新型汞离子CQDs-CuNCs比率荧光探针的构建及在螃蟹中的应用

汞是一种典型的低剂量高毒性物质,广泛存在于环境和水体中,可通过食物链传递并累积,从而对人体造成危害。因此,准确快速的监测食品中汞离子（Hg2+）含量对于保障食品安全具有重要意义。目前,常用的Hg2+检测方法包括液相色谱-原子荧光光谱法（LC-AFS）、电感耦合等离子质谱法（ICP-MS）、电化学法和荧光分析法。比率型荧光探针具有双发射荧光特性,其中内置校准功能可降低因探针浓度和各种环境因素产生的检测误差,可以有效的克服单发射荧光探针的不足。本研究提出了基于碳量子点（CQDs）和铜纳米簇（CuNCs）的新型比率型荧光探针用于螃蟹中Hg2+的快速检测。主要研究内容和结果如下：（1）CQDs-CuNCs复合体系的制备。以蔗糖为碳源,聚乙二醇为钝化剂,通过微波介导法合成CQDs;以抗坏血酸为还原剂和稳定剂通过水热法合成CuNCs,后通过自组装制成CQDs-CuNCs复合体系。（2）CQDs-CuNCs复合体系的表征。利用高倍透射电子显微镜（HRTEM）、紫外-可见吸收光谱（UV-Vis）、荧光光谱（FL）和傅里叶变换红外光谱（FTIR）对CQDs-CuNCs复合体系表征,结果显示,该研究成功合成了具有双发射特性的CQDs-CuNCs比率型荧光探针。（3）CQDs-CuNCs复合体系的稳定性测试。将CQDs-CuNCs比率型探针与传统的单通道CuNCs探针的稳定性进行对比。结果表明,当探针浓度漂移和测量温度波动时,CQDs-CuNCs比率型探针比单发射的CuNCs抗干扰能力更强,稳定性更高。（4）CQDs-CuNCs复合体系对Hg2+的检测。当Hg2+存在时,复合体系中的CuNCs发生团聚,而CQDs基本不受影响,导致443 nm处的CuNCs荧光猝灭而545 nm处的CQDs荧光强度几乎不变。依据荧光强度的比值（I_{443 nm}/I_{545 nm}）与Hg2+浓度的关系实现定量检测。在对标准Hg2+检测时,CQDs-CuNCs复合体系的I_{443 nm}/I_{545 nm}和单发射CuNCs的猝灭率与Hg2+浓度（0.1～12 μmol·L-1）均呈现良好的线性关系,相关系数分别达到0.994 7和0.991 6,检测限（3σ/S）分别为2.83和3.62 nmol·L-1。在螃蟹样品检测中,CQDs-CuNCs比率型探针和单发射的CuNCs得到回收率分别为102.5%~105.4%和104.2%~112.5%,说明CQDs-CuNCs复合体系比单发射CuNCs对Hg2+具有更高的灵敏性和稳定性。以上结果表明,本研究所构建的CQDs-CuNCs比率型荧光探针能够用于食品中Hg2+的快速、准确检测。     

A Quninolylthiazole Derivatives as an ICT-Based Fluorescent Probe of Hg(II) and its Application in Ratiometric Imaging in Live HeLa Cells

As a structural analogue of pyridylthiazole, 2-(2-benzothiazoyl)-phenylethynylquinoline (QBT) was designed as a fluorescent probe for Hg(II) based on an intramolecular charge transfer (ICT) mechanism. The compound was synthesized in three steps starting from 6-bromo-2-methylquinoline, with moderate yield. Corresponding studies on the optical properties of QBT indicate that changes in the fluorescence ratio of QBT in response to Hg(II) could be quantified based on dual-emission changes. More specifically, the emission spectrum of QBT before and after interactions with Hg(II) exhibited a remarkable red shift of about 120 nm, which is rarely reported in ICT-based fluorescent sensors. Finally, QBT was applied in the two-channel imaging of Hg(II) in live HeLa cells.     

在轨光学遥感仪器探测灵敏度的建模分析与应用

在分析光学遥感仪器探测信息中主要噪音源的基础上,提出了一种改进空间结构函数分析的仪器探测灵敏度在轨评价方法,包括：基于多项式递推分解的整体噪音估计模型,以及减小系统误差及修正模数转换噪音影响等基本技术途径.仿真结果证实,该改进算法的噪音估计准确度优于传统的高斯估计和基于外推的结构函数分析方法.针对实际观测数据,在去除模数转换噪音影响后,仪器噪音等效温度差指标的在轨评价准确度可达±0.05 K.该评价方法已在FY-2D静止气象卫星在轨测试中得到成功应用.     

A Highly Selective Fluorescent Probe for Detection of Biological Samples Thiol and Its Application in Living Cells

Probe 1 was designed and synthesized as a new fluorescent molecular probe for thiols in PBS buffer at physiological condition. This fluorescent molecular probe consists of a thiol reaction moiety bound to a coumarin fluorophore. Its fluorescence quantum yield is low, but a drastic enhancement of fluorescence intensity was observed in the presence of thiols. Possible interference with other analytes was examined. Probe 1 displays a highly selective fluorescent enhancement with thiols, and the probe was successfully applied to thiols determination in intracellular, in human urine and blood samples.     

运用响应面分析法优化激光诱导土壤等离子体测试参数

测试参数的选择和优化是进行激光诱导击穿光谱（LIBS）试验的重要步骤之一,合适的测试参数能够保障所得光谱数据的准确性。本研究运用LIBS技术,以土壤中主要元素（硅、铁、镁、钙、铝、钠、钾等）为载体,研究LIBS不同测试参数对元素谱线特性影响,优化得到普适的土壤测试条件。设计了以LIBS系统中激光脉冲能量（LE）、延迟时间（DT）和聚焦透镜到样品的距离（LTSD）三因素的二次中心组合的试验,以土壤中主要元素的特征谱线组合信背比（SBR）Y_SBR为目标函数,分析了三因素之间交互作用对Y_SBR的影响。结果表明：因素DT对Y_SBR的线性效果显著,而LE和LTSD对Y_SBR的线性效果均不显著;三者的交互影响对Y_SBR的交互效果都不显著;对于二次项LE2,DT2和LTSD2对Y_SBR的曲面效应均显著。优化得到最佳的试验条件是：激光能量LE为103.09 mJ,延迟时间为2.92 μs,透镜到样品的距离LTSD为97.69 mm,得到最大组合信背比Y_SBR为198.602。这些测试参数是后期LIBS数据准确分析的前提,为田间实地土壤LIBS检测参数的选择提供重要的借鉴。     

A Rapid Near-Infrared Fluorescent Probe for Cysteine Based on Isophorone and its Application in B16 Cell Imaging

A novel near-infrared fluorescent probe SWJT-5 based on dicyanoisophorone was synthesized. It achieved the rapid (within 40 s) and discriminative detection of Cys over Hcy and GSH with a large Stokes shift (205 nm). It showed high selectivity and sensitivity for Cys, and had an obvious enhancement of fluorescence emission. The detection limit was 0.43 μM. This probe also had low background interference and little damage to biological samples. Therefore, SWJT-5 had been applied to bioimaging in living cells successfully.

     

A Turn Off Fluorescence Probe Based on Carbon Dots for Highly Sensitive Detection of BRCA1 Gene in Real Samples and Cellular Imaging

Journal of Fluorescence - In this research, DNA-modified carbon dots (CDs) were exploited to construct a fluorescence assay for breast cancer genes (BRCA1, a potential marker for cancer diagnosis)...     

土壤中铅、砷、铬、铜和锌含量的连续快速测定

建立了土壤中铅、砷、铬、铜和锌含量的连续快速测定方法。土壤样品经微波消解,用同一份消解液,分别连续测定土壤中的铅、砷、铬、铜和锌含量,铬、铜和锌采用火焰原子吸收光谱法,铅和砷采用氢化物发生-原子荧光光谱法。采用本方法,对环境土壤标准样品ESS-1黑钙土(GSBZ50011)和ESS-3红壤(GSBZ50013)进行多次测定,检测结果与标样的推荐值吻合。经统计计算,回收率为95.2%—103.6%,精密度RSD均小于7%。本法操作简单快速,光谱测定结果已成功地用于无公害水果和蔬菜生产基地的土壤环境质量评价。     

A New Fluorescent Probe, ABM: Properties and Application in Clinical Diagnostics

Properties of benzanthrone aminoderivative ABM (conditional name) as a potential fluorescent probe were investigated. Spectral characteristics of the compound in different solvents as well as their binding to model lipid membranes (liposomes) and human peripheral blood mononuclear cells (lymphocytes; ly) were determined. The fluorescence was found to be sensitive polarity changes to the environment. Distinctions were observed in the spectral characteristics of the investigated compound when bounded to liposomes. It was established that spectral characteristics of ABM in cell suspension qualitatively characterize the structural and functional alterations of ly during pathological phenomena and correlate directly with the clinical view of disease. The ABM is shown to be a perspective in the screening for various pathologies.     

A Sensitive and Selective Fluorescent Coumarin-Based Probe for Detection of Hypochlorite ion and its Application to Cellular Imaging

Selective, sensitive fluorescent probes for ClO^? are desirable due to the importance of ClO^? in biological processes. Herein, a readily available turn-off fluorescent probe for ClO^? is reported, which displays highly selectivity and sensitivity over other common anions and reactive oxygen/nitrogen. Moreover, it is able to detect ClO^? in Ramos cells via cellular imaging.     

海水硝酸盐/亚硝酸盐原位快速测量仪

基于SIA顺序注射法以及分光光度原理研制了海水硝酸盐/亚硝酸盐原位快速测量仪。对最佳不完全显色反应时间以及硝酸盐镉铜柱还原速度进行了实验优化筛选,采用液芯波导替代比色皿作为样品池,在实现原位快速测量(测量时间可短至4 min)的同时也大大减少了样品量,缩小了仪器体积、 重量,降低了仪器功耗,提高其灵敏度(nmol·L-1),使其更适于原位测量。仪器具有良好的通用性和可扩展性,稍作调整,即可用于不同海域各种营养要素的剖面及定点测量。     

乌洛托品的表面增强拉曼光谱研究及其在粉丝快速检测中的应用

计算了乌洛托品的拉曼光谱,并以银溶胶为活性基底研究了乌洛托品的表面增强拉曼光谱(SERS)。研究了氯化钠作为促凝剂时的增强效果,结果表明对于银溶胶氯化钠有很好的优化作用。测量不同浓度乌洛托品溶液的SERS,当乌洛托品水溶液浓度低至10-8 g/mL时,依然可以得到明显的拉曼光谱信号。选择1052cm-1处的拉曼特征峰作为研究对象,建立了乌洛托品SERS特征峰强与水溶液浓度之间的函数关系。将这种乌洛托品的检测方法应用于粉丝样品的检测之中,检测下限为10-6g/mL。此种方法操作简便快捷,在粉丝中乌洛托品的快速定性检测方面具有特有的优势。     

Fluorescence and HPLC Detection of Hydroxyl Radical by a Rhodamine-Nitroxide Probe and its Application in Cell Imaging

A rhodamine nitroxide probe was designed to detect the hydroxyl radical (·OH), which presented high selectivity for ·OH over other reactive oxygen species (ROS) and linear fluorescence response to ·OH produced by Fenton reaction. The product was detected by HPLC-MS, indicating that the main product of the reaction was O-methylhydroxylamine and the product peak areas measured by HPLC-UV/vis and HPLC-FLD both enhanced proportionally with the increase of ·OH concentration. The application of the probe in biological system was explored to trace the production of ·OH in cells under oxidative stress condition induced by rotenone which can inhibit the mitochondria respiratory chain complex I and we found that appropriate rotenone may induce the normal human liver cells (L02) and human hepatoma cells (HepG2) to produce ·OH at different degrees.     

阳离子铝酞菁红区荧光探针在纳克级RNA定量分析中的应用

荷正电的四取代三甲基碘化铵铝酞菁(Tetra(trimethylammionio) aluminum phthalocyanine,TTMAAlPc)是新近出现的、很有应用潜力的新型红区荧光化合物。研究表明,弱碱性条件,RNA对TTMAAlPc的荧光具有高效猝灭作用,且猝灭程度与RNA含量呈线性正相关。据此发现建立了可测定纳克级RNA的高灵敏定量分析新方法,并对原理进行了讨论。考察了pH、缓冲体系、反应时间、温度、TTMAAlPc浓度的影响,确定了最佳反应条件(pH 8.0的广泛缓冲液、反应5 min、室温、浓度为2×10-6 mol·L-1的TTMAAlPc)。在最佳条件下,方法的线性回归方程为y=-15.0+0.51x,相关系数r=0.998 6,线性范围7.71~1 705.57 ng·mL-1,检测限为1.55 ng·mL-1。本法灵敏度高、线性范围宽、对RNA测定常见干扰物质包括阴、阳离子、表面活性剂和维生素等的抗干扰能力强,且操作简便。该法应用于实际样品RNA含量的测定,取得了满意的结果。还以参比法首次测定了不同pH下TTMAAlPc的荧光量子产率,结果显示TTMAAlPc具有较高的荧光量子产率,且对大范围的酸度稳定,表明TTMAAlPc是极具应用潜力的新型红色荧光探针,值得深入研究,开拓其应用。     

扫描近场光学显微镜探针与光场相互作用的分析

采用时域有限差分方法对镀金属膜光纤探针在近场光探测中对光场产生的扰动和相互作用过程进行了数值分析。选择纳米孔径的隐失场光场和镀金属膜光纤探针建立了近场光探测的理论模型,讨论了探针孔径尺寸、扫描高度等因素对光场探测的影响,以及测量光场与初始光场之间的关系等。研究结果表明,当探针孔径尺寸与待测纳米孔径尺寸相当,探针扫描高度在接近探针孔径尺寸的一半时,测量得到的光场分布数据能够准确描述初始光场分布。     

Determination and Control of Pesticide Residues in Beverages: A Review of Extraction Techniques,Chromatography, and Rapid Detection Methods

Abstract

We present a review concerning the determination and control of pesticide residues and transformation products in beverages. We review preparation methods using microextraction techniques, which are time-consuming, inexpensive, simple, and endeavor to be environment friendly. Mass spectrometry (MS) and tandem mass spectrometry (MS/MS) technologies are able to detect and quantify matrix-induced chromatographic response effects (matrix effects) accurately, even with the low milligram per kilogram levels. Rapid detection technology is an important tool in food product analysis. We review the technology to analyze the persistence of pesticide residues in beverages in order to effectively control their quality and safety.     

表面增强拉曼光谱准确检测玉米中杀螟硫磷农药残留

杀螟硫磷是一种在农作物上广泛使用的有机磷杀虫剂,常用于玉米上害虫的防治。过量或者不合理施用导致的残留积累关系到食品安全和人体健康。常规检测杀螟硫磷的方法有气相色谱-质谱法、高效液相色谱法,其准确性虽好,但存在需要专业人员介入、样品前处理复杂、检测时间长等缺点。表面增强拉曼光谱(SERS)法具有分析速度快、检测灵敏度高和特异性好等优点,被广泛应用于农产品中痕量残留的快速检测。利用表面增强拉曼光谱结合化学计量学方法实现玉米中杀螟硫磷残留的准确检测。以两步种子生长法合成的纳米金棒作为拉曼增强基底,测量600～1 800 cm-1范围内的拉曼光谱。对比杀螟硫磷乙醇溶液和金棒的光谱,确定杀螟硫磷的特征峰在650,830,1 082,1 241,1 344和1 581 cm-1处。采用简单预处理方法快速提取玉米中的杀螟硫磷残留。将受污染的玉米样品粉碎后,利用乙醇溶剂对残留进行两次提取,每次获取的提取液经离心获得上清液,将上清液合并混匀,在水浴中蒸发浓缩,浓缩后的上清液用于采集SERS光谱。每个浓度制备50个平行样本。各浓度残留提取液中的残留参考值采用色质联用方法测定。对比残留提取液的光谱,1 082,1 241和1 581 cm-1处特征峰强度随残留浓度的降低而迅速变弱甚至消失,650,830和1 344 cm-1处的特征峰直至残留浓度为0.48 μg·mL-1时依然可见。当浓度低至0.37 μg·mL-1时,所测光谱与空白提取液光谱相似。采用主成分分析(PCA)提取不同浓度杀螟硫磷残留光谱的主体信息,其中残留为0.37 μg·mL-1和空白提取液光谱的主成分得分重叠,进而判断SERS方法对玉米中杀螟硫磷残留的检测限可达到0.48 μg·mL-1,低于国家规定的农作物中最大残留限,体现出SERS检测的高灵敏性。选取浓度为14.25 μg·mL-1的50个样本分析其650,830和1344 cm-1处的特征峰强度变化可知,所采集的光谱呈现出较好的重复性,相对标准偏差(RSD)值仅为3.12%。对杀螟硫磷残留的定量分析采用支持向量机回归(SVR)实现,Savitzky-Golay卷积平滑和小波变换(WT)用于本次光谱数据的预处理。校正集和预测集样本的划分采用Kennard-Stone算法实现,模型的性能采用校正均方根误差(RMSEC)、校正集决定系数(R2_c)、预测均方根误差(RMSEP)和预测集决定系数(R2_p)评估。最优模型为SVR结合WT所构建的,具有最小的预测误差,其中校正集的RMSEC=0.103 2 μg·mL-1,R2_ｃ=0.999 74,预测集的RMSEP=0.134 1 μg·mL-1,R2_p=0.999 60。同时,最优模型的预测值与色质联用法所测值基本一致,其预测回收率为95.31%～100.66%。以上表明,SERS结合化学计量学方法检测玉米中杀螟硫磷残留是准确可行的,且有望推广到农作物中多种农药残留的检测,为农产品的安全检测提供一种新思路。