cardiac edema from slight phenotype (B) to severe phenotype (C) compared to control embryos with normal heart (A) at 108 hpf. (D) A scatter plot showing the edema index (EI) of embryos exposed with different concentration of sodium nitrite. EI is defined as b/a. Average ± standard errors of EIs were shown in lines. (E–G) Histological sections showing 100 mg/l sodium nitrite exposure caused defective structure of zebrafish heart at 108 hpf. Compared to control embryos with normal pericardial membrane, myocardium and both superior and inferior valve leaflets (E), 4/7 embryos exposed to the nitrite showed thinner pericardial membrane and myocardium, and only superior valve leaflet but no formation of inferior valve leaflet (F), whereas 3/7 of the treated embryos displayed thinner pericardial membrane and myocardium and no formation of either superior or inferior leaflets (G). a: the semi-diameter of ventricle; b: the semi-diameter of the pericardial cavity. Red star (*): pericardial membrane; Black star (*): myocardium; Black arrow: position of superior valve leaflet; Black arrowhead: position of inferior valve leaflet; A: atria; V: ventricle.</p

Inhibiting NO signaling in nitrite-exposed embryos partially rescued defective development of cardiac valve in zebrafish embryos.

<p>(A) The cGMP level was dramatically increased in the nitrite-exposed embryos at 24, 36, 48 and 76 hpf, respectively. **: P<0.01. The values of cGMP amount in all the control embryos were normalized to 1.0, respectively. The value of cGMP amount in the nitrite-exposed embryos was the fold of the control embryos at the same developmental stage. (B) A scatter plot showing the increased EIs in the nitrite-exposed embryos were significantly reduced by microinjecting ODQ (sGC inhibitor) into nitrite-exposed embryos. Different treatments of embryos were shown in X-axis. EI (shown in Y-axis) of each embryos was shown in the plot. Average ± standard errors of EIs were shown in lines. (C–E) Defective histological structures of heart caused by excessive nitrite were partially rescued by microinjection of ODQ into nitrite-exposed embryos. Embryos were observed at 108 hpf. Compared to control embryos with normal pericardial membrane, myocardium and both superior and inferior valve leaflets (C), 6/8 embryos exposed to the nitrite showed thinner myocardium and defective formation of either superior or inferior leaflets (D). ODQ microinjection resulted in 3/6 of the embryos developed both superior and inferior leaflets (E). (F–T) Microinjection of ODQ partially rescued the diminished expressions of valve progenitor makers in zebrafish embryos at 48 hpf. <i>nppa</i> is not expressed in the AVC (rectangular box) of control embryos (F) but was ectopically expressed in the AVC of nitrite-exposed embryos (K). Microinjection of ODQ into nitrite-exposed embryos prevented 7 of 15 embryos from expressing <i>nppa</i> in AVC (P). Compared to control embryos, nitrite exposure significantly decreased or abolished expressions of <i>bmp4</i> (G, L), <i>vcana</i> (H, M), <i>notch1b</i> (I, N) and <i>has2</i> (J, O) in AVC. However, microinjection of ODQ into nitrite-exposed embryos resumed expressions of <i>bmp4</i> (Q), <i>vcana</i> (R), <i>notch1b</i> (S) and <i>has2</i> (T) in about half embryos. Red star (*): pericardial membrane; Black arrow: position of superior valve leaflet; Black arrowhead: position of inferior valve leaflet; A: atria; V: ventricle.</p

Azaisoquinolinones: N Positions Tell You Different Stories in Their Optical Properties

Since isoquinolinones and their derivatives have been demonstrated to be powerful building blocks in constructing larger acenes and twistacenes, azaisoquinolinones and their analogues could also be important intermediates to approach larger N-heteroacenes. In this paper, we are interested in developing a concise method to synthesize novel azaisoquinolinones building blocks and studying their physical properties. Our results showed that the different N positions have a large effect on the optical and electrochemical properties of azaisoquinolinones. For example, protonation of 6- and 7-azaisoquinolinones shows different shifts of UV–vis and FL spectra. More interestingly, 6- and 7-azaisoquinolinones exhibited different interactions with metal ions in CH₃CN solution. Upon the addition of 2 equiv of Fe³⁺, 6-azaisoquinolinone displayed an absorption wavelength red-shifted from 470 to 540 nm (Δλ = 70 nm) with a color change from yellow to red, while the interaction between Fe³⁺ and 7-azaisoquinolinone was very weak and there was no obvious color change (Δλ = 18 nm). Moreover, theoretical calculations confirmed the different optical properties with 6- and 7-azaisoquinolinones

Azaisoquinolinones: N Positions Tell You Different Stories in Their Optical Properties

Since isoquinolinones and their derivatives have been demonstrated to be powerful building blocks in constructing larger acenes and twistacenes, azaisoquinolinones and their analogues could also be important intermediates to approach larger N-heteroacenes. In this paper, we are interested in developing a concise method to synthesize novel azaisoquinolinones building blocks and studying their physical properties. Our results showed that the different N positions have a large effect on the optical and electrochemical properties of azaisoquinolinones. For example, protonation of 6- and 7-azaisoquinolinones shows different shifts of UV–vis and FL spectra. More interestingly, 6- and 7-azaisoquinolinones exhibited different interactions with metal ions in CH₃CN solution. Upon the addition of 2 equiv of Fe³⁺, 6-azaisoquinolinone displayed an absorption wavelength red-shifted from 470 to 540 nm (Δλ = 70 nm) with a color change from yellow to red, while the interaction between Fe³⁺ and 7-azaisoquinolinone was very weak and there was no obvious color change (Δλ = 18 nm). Moreover, theoretical calculations confirmed the different optical properties with 6- and 7-azaisoquinolinones

Graphdiyne-Supported NiFe Layered Double Hydroxide Nanosheets as Functional Electrocatalysts for Oxygen Evolution

Graphdiyne (GDY), a novel two-dimensional full-carbon material, has attracted lots of attention because of its high conjugated system comprising sp² and sp-hybridized carbons. The distinctive structure characteristics endow it unique electronic structure, uniform distributed pores and excellent chemical stability. A novel GDY-supported NiFe layered double hydroxide (LDH) composite was successfully prepared for the first time. By taking advantage of the increased surface active areas and improved conductivity, the designed hierarchical GDY@NiFe composite exhibits outstanding catalytic activity that only required a small overpotential about 260 mV to achieve the current density of 10 mA cm^–2. The nanocomposite shows excellent durability in alkaline medium implying a superior OER electrocatalytic activity. It is anticipated that the as-prepared GDY@NiFe composite electrocatalyst provide new insights in designing graphdiyne-supported electrocatalyst materials for oxygen evolution application

Revealing Adsorption Mechanism of <i>p</i>‑Mercaptobenzoic Acid with TiO₂ Surfaces Using Electric Field-Enhanced Semiconductor SERS

p-Mercaptobenzoic acid (4-MBA) is a typical molecular probe for a surface-enhanced Raman scattering (SERS) study of the enhancement performance of semiconductor nanoparticles. Understanding the molecular adsorption mechanism of 4-MBA on a semiconductor surface is crucial to reveal the enhancement mechanism of semiconductor SERS. Herein, two types of submicrometer-sized TiO2 particles with amorphous (denoted as a-TiO2) and anatase structures (denoted as c-TiO2) were fabricated, and their potential as SERS-active substrates with high electric-field enhancement was explored based on the near-field scattering theory and finite-element method simulation. The electric field-enhanced semiconductor SERS provide a better vision for us to study the adsorption modes of molecules on the TiO2 surface. On this basis, adsorption behaviors of 4-MBA on a-TiO2 and c-TiO2 particles were systematically studied by the semiconductor SERS and density functional theory. The results demonstrated that the adsorption mechanism of 4-MBA with TiO2 surfaces is highly dependent on the exposure of acid sites of TiO2 surfaces. 4-MBA adsorbs preferentially on Brønsted acid sites of a-TiO2 through a carboxyl group, in contrast on Lewis acid sites of c-TiO2 through a sulfhydryl group. Furthermore, 4-MBA molecules may form multilayer adsorption on TiO2 surfaces through the hydrogen bond and/or π–π stacking interaction. Research results not only provide a new insight to re-evaluate the chemical enhancement mechanism for TiO2–4-MBA systems but also provide a theoretical guidance for the modification of TiO2 surface with organic molecules containing carboxyl and sulfhydryl groups

A New Class of Conjugated Polymers Having Porphyrin, Poly(<i>p</i>-phenylenevinylene), and Fullerene Units for Efficient Electron Transfer

A series of new polymers containing porphyrin, poly(p-phenylenevinylene) (PPV), and/or a pendant fullerene unit has been synthesized. The cyclic voltammetry showed us a good candidate for a photoinduced electron-transfer system. More important, the photocurrent measurement revealed an interesting phenomenon that the photocurrent increased with the contents of the fullerene in the polymers increased. SEM images displayed the aggregation superstructures of three polymers. Nanobriquetting, nanofiber, and hierarchical porous structure were observed, respectively. The results indicated that the axial coordination of metal porphyrin and Bipy was very important to control the aggregation morphologies of the polymers

Photoisomerization of Spiropyran for Driving a Molecular Shuttle

A novel light-powered molecular shuttle was synthesized which can switch the movement of a macrocycle between two distinct stationsdipeptide and zwitterionic MEby exploiting the photoisomerization of spiropyran. The macrocycle resides selectively in the dipeptide station in the SP form and moves to the ME station under the irradiation of UV light. This movement process of the macrocycle is accompanied by reversible absorptive output signals which can be detected by the naked eye