用于检测重金属离子的磁性荧光复合微球

采用静电逐层自组装的方法,首先将PSS和PAH聚电解质交替沉积在CaCO3中空微球表面,然后将Fe3O4磁性纳米粒子与CdSe量子点负载在中空微球表面不同的聚电解质层中,制备出具有磁性和荧光双重功能的复合微球,并将其作为荧光离子探针,研究了其对Cu2+和Pb2+离子检测的灵敏度、选择性及可行性。结果表明,复合微球显示出良好的磁性和荧光性能,对Cu2+和Pb2+离子的检测具有较高的灵敏度和选择性。尤为重要的是,可通过磁分离的方法将微球快速地从待测液中回收,从而能够避免量子点对环境造成的二次污染。     

金属离子对CdS量子点/聚酰胺-胺树形分子纳米复合材料光致发光性能的影响

以聚酰胺-胺树形分子为模板制备了分散好、尺寸均匀的CdS量子点，并用分光光度滴定法研究了Cd²⁺、Zn²⁺、Pb²⁺、Cu²⁺、Mn²⁺几种金属离子对其光致发光性能的影响。发现不同离子对CdS量子点的发光性能影响不同:Cd²⁺和Zn²⁺使量子点荧光增强，Pb²⁺、Cu²⁺和Mn²⁺使其荧光有不同程度淬灭。这归因于金属离子对CdS量子点表面的修饰作用。Cd²⁺能减少由S^2-悬键构成的非辐射复合中心，增强树形分子对量子点表面缺陷的钝化作用，并能在量子点周围形成类肖特基能垒，从而显著增大CdS量子点的光致发光效率。由于ZnS与CdS的晶格参数非常接近，Zn²⁺能起到与Cd²⁺类似的作用，使CdS量子点的发光效率大大增强。Pb²⁺和Cu²⁺能取代Cd²⁺在CdS量子点表面生成窄带隙的壳层，对其发光有很强的淬灭作用。由于块体PbS的带隙比块体CuS窄，故Pb²⁺的淬灭能力强于Cu²⁺。Mn²⁺能破坏Cd²⁺与PAMAM树形分子的配位键，降低树形分子对CdS量子点表面缺陷的钝化作用，且其本身在量子点表面构成了新的荧光淬灭中心，但Mn²⁺也能形成较弱的类肖特基能垒，故对量子点的发光淬灭作用较弱。     

磁性壳聚糖复合微球的制备及其Cu2+吸附性能

以球磨后的粉煤灰磁珠（MS）颗粒为磁核,通过溶胶凝胶法和反相微乳液法依次包覆SiO₂和壳聚糖（CS）,制备了MS@SiO₂@CS磁性微球。利用扫描电镜及能量色散谱仪、热重分析仪、红外光谱仪、X射线衍射仪、振动样品磁强计对所得样品的结构和磁性进行了系统表征。结果表明,磁珠颗粒表面实现了逐层包覆,较均匀的分散于壳聚糖基体中,MS@SiO₂@CS微球的比饱和磁化强度可达7.04 emu·g^-1。Cu²⁺离子吸附实验表明,所得磁性壳聚糖微球对Cu²⁺具有良好的吸附能力,最大吸附量可达11.08 mg·g^-1;而且可通过磁选法高效固液分离。吸附动力学研究表明,MS@SiO₂@CS微球对Cu²⁺离子的吸附符合准二级动力学模型,以化学吸附为主。     

中空纳米二氧化硅复合微球的制备及其对蛋白的亲和分离

利用水热法合成了中空巯基纳米二氧化硅微球(SiO₂-SH), 然后在其表面修饰亚氨基二乙酸基团(-IDA), 形成了中空SiO₂-SH/IDA双功能化纳米微球。利用该纳米微球表面的-SH和-IDA双功能团, 可以更多的吸附溶液中的Ni²⁺, 形成SiO₂-SH/IDA-Ni²⁺复合微球从而可以更好的分离以六聚组氨酸为标签的(His-tagged)蛋白。结果显示制备的样品对分离His-tagged蛋白具有广谱性, 并且具有较好的再生能力。     

中空纳米二氧化硅复合微球的制备及其对蛋白的亲和分离

利用水热法合成了中空巯基纳米二氧化硅微球(SiO₂-SH), 然后在其表面修饰亚氨基二乙酸基团(-IDA), 形成了中空SiO₂-SH/IDA双功能化纳米微球。利用该纳米微球表面的-SH和-IDA双功能团, 可以更多的吸附溶液中的Ni²⁺, 形成SiO₂-SH/IDA-Ni²⁺复合微球从而可以更好的分离以六聚组氨酸为标签的(His-tagged)蛋白。结果显示制备的样品对分离His-tagged蛋白具有广谱性, 并且具有较好的再生能力。     

α-Fe2O3、γ-Al2O3、SiO2混合体系的表面配位反应

运用自动电位滴定技术分别研究了纳米α-Fe₂O₃、γ-Al₂O₃、SiO₂单一体系及三组分混合体系中氧化物表面的酸碱性质和对重金属离子Cu²⁺、Pb²⁺、Zn²⁺的吸附行为. 依据表面配位理论恒电容模式(CCM), 计算了相应的表面酸碱配位常数. 结果表明: α-Fe₂O₃/γ-Al₂O₃/SiO₂三组分混合体系的表面化学反应并非是单一体系的简单叠加, 而是存在着不同矿物表面间复杂的交互作用. 三组分表面酸碱反应平衡式和相应的酸碱反应平衡常数分别为: ≡XOH₂⁺?≡XOH+H⁺ (lgK_a1=-4.23), ≡XOH?≡XO^-+H⁺(lgK_a2=-8.41). 根据重金属离子Cu²⁺、Pb²⁺、Zn²⁺在α-Fe₂O₃/γ-Al₂O₃/SiO₂混合体系表面的吸附行为, 计算得到Cu²⁺、Pb²⁺、Zn²⁺在混合体系表面配位反应及其平衡常数如下: ≡XOH＋M²⁺?≡XOM⁺+H⁺; lgK=-2.20, -1.90, -3.20 (M=Cu, Pb, Zn).     

单分散SnO2中空微纳米球的制备和性质

模板法是制备无机中空微纳米球的重要方法之一. 本文以苯乙烯为单体, 通过乳液聚合得到粒径约为620 nm的单分散聚苯乙烯(PS)微球. 以磺化后的聚苯乙烯(PSS)微球为模板, 利用阴阳离子静电吸附作用, 将PSS与前驱体SnSO₄中的Sn²⁺结合. 通过Sn²⁺在乙醇-水介质中的水解作用得到核-壳复合结构, 再经高温煅烧, 得到SnO₂中空微纳米球. 实验对前驱体的浓度、表面活性剂的用量、反应时间及模板选择等方面做了研究,通过扫描电镜(SEM)、X 射线衍射(XRD)、红外(IR) 光谱、热重分析(TGA)、H₂ 程序升温还原(H₂-TPR)、Brunauer-Emmett-Teller (BET)比表面积等技术深入探究SnO₂中空微纳米球的结构, 并对比中空SnO₂与实心粒子的氧化还原特性. BET和H₂-TPR显示将SnO₂制备成微纳米空心球后其比表面积增大, 表面氧空位明显增多, 氧化活性明显提高. 从IR 及XRD推断核-壳结构形成机理, 进而优化出简单合理的实验方案, 获得表面光滑、结构致密, 包覆厚度可控的SnO₂中空微纳米球.     

螯合树脂研究 Ⅻ.以聚硫醚为主链的异丙巯基胺树脂的合成及其吸附性能

 由聚环硫氟丙烷与多乙烯多胺反应制得的聚合物(PB)再与环硫丙烷反应,合成了四种以聚硫醚为主链的异丙巯基胺树脂(PBM_1-4)。树脂对Au³⁺、Pd²⁺、Pt⁴⁺、Ag⁺和Hg²⁺等离子具有强的吸附能力,对Cu²⁺次之,对Zn²⁺和Pb²⁺很弱。树脂对贵金属具有高的选择性,能从含Au³⁺、Cr³⁺、Co²⁺、Ni²⁺、Cu²⁺、Mn²⁺、Zn²⁺和Fe³⁺的溶液中定量吸附Au³⁺而不吸附其它离子。     

铅离子与镉离子高选择性的大环化合物:对称四甲基六元瓜环与过渡金属及重金属离子的配合作用

利用微分脉冲伏安法研究了对称四甲基六元瓜环(TMeQ[6])与过渡金属的相互作用。结果表明该主体大环化合物对Pb²⁺和Cd²⁺离子具有较好的选择性作用。伏安数据测定表明Pb²⁺及Cd²⁺离子与对称四甲基六元瓜环以n_M²⁺/n_TMeQ[6]=2配位, 其配合平衡常数分别为(K_Pb²⁺=2.12×10⁹ L²·mol^-2, K_Ca²⁺=2.10×10⁹ L²·mol^-2)。Pb²⁺离子与TMeQ[6]的晶体结构进一步证实了上述实验结果。     

1,8-萘酰亚胺为发色团的Zn2+荧光探针的合成及性能研究

合成了以1,8-萘酰亚胺为发色团,以联吡啶为离子受体的Zn²⁺荧光探针,并进行了表征及离子识别性能的研究。研究表明该化合物对Zn²⁺具有良好的识别性能,同时相对于Ca²⁺, Cd²⁺, Co²⁺, Cu²⁺, Hg²⁺, Fe³⁺, Mn²⁺, Ni²⁺, Pb²⁺等金属离子具有良好的选择性。     

Integration of Metal-Organic Frameworks with Bi-Nanoprobes as Dual-Emissive Ratiometric Sensors for Fast and Highly Sensitive Determination of Food Hazards

Functional nanoprobes which detect specific food hazards quickly and simply are still in high demand in the field of food-safety inspection research. In the present work, a dual-emission metal-organic framework-based ratiometric fluorescence probe was integrated to detect Cu²⁺ and Pb²⁺ with rapidness and ease. Specifically, quantum dots (QDs) and carbon quantum dots (CQDs) were successfully embedded into zeolitic imidazolate framework-67 (ZIF-67) to function as a novel ratiometric fluorescent sensing composite. The ratiometric fluorescence signal of CQDs/QDs@ZIF-67 was significantly aligned with the concentration of metal ions to give an extremely low detection limit of 0.3324 nM. The highly sensitive and selective CQDs/QDs@ZIF-67 composite showed potential for the rapid and cost-effective detection of two metal ions.     

Luminescent CdSe-ZnS quantum dots as selective Cu2+ probe

Luminescent CdSe-ZnS quantum dots (QDs) were modified with bovine serum albumin (BSA) and used as selective copper ion probe. The fluorescence of the water-soluble QDs can be quenched only by Cu²⁺ and Fe³⁺ in physiological buffer solution. Approximate concentrations of other physiologically important cations, such as Zn²⁺, Na⁺ and K⁺ etc. have no effect on the fluorescence. Adding F⁻ to form the colorless complex FeF₆³⁻ can eliminate the interference of Fe³⁺. The detection limit of Cu²⁺ ions was 10 nM. The results can be explained in terms of strong binding of Cu²⁺ onto the surface of CdSe resulting in a chemical displacement of Cd²⁺ ions and the formation of CuSe on the surface of the QDs.     

Spectrofluorometric Determination of Mercury and Lead by Colloidal CdS Nanomaterial

Heavy metal ions such as Hg and Pb are hazardous due to very high toxicity, mobility, and ability to accumulate through the food chain or atmosphere in the environment system. Therefore, ultrasensitive determination of mercury and lead is important to provide an evaluation index of ions in aqueous environment. This paper describes the investigation of surface modified quantum dots (QDs) as a sensing receptor for Hg²⁺ and Pb²⁺ ion detection by optical approach. Water-soluble L-cysteine-capped CdS QDs have been synthesized in aqueous medium. These functionalized nanoparticles were used as a fluorescence sensor for Hg²⁺ and Pb²⁺ ions, involved in the fluorescence quenching. The effect of foreign ions on the intensity of CdS QDs showed a low interference response toward other metal ions except Cu²⁺ and Fe²⁺ ions. The limit of detection (LOD) of this system is found to be 1.0 and 3.0 nM for Hg²⁺ and Pb²⁺ ions, respectively.     

Simultaneous determination of Hg(II) and Cu(II) in water samples using fluorescence quenching sensor of N-doped and N,K co-doped graphene quantum dots

The present study was aimed to use of N doped graphene quantum dots (N-GQDs) and N,K co-doped graphene quantum dots (N,K-GQDs) as a fluorescence quenching sensor to determine both mercury and copper in water sample, simultaneously using simple fluorescence protocol. Each of N-GQDs or N,K-GQDs was optimized separately with 1–5% (w/v) HNO₃ or KNO₃, respectively, and their quantum yields were determined and compared. It was found that N-GQDs, obtained from 3% (w/v) HNO₃ doped resulted higher fluorescence intensity at the maximum excitation and emission wavelengths of 370 and 460 nm, respectively, with higher quantum yield (QY = 83.42%) compared with that of undoped GQDs (QY = 16.35%). While N,K-GQDs obtained from 5%(w/v) KNO₃ gave somewhat different fluorescence spectrum, but still had the same maximum excitation and emission wavelengths with rather highest QY (94.07%). However, it is interesting that detection sensitivity expressed as slope of their calibration curve (y = 5.43x − 19.48; r² = 0.9971) of the N-GQDs is rather higher than that (y = 1.29x + 17.66; r² = 0.9977) of the N,K-GQDs for Hg²⁺ fluorescence quenching sensor, and the fluorescence intensity of N-GQDs had better selectively quenching effect only by both Hg²⁺ and Cu²⁺. Thus, their quenching effects were selected to develop the fluorescence turn-off sensor for trace level of both metal ions in real water samples. For method validation, the N-GQDs exhibited high sensitivity to detect both Hg²⁺ and Cu²⁺ with wide linear ranges of 20–100 μM and 100–500 μM, respectively. Limit of detection (LOD) and limit of quantitation (LOQ) were 0.42 μM & 1.41 μM for Hg²⁺ and 13.19 μM & 43.97 μM for Cu²⁺, respectively, with their precision expressed as an intra-day and an inter-day analysis of 6.98% & 11.35% for Hg²⁺ and 11.78% & 9.43% for Cu²⁺, respectively. Also the study of matrix analysis of the water samples (drinking water and tap water), was carried out using N-GQDs and N,K-GQDs resulted good percentage recoveries in comparison with those using undoped GQDs under the same optimum conditions.     

Cadmium sulfide quantum dots modified by chitosan as fluorescence probe for copper (II) ion determination

CdS quantum dots (QDs) have been prepared and modified with chitosan. Based on the quenching of fluorescence signals of the functionalized CdS QDs at 531 nm wavelength and enhancement of signals the 400–700 nm wavelength range by Cu²⁺ at pH 4.2, a simple, rapid and specific method for Cu²⁺ determination is presented. Under optimum conditions, the relative fluorescence intensity of CdS QDs is linearly proportional to copper concentration from 8.0 nmol L^?1 to 3.0 μmol L^?1 with a detection limit of 1.2 nmol L^?1. The mechanism can be explained in terms of strong binding of Cu²⁺ onto the surface of CdS, resulting in a chemical displacement of Cd²⁺ ions and the formation of CuS on the surface of the QDs.     

Europium-decorated graphene quantum dots as a fluorescent probe for label-free,rapid and sensitive detection of Cu and l-cysteine

In this work, europium-decorated graphene quantum dots (Eu-GQDs) were prepared by treating three-dimensional Eu-decorated graphene (3D Eu-graphene) via a strong acid treatment. Various characterizations revealed that Eu atoms were successfully complexed with the oxygen functional groups on the surface of graphene quantum dots (GQDs) with the atomic ratio of 2.54%. Compared with Eu free GQDs, the introduction of Eu atoms enhanced the electron density and improved the surface chemical activities of Eu-GQDs. Therefore, the obtained Eu-GQDs were used as a novel “off-on” fluorescent probe for the label-free determination of Cu²⁺ and l-cysteine (L-Cys) with high sensitivity and selectivity. The fluorescence intensity of Eu-GQDs was quenched in the presence of Cu²⁺ owing to the coordination reaction between Cu²⁺ and carboxyl groups on the surface of the Eu-GQDs. The fluorescence intensity of Eu-GQDs recovered with the subsequent addition of L-Cys because of the strong affinity of Cu²⁺ to L-Cys via the Cu–S bond. The experimental results showed that the fluorescence variation of the proposed approach had a good linear relationship in the range of 0.1–10 μM for Cu²⁺ and 0.5–50 μM for L-Cys with corresponding detection limits of 0.056 μM for Cu²⁺ and 0.31 μM for L-Cys. The current approach also displayed a special response to Cu²⁺ and L-Cys over the other co-existing metal ions and amino acids, and the results obtained from buffer-diluted serum samples suggested its applicability in biological samples.     

One‐Pot Green Synthesis of Nitrogen‐Doped Carbon Quantum Dots for Cell Nucleus Labeling and Copper(II) Detection

The doping of nitrogen into carbon quantum dots is vitally important for improved fluorescence performance. However, the synthesis of nitrogen‐doped carbon quantum dots (N‐CQDs) is usually conducted under strong acid and high temperature, which results in environmental pollution and energy consumption. Herein, the N‐CQDs were prepared by a mild one‐pot hydrothermal process. The hydrothermal reaction temperature was adjusted to control the particle size, nitrogen/carbon atomic ratio, and quantum yield. The products were water soluble with a narrow particle size distribution and good dispersion stability over a wide pH range. The N‐CQDs could penetrate into the HeLa cell nucleus without any further functionalization. Moreover, the fluorescence of N‐CQDs could be selectively quenched by Cu²⁺, which suggested applications for the detection of Cu²⁺ in human plasma.     

Zinc oxide nanostructured platform for electrochemical detection of heavy metals

ZnO nanoparticles (ZnO-NP) were prepared by a facile precipitation technique using di-isopropyl amine as precipitating agent. The morpho-structure and porosity of the as-prepared nano-powder were investigated by FT-IR analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), and BET analysis. By drop-casting, a composite film was deposited to obtain ZnO-NP-Nafion/GCE modified electrode. The modified electrode was investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and square wave anodic stripping voltammetry (SWASV) for the detection of Pb²⁺, Cd²⁺, Cu²⁺, and Fe³⁺, and it was successfully applied for the detection of Pb²⁺ and Cu²⁺ in real water samples.     

Highly fluorescence Ta4C3 MXene quantum dots as fluorescent nanoprobe for heavy ion detection and stress monitoring of fluorescent hydrogels

Compared with other transition metal Mxene derived quantum dots（MQD_S）,Ta-based Mxene quantum dots have good functionality,but Ta-based Mxene quantum dots and their applications have not been studied so far.In this paper,we report for the first time the synthesis of high fluorescence quantum yield（QY） N-doped Ta₄ C₃ quantum dots（N-MQDs） using Ta₄ C₃ quantum dots in acid reflux damaged Ta₄ C₃ nanosheets as precursors and ...