Photo-catalytic Staphylococcus aureus inactivation and biofilm destruction with novel bis-tridentate iridium(III) photocatalyst

Bacterial infection is currently a serious challenge globally, causing death of thousands of human beings. New antimicrobial agents with novel mechanism of action are urgently needed. Transition metal complexes have shown great potentials in photodynamic and photocatalytic therapy. Herein, we take full advantage of metal photocatalyst and successfully developed a novel cyclometalated iridium(III) complex (Ir1) with higher biofilm damage efficiency than the clinical antibiotics. Ir1 synergistically generates reactive oxygen species and coenzyme photocatalytic activity with high efficiency under white light irradiation. Combined with these properties, Ir1 exhibited excellent photoinactivation of S. aureus and effectively damaged the biofilm. This work provides a new approach for the development of antibacterial photodynamic therapy.     

Manipulation of the PdAu‒PdAuOx interface on Pd-Au bimetallic catalysts for the direct synthesis of hydrogen peroxide

Direct synthesis of H₂O₂ from H₂ and O₂ via heterogeneous catalysis is an environmentally friendly and atomically economic alternative to the traditional anthraquinone oxidation (AO) process. Optimizing the electronic and geometric structures of the active metals to break the current limitations of hydrogenation rate and H₂O₂ selectivity is a promising and challenging topic. In this study, a series of Pd-Au bimetallic catalysts supported on TiO₂ with a metal loading of 3.0 wt% and a constant Pd/Au molar ratio (Pd:Au = 2:1) were prepared. The catalysts were reduced in H₂ at different temperatures (473, 573 and 673 K), and their catalytic activity for the direct H₂O₂ synthesis were evaluated at 283 K and 0.1 MPa. H₂ reduced Pd-Au catalysts exhibited superior performance in direct H₂O₂ synthesis. The maximum H₂O₂ selectivity of 87.7% and H₂O₂ yield of 3116.4 mmol h⁻¹ g_Pd⁻¹ were achieved over the Pd_2.0Au_1.0-573 catalyst with a H₂ conversion of 12.8%. The tailored local chemical environment caused by H₂ reduction creates a balanced ratio of Pd⁰ and PdO_x sites, thus improving the selectivity towards H₂O₂. This work developed an effective strategy for fabrication of highly active and stable Pd-based H₂O₂ synthesis catalysts with high H₂O₂ yield.     

3D microgel with extensively adjustable stiffness and homogeneous microstructure for metastasis analysis of solid tumor

3D microgels with various mechanical properties have been important platforms tumor metastasis analysis, and widely adjustable stiffness is crucial for deeper researches. Herein, by mixing biodegradable polylactic acid (PLA) nanofibers in the modified alginate with different concentrations of Ca²⁺, we significantly enhance the stiffness range of microgels while retaining the pore size, which provides bionic microenvironment for tumor analysis. As a proof of concept, we simulated the mechanical characteristics of breast tumors by encapsulating cells in 3D microgels with diverse stiffness, and analyzed cellular behaviors of two typical breast cancer cell lines: MCF-7 and SUM-159. Results showed that with the addition of 2.0% (w/v) PLA short nanofibers, the Young's modulus of modified alginate increased more than three-fold. Besides preserving high survival and proliferation rates, both cells also displayed stronger migration ability in soft microgel spheres, where RT-qPCR analysis revealed the underlying changes at the genetic level. This systematic study demonstrated our method is powerful for creating widely adjustable 3D mechanical microenvironment, and the results of cellular behavior analysis shows its promising application prospects in tumorigenesis and progression.     

Selective In Situ Analysis of Mature microRNAs in Extracellular Vesicles Using a DNA Cage-Based Thermophoretic Assay

Mature microRNAs (miRNAs) in extracellular vesicles (EVs) are involved in different stages of cancer progression, yet it remains challenging to precisely detect mature miRNAs in EVs due to the presence of interfering RNAs (such as longer precursor miRNAs, pre-miRNAs) and the low abundance of tumor-associated miRNAs. By leveraging the size-selective ability of DNA cages and polyethylene glycol (PEG)-enhanced thermophoretic accumulation of EVs, we devised a DNA cage-based thermophoretic assay for highly sensitive, selective, and in situ detection of mature miRNAs in EVs with a low limit of detection (LoD) of 2.05 fM. Our assay can profile EV mature miRNAs directly in serum samples without the interference of pre-miRNAs and the need for ultracentrifugation. A clinical study showed that EV miR-21 or miR-155 had an overall accuracy of 90 % for discrimination between breast cancer patients and healthy donors, which outperformed conventional molecular probes detecting both mature miRNAs and pre-miRNAs. We envision that our assay can advance EV miRNA-based diagnosis of cancer.     

Ag改性纳米ZnO薄膜及光催化活性

采用溶胶-凝胶法和光还原沉积贵金属法结合制备出Ag改性的纳米ZnO薄膜。利用FESEM、XPS、ESR、UV-Vis分析了纳米Ag-ZnO薄膜的表面形貌、表面组成和光谱特征。FESEM分析表明银在纳米ZnO薄膜表面形成原子簇而没有形成均匀覆盖层。XPS分析表明负载在纳米ZnO薄膜表面的银以Ag⁰形式存在; 相对于纳米ZnO薄膜, 纳米Ag-ZnO薄膜中晶格氧的含量有所下降,而表面羟基氧和吸附氧的含量显著增加。纳米Ag-ZnO薄膜的ESR峰强比纳米ZnO薄膜大,表明纳米Ag-ZnO薄膜中束缚单电子的氧空位的浓度高于纳米ZnO薄膜。UV-Vis分析纳米Ag-ZnO薄膜的紫外可见吸收光谱可能是纳米银粒子与纳米ZnO薄膜共同作用的结果。以甲基橙为模拟污染物,考察了纳米Ag-ZnO薄膜的光催化活性以及银沉积量对催化剂活性的影响。光催化降解结果表明,银的沉积量为0.018 2 mg·cm^-2的纳米Ag-ZnO薄膜的光催化活性最高,在紫外光照射3 h后甲基橙降解率约为78%,而纳米ZnO薄膜约为62%。     

Subwavelength structures for high power laser antireflection application on fused silica by one-step reactive ion etching

In this paper we report a simple method to fabricate a novel subwavelength structure surface on fused silica substrate using one-step reactive ion etching with two-dimensional polystyrene colloidal crystals as masks. The etching process and the morphologies of the obtained structure are controlled. We show that the period of the obtained fused silica pillar-like arrays were determined by the initial polystyrene nanoparticle size. The height of pillar arrays can be adjusted by controlling the etching duration, which is proved to be of importance in tailoring the antireflection properties of subwavelength structures surface. The novel subwavelength structures surface exhibit excellent broadband antireflection properties, but the size of the pillar affects the antireflective properties in short wavelength region. We anticipate this method would offer a convenient and scalable way for inexpensive and high-efficiency high power laser field designs.     

猫眼效应中离焦量对激光回波发散角的影响

平行光束或者激光束在光轴方向上照射焦平面成像系统时会产生猫眼效应,焦平面探测器安装的正交性与离焦量直接影响猫眼回波的光学特性,进而影响基于猫眼效应的探测系统的性能。针对猫眼效应中离焦量与后向反射光束发散角之间关系,利用物理光学进行分析,建立理论模型,对焦距为0.18 m的焦平面探测成像系统进行数值计算得到:在离焦量为0.16 mm时,发散角最小（0.019 mrad）。搭建实验系统,测试离焦量与猫眼回波发散角,测得离焦量在0.15 mm附近存在最小的发散角为0.025 mrad,与计算结果0.019 mrad基本吻合。研究表明:1） 负离焦对发散角的影响大于正离焦;2） 猫眼回波发散角基本上随着离焦量绝对值的增加而变大,但是变化曲线并不关于零离焦量点对称,而是在某个正离焦处存在一个最小发散角。     

One-pot sonochemical synthesis of 1,3-thiazolidin-4-ones using nano-CdZr4(PO4)6 as a robust heterogeneous catalyst

An efficient three-component synthesis of 1,3-thiazolidin-4-ones is described by one-pot condensation of aldehydes, aniline and thioglycolic acid with nano-CdZr₄(PO₄)₆ as a robust heterogeneous catalyst under ultrasonic irradiation. Use of simple and readily available starting materials, experimental simplicity, applying the sonochemical methodology as an efficient method and innocuous means of activation in synthetic chemistry are some advantages of this protocol.     

Coloring random triangulations

We introduce and solve a two-matrix model for the tri-coloring problem of the vertices of a random triangulation. We present three different solutions: (i) by orthogonal polynomial techniques, (ii) by use of a discrete Hirota bilinear equation, (iii) by direct expansion. The model is found to lie in the universality class of pure two-dimensional quantum gravity, despite the non-polynomiality of its potential.