激光显微共聚焦拉曼光谱仪变温系统的设计与研制

针对常规激光显微共聚焦拉曼光谱仪无法满足物质变温,特别是低温测试需求的问题,设计了适用于拉曼光谱仪的高精度变温系统。该系统采用GM制冷机作为制冷源,利用高纯无氧铜作为导冷介质,通过将GM制冷机的冷量传导至样品台,并利用控温仪进行温度控制,可以实现待测样品10 K-402 K范围的温度变化控制,控温精度高于0.008 K。相比于常规的低温测试设备,该系统无需采用液氮、液氦进行制冷,大幅降低了设备的使用及维护费用。同时,使用激光显微共聚焦拉曼光谱仪搭载该系统,成功获得了Si、V₂O₅等材料的变温拉曼光谱,验证了激光显微共聚焦拉曼光谱仪变温系统设计的可靠性。     

Controllable Assembly and Properties of Brain Targeting Peptides with Tetrahedral Framework Nucleic Acids北大核心CSCD

In this study,the armed tetrahedral DNA nanostructures（TDN）are designed to bind single or three complementary strands of armed chain（1-ANG-TDN,3-ANG-TDN）which is modified with angiopep-2 or other brain targeting peptides（TAT,TGN）. We compare the cell viability and cellular uptake of 1-ANG-TDN or 3-ANG-TDN in brain capillary endothelial（bEnd. 3）cells and Uppsala 87 malignant glioma（U87） cells. In addition,the cell viability and cellular uptake of ANG-TDN,TAT-TDN and TGN-TDN in bEnd. 3 cells are investigated respectively. The results show that these probes are not cytotoxic to bEnd. 3 cells and U87 cells at concentrationsbelow 100 nmol/L. After being incubated with bEnd. 3cells for 0. 5 h,the cellular uptake of 3-ANG-TDN is higher than that of 1-ANG-TDN（P<0. 01）. After being incubated with U87 cells for 1h,the cellular uptake of 3-ANG-TDN is higher than that of 1-ANG-TDN（P<0. 01）. After 2 h,there is no obvious difference in cellular uptake between 1-ANG-TDN and 3-ANG-TDN. ANG-TDN,TAT-TDN and TGN-TDN are up-taken by bEnd. 3 cells much more than TDN（P<0. 01）. However,there isno statistical difference among ANG-TDN,TAT-TDN and TGN-TDN（P>0. 05）. These results indicate that the targeting of ANG-TDN probe can be improved by increasing the number of peptides or prolonging the co-incubation time. This discovery providesareference for the multifunctional modification of tetrahedral framework nucleic acid. When a single peptidelinked with TDN achieves the brain targeting,other sites of TDN can be modified by other functional groups to expand the structure and function. Tetrahedral framework nucleic acids can be used not only as an assembly platform for ANG peptides,but also for the assembly of other brain-targeting peptides （TAT and TGN）to design brain-targeting probes. © 2022, Science Press (China). All rights reserved.