Ferrocene-Containing Nucleic Acid-Based Energy-Storage Nanoagent for Continuously Photo-Induced Oxidative Stress Amplification

Regulation of cellular oxidative stress plays a critical role in revealing the molecular mechanisms of cellular activities and thus is a potential strategy for tumor treatment. Optical methods have been employed for intelligent regulation of oxidative stress in tumor regions. However, long-time continuous irradiation inevitably causes damage to normal tissues. Herein, a ferrocene-containing nucleic acid-based energy-storage nanoagent was designed to achieve the continuous photo-regulation of cellular oxidative stress in the dark. Specifically, the photoenergy stored in the agent could convert effectively and accelerate Fenton-like reaction continuously, augmenting cellular oxidative stress. This nanoagent could also silence oxidative damage repair genes to further amplify oxidative stress. This strategy not only provides oxidative stress regulation for studying the molecular mechanisms of biological activities, but also offers a promising step toward tumor microenvironment modulation.

Grain-Boundary-Induced Drastic Sensing Performance Enhancement of Polycrystalline-Microwire Printed Gas Sensors

The development of materials with high efficiency and stable signal output in a bent state is important for flexible electronics. Grain boundaries provide lasting inspiration and a promising avenue for designing advanced functionalities using nanomaterials. Combining bulk defects in polycrystalline materials is shown to result in rich new electronic structures, catalytic activities, and mechanical properties for many applications. However, direct evidence that grain boundaries can create new physicochemical properties in flexible electronics is lacking. Here, a combination of bulk electrosensitive measurements, density functional theory calculations, and atomic force microscopy technology with quantitative nanomechanical mapping is used to show that grain boundaries in polycrystalline wires are more active and mechanically stable than single-crystalline wires for real-time detection of chemical analytes. The existence of a grain boundary improves the electronic and mechanical properties, which activate and stabilize materials, and allow new opportunities to design highly sensitive, flexible chemical sensors.

Critical Role of Water and Oxygen Defects in C-O Scission during CO2 Reduction on Zn2GeO4(010)

Exploration of catalyst structure and environmental sensitivity for C-O bond scission is essential for improving the conversion efficiency because of the inertness of CO₂. We performed density functional theory calculations to understand the influence of the properties of adsorbed water and the reciprocal action with oxygen vacancy on the CO₂ dissociation mechanism on Zn₂GeO₄(010). When a perfect surface was hydrated, the introduction of H₂O was predicted to promote the scission step by two modes based on its appearance, with the greatest enhancement from dissociative adsorbed H₂O. The dissociative H₂O lowers the barrier and reaction energy of CO₂ dissociation through hydrogen bonding to preactivate the C-O bond and assisted scission via a COOH intermediate. The perfect surface with bidentate-binding H₂O was energetically more favorable for CO₂ dissociation than the surface with monodentate-binding H₂O. Direct dissociation was energetically favored by the former, whereas monodentate H₂O facilitated the H-assisted pathway. The defective surface exhibited a higher reactivity for CO₂ decomposition than the perfect surface because the generation of oxygen vacancies could disperse the product location. When the defective surface was hydrated, the reciprocal action for vacancy and surface H₂O on CO₂ dissociation was related to the vacancy type. The presence of H₂O substantially decreased the reaction energy for the direct dissociation of CO₂ on O_2c1- and O_3c2-defect surfaces, which converts the endoergic reaction to an exoergic reaction. However, the increased decomposition barrier made the step kinetically unfavorable and reduced the reaction rate. When H₂O was present on the O_2c2-defect surface, both the barrier and reaction energy for direct dissociation were invariable. This result indicated that the introduction of H₂O had little effect on the kinetics and thermodynamics. Moreover, the H-assisted pathway was suppressed on all hydrated defect surfaces. These results provide a theoretical perspective for the design of highly efficient catalysts.

Preparation of Fe3O4/TiO2 magnetic mesoporous composites for photocatalytic degradation of organic pollutants

Fe₃O₄/TiO₂ magnetic mesoporous composites were synthesized through a sol-gel method with tetra-n-butyl titanate as precursor and surfactant P123 as template. The as-prepared Fe₃O₄/TiO₂ composites were characterized by X-ray diffraction, diffuse reflectance spectroscopy, nitrogen adsorption-desorption isotherm and pore size distribution. The as-synthesized products were applied as photocatalysis for the degradation of Acid Black ATT and tannery wastewater under UV lamp irradiation. Fe₃O₄/TiO₂-8 composites containing Fe₃O₄ of 8 wt% were selected as model catalysts. The optimal catalyst dosage was 3 g/L in this photocalytic system. The magnetic Fe₃O₄/TiO₂ composites possessed good photocatalytic stability and durability. This approach may provide a platform to prepare a magnetic composite to optimize the catalytic ability.

Preparation of mesoporous TiO2 with enhanced photocatalytic activity towards tannery wastewater degradation

Ordered mesoporous TiO₂ materials are successfully synthesized via a sol-gel route using butyl titanate as a precursor and sodium dodecyl benzene sulfonate surfactants as soft templates. The as-prepared TiO₂ samples possess a relatively high surface area of 40.03 m²/g and the center of pore diameter distribution of 13.04 nm. They exhibit excellent photocatalytic activity towards degradation of organic pollutants in tannery wastewater under UV-light and natural sunlight irradiation. The effect of the catalyst dosage, the pH value of the solution and the concentration of H₂O₂ are discussed in detail. This work would pave an avenue for purifying various industrial wastewaters through an advanced photocatalytic oxidation process.

Controlled growth of hexagonal Zn2GeO4 nanorods on carbon fibers for photocatalytic oxidation of p-toluidine

Hexagonal Zn₂GeO₄ nanorods grown on the surface of carbon fiber substrates have been prepared for photocatalytic oxidation of p-toluidine.