A stimulus-responsive hexahedron DNA framework facilitates targeted and direct delivery of native anticancer proteins into cancer cells

The targeted and direct intracellular delivery of proteins plays critical roles in biological research and disease treatments, yet remains highly challenging. Current solutions to such a challenge are limited by the modification of proteins that may potentially alter protein functions inside cells or the lack of targeting capability. Herein, we develop a stimulus-responsive and bivalent aptamer hexahedron DNA framework (HDF) for the targeted and direct delivery of native therapeutic proteins into cancer cells. The unmodified proteins are caged inside the HDF nanostructures assembled from six programmable single stranded DNAs to protect the proteins from degradation by cathepsins and enhance their targeting capability and delivery efficiency with the nanostructure-integrated aptamers. In addition, the protein drugs can be selectively released from the HDF nanostructures by the intracellular ATP molecules to induce tumor cell apoptosis, highlighting their promising application potential for cell biology and precise protein medicines.

A bivalent aptamer hexahedron DNA framework can facilitate the targeted intracellular delivery of native RNase A to result in effective cancer cell apoptosis.     

A Low-Cost and Environmentally Friendly Mixed Polyanionic Cathode for Sodium-Ion Storage

Sodium-ion batteries (NIBs) are the most promising alternatives to lithium-ion batteries in the development of renewable energy sources. The advancement of NIBs depends on the exploration of new electrode materials and fundamental understanding of working mechanisms. Herein, via experimental and simulation methods, we develop a mixed polyanionic compound, Na₂Fe(C₂O₄)SO₄⋅H₂O, as a cathode for NIBs. Thanks to its rigid three dimensional framework and the combined inductive effects from oxalate and sulfate, it delivered reversible Na insertion/desertion at average discharging voltages of 3.5 and 3.1 V for 500 cycles with Coulombic efficiencies of ca. 99 %. In situ synchrotron X-ray measurements and DFT calculations demonstrate the Fe²⁺/Fe³⁺ redox reactions contribute to electron compensation during Na⁺ desertion/insertion. The study suggests mixed polyanionic frameworks may provide promising materials for Na ion storage with the merits of low cost and environmental friendliness.     

Discovery of long-wavelength photoactivatable diaryltetrazoles for bioorthogonal 1,3-dipolar cycloaddition reactions

Several long-wavelength (365 nm) photoactivatable diaryltetrazoles were discovered by screening a series of substituted diaryltetrazoles and subsequently showed excellent reactivity in the photoactivated 1,3-dipolar cycloaddition reactions toward electron-deficient and conjugated alkenes in organic solvents as well as an alkene-containing protein in the aqueous buffer.     

Preparation and photocatalytic properties of Fe3+-doped Ag@TiO2 core-shell nanoparticles

Ag@TiO2 core-shell-type nanophotocatalysts have been prepared using a simple and convenient method. The products were characterized by TEM, XRD, and UV-vis spectra. To make the catalysts achieve the highest photocatalytic activity under UV light illumination, the Ag content of Ag@TiO2 was optimized. The results showed that Ag@TiO2-doped Fe3+ extend their absorption into the visible region. Among the Fe3+-doped samples, Ag@Fe-TiO2 with low Ag content showed higher photocatalytic activity under visible light illumination. An excessive added amount of Ag would reduce Fe3+ to Fe2+ and make them difficult to be incorporated into the lattice of titania. From the experiments, we found that Fe3+ ions could stabilize the Ag@TiO2 colloid by holding back the aggregation of the core-shell nanoparticles.     

聚苯乙烯/纳米铝复合材料的流变特性及纺丝研究

为有效制得Z箍缩氘代聚苯乙烯/纳米铝(DPS/AlNPs)导电丝阵材料,采用PS中掺入AlNPs制备PS/AlNPs复合材料纤维进行模拟研究。研究了温度及剪切速率等因素对PS/AlNPs复合材料流变性能的影响、复合材料熔体的结构变化及流动状态与可纺性能的关系,以及PS/AlNPs纤维的形貌、热稳定性能和力学性能。结果表明：PS/AlNPs熔体属于典型剪切变稀型非牛顿流体,熔体的表观粘度与温度呈现负相关,240~260 ℃时复合材料的非牛顿指数介于0.462~0.546,结构黏度系数介于1.8~2.1,黏流活化能介于77.2~104.6 kJ·mol^-1,具有良好的可纺性。PS/AlNPs纤维表面光滑,对AlNPs粒子包覆良好且对其抗氧化非常有利,其中当AlNPs质量分数为1%时纤维的断裂伸长率突出、掺量为5%时其断裂强度较高。     

A biosynthetic route to photoclick chemistry on proteins

Light-induced chemical reactions exist in nature, regulating many important cellular and organismal functions, e.g., photosensing in prokaryotes and vision formation in mammals. Here, we report the genetic incorporation of a photoreactive unnatural amino acid, p-(2-tetrazole)phenylalanine (p-Tpa), into myoglobin site-specifically in E. coli by evolving an orthogonal tRNA/aminoacyl-tRNA synthetase pair and the use of p-Tpa as a bioorthogonal chemical "handle" for fluorescent labeling of p-Tpa-encoded myoglobin via the photoclick reaction. Moreover, we elucidated the structural basis for the biosynthetic incorporation of p-Tpa into proteins by solving the X-ray structure of p-Tpa-specific aminoacyl-tRNA synthetase in complex with p-Tpa. The genetic encoding of this photoreactive amino acid should make it possible in the future to photoregulate protein function in living systems.     

咪唑修饰萘酰亚胺与DNA的作用及其细胞毒性

设计合成了咪唑及其烷基化咪唑阳离子基团修饰的萘酰亚胺衍生物。利用紫外-可见吸收光谱、荧光光谱、圆二色谱和荧光共振能量转移等方法研究了它们与小牛胸腺DNA(CT DNA)和G-四链体DNA的相互作用。这些化合物对端粒DNA序列的G-四链体有很高的结合能力(K_α4×10~6 L·mol~(-1)),并能够稳定G-四链体。DNA粘度实验结果表明萘酰亚胺衍生物与CT DNA通过插入作用结合。Autodock分子对接模拟结果表明这些化合物通过疏水作用、静电作用或氢键等方式与人体端粒G-四链体的loop和沟槽部分结合。咪唑阳离子基团修饰的萘酰亚胺衍生物4a–c能够定位于细胞核,对肺癌细胞的细胞毒性要高于咪唑基团修饰的萘酰亚胺衍生物3。化合物4a和4b对肺癌细胞A549的细胞毒性明显高于正常人胚肺成纤维细胞MRC-5,表现出良好的抗癌活性。     

微下拉法生长Tb3AlxGa5-xO12磁光晶体及其性能表征

Tb₃Ga₅O₁₂晶体是一种具有良好磁光性能的主流商用材料,但生长过程中存在严重的氧化镓挥发问题,导致晶体难以满足高功率应用的发展需求,而菲尔德常数较大的Tb₃Al₅O₁₂晶体的不一致熔融特性使该晶体难以生长,因此亟需探索新型高质量磁光晶体以满足高功率应用需求。基于此,本文采用微下拉法在高纯氩气和二氧化碳混合气氛下生长了Tb₃Al_xGa_5-xO₁₂(TAGG)系列高掺铝磁光晶体。摇摆曲线测试结果表明TAGG磁光晶体拥有高结晶质量。透过光谱和磁光特性测试结果表明,与传统Tb₃Ga₅O₁₂晶体相比,TAGG磁光晶体具有更高的透过率和更大的菲尔德常数,是一种非常有潜力的可应用于高功率激光系统的低成本磁光材料。