Latest ArticlesRecently, photodynamic therapy (PDT) has been extensively applied in clinical and coadjuvant treatment of various kinds of tumors. However, the photosensitizer (PS) of PDT still lack of high production of singlet oxygen (1O2), low cytotoxicity and high biocompatibility. Herein, we propose a facile method for establishing a new core-shell structured Sn nanocluster@carbon dots (CDs) PS. Firstly, Sn4+@S-CDs complex is synthesized using the sulfur-doped CDs (S-CDs) and SnCl4 as raw materials, and subsequently the new PS (Sn nanocluster@CDs) is obtained after vaporization of Sn4+@S-CDs solution. Remarkably, the obtained Sn nanocluster@CDs show an enhanced fluorescence as well as a higher 1O2 quantum yield (QY) than S-CDs. The high 1O2 QY (58.3%) irradiated by the LED light (400–700 nm, 40 mW/cm2), induce the reduction of 4T1 cancer cells viability by 25%. More intriguingly, no visible damage happens to healthy cells, with little impact on liver tissue due to renal excretion, both in vitro and in vivo experiments demonstrate that Sn nanocluster@CDs may become a promising PS, owning a high potential for application in PDT.
Chiral α-substituted 1, 3-dihydroisobenzofurans are key scaffolds in a number of bioactive natural products and synthetic pharmaceuticals. However, catalytic asymmetric approaches have been rarely developed. Here, a redox deracemization technology is adopted to address the catalytic asymmetric synthesis. A broad range of α-aryl substituted 1, 3-dihydroisobenzofurans are effectively deracemized in high efficiency with excellent ee. α-Alkynyl substituted ethers were also compatible with the deracemization technology.
Being abundant and active, Fe2O3 is suitable for selective oxidation of H2S. However, its practical application is limited due to the poor sulfur selectivity and rapid deactivation. Herein, we report a facile template-free hydrothermal method to fabricate porous α-Fe2O3/SnO2 composites with hierarchical nanoflower that can obviously improve the catalytic performance of Fe2O3. It was disclosed that the synergistic effect between α-Fe2O3 and SnO2 promotes the physico-chemical properties of α-Fe2O3/SnO2 composites. Specifically, the electron transfer between the Fe2+/Fe3+ and Sn2+/Sn4+ redox couples enhances the reducibility of α-Fe2O3/SnO2 composites. The number of oxygen vacancies is improved when the Fe cations incorporate into SnO2 structure, which facilitates the adsorption and activation of oxygen species. Additionally, the porous structure improves the accessibility of H2S to active sites. Among the composites, Fe1Sn1 exhibits complete H2S conversion with 100% sulfur selectivity at 220 ℃, better than those of pure α-Fe2O3 and SnO2. Moreover, Fe1Sn1 catalyst shows high stability and water resistance.
A heterojunction of Sm-doped g-C3N4/Ti3C2 MXene (SCN/MX) was constructed via prepolymerization and solid mixture-calcination method. The modified g-C3N4 presented a hollow porous seaweed-like shape which can increase its specific area and active sites. In SCN/MX composite, the optical properties, no matter optical absorption ability or separation performance of photo-induced electrons and holes, were enhanced. Among them, Sm-doping may play an important role on transferring the photogenerated electrons to suppress their recombination, and Ti3C2 MXene would broaden light absorption and further improve the carrier migration efficiency. The SCN/MX presented higher photocatalytic degradation efficiency (> 99%) of ciprofloxacin under visible light irradiation. The quenching experiments and electron spin-resonance spectroscopy confirmed that the dominated active materials were superoxide radical and holes. The degradation mechanisms of ciprofloxacin (CIP) over the SCN/MX were attacking of the active materials on the piperazine ring and quinolone ring, and the final products were CO2, H2O and F−.
Nanocomposites comprising flexible polymers and high dielectric constant inorganic nanoparticles are considered to be one of the promising candidates for electrostatic capacitor dielectrics. However, the effect of interfacial property on electrical energy storage of dielectric polymer nanocomposites is still not clear. Herein, the role of the polarity of the interfacial region is investigated. For this purpose, three polymers with different polarity, polymethyl methacrylate (PMMA), polyglycidyl methacrylate, and polymethylsulfonyl ethyl methacrylate (PMSEMA) are attached onto BaTiO3 (BT) nanoparticle surface via surface-initiated reversible addition-fragmentation chain transfer polymerization. It is found that the polarity of shell polymers shows an apparent effect on the dielectric and energy storage of dielectric polymer nanocomposites. For example, PMSEMA@BT (shell polymer possesses the highest polarity) increases dielectric loss and decreases the breakdown strength of the nanocomposites, leading to lower energy storage capability. However, PMMA@BT (shell polymer possesses the lowest polarity) can induce higher breakdown strength of the nanocomposites. As a result, the PMMA@BT nanocomposite exhibits the highest electrical energy storage capability among the three nanocomposites. This research provides new insight into the design of core-shell nanofillers for dielectric energy storage applications.
Photocatalysis technology has been proved to be a potential strategy for removal of organic dyes, however high-power light sources are generally necessary to initiate photocatalytic reaction. In this work, we employed an excellent photocatalyst of Bi2WO6 with visible light harvest and meanwhile an intrinsic ferroelectricity, which realized the efficient degradation of organic dye via the synergetic photopiezocatalysis. Through coupling the illumination by a low-power (9 W) LED and the ultrasonic vibration (120 W) by an ultrasonic cleaner, the nanoflower-like Bi2WO6 composed of ultrathin nanosheets showed a much more enhanced photopiezocatalysis performance for purification of organic dye than the individual photocatalysis and piezocatalysis. Furthermore, the high mineralization efficiency and the good durability of the Bi2WO6 catalyst were demonstrated. The possible mechanism of photopiezocatalysis was finally proposed, where the ultrasound-induced piezoelectric field in Bi2WO6 drove photo-generated electrons and holes to diffuse along opposite directions, consequently promoting the separation efficiency of charge carriers. This work indicates that the synergetic photopiezocatalysis by coupling irradiation and ultrasonic vibration is a promising strategy to purify organic pollutants in wastewater.
A label-free and sensitive electrochemical biosensing strategy for a hepatocellular carcinoma biomarker of miRNA-122 has been proposed based on hybridization induced ion-barrier effect on the electroactive sensing interface. First, a bifunctional electroactive electrode with the nanocomposite of Prussian blue (PB) and gold nanoparticles (AuNPs) was prepared through a two-step electrodeposition process. The PB endows the electrode excellent K+-dependent voltammetric signal and the AuNPs act as the matrix for the self-assembly immobilization of the thiolated probe DNA. Upon specific hybridization of probe DNA with the target miRNA-122, the formed double duplex induced the ion-barrier effect, which blocked the diffusion of the K + from the bulk solution to the electrode surface. As a result, the voltammetric signal of the PB on the electrode was surpressed, and thus the target miRNA-122 was monitored. The sensing assay showed that the miRNA-122 could be analyzed in the concentration range from 0.1 fmol/L to 1.0 nmol/L, with a detection limit of 0.021 fmol/L. The practical applicability of the biosensor was also verified by the spiking serum assay.
Developing an excellent photocatalysis system to remove pesticides from water is an urgent problem in current environment purification field. Herein, a Z-scheme WO3/g-C3N4 photocatalyst was prepared by a facile in-situ calcination method, and the photocatalytic activity was investigated for degradation of nitenpyram (NTP) under visible light. The optimal Z-scheme WO3/g-C3N4 photocatalyst displayed the highest rate constant (0.036 min−1), which is about 1.7 and 25 times higher than that of pure g-C3N4 and WO3, respectively. The improvement of photocatalytic performance is attributed to fast transfer of photogenerated carriers in the Z-scheme structure, which are testified by electron spin resonance (ESR) experiments, photocurrent and electrochemical impedance spectra (EIS) measurements. Moreover, the effects of typical water environmental factors on the degradation NTP were systematically studied. And the possible degradation pathways of NTP were deduced by the intermediates detected by high-performance liquid chromatography-mass spectrometry (HPLC-MS). This work will not only contribute to understand the degradation mechanism of pesticides in real water environmental condition, but also promote the development of new technologies for pesticide pollution control as well as environmental remediation.
Overall water photo-splitting is a prospective ideal pathway to produce ultra-clean H2 energy by semiconductors. However, the band structure of many semiconductors cannot satisfy the requirement of H2 and O2 production at the same time. Herein, we illustrate that carbon dots (CDs)/Bi2WO6 photocatalyst with compensatory photo-electronic effect has enhanced activity for overall water photo-splitting without any sacrificial agent. In this complex photocatalytic system, the photo-potential provided by CDs makes the CDs/Bi2WO6 (C-BWO) composite could satisfy the band structure conditions for overall water photo-splitting. The C-BWO composite (3 wt% CDs content) exhibits optimized hydrogen evolution (oxygen evolution) of 0.28 μmol/h (0.12 μmol/h) with an approximate 2:1 (H2: O2) stoichiometry at normal pressure. We further employed the in-situ transient photovoltage (TPV) technique to study the photoelectron extraction and the interface charge transfer kinetics of this composite catalyst.
Highly active and low-cost catalytic electrodes for urea oxidation reaction (UOR) are always crucial for exploration of urea fuel cells. Herein, novel york-shell-structural Ni2P/C nanosphere hybrids (Ni2P/C-YS) are rationally constructed via a hydrothermal method and subsequent phosphidation treatment under different temperature ranging from 250 ℃ to 450 ℃ for UOR applications. In the in-situ constructed hollow york-shell structure, the coupling of conductive carbon materials and active Ni2P allows numerous interfaces facilitating the electron transfer and thereby accelerating the catalytic kinetics. The results demonstrate that Ni2P/C-YS-350 nanocomposite can boost the UOR process with a low potential of 1.366 V vs. RHE at a current density of 50 mA/cm2 in alkaline electrolyte and afford the superior durability with negligible potential decay after 23 h. This study presents that the carbon coated Ni2P hybrid with the optimized crystallinities and hollow york-shell configurations can be a promising candidate for application in urea fuel cells.
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