碳纳米管修饰金电极检测特定序列DNA

利用化学偶联法将末端修饰氨基的寡聚核苷酸固定在表面修饰有羧基化碳纳米管(CNTs-COOH)的金电极表面, 制备新型核酸探针, 可以特异性结合目标单链寡聚核苷酸. 以阿霉素作为嵌合指示剂, 利用示差脉冲法测定杂交的结果. 经过实验条件的优化, 测定DNA浓度在1.0×10^－6～1.0×10^－9 mol/L呈良好的线性关系. 检测限为: 2.54×10^－10 mol/L. 碳纳米管特有的纳米结构对检测结果的放大作用, 提高了该传感器的检测限和灵敏度.     

Approximate expressions and the relationship between pyramidalization (out‐of‐plane deformation) characteristics of trigonal centers

Fairly accurate approximate expressions for commonly used characteristics of non‐planarity of trigonal sp²‐hybridized centers are reported. It is shown that the behavior of all these parameters as a function of bond angles (α, β, γ) is determined primarily by the square‐root of the difference [360° ? (α + β + γ)]. This quantity is proposed as a new versatile measure of pyramidalization. © 2012 Wiley Periodicals, Inc.     

Synthesis of novel scaffolds based on thiazole or triazolothiadiazine linked to benzofuran or benzo[d]thiazole moieties as new hybrid molecules

Abstract

A synthesis of novel hybrid molecules containing thiazole or bis(thiazoles) each bearing benzofuran and/or benzo[d]thiazole moieties by the reaction of the appropriate thioamide derivatives with the corresponding bis-bromoacetyl derivatives is reported. Mono- and bis(triazolothiadiazine) derivatives based on benzofuran or benzo[d]thiazole moieties were also synthesized in good yields by the reaction of the appropriate bis(bromoacetyl) derivatives with each of 4-amino-5-mercapto-1,2,4-triazoles and their corresponding bis-derivatives.     

A novel phosphoramidite method for automated synthesis of oligonucleotides on glass supports for biosensor development

Two protocols for functionalization of glass supports with hexaethylene glycol (HEG)-linked oligonucleotides were developed. The first method (standard amidite protocol) made use of the 2-cyanoethyl-phosphoramidite derivative of 4,4′-dimethoxytrityl-protected HEG. This was first coupled to the support by standard solid-phase phosphoramidite chemistry followed by extension with a thymidylic acid icosanucleotide. Stepwise addition of the linker phosphoramidite graduated at 1% (relative to the total sites available) perstep at 50°C resulted in an optimal yield of immobilized oligonucleotides at a density of 2.24 × 10¹⁰ strands/mm². This observed loading maximum lies well below the theoretical maximum loading owing to nonspecific adsorption of HEG on the glass and subsequent blocking of reactive sites. Surface loadings as high as 3.73 × 10¹⁰/mm² and of excellent sequence quality were achieved with a reverse amidite protocol. The support was first modified into a 2-cyanoethyl-N,N-diisopropylphosphoramidite analog followed by coupling with 4,4′-dimethoxytrityl-protected HEG. This protocol is conveniently available when using a conventional DNA synthesizer. The reverse amidite protocol allowed for control of the surface loading at values suitable for subsequent analytical applications that make use of immobilized oligonucleotides as probes for selective hybridization of sample nucleic acids of unknown sequence and concentration.     

柱前衍生高效液相色谱-质谱法测定水稻中尼克烟酰胺含量

建立了柱前衍生高效液相色谱-质谱联用(HPLC-MS)测定水稻中尼克烟酰胺含量的方法.样品中尼克烟酰胺经水提取后,与9-芴甲基氯甲酸酯(FMOC-Cl)衍生,采用液相色谱质谱联用仪测定.系统研究了衍生剂浓度和衍生介质等条件对衍生效率的影响.通过优化流动相酸度和梯度洗脱等条件,提高了方法灵敏度.尼克烟酰胺在0.1～5.0 mg/L范围内呈良好的线性关系(r=0.9983),对水稻的根、茎、叶及大米的标准加入实验表明,方法的添加回收率在72.0%～89.2%之间; 相对标准偏差为2.3%～9.6%; 方法检出限为0.05 mg/kg.方法简便、准确可靠,可以满足水稻中生理水平尼克烟酰胺的定性定量分析.     

离心破乳-气相色谱法测定黑米中残留抑霉唑的研究

报道了离心破乳-气相色谱法测定黑米中残留抑霉唑的方法. 考察了不同离心速率、不同离心时间的破乳效率. 试样以V(正己烷):V(乙酸乙酯)＝1:1提取, 经毛细管气相色谱柱HP-5 (30 m×0.25 mm×0.25 μm)分离, μ-ECD检测器测定. 方法检出限为1.0×10-3 mg/kg (S/N=3). 在添标水平0.05、 0.25和0.50 mg/kg时的平均回收率为92.3%～104.3%, 相对标准偏差为6.9%～9.3%. 线性范围为0.02～1.0 mg/L (r2=0.9994). 方法适合黑米中残留抑霉唑的测定.     

GC/MS测定锅巴中丙烯酰胺含量

建立了一种测定市售锅巴中的丙烯酰胺含量的方法.该法样品前处理不必经过溴化衍生,样品脱脂后用水提取丙烯酰胺,提取液过活性炭柱,再用乙酸乙酯将活性炭柱中吸附的丙烯酰胺洗脱.洗脱液浓缩后经气相色谱-质谱(GC-MS)定量分析,检测限为0.06 mg/kg,适合测定市售锅巴中的丙烯酰胺的含量.还考察了丙烯酰胺在水的固液两相中的分配比.     

分子印迹固相萃取-液相色谱质谱联用对4种磺酰脲类除草剂残留的测定

采用苄嘧磺隆分子印迹固相萃取柱(MISPE)对加标大米中的苄嘧磺隆、甲磺隆、苯磺隆和烟嘧磺隆4种磺酰脲类除草剂进行净化和富集预处理,并采用LC-MS方法进行定量分析.质谱条件为:正离子检测模式(M+H),检测质量范围为m/z 200 ～800 ,毛细管电压3.93 kV,锥孔电压20 V,脱溶剂温度250 ℃,辅助气流速4 L/min.4种磺酰脲类除草剂在0.01 ～0.70 mg·L~(-1)范围内线性良好.回收率为68% ～100%,表明样品液中的烟嘧磺隆、甲磺隆、苯磺隆和苄嘧磺隆能直接被分子印迹固相萃取柱中的印迹位点保留,而杂质几乎不被保留.分子印迹固相萃取柱对磺酰脲类除草剂表现出良好的识别性能.     

电化学石英晶体微天平研究界面电场对DNA杂交的影响

采用电化学石英晶体微天平, 现场监测不同界面电场下完全匹配的靶标DNA和不完全匹配的靶标DNA分别与寡聚核苷酸探针分子杂交的过程. 结果表明, 电极表面荷正电时DNA表观杂交效率比电极表面荷负电时高, 但假阳性比较显著; 而电极表面荷负电时能有效地抑制错配杂交. 探讨了引入界面电场后探针分子取向和微观作用力对DNA杂交的影响.     

萜类化合物13C NMR化学位移的定量构谱相关研究

利用原子电性作用矢量(Atomic electro-negativity interaction vector,AEIV)和原子杂化状态指数(Atomic hybridization state index,AHSI)对萜类化合物中的C原子进行结构表征并与其核磁共振碳谱(13C NMR)建立了优良的定量构谱相关(QSSR)模型.其中29个单萜类化合物中的290个C原子建模的计算值经留一法(Leave-one-out,LOO)交互校验(Cross-validation,CV)预测值的复相关系数(R)分别为0.9900和0.9867,进一步使用倍半萜、二萜、三萜化合物分子中65个C原子的13C NMR化学位移值来检测该模型的稳定性,模型预测值和观测值间复相关系数(R)为0.9777,取得了令人满意的结果.