Carbon cloth supporting spinel CuMn0.5Co2O4 nanoneedles with the regulated electronic structure by multiple metal elements as catalysts for efficient oxygen evolution reaction.

Developing transition metal oxide catalysts to replace the noble metal oxide catalysts for efficient oxygen evolution reaction (OER) is essential to promote the practical application of water splitting. Herein, we designed and constructed the carbon cloth (CC) supporting spinel CuMn0.5Co2O4 nanoneedles with regulated electronic structure by multiple metal elements with variable chemical valences in the spinel CuMn0.5Co2O4. The carbon cloth not only provided good conductivity for the catalytic reaction but also supported the well-standing spinel CuMn0.5Co2O4 nanoneedles arrays with a large special surface area. Meanwhile, the well-standing nanoneedles arrays and mesoporous structure of CuMn0.5Co2O4 nanoneedles enhanced their wettability and facilitated access for electrolyte to electrochemical catalysis. Besides, the regulated electronic structure and generated oxygen vacancies of CuMn0.5Co2O4/CC by multiple metal elements improved the intrinsic catalytic activity and the durability of OER activity. Profiting from these merits, the CuMn0.5Co2O4/CC electrode exhibited superior OER activity with an ultralow overpotential of 189 mV at the current density of 10 mA⋅cm-2 and a smaller Tafel slope of 64.1 mV⋅dec-1, which was competitive with the noble metal oxides electrode. And the CuMn0.5Co2O4/CC electrode also exhibited long-term durability for OER with 95.3% of current retention after 1000 cycles. Therefore, the competitive OER activity and excellent cycling durability suggested that the CuMn0.5Co2O4/CC electrode is a potential candidate catalyst for efficient OER.

Multifunctional effects of hollow flower-like CoTiO3 microspheres wrapped by reduced graphene as sulfur host in Li-S battery.

The poor conductivity of sulfur, the shuttle effect and sluggish redox reaction kinetics of lithium polysulfides (LiPSs) are considered the main obstacles to the practical application of Lithium-sulfur (Li-S) batteries. Thus, it is urgent to design multifunctional host materials to eliminate these obstacles. Herein, we designed a hollow flower-like CoTiO3 wrapped by reduced graphene oxide (h-CoTiO3@rGO) as sulfur host materials. The hollow structure of h-CoTiO3@rGO not only endows sufficient space for high sulfur loading, but also physically and chemically confines the shuttle effect of LiPSs through the formation of Co-S chemical bonding. The large specific surface area and excellent electrocatalytic ability of h-CoTiO3@rGO provide amounts of active sites to accelerate the redox reaction of LiPSs. Meanwhile, the conductive reduced graphene oxide (rGO) covered on the surface of CoTiO3 microspheres offers an interconnected conductive network to support the fast electron/ion transfer. Profit from these merits, the battery employing the multifunctional h-CoTiO3@rGO as sulfur host exhibited excellent cycling stability with an ultralow capacity fading of 0.0127 % per cycle after 500 cycles at 1C. Even the battery with high sulfur loading of 5.2 mg/cm2 still delivered a high area capacity of 5.02 mAh/cm2, which was competitive with the commercial Li-ion batteries. Therefore, the competitive capacity and superior cycling stability suggest that the h-CoTiO3@rGO/S cathode is a potential candidate for high-performance Li-S batteries.

Au/Ag composite-based SERS nanoprobe of Cr3.

Quantitative characterization of Cr3+, an important element revealing human metabolism and biological environmental variation, is still difficult to achieve by conventional biochemical methods due to the lack of high-sensitivity, real-time techniques with rapid response detection. Using surface-enhanced Raman scattering (SERS), we construct an Au/Ag composite-based SERS nanoprobe for the quantitative characterization of Cr3+ content in solution, in which DL-mercaptosuccinic acid (DL-MSA) is employed for Raman signal enhancement, and 4-mercaptobenzoic acid (4-MBA) is chosen as the Raman reporter. The achieved result demonstrates obvious advantages of the synthesized Au/Ag composite-based SERS nanoprobe in sensitivity and response speed. Importantly, this Au/Ag composite-based SERS nanoprobe might provide a new strategy for dynamic monitoring of Cr3+ content in human metabolism.

Dynamic monitoring and quantitative characterization of intracellular H2O2 content by using SERS based boric acid nanoprobe.

Quantitative characterization of intracellular H2O2 content, which is still difficult by the conventional biochemical methods due to the lack of real-time and non-invasive technique of single cell measurement, is a useful solution for cell state assessment. Based on the surface enhanced Raman scattering (SERS), we construct a novel boric acid (BA) nanoprobe to perform quantitative characterization of H2O2 content, in which the p-thiol benzene boric acid (4-MPBA) reporter molecule modified with gold nanorods (AuNRs) is employed for Raman signal enhancement. The achieved result demonstrates obvious advantages of the synthesized AuNRs/4-MPBA/BA nanoprobe in measurement sensitivity of H2O2 content. Importantly, this AuNRs/4-MPBA/BA nanoprobe will provide a powerful tool for dynamic monitoring and quantitative characterization of intracellular H2O2 content during cell apoptosis or other cell growth processes, and then achieve important reference data for studying the corresponding molecular mechanism.

Ultrafast Response and High Selectivity toward Acetone Vapor Using Hierarchical Structured TiO2 Nanosheets.

For the development of high-performance gas sensors, ultrafast response and high selectivity are critical requirements for many practical applications. An alternative strategy is to employ hierarchical nanostructured materials in gas sensors. In this work, we report newly synthesized TiO2 hexagonal nanosheets with a hierarchical porous structure, which demonstrate an ultrafast gas response and high selectivity toward acetone vapor for the first time. A simple one-step annealing process to prepare hierarchical TiO2 nanosheets derived from layered TiSe2 nanosheet templates is reported. The hierarchical structure interlaced with anatase TiO2 nanosheets showed an open porous characteristic. The average pore size was about 20 nm examined using a high-resolution TEM. The gas sensing properties toward acetone vapor of the novel hierarchical structured TiO2 nanosheets were characterized in detail including optimal operation temperature, sensitivity, selectivity, response/recovery time, and long-term stability. The gas sensing response and recovery times were 0.75 s and 0.5 s, respectively. We attribute these superior response properties to its unique hierarchical pore structure with a high specific surface area. The results show great potential for acetone vapor detection, particularly in dynamic ultrafast monitoring by using the synthesized hierarchical structured TiO2 nanosheets.

Study on the precise mechanism of Mitoxantrone-induced Jurkat cell apoptosis using surface enhanced Raman scattering.

Mitoxantrone (MTX), one representative of anthraquinone ring anticancer drugs, reveals excellent anticancer effects in acute leukemia. Though current studies have shown that MTX-induced acute leukemia cell apoptosis is implemented by inserting into DNA, and then leading to DNA breakage and the subsequent transcription termination, but the specific location information of MTX embedded in DNA remains unknown. In this study, combining surface enhanced Raman scattering (SERS) and principal component analysis (PCA), we achieve the biochemical changes of MTX-induced Jurkat cell apoptosis and the location information of MTX embedded in DNA. In contrast, we also present the corresponding result of Daunorubicin (DNR)-induced Jurkat cell apoptosis. It is found that the location of MTX embedded in DNA of Jurkat cell is different from DNR, in which the action site of MTX is mainly implemented by blocking and destroying AT base pairs while DNR is performed by embedding and destroying GC base pairs and then the base A. Clearly, this achieved information is very useful for the designing and modification of anthraquinone ring anticancer drugs.

Raman spectrum spectral imaging revealing the molecular mechanism of Berberine-induced Jurkat cell apoptosis and the receptor-mediated Berberine delivery system.

Berberine (BBR), a traditional Chinese herb extract medicine, reveals some anticancer effects in leukemia, but it remains controversial about the molecular mechanism of BBR-induced leukemia cell apoptosis. In this study, combining Raman spectrum and spectral imaging, both the biochemical changes of BBR-induced Jurkat cell apoptosis and the precise distribution of BBR in single cell are presented. In contrast, we also show the corresponding results of Jatrorrhizine (JTZ) and Palmatine (PMT), two structural analogues of BBR. It is found that all three structural analogues can induce cell apoptosis by breaking DNA and the main action sites are located in phosphate backbone and base pair groups, but their action on cell cycle are different, in which BBR leads to the S phase arrest while JTZ and PMT are on the G2 phase arrest. Moreover, from the Raman spectra of DNA treated with different drugs, we find that the content of phosphate backbone and base pair groups in BBR-treated DNA are larger than those in JTZ or PMT. And this result reflects the strong capability of BBR breaking DNA backbone relative to JTZ or PMT, suggesting that the existence of methylene-dioxy on the 2, 3 units of A ring on the quinoline ring can greatly enhance the capability of BBR breaking DNA backbone, so the action effect of BBR-induced Jurkat cell apoptosis is better than those of PMT or JTZ. Further, by using Raman spectral imaging approach, we achieve the precise distribution of BBR in single cell, it is found that the receptor-mediated BBR targeting delivery based single-wall carbon nanotube and folic acid (SWNT/FA) reveals excellent performance in BBR targeting delivery relative to the conventional BBR diffusion approach. Importantly, these results demonstrate that Raman spectrum and spectral imaging should be a powerful tool to study the molecular mechanism of drug-induced cell apoptosis and evaluate the efficiency of drug delivery system.

Synthesis and coloration of highly dispersive SiO2/BiVO4 hybrid pigments with low cost and high NIR reflectance.

Highly dispersed SiO2/BiVO4 hybrid pigments with a spherical structure and high near-infrared (NIR) reflectance have been successfully fabricated by a facile sol-gel method followed by calcination. The dispersed and uniformly spherical particles of the hybrid pigments were caused by the support provided by SiO2 microspheres, and their color was adjusted via the band-gap energy, which was changed with the incorporation of SiO2 microspheres. The SiO2/BiVO4-3 hybrid pigment presented higher yellow hues (b* = 91.42) and more dispersed spherical particles than other as-prepared hybrid pigments and commercially available BiVO4-based yellow pigment. This strategy could save 72 wt% resource of BiVO4 while yielding the same amount of yellow pigment with high color performance. Therefore, the prepared hybrid pigments not only dramatically decreased the cost of expensive pigments, but also saved scarce resources and reduced environmental pollution. In addition, the SiO2/BiVO4-3 hybrid pigment also presented high NIR reflective performance, which demonstrated that it would be a favorable candidate for colorful NIR reflective pigments with wide applications in heat insulation.