Reactivity of the Hydroxy Groups in Melezitose and Their Selective Protection

The reactivity of melezitose hydroxy groups was studied by tritylation in pyridine with subsequent acetylation. After partial detritylation of the products, acetyl group transfer from position 4 to 6 was observed. The structure of the prepared melezitose derivatives was established on the basis of their IR, ¹H, ¹³C, and ¹H-¹H COSY NMR, and mass spectra (fast atom bombardment), as well as from the results of model calculations performed with the aid of SGI Indigo Molecule-Pattern-Work-Station software package (Biosym) where the potential energy function was approximated with the CVFF potential. The reactivity of primary hydroxy groups in melezitose was found to decrease in the following order: 6' > 6 6' > 1'.     

半壳结构金纳米膜的局域表面等离子体共振效应

采用纳米模版印刷术和化学自组装技术制备了半壳结构的金粒子膜.利用场发射扫描电子显微镜和光谱仪等测试手段对样品的结构和光学性质进行了分析.研究发现，该结构的金膜所具有独特的局域表面等离子体共振效应取决于样品的粒子大小、间距等微观结构，且其峰值吸收波长对其周围环境介质的介电常数变化十分敏感.实验结果表明，粒子排列均匀的亚单层膜结构是控制光学性质稳定的关键. 关键词： 局域表面等离子体共振 半壳结构 纳米模版印刷术     

Cu-DNAzyme facilitates highly sensitive immunoassay

A simple Cu-DNAzyme system is used for signal transduction of a CuO nanoparticle-labeled immunoassay, which makes the immunoassay fast, simple, cost-effective, and sensitive, thus promising for biomedical applications and point-of-care testing.     

Criteria for the field boundaries of an axially symmetric ultrawideband radiator

Criteria for the near and far electromagnetic fields of ultrawideband radiation are considered based on a numerical simulation. To estimate the field boundaries for ultrawideband radiation, it is proposed to use the condition of the maximum (near field) and minimum (far field) differences between the time dependences of the electromagnetic field components. The approach proposed has been approved for an axially symmetric radiator excited by voltage pulses of varied waveform and duration. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 46–50, September, 2008.     

基于3D打印薄层池和流场形电极的镉离子流动检测系统

首次提出了流场形(FFS)电极的概念,并印制了FFS三电极体系.结合3D打印的薄层流通池(TLFC),采用方波溶出伏安法(SWSV),构建了镉离子(Cd2+)流动电化学检测系统.考察了电极形状、测量方式、流速、介质条件、富集时间等条件的影响.结果表明,此检测系统测量灵敏度高,重现性和稳定性好.在优化条件下,Cd2+浓度在2 ～ 100 μg/L范围内与溶出峰电流呈良好的线性关系,相关系数为0.997,检出限为0.5 μg/L.将本方法应用于环境水样和生物甲烷发酵液中痕量Cd2+的检测,结果与ICP-AES无显著性差异,加标回收率为90％ ～ 106％.     

三(3,5-二氟苄基)氯化锡和四(邻氯苄基)锡的合成、晶体结构及量子化学

3,5-二氟苄基氯和邻氯基苄基氯在适当的溶剂中与锡粉反应,合成了三(3,5-二氟苄基)氯化锡(1)和四(邻氯苄基)锡(2),经X射线衍射方法测定了新化合物的晶体结构。化合物1属单斜晶系,空间群为C2/c,晶体学参数:a=1.858 33(11)nm,b=1.140 98(7)nm,c=2.690 06(16)nm,β=109.288(10)°,V=5.383 6(6)nm3,Z=8,Dc=1.532 g·cm~(-3),μ(Mo Kα)=13.61 cm~(-1),F(000)=2 480,R1=0.085 1,wR~2=0.168 1。化合物2属单斜晶系,空间群为P21/m,晶体学参数:a=0.585 54(5)nm,b=1.969 74(18)nm,c=0.857 86(8)nm,β=95.204 0(10)°,V=0.985 34(15)nm3,Z=2,Dc=1.805 g·cm~(-3),μ(Mo Kα)=14.91 cm-1,F(000)=524,R1=0.054 0,wR_2=0.163 9;中心锡原子为畸变四面体构型。对其结构进行量子化学从头计算,探讨了化合物的稳定性、分子轨道能量以及部分前沿分子轨道的组成特征。测定了化合物的热稳定性。     

Detection of mutant p53 using field-effect transistor biosensor

We assessed the abilities of wild p53 and mutant p53 proteins to interact with the consensus DNA-binding sequence using a MOSFET biosensor. This is the first report in which mutant p53 has been detected on the basis of DNA-protein interaction using a FET-type biosensor. In an effort to evaluate the performance of this protocol, we constructed the core domain of wild p53 and mutant p53 (R248W), which is DNA-binding-defective. After the immobilization of the cognate DNA to the sensing layer, wild p53 and mutant p53 were applied to the DNA-coated gate surface, and subsequently analyzed using a semiconductor analyzer. As a consequence, a significant up-shift in drain current was noted in response to wild p53, but not mutant p53, thereby indicating that sequence-specific DNA-protein interactions could be successfully monitored using a field-effect-based biosensor. These data also corresponded to the results obtained using surface plasmon resonance (SPR) measurements. Taken together, our results show that a FET-type biosensor might be promising for the monitoring of mutant p53 on the basis of its DNA-binding activity, providing us with very valuable insights into the monitoring for diseases, particularly those associated with DNA-protein binding events.     

An Improved Ion-Pair Reversed Phase LC Method for Analysis of Major Impurities of Phosphorothioate Oligonucleotide Cantide

An improved ion-pair reversed phase LC (IP-RP-LC) method was developed using triethylammonium/hexafluoroisopropanol (TEA/HFIP) buffer as the mobile phase as an alternative to capillary gel electrophoresis (CGE) and ion-exchange chromatography (IEC) for routine quality control of the synthetic 20-mer phosphorothioate oligonucleotide (PS-ODN) Cantide. The most commonly observed impurities included an oligomer with a deletion at the 5′-end (5′n-1) and a monophosphodiester (P=S/O). The method described here was sufficiently selective to simultaneously separate and identify these impurities. To the best of our knowledge, this is the first report on the separation of P=S/O analogs from PS-ODN using IP-RP-LC. Relatively high TEA concentrations and higher pH values were recommended. The separation performance was maintained even in the presence of multiple P=S/O fragments containing different PO residues. The method was successfully applied to the analysis of failure sequences of authentic crude Cantide as well as the purified product. In addition to 5′n-1 and P=S/O analogs, some minor impurities such as 3′n-1 oligomers were also partially resolved.     

高效阴离子交换色谱-铜/铂修饰电极安培法测定大观霉素

采用阴离子交换色谱分离,在CuSO4溶液中加入少量镧系化合物,经电沉积制备La3+-Cu/pt/CME工作电极,建立了直流安培电化学法(DC)直接检测硫酸大观霉素的方法。考察了流动相浓度、测定电位等参数对色谱分离和测定的影响。在固定相为CarboPac PA10阴离子交换柱、流动相为26mmol/L NaOH,流速为0.6mL/min的色谱条件下,检测电位为0.68V时,硫酸大观霉素峰面积与其浓度在0.12～12mg/L(r=0.9991)和12～280mg/L(r=0.9995)两个范围内呈线性。本方法不需要柱前和柱后衍生化,能同时测定硫酸大观霉素中的主要组分和杂质。修饰电极制作方法简单,催化稳定性好,可作为电化学传感器测定硫酸大观霉素中的各组分。