Imaging Dynamic Collision and Oxidation of Single Silver Nanoparticles at the Electrode/Solution Interface

The electrochemical interface is an ultrathin interfacial region between the electrode surface and the electrolyte solution and is often characterized by numerous dynamic processes, such as solvation and desolvation, heterogeneous electron transfer, molecular adsorption and desorption, diffusion, and surface rearrangement. Many of these processes are driven and modulated by the presence of a large interfacial potential gradient. The study and better understanding of the electrochemical interface is important for designing better electrochemical systems where their applications may include batteries, fuel cells, electrocatalytic water splitting, corrosion protection, and electroplating. This, however, has proved to be a challenging analytical task due to the ultracompact and dynamic evolving nature of the electrochemical interface. Here, we describe the use of an electrochemical nanocell to image the dynamic collision and oxidation process of single silver nanoparticles at the surface of a platinum nanoelectrode. A nanocell is prepared by depositing a platinum nanoparticle at the tip of a quartz nanopipette forming a bipolar nanoelectrode. The compact size of the nanocell confines the motion of the silver nanoparticle in a 1-D space. The highly dynamic process of nanoparticle collision and oxidation is imaged by single-particle fluorescence microscopy. Our results demonstrate that silver nanoparticle collision and oxidation is highly dynamic and likely controlled by a strong electrostatic effect at the electrode/solution interface. We believe that the use of a platinum nanocell and single molecule/nanoparticle fluorescence microscopy can be extended to other systems to yield highly dynamic information about the electrochemical interface

Three-Dimensionally Nanometallic Superstructure Synthesized via a Single-Particle Soft-Enveloping Strategy

Three-dimensionally (3D) integrated metallic nanomaterials composed of two or more different types of nanostructures make up a class of advanced materials due to the multidimensional and synergistic effects between different components. However, designing and synthesizing intricate, well-defined metallic 3D nanomaterials remain great challenges. Here, a novel single-particle soft-enveloping strategy using a core–shell Au NP@mSiO2 particle as a template was proposed to synthesize 3D nanomaterials, namely, a Au nanoparticle@center-radial nanorod-Au-Pt nanoparticle (Au NP@NR-NP-Pt NP) superstructure. Taking advantage of the excellent plasmonic properties of Au NP@NR-NP by the synergistic plasmonic coupling of the outer Au NPs and inner Au nanorods, we can enhance the catalytic performance for 4-nitrophenol hydrogenation using Au NP@NR-NP-Pt NP as a photocatalyst with plasmon-excited hot electrons from Au NP@NR-NP under light irradiation, which is 2.76 times higher than in the dark. This process opens a door for the design of a new generation of 3D metallic nanomaterials for different fields

Three-Dimensionally Nanometallic Superstructure Synthesized via a Single-Particle Soft-Enveloping Strategy

Three-dimensionally (3D) integrated metallic nanomaterials composed of two or more different types of nanostructures make up a class of advanced materials due to the multidimensional and synergistic effects between different components. However, designing and synthesizing intricate, well-defined metallic 3D nanomaterials remain great challenges. Here, a novel single-particle soft-enveloping strategy using a core–shell Au NP@mSiO2 particle as a template was proposed to synthesize 3D nanomaterials, namely, a Au nanoparticle@center-radial nanorod-Au-Pt nanoparticle (Au NP@NR-NP-Pt NP) superstructure. Taking advantage of the excellent plasmonic properties of Au NP@NR-NP by the synergistic plasmonic coupling of the outer Au NPs and inner Au nanorods, we can enhance the catalytic performance for 4-nitrophenol hydrogenation using Au NP@NR-NP-Pt NP as a photocatalyst with plasmon-excited hot electrons from Au NP@NR-NP under light irradiation, which is 2.76 times higher than in the dark. This process opens a door for the design of a new generation of 3D metallic nanomaterials for different fields

Immunohistochemical staining (dark brown coloring) for Bcl-2 protein in lung specimens from chickens incubated under normal and hypoxic conditions.

<p>Bcl-2 protein expression in lung samples from nW, hT, and hW gradually increased moderately from E16 to E18 before the onset of lung functioning (E–H), and disappeared at E19. By E18 in nW lungs, weaker Bcl-2 expression was observed relative to hT (G) and hW (H) chicken groups. In nT chicken sections, Bcl-2 protein staining was nearly unchanged throughout the developmental stages examined (A, E, K). To see details of the E18 lung structure, higher-magnification photomicrographs were taken. Bcl-2 staining was detected in the mesenchyme (arrows) around the ACs and not in the infundibula or atrias of chicken lung (F’, G’, H’)”. In the hW section at E18, Bcl-2 staining was strong (arrow in H’), but weaker in hT and nW at this stage (arrows in G’, F’). Scale bar  =  200 µm.</p

Bipolar Electrochemistry on a Nanopore-Supported Platinum Nanoparticle Electrode

In this Technical Note, we describe a method to fabricate nanopore-supported Pt nanoparticle electrodes and their use in bipolar electrochemistry. A Pt nanoparticle is deposited on the orifice of a solid-state nanopore inside a focused-ion beam (FIB) system. Complete blockage of the nanopore with Pt metal forms a closed bipolar nanoparticle electrode whose size and shape can be tunable in one simple step. Nanoparticle electrodes and their arrays can be prepared on different substrates such as the tip of a glass pipet, a double-barrel pipet, and a freestanding silicon nitride membrane. Steady-state voltammetry can be performed on such nanoparticle electrodes via bipolar electrochemistry. Moreover, an array of Pt nanoparticles can be used for fluorescence-enabled electrochemical microscopy. Future use of highly advanced FIB systems may allow nanoparticles of <10 nm to be fabricated which may enable coupled electrochemical reactions of single redox molecules. Pipette-supported single particle electrodes may also find useful applications in high resolution imaging with nanoscale scanning electrochemical microscopy (SECM) and neurochemical analysis inside single cells

Expression of miRNAs in chicken lung tissues.

<p>(A) Total RNA from tissues from E19 chicken embryos was blotted with probes for miR-15a, miR-144 and U6 (loading control). miR-15a and miR-144 were identified in late-stage embryonic lung tissue. In each sample, the total RNA was mixed with samples from 9 chickens. (B) Quantitative expression analysis of miR-15a showed hypoxia-related expression that was affected by both the species and environmental conditions. The hW chicken group was most sensitive relative to other three groups. In the nW chicken group, there was a response at E19. At E19 of the nW chicken group, the expression of miR-15a remained relatively high in the hT chicken group compared with the nT, nW chicken groups and was largely unchanged in the nT chicken group through the whole embryo stages. Data are expressed as the mean ± SEM for each group. (C) Quantitative expression analysis of miR-15a and miR-16 in the embryonic lung, heart, brain and liver at E16 and E19 tissues and were expressed as the mean ± SEM for each group. Under hypoxia stress, miR-15a was more highly expressed at E19 than at E16 in the brain, heart and lung for the hW group and in the lung and brain for the hT group. miR-16 showed a weak response to stress in the embryonic lung (hW). Result statistically different are indicated with an asterisk/s (* <i>P</i><0.05; ** P<0.01; ns : not significant). E16-20  =  embryonic d13-20, respectively. d1, d2, d3  =  the 1^st day after hatching, the 2^nd day after hatching, the 3^rd day after hatching.</p

Analysis of apoptosis in lung specimens from chickens incubated under normal and hypoxic conditions.

<p>From E16 to E18, no TUNEL staining was identified (A–H). At E19, apoptotic cells were localized in the mesenchyme surrounding the atrias and infundibula of the chicken lungs (L, M, N). There was no obvious staining in nT chicken at E19 (K). At higher magnification, staining was clearly seen in the regions between ACs and not in the parabronchi, atrias, or infundibula (arrows in L’, M’, N’). hW staining at E19 (arrow in N’) was clearly darker than that observed in hT or nW lung sections at this stage (arrows in M’, N’). The tube density in hW at E19 was also higher than that in sections from those other two groups. Scale bar  =  200 µm.</p

<i>bcl-2</i> is a target gene of miR-15a, but not miR-16 in chicken lung.

<p>(A) miR-15a regulates the translation of <i>bcl-2</i> mRNA through a sequence that is not conserved with human sequence. miR-15a and the binding site in the gga-<i>bcl-2</i> 3′-UTR are shown, but miR-16 shows no target site in this part of the sequence. (B) miR-15a/16 have a consistent target site in human <i>bcl-2</i> 3′-UTR. The miR-15a binding site in the <i>bcl-2</i> 3′-UTR sequence mediates translation repression by miR-15a. (C) The luciferase reporter vector contains two luciferase cDNAs, Renilla luciferase (hRluc) and firefly luciferase (hluc). The <i>bcl-2</i> 3′-UTR was fused to the hRluc cDNA downstream sequence. In co-transfected cells, the miR-15a mimic decreased the expression of hRluc and miR-15a mimic inhibitor rescued hRluc activity; no differences were seen for miR-16. Data are expressed as the mean ± SEM. * <i>P</i><0.05, ** <i>P</i><0.01.</p

Myh10 Is Upregulated During Ciliogenesis.

<p>(A) Schematic illustration of selected gene expression analysis during ciliogenesis in time course. (B) Myh10 protein level is upregulated during ciliogenesis. RPE-Mchr1^GFP cells serum starved (0.2% FBS) for 0, 1, 2, 6, 12 and 24 hours were collected for western blot analysis of Myh10 (upper panel) and Myh9 (middle panel) protein level. β-actin was used an internal loading control. (C) Relative protein bands from (B) were quantified using Fiji gel analysis function. Results from three independent experiments were quantified, normalized to β-actin loading control and averaged. *, t-test p<0.01. (D) Myh10 mRNA is upregulated during ciliogenesis. mRNA samples collected at indicated serum starvation time points were used as template for real-time PCR to measure Myh9 (black line) and Myh10 (red line) mRNA expression levels. Error bars represent standard deviations (s.d.) from triple biological replicates.</p

HIF-1α and Bcl-2 expression in lung tissue under hypoxia and normoxia conditions.

<p>Data were obtained from hT, hW, nT, and nW chicken tissues at E16, E18, E19, and E20. (A) Quantitative expression analysis of HIF-1α mRNA in embryonic lung at E16, E18, E19, and E20. The stress reaction in hW was robust as compared with the smooth response in hT. Data are expressed as the mean ± SEM for each group. (B) Quantitative expression analysis of <i>bcl-2</i> mRNA in the embryonic lung, heart, brain and liver at E16 and E19. There were no changes in the expression of <i>bcl-2</i> mRNA between the E16 and E19 in each kind of embryonic tissues. Data are expressed as the mean ± SEM for each group. (C) Analysis of HIF-1α and Bcl-2 expression at the protein level in lung tissue (shown in western blot and densitometry value). HIF-1α protein expression increased from E16 to E19, however in different level in hT, hW, nT, and nW group. Bcl-2 protein did show different levels of expression across different time points and different groups. (* <i>P</i><0.05; ** P<0.01; ns  =  not significant).</p