Ag@SiO_2/ZnO@SiO_2的制备及其对水溶液中生物分子的分析检测

采用一种操作简单、反应条件温和的方法在室温下制备了Zn O@SiO2和Ag@SiO2/Zn O@SiO2,利用透射电子显微镜(TEM)、紫外吸收光谱(UV)、荧光光谱(FL)、纳米粒度和ZETA电位分析仪等技术对所制备纳米粒子的粒径大小、吸收光谱、发光性质进行表征。结果表明,Zn O@SiO2核壳量子点的平均粒径为3~8 nm,最大紫外吸收波长在330 nm左右,可发射510 nm的黄绿色荧光。而Ag@SiO2增强了Zn O@SiO2核壳量子点的荧光,未改变Zn O@SiO2核壳量子点的发射峰位置,同时Ag@SiO2显著增强了Zn O@SiO2核壳量子点的荧光稳定性。利用L-半胱氨酸和血红蛋白对量子点荧光不同程度的猝灭作用,建立了一种简单、快速、灵敏的检测分析方法。在最佳条件下,L-半胱氨酸和血红蛋白的浓度分别在0.068~10.10 mg/L和4.00×102~4.00×103mg/L范围内与溶液的荧光强度呈良好的线性关系,相关系数(r2)分别为0.993 8和0.995 1,以3.37 mg/L的L-半胱氨酸标准溶液进行11次平行实验,相对标准偏差(RSD)为1.3%,以3倍标准偏差计算检出限为6.92×10-3mg/L。以2.00×103mg/L的血红蛋白标准溶液进行11次平行实验,相对标准偏差为2.5%,以3倍标准偏差计算检出限为2.04 mg/L。     

富镉离子CdS量子点电化学发光法检测L-半脐氨酸

采用一锅法,通过控制镉硫比合成了表面富镉离子的硫化镉量子点,利用L-半胱氨酸可与量子点表面Cd2+结合,使量子点表面钝化,从而增强其电化学发光信号的性质,实现了对L-半胱氨酸的选择性检测.对合成的量子点进行了表征,优化了检测条件.在优化的条件下,L-半胱氨酸在5.0×10-9~1.0×10-5 mol/L浓度范围内与ECL信号呈良好的线性关系,检出限为1.2×10-9 mol/L(S/N=3).本方法对L-半胱氨酸具有良好的选择性,用于实际样品中L-半胱氨酸的测定,结果令人满意.     

迷迭香酸的CdTe量子点荧光探针同步荧光法测定

基于迷迭香酸对CdTe量子点荧光的猝灭效应,建立了一种高灵敏度的测定微量迷迭香酸的同步荧光法.在pH 5.7的缓冲溶液中,当固定波长差为210 nm时,CdTe量子点的同步荧光最大发射波长位于320 nm.在最佳实验条件下,迷迭香酸质量浓度在0.36 ～11.52 mg·L-1(1.00×10-6 ～3.20×10-5 mol/L)范围与CdTe量子点的同步荧光强度存在良好的线性关系.其线性回归方程为I0F/IF=0.931 7+0.128 9 ρ(mg·L-1),相关系数r=0.998 2,检出限为0.16 mg·L-1.10次重复测定2.16 mg·L-1 的迷迭香酸,相对标准偏差为2.8%.同时对其同步荧光猝灭机理进行了探讨.     

基于CdTe量子点的荧光猝灭-恢复法测定L-半胱氨酸

以巯基乙酸为稳定剂,合成了水溶性CdTe量子点(QDs),基于Ni~(2+)存在下,利用CdTe QDs荧光猝灭-恢复技术,建立了测定L-半胱氨酸的新方法。考察了缓冲溶液pH及Ni~(2+)浓度等对测定的影响。在pH=10.0的硼砂缓冲溶液中,Ni~(2+)浓度为40μmol/L条件下,L-半胱氨酸浓度在6.0×10~(-6)~5.0×10~(-5) mol/L范围内与量子点荧光恢复程度呈良好的线性关系,相关系数为0.9990,方法的检出限为2.1×10~(-6) mol/L。该方法应用于果汁和蜂蜜样品中L-半胱氨酸的检测,结果满意。     

酶抑制动力学光度法测定L-半胱氨酸

利用L-半胱氨酸对血红蛋白模拟酶催化体系的抑制作用,建立了酶抑制动力学光度法测定L-半胱氨酸的新方法。研究了该抑制反应的最佳实验条件及动力学行为,测定的线性范围为2.2×10-7~8.8×10-6mol/L,检出限为5.4×10-8mol/L。对浓度为7.8×10-6mol/L的L-半胱氨酸进行11次平行测定,其相对标准偏差为4.1%。该法已用于明胶中L-半胱氨酸的测定。     

基于Cu2-x Se纳米颗粒与罗丹明B的能量转移测定L-半胱氨酸

以硒化铜纳米颗粒为能量受体,以罗丹明B为能量供体,二者之间通过光诱导电子转移而猝灭罗丹明B的荧光;而 L-半胱氨酸能够诱导罗丹明 B 荧光的恢复,从而建立了测定 L-半胱氨酸的新方法。在pH 4.6、温度为30℃条件下混合2 mun后,罗丹明B在575 nm处的荧光强度与溶液中L-半胱氨酸的浓度在2.5×10-7~1.1×10-6 mol/L浓度范围内呈良好的线性关系,检出限(3σ/k)为5.5×10-8 mol/L。常见的氨基酸对半胱氨酸的测定干扰小,方法快速、选择性好。     

基于L-半胱氨酸功能化的MoS_2荧光量子点检测Hg~(2+)

本文采用水热法,以Na_2MoO_4为钼源,L-半胱氨酸作为硫源及稳定剂,合成荧光二硫化钼量子点(MoS2QDs),利用紫外-可见光谱、荧光光谱和红外光谱对量子点的结构和性能进行了表征。所合成MoS2QDs呈现较强蓝色荧光的性能,并具有较好的分散性。MoS_2QDs作为探针与Hg~(2+)作用后产生荧光猝灭现象,由此建立了一种测定Hg~(2+)的荧光分析新方法。该方法对Hg~(2+)测定的线性范围是5.0×10-7~2.0×10-4 mol/L,检测限为2.3×10-7 mol/L,相关系数为0.998。该方法具有操作简单、灵敏度高和选择性好等特点,可用于自来水水样中痕量Hg~(2+)的测定。     

5,5′-二硫硝基苯甲酸柱前衍生高效液相色谱法测定酶促反应液中的L-半胱氨酸

以5,5′-二硫硝基苯甲酸(DTNB)为柱前衍生试剂对酶促反应液进行衍生化,用C18色谱柱在室温下采用二元梯度洗脱,于330 nm波长下检测,同时以2-巯基乙醇和二硫苏糖醇(DTT)为对照,对L-半胱氨酸的分离峰进行确认,并对酶促反应液中的L-半胱氨酸进行分离测定。L-半胱氨酸浓度为5~950 μmol/L时,其浓度与峰面积呈显著的线性关系。高、中、低浓度水平的L-半胱氨酸加标回收率为99.7%~100.5%,相对标准偏差小于1.3%,检测限为0.8 μmol/L。方法简便、快速、可靠。用于样品分析,结果     

功能性碲化镉纳米荧光探针荧光猝灭法测定过氧化氢

用L-半胱氨酸作稳定剂制备了碲化镉量子点,并选取回流时间为21 min,具有发射波长为555 13m的量子点作为测定过氧化氢荧光探针.在pH 8.0的磷酸盐缓冲溶液中,过氧化氢与碲化镉量子点反应而使其氧化,导致其荧光的猝灭.结果显示,荧光强度的减弱程度(△F)与过氧化氢的浓度在1.0×10-7～6.0×10-5mol·L-1之间呈线性关系.此方法的检出限(3s/b)为8.0×10-8mol·L-1应用此方法测定了雨水中过氧化氢的含量,并以此样品作基体,用标准加入法进行了回收试验,测得平均回收率为99.5%.     

基于CdSe/ZnS量子点构建丝裂霉素荧光检测体系的研究

建立了一种基于CdSe/ZnS量子点的快速、高效的检测丝裂霉素的荧光方法。pH=7.4,反应10 min,CdSe/ZnS量子点的荧光随丝裂霉素浓度增加而猝灭,量子点的荧光强度与丝裂霉素的浓度呈良好的线性关系,适用于丝裂霉素浓度1.8~60 μmol/L,且相关系数为0.996,丝裂霉素的检测限为0.11 μmol/L,该方法相对无共存物质的干扰,并证明完全适用于丝裂霉素注射液与尿液中丝裂霉素的测定。     

D-Proline capped gold nanoclusters for turn-on detection of serum Raltitrexed

Using D-proline (D-Pro) as the reducing agent and capper, D-Pro@AuNCs was rapidly constructed. Its fluorescence could be quenched by AuNPs. Due to the electrostatic interaction between anticancer drug Raltitrexed (RTX) and AuNPs induced fluorescence "turn-on" principle, the resultant fluorescent probe exhibited good selectivity and sensitivity for detecting RTX in rat serums.     

A Simple and Rapid Label-free Fluorimetric “Turn Off-on” Sensor for Cadmium Detection Using Glutathione-capped CdS Quantum Dots

A convenient label-free fluorescence(FL) nanoprobe for rapid detection of cadmium(Cd) was established using glutathione-capped CdS quantum dots(QDs) and 1,10-phenanthroline(phen). The prepared CdS QDs exhibited a strong FL emission at 536 nm, which could be quenched by phen due to the photoinduced hole transfer(PHT) mechanism. The existence of Cd effectively recovered the FL intensity of CdS QDs, which was due to the easy detachment of phen from the surface of QDs to form[Cd(phen)₂(H₂O)₂]²⁺ in solution. Cd concentrations were linearly correlated with the FL intensity in the range of 0.0625-1.25 μmol/L under the optimized conditions and the detection limit was 0.01 μmol/L. Finally, the Cd concentration was accurately quantified in real water sample using the proposed sensor.     

基于L-半胱氨酸/CdTe量子点修饰电极的电化学传感器的制备及其对Pb~(2+)的检测

成功制备了由L-半胱氨酸和CdTe量子点作为修饰材料的电化学传感器并用于水体中Pb~(2+)的检测。巯基丙酸修饰的CdTe量子点通过水相合成,表面含有大量羧基,与L-半胱氨酸表面的氨基形成酰胺键,修饰于金电极表面。通过荧光分光光度计、透射电子显微镜、红外光谱、X射线衍射对L-Cys/CdTe QDs复合材料进行表征。采用循环伏安法(CV)研究了L-Cys/CdTe QDs修饰成分在金电极上的电化学性能及CdTe量子点的最佳自组装时间。采用差分脉冲溶出伏安法(DPSV)研究了铅离子在修饰电极上的电化学行为。在优化实验条件下,Pb~(2+)浓度在1.0×10~(-6)~1.0×10~(-2) mol/L范围内与其峰电流呈良好的线性关系,相关系数(r2)为0.993 8,检出限(3σ,n=5)为4.0×10~(-7) mol/L。该传感器具有良好的重现性和稳定性,有望用于实际水样中铅离子的检测。     

11-Mercaptoundecanoic acid functionalized gold nanoclusters as fluorescent probes for the sensitive detection of Cu2+ and Fe3+ ions

Metal ions are physiologically essential,but excessive metal ions may cause severe risk to plants and animals.Here,we prepared gold nanoclusters(Au NCs) protected by 11-mercaptoundecanoic acid(11-MUA),which have excellent fluorescence properties for the detection of metal ions.The results showed that the copper ions(Cu~(2+)) and iron ions(Fe~(3+)) in the solution have obvious quenching effect on the fluorescence intensity of Au NCs.The detection range of Fe~(3+) was 0.8–4.5 mmol/L(R~2= 0.992) and 4.5–11.0 mmol/L(R~2= 0.997).And Cu~(2+) has a lower linear range(0.1–1.0 mmol/L,R2= 0.993).When EDTA was added into the reaction system,it was observed that the quenching effect of Cu~(2+) and Fe~(3+)on Au NCs showed different phenomenon.Then,the effect of metal ions on the fluorescence of Au NCs was investigated.The selective detection of Cu~(2+) was achieved by EDTA masking of Fe~(3+).In addition,we realized the metal ions detection application of Au NCs in the serum     

d-Proline capped gold nanoclusters for turn-on detection of serum Raltitrexed

With d-proline as the reducing and capping agent, fluorescent gold nanoclusters were rapidly prepared (d-Pro@AuNCs) within 10 min at 100 °C. In the present of gold nanoparticles, the fluorescence of d-Pro@AuNCs was remarkably quenched. Interestingly, based on the electrostatic interaction between anticancer drug Raltitrexed and gold nanoparticles induced fluorescence “turn-on” principle, a high selective assay for detection of Raltitrexed was established with the probe associating the fluorescence emission at 435 nm. The fluorescence intensity of d-Pro@AuNCs linearly correlated with the concentration of Raltitrexed in the range from 5.0 μmol/L to 40.0 μmol/L (R² = 0.999) and the limit of detection was 1.9 μmol/L. Further, after Raltitrexed was abdominal injected in rats, a metabolic approach was constructed with the prepared fluorescent probe. It showed great potential of AuNCs-based sensing probes for application in analysis of serum anticancer drugs.     

Functionalized cadmium sulfide quantum dots as fluorescence probe for silver ion determination

CdS quantum dots (QDs) modified with l-cysteine has been prepared by one step. They are water-soluble and biocompatible. To improve CdS QDs stability and interaction between silver ion and functionalized CdS QDs in aqueous solution, some amounts of fresh l-cysteine were added to functionalized CdS solution. Based on the characteristic fluorescence enhancement of CdS QDs at 545 nm by silver ions in the presence of some amounts of fresh l-cysteine, simultaneously, a gradual red shift of fluorescence emission bands of CdS QDs from 545 to 558 nm was observed. A simple, rapid, sensitive and specific detection method for silver ion was proposed. Under optimum conditions, the fluorescence intensity of CdS QDs is linearly proportional to silver concentration from 2.0 × 10⁻⁸ to 1.0 × 10⁻⁶ mol/L with a detection limit of 5.0 × 10⁻⁹ mol/L. In comparison with single organic fluorophores, functionalized CdS quantum dots are brighter, more stable against photobleaching, and don’t suffer from blinking. Furthermore, owing to the fluorescence enhancement effect of CdS QDs by silver ion, the proposed method showed lower detection blank and higher sensitivity. Possible fluorescence enhancement mechanism was also studied.     

Determination of silver ion with cadmium sulfide quantum dots modified by bismuthiol II as fluorescence probe

CdS quantum dots (QDs) modified with bismuthiol II potassium salt is prepared in one step. Based on the characteristic fluorescence enhancement of CdS QDs at 480 nm by silver ions, simultaneously, a red shift of fluorescence emission bands of CdS QDs from 460 to 480 nm is observed. A simple, rapid, sensitive and specific detection method for silver ion is proposed. Under optimum conditions, the fluorescence intensity of CdS QDs was linearly proportional to silver ion concentration from 0.01 to 5.0 micromol L(-1) with a detection limit of 1.6 nmol L(-1). In comparison with single organic fluorophores, functionalized CdS quantum dots are brighter, more stable against photobleaching and do not suffer from blinking. Furthermore, the proposed method shows higher sensitivity and selectivity. A possible fluorescence enhancement mechanism is also studied.     

新型荧光分子印迹膜特异性识别和检测目标蛋白质

制备了一种新型荧光分子印迹膜(L-半胱氨酸修饰的量子点嵌入的分子印迹膜(QDs@MIM)),并将其作为荧光人工受体用于目标蛋白质(溶菌酶)的特异性识别和检测。QDs@MIM以溶菌酶为模板分子、丙烯酰胺为功能单体、L-半胱氨酸修饰的量子点为辅助单体、N,N′-亚甲基双丙烯酰胺为交联剂,在预硅烷化的玻璃板上制备而成。在最佳条件下,QDs@MIM对溶菌酶检测的线性范围为0.1~1.0μmol/L,吸附平衡时间为4 min,选择性因子为6.2。该方法操作简单、吸附平衡时间短、选择性高,具备作为生物传感器快速分析样品中目标蛋白质的潜力。     

Gold Nanoclusters Templated by Poly-cytosine DNA as Fluorescent Probes for Selective and Sensitive Detection of Thiocyanate

Gold nanoclusters(AuNCs) were prepared in the presence of the nucleobases of poly-cytosine DNAs in this paper. We have demonstrated tliat the fluorescence of the AuNCs is quenched by thiocyanate(SCN^-) through the interaction between SCN^- and gold atoms. AuNCs can receive energy from nucleobases to boost their emission intensity, while in the presence of SCN^-, they coordinate with Au atoms and influence the energy transfer between the nucleobases and AuNCs, leading to the fluorescence quenching. The decreased fluorescence intensity was in proportion to the concentration of SCN^- in the range of 8.0×10^-7-1.5×10^-5 mol/L with a limit of detection of 4.2×10^-7 mol/L(3σ). We further validated the practice of this probe througli the detection of SCbT in natural water samples.     

Synthesis of positively charged CdTe quantum dots and detection for uric acid

The CdTe dots (QDs) coated with 2-Mercaptoethylamine was prepared in aqueous solution and characterized with fluorescence spectroscopy, UV-Vis absorption spectra, high-resolution transmission electron microscopy and infrared spectroscopy. When the λex=350 nm, the fluorescence peak of positively charged CdTe quantum dots is at 592 nm. The uric acid is able to quench their fluorescence. Under optimum conditions, the change of fluorescence intensity is linearly proportional to the concentration of uric acid in the range 0.4000-3.600 μmol L(-1), and the limit of detection calculated according to IUPAC definitions is 0.1030 μmol L(-1). Compared with routine method, the present method determines uric acid in human serum with satisfactory results. The mechanism of this strategy is due to the interaction of the tautomeric keto/hydroxyl group of uric acid and the amino group coated at the CdTe QDs.