Le Yu

Hydrophilic Co@Au Yolk/Shell Nanospheres: Synthesis, Assembly, and Application to Gene Delivery

[*] Prof. S.-H. Yu, Y. Lu, Y. Zhao, L. Dong, C. Shi, M.-J. Hu Division of Nanomaterials and Chemistry Hefei National Laboratory for Physical Sciences at the Microscale Department of Chemistry University of Science and Technology of China Hefei, Anhui 230026 (P. R. China) E-mail: shyu@ustc.edu.cn L. Yu, Prof. L.-P. Wen Hefei National Laboratory for Physical Sciences at the Microscale School of Life Sciences University of Science and Technology of China Hefei 230027 (P. R. China)

Ordering Ag nanowire arrays by a glass capillary: A portable, reusable and durable SERS substrate

Assembly of nanowires into ordered macroscopic structures with new functionalities has been a recent focus. In this Letter, we report a new route for ordering hydrophilic Ag nanowires with high aspect ratio by flowing through a glass capillary. The present glass capillary with well-defined silver nanowire films inside can serve as a portable and reusable substrate for surface-enhanced Raman spectroscopy (SERS), which may provide a versatile and promising platform for detecting mixture pollutions. By controlling the flow parameters of nanowire suspensions, initially random Ag nanowires can be aligned to form nanowire arrays with tunable density, forming cambered nanowire films adhered onto the inner wall of the capillary. Compared with the planar ordered Ag nanowire films by the Langmuir-Blodgett (LB) technique, the cambered nanowire films show better SERS performance.

The Electrochemistry with Lithium versus Sodium of Selenium Confined To Slit Micropores in Carbon

Substitution of selenium for sulfur in the cathode of a rechargeable battery containing Sx molecules in microporous slits in carbon allows a better characterization of the electrochemical reactions that occur. Paired with a metallic lithium anode, the Sex chains are converted to Li2Se in a single-step reaction. With a sodium anode, a sequential chemical reaction is characterized by a continuous chain shortening of Sex upon initial discharge before completing the reduction to Na2Se; on charge, the reconstituted Sex molecules retain a smaller x value than the original Sex chain molecule. In both cases, the Se molecules remain almost completely confined to the micropore slits to give a long cycle life.

Macroscopic‐Scale Alignment of Ultralong Ag Nanowires in Polymer Nanofiber Mat and Their Hierarchical Structures by Magnetic‐Field‐Assisted Electrospinning

1D nanomaterials have attracted explosive attention in the context of the physical and chemical fi elds, owing to their potential for novel applications in electronic and optical devices. [ 1 ] With the development of synthetic methodologies, 1D nanomaterials have achieved great success and a wide variety of different materials from organic polymers to inorganic compounds have been prepared. [ 2 , 3 ] Recently, research activities in the fi eld of nanoscience are shifting from the preparation of individual nanoparticles (NPs) to the preparation of NP assemblies and the realization of their applications. [ 4 ] From the viewpoint of application, assembly of these 1D nanomaterials into functional nanomaterials and devices is required, especially for alignment in large scale, which is still one of the most diffi cult problems hindering their applications. Various methods based on self-assembly or directed self-assembly techniques have been used to assemble nanomaterials into functional devices. Several reviews focused on assembly have also appeared. [ 4–6 ] However, most of these methods have been applied to assemble 1D nanostructures with low aspect ratios, such as NPs and nanorods (NRs); few techniques have been successfully applied to assemble nanowires (NWs) with high aspect ratios because the magnitude and range of the repulsive forces of wires, rods, and

Rare earth oxide nanocrystals as a new class of autophagy inducers.

Functional interaction of nanomaterial with autophagy, a fundamental biological process for cellular degradation, is of great interest to nanobiology. Rare earth nanomaterials hold tremendous potential for a variety of diagnostic and therapeutic applications and have also been reported to protect cells against bacterial, viral and oxidative stress. In a brief communication we report that both light and heavy classes of rare earth oxide nanocrystals (REOs) elicit an autophagic response in HeLa cells, a human cancer cell line, in a dose- and time-dependent manner. The autophagy induced by REOs is complete and is accompanied by vacuolization within the cytoplasm. Autophagy induction may help explain some of the biological effects caused by REOs, and at the same time raises a special point of consideration for this type of nanomaterial, with regard to both safety assessment and application exploration.

Improving the luminescence enhancement of hybrid Au nanoparticle-monolayer MoS 2 by focusing radially-polarized beams

Monolayer transition-metal dichalcogenides (TMDs) have grown as fantastic building blocks for optoelectronic applications, owing to their direct band gap, transparency, and mechanical flexibility. Since the luminescence of monolayer TMDs suffers from low light absorption and emission, surface plasmons, which confine light at subwavelength and enhance the local electric field, are utilized to boost both excitation and emission fields of TMDs, enabling strong light-matter interaction at the nano-scale. Meanwhile, radially-polarized beams (RPBs) as new and attractive excitation source have found many applications in surface plasmon polaritons, optical tweezer and so on. Here, by using RPBs, we demonstrate the photoluminescence (PL) enhancement of monolayer molybdenum disulfide (MoS2) hybridized with 210 nm-diameter gold nanoparticle (AuNP) is improved by about 1.37-fold compared with linearly-polarized beams (LPBs). Besides, the PL enhancement with RPBs depends on the size of AuNP as well. With 210nm-diameter AuNP, the PL enhancement is more than 1.5-fold higher than that with 60nm-diameter AuNP. This study highlights that RPBs are superior to LPBs for tuning the near-field system response and shows that RPBs drive a valuable avenue to further study the emerging two-dimentional materials.

Efficient gene transfer to rat fetal osteoblastic cells by synthetic peptide vector system.

We synthesized a 15-amino acid bi-functional synthetic peptide, RPC2, with the sequence Ac-CGKRKWSQ PKKKRKV-Cysteamide, which consists of a 7-amino acid nuclear localization signal (NLS) domain at the carboxyl terminus that electrostatically binds DNA and a 5-amino-acid tumor-homing domain at the amino terminus. This peptide efficiently delivered GFP and Renilla luciferase reporter genes into rat primary osteoblastic cells while exhibiting low cytotoxicity. The optimal delivery was achieved when the ratio of DNA: RPC2 reached 1:10 (w/w). Transfection efficiency can be further enhanced by the addition of Lipofectamine 2000 and modification of RPC2. These results indicated that RPC2 can deliver exogenous DNA into primary osteoblastic cells with low cytotoxicity and be potentially utilized in experimental and clinical applications in the field of bone tissue engineering.

Gap plasmon-enhanced photoluminescence of monolayer MoS2 in hybrid nanostructure*

Monolayer transition-metal dichalcogenides (TMDs) have attracted a lot of attention for their applications in optics and optoelectronics. Molybdenum disulfide (MoS2), as one of those important materials, has been widely investigated due to its direct band gap and photoluminescence (PL) in visible range. Owing to the fact that the monolayer MoS2 suffers low light absorption and emission, surface plasmon polaritons (SPPs) are used to enhance both the excitation and emission efficiencies. Here, we demonstrate that the PL of MoS2 sandwiched between 200-nm-diameter gold nanoparticle (AuNP) and 150-nm-thick gold film is improved by more than 4 times compared with bare MoS2 sample. This study shows that gap plasmons can possess more optical and optoelectronic applications incorporating with many other emerging two-dimensional materials.