蛋白质对溴鼠灵的荧光增敏及分析应用

实验发现, 牛血清白蛋白可以大大增强杀鼠剂溴鼠灵的荧光. 利用荧光猝灭法考察了溴鼠灵和牛血清白蛋白的相互作用. 结果表明溴鼠灵对牛血清白蛋白的内源荧光有较强的猝灭作用, 两者形成了新的复合物, 属于静态荧光猝灭. 跟据荧光增敏现象, 建立了水溶液中测定溴鼠灵的荧光方法. 在优化实验条件下, 线性范围为5.0×10-8～4.0×10-7 mol/L和4.0×10-7～1.5×10-5 mol/L, 检出限为5.9×10-9 mol/L. 该方法用于渠水中微量溴鼠灵的测定, 回收率为94.1%～101.3%.     

RhB/Chitosan/SiO_2荧光纳米粒子的制备及Cu~(2+)检测应用

采用反相微乳液法合成了Chitosan/SiO_2纳米粒子,通过振荡组装将荧光染料罗丹明B(RhB)固定于该纳米粒子上,制备成RhB/Chitosan/SiO_2纳米粒子。基于Cu~(2+)对Rh B/Chitosan/SiO_2纳米粒子的荧光猝灭作用建立了定量测定Cu~(2+)的荧光分析方法,探讨了测定机理,优化了实验条件。在优化条件下,Cu~(2+)浓度与体系荧光猝灭值在2. 4×10~(-7)～2. 5×10~(-5)mol/L范围内呈线性关系,线性方程ΔF=2. 98×10~7c+612. 11(r=0. 997),检出限为0. 22μmol/L (3s/k),方法用于延河水中Cu~(2+)的测定,加标回收率为98. 7%～103. 3%。     

基于罗丹明B/壳聚糖/SiO_(2)纳米粒子的荧光分光光度法检测苦味酸北大核心CSCD

本文基于苦味酸对罗丹明B(RhB)的荧光猝灭作用,以RhB/壳聚糖(CS)/SiO_(2)纳米粒子为探针,建立了一种检测苦味酸的荧光分析新方法。实验采用反相微乳液法,以CS为模板合成了CS/SiO_(2)纳米粒子,然后通过振荡组装制备得到RhB/CS/SiO_(2)纳米粒子,并基于苦味酸对RhB/CS/SiO_(2)纳米粒子的荧光猝灭作用实现了苦味酸的检测。在优化的实验条件下,5.0×10^(-6)~6.0×10^(-4)mol/L浓度范围内苦味酸与体系荧光猝灭值呈线性关系(r=0.9990),检出限为3.0×10^(-6)mol/L。方法用于水样中苦味酸的测定,回收率在98.0%~100.4%之间。     

5-BrSAF-盐酸头孢他美酯荧光体系的研究及分析应用

在p H 7.40的磷酸盐(PBS)缓冲溶液中,盐酸头孢他美酯(CPH)可使5-溴水杨基荧光酮(5-Br SAF)的内源性荧光显著猝灭,据此建立了荧光猝灭法测定CPH的新方法。CPH的浓度在8.0×10-10~1.8×10-8mol/L范围内与体系的荧光猝灭值△F呈良好的线性关系,方法检出限为3.8×10-10mol/L,相对标准偏差为1.8%(n=5,c=8.0×10-9mol/L)。方法用于样品中CPH的测定,回收率为98.0%~103.5%。对体系的猝灭机理进行了研究,通过测定荧光寿命、探讨温度对猝灭常数的影响以及紫外吸收光谱的变化,确定CPH与5-Br SAF之间的猝灭过程为静态猝灭。     

非诺呋他林猝灭BSA荧光的机理研究及分析应用

在pH=7.4的Tris-HCl缓冲溶液中,非诺呋他林对牛血清白蛋白(BSA)的荧光有明显的猝灭作用,据此提出了以BSA为荧光试剂,利用其内源性荧光的变化来测定非诺呋他林的荧光分析新方法。在选定的实验条件下,非诺呋他林浓度在8.0×10-9~2.8×10-7 mol/L范围内与荧光猝灭值△F呈良好的线性关系(相关系数为0.9955),方法检出限为5.4×10-9 mol/L,相对标准偏差为0.86%(c=2.0×10-7 mol/L,n=5)。该方法用于样品中非诺呋他林的测定,结果满意。同时对体系的猝灭机理进行了研究。     

基于纳米金-罗丹明B体系检测甲巯咪唑的研究

基于不同聚集态金纳米粒子(Au NPs)对罗丹明B(Rh B)的荧光猝灭作用,建立了一种简单、灵敏、快速测定药物甲巯咪唑的新方法。初步探讨了方法机理,并对p H值、反应时间、Au NPs和Rh B的浓度等实验条件进行了优化。优化实验条件下,方法的线性范围为4.38×10-8~0.876×10-5mol/L,检出限(S/N=3)为3.30×10-8mol/L。该法用于甲巯咪唑药品中甲巯咪唑的测定,获得了满意结果。     

基于石墨相氮化碳的荧光法检测过氧化氢

利用热解法合成了石墨相氮化碳(g-C_3N_4)纳米片,邻苯二酚(CA)在辣根过氧化物酶(HRP)和H2O2的催化氧化作用下形成的邻苯醌能有效猝灭g-C_3N_4的荧光。研究了不同反应条件对荧光猝灭效率的影响。在最佳条件下,g-C_3N_4的荧光猝灭效果与H_2O_2的浓度之间存在良好的线性关系,其线性范围为5.0×10~(-8)~7.0×10~(-5)mol/L,检出限为1.6×10-8mol/L。方法已用于牛奶中H_2O_2含量的检测。     

AgInS_2∶Mn@ZnS量子点在测定胰蛋白酶中的应用

基于胰蛋白酶能够选择性地猝灭AgInS_2∶Mn@ZnS量子点(QDs)的荧光和磷光,建立了一种检测胰蛋白酶的新方法。实验考察了AgInS_2∶Mn@ZnS QDs对常见蛋白质的选择性以及酸度的影响,优化了测定胰蛋白酶的条件。结果表明,在pH=8.0的磷酸盐缓冲溶液中,荧光猝灭法测定胰蛋白酶的线性范围为5.0×10~(-7)~4.0×10~(-6)mol/L(R=0.9975),检出限为5.0×10~(-8) mol/L;磷光猝灭法测定胰蛋白酶的线性范围为5.0×10~(-7)~3.5×10~(-6) mol/L(R=0.9940),检出限为4.7×10~(-8) mol/L。不同加标水平下的加标回收率在94.1%~107.2%之间,相对标准偏差小于3%。该方法成功地应用于尿样中胰蛋白酶的测定。     

海藻酸钠-纳米金复合物荧光猝灭法测定纺织品中的铬(Ⅵ)

生态纺织品中铬(Ⅵ)含量有严格的限制.本实验利用海藻酸钠一步法成功合成了纳米金溶胶,并对其荧光特性进行了研究.结果表明,海藻酸钠-纳米金复合物(AuNPs-SA)在激发波长λex=330 nm处表现出最强荧光特性,在该激发波长下,最大发射波长λem=415 nm.铬(Ⅵ)对海藻酸钠-纳米金复合物的荧光有猝灭效应,纳米金荧光强度随铬(Ⅵ)浓度的增加而减弱,利用其荧光猝灭特性建立了铬(Ⅵ)定量分析方法.调节AuNPs-SA溶液至pH 7.0,加入Cr(Ⅵ),反应40 min后,测定荧光强度变化.铬(Ⅵ)浓度在1.0×10-8～9.0×10-8 moL/L范围内与F/F0有较好的线性关系(R=0.9919),方法的检出限(S/N=3)为5.0×10-9 mol/L.本方法用于纺织品中苎麻与涤纶的痕量铬(Ⅵ)的检测,所得结果与国家标准方法(GB/T 17593.3-2006)没有显著性差异.     

Tb3+-钛铁试剂络合物荧光猝灭法测定含磷酸基辅酶

含磷酸基辅酶磷酸吡哆醛(PALP)、烟酰胺腺嘌呤二核苷酸(NAD)、烟酰胺腺嘌呤磷酸二核苷酸(NADP)、黄素腺嘌呤二核苷酸(FAD)可显著猝灭铽-钛铁试剂(Tb3 -TR)络合物的荧光,其荧光猝灭值△F=F0-F分别与PALP、NAD、NADP和FAD的浓度呈线性关系。分别对测定条件进行了优化,并研究了干扰物质情况,建立了Tb3 -TR络合物荧光探针灵敏测定PALP、NAD、NADP和FAD的方法。PALP、NAD、NADP和FAD的检出限分别为:1.1×10-7mol/L、6.4×10-8mol/L、1.6×10-8mol/L和1.15×10-8mol/L。     

Fluorescence quenching method for the determination of catechol with gold nanoparticles and tyrosinase hybrid system

<正>The determination method of catechol by fluorescence quenching was developed.The assay was based on the combination of the unique property of gold nanoparticles with tyrosinase enzymatic reaction.In the presence of tyrosinase,the fluorescence of gold nanoparticles was quenched by catechol which can be employed to detect catechol.Under the optimal conditions,a linear range 5.0×10~(-7)-1.0×10~(-3) mol L~(-1) and a detection limit 1.0×10~(-7) mol L~(-1) of catechol were obtained.o-Quinone intermediate produced from the enzymatic catalyzed oxidation of catechol was considered to play the main role in the fluorescence quenching.     

Encoded and enzyme-activated nanolithography of gold and magnetic nanoparticles on silicon

A C18 monolayer-functionalized Si surface is electrochemically patterned to yield a carboxylic acid-terminated pattern. Tyramine is covalently linked to the pattern to yield an encoded nanostructure for the enzyme tyrosinase. The biocatalytic oxidation of the tyramine residues yields catechol moieties that control the assembly of boronic acid-functionalized Au nanoparticles (NPs) or magnetic NPs. The different NPs are linked to the patterns by the formation of complexes between the boronic acid residues or Fe3+ ions and the catechol ligands.     

Ultrasensitive determination of 1,4-dihydroxybenzene based on fluorescence resonance energy quenching of luminescent quantum dots modified on surface of silica nanoparticles

An ultrasensitive solid-phase fluorescence resonance energy quenching (FREQ) method for determination of 1,4-dihydroxybenzene (DHB) using mercaptosuccinic acid (MSA)-capped CdTe quantum dots (QDs) immobilized on silica nanoparticles (NPs) as donors was developed. In the method, silica NPs were first modified with 3-aminopropyltriethoxysilane (APTS). Then, MSA-capped CdTe QDs were immobilized on the surface of the APTS-modified silica NPs. Finally, DHB in the solution was attached to the empty sites on the surface of silica NPs with QDs through electrostatic interaction. The fluorescence emission of the QDs was quenched by the proximal DHB molecules on the silica NPs. The quenching efficiency of the solid-phase FREQ method was 200-times higher than that of the solution-phase FREQ method. Using the ultrasensitive solid-phase FREQ method, DHB as low as 2.4 × 10⁻¹² mol/L could be detected. The method was applied to quantify trace DHB in water samples.     

Effects of Fumed Silica on the Viscosity of Acrylic Latex System

Effects of fumed silica on the viscosity of acrylic latex system were studied by recording curves of the shear complex viscosity over shear rate and temperature and by measuring apparent viscosity with a variety of fumed silica concentrations at various steady angular velocities. Results show that the fumed silica obviously affects the shape and value of curves on the amplitude of complex viscosity versus either shear rate or temperature diagrams. Both dynamic and steady shear measurements illustrate a shear thinning phenomena for the acrylic latex filled with fumed silica. Dependence of the apparent viscosity on the fumed silica concentration can be satisfactorily modeled by the Krieger‐Dougherty expression. A fitted parameter that quantitatively describes the sensitivity of the effect of fumed silica on the acrylic latex system increases with angular velocity, but decreases with latex solid content.     

Fluorescence assay of catecholamines based on the inhibition of peroxidase-like activity of magnetite nanoparticles

We report a fluorescence approach for the highly selective and sensitive detection of catecholamines using magnetite nanoparticles (Fe₃O₄ NPs) in the presence of Amplex UltraRed (AUR) and H₂O₂. Fe₃O₄ NPs catalyze H₂O₂-mediated oxidation of AUR. The resulting product fluoresces (excitation/emission maxima, ca. 568/587 nm) more strongly, relative to AUR. When catecholamines bind to Fe₃O₄, the complexes that are formed induce decreased activity of Fe₃O₄ NPs, mediated through the coordination between Fe³⁺ on the NP surface and the catechol moiety of catecholamines. As a result, Fe₃O₄ NPs-catalyzed H₂O₂-mediated oxidation of AUR is inhibited by catecholamines. The limits of detection for dopamine (DA), l-DOPA, norepinephrine, and epinephrine were 3 nM, 3 nM, 3 nM, and 6 nM, respectively. The Fe₃O₄ NPs-H₂O₂-AUR probe exhibited high selectivity (>1000-fold) toward catecholamines over other tested biomolecules that commonly exist in urine. Four catecholamines had similar sensitivity because the inhibition of the Fe₃O₄ NPs activity relies on the presence of the catechol moiety. This approach also allowed the determination of tyrosinase activity because tyrosinase catalyzes the conversion of l-tyrosine to l-DOPA. We validated the practicality of the use of the Fe₃O₄ NPs-H₂O₂-AUR probe for the determination of the concentrations of DA in urine samples.     

Hydrophobicity modification of woven cotton fabric by hydrophobic fumed silica coating

Water repellency of woven cotton fabric was achieved by coating with the aqueous dispersion containing organosilane agent (HDTMS) and fumed silica. The coating agents were applied using padding method and then followed by batching the coated fabric at the ambient temperature for 24 h to allow the condensation reaction between HDTMS silanol group and fumed silica silanol group, rendering silica particles hydrophobic. An ultrasonicator was employed to prepare the homogenous coating dispersion. The water repellency evaluated by water contact angle determination which showed the contact angle over 110° was obtained with low amount of applied HDTMS of 1 wt%. The effect of fumed silica addition on an increase in fiber surface roughness geometry showed the influential result in improving the water contact angle. From durability to washing test, the hydrophobic coatings evidenced from SEM and ATR/FTIR remained adhering to fiber surface, indicating the durability. After washing, the coating on the fabric with fumed silica addition appeared to be scatter particles which made a contribution to the higher contact angle value when compared to sheet-like layer coating in case of HDTMS coating alone.     

Novel Surface-Enhanced Fluorescence D Etection of Polynuclear Aromatic Hydrocarbons Separated by Paper Chromatography

Abstract

Amorphous famed silica was used to enhance the fluorescence signal of a mixture of polynuclear aromatic (PMA) compounds separated by paper chromatography. Benzo[a]pyrene-r-7, t-8, 9, 10-tetrahydrotetrol (BPT) and benzo[a]pyrene (BaP) were well resolved by paper chromatography using a 50% (v/v) mixture of acetonitrile and 5 mM pH 7.0 phosphate buffer as the chromatographic solvent. A 200–400% enhancement of the fluorescence intensity was observed when fumed silica was applied to the chromatographic paper prior to separation. the results demonstrate that paper chromatography using fumed silica treated paper offers a simple, cost-effective method to improve sensitivity for fluorescence detection of PNA components in environmental samples relative to untreated paper.     

化学反应-顶空气相色谱法测定气相二氧化硅表面硅羟基

建立了一种基于化学反应-顶空气相色谱测定气相二氧化硅表面硅羟基含量的新方法.实验取气相二氧化硅放入顶空瓶中于105℃烘箱中加热2 h去除水分,将甲苯稀释的格氏试剂注入密闭的顶空瓶中,格氏试剂与气相二氧化硅表面硅羟基快速反应产生甲烷(CH4),甲烷量与气相二氧化硅表面硅羟基含量成正比.经过气相色谱-氢火焰离子化检测器测定...     

A disposable, screen-printed electrode for the amperometric determination of azide based on the immobilization with catalase or tyrosinase.

A disposable, screen-printed electrode based on the immobilization of catalase or tyrosinase was developed to construct biosensors for the amperometric determination of azide. The determination principles for azide by these two methods are based on inhibiting the enzymatic consumption of an electrode-detectable substance (hydrogen peroxide or catechol) on an enzyme-immobilized electrode. Both of these methods show a sensitive detection range and a short measuring time.     

An optical catechol biosensor based on a desert truffle tyrosinase extract immobilized into a sol–gel silica layered matrix

An optical biosensor for the determination of catechol, a widely used yet toxic and carcinogenic molecule, is proposed using a crude extract of desert truffle (Terfezia leonis Tul.) as an enzymatic source of tyrosinase. The biosensor is constructed by the immobilization of tyrosinase crude extract in a bi-layered silica gel film prepared by dip-coating of an alkoxide/colloidal silica solution containing the enzyme on glass slide. Encapsulation has a moderate effect of the enzyme optimal pH stability but largely increases its thermal stability. Immobilized enzymes have a higher substrate affinity towards catechol but smaller maximum conversion velocity. The optical biosensor provides a linear response for catechol in the concentration range of 50–400?µM and a limit of detection was 52?µM. AFM studies show that the enzymes impact on the silica gel structure, preventing further deposition of additional layers. Comparison with similar dopamine biosensors points out that the impact of encapsulation on enzymatic activity may depend on the considered substrate.

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