金纳米颗粒表面能量转移及巯基化合物的检测

二氧化硅稳定的金纳米颗粒(Au-SiO₂)与罗丹明B之间发生表面能量转移,使罗丹明B荧光猝灭。 金纳米颗粒对罗丹明B的Stern-Volmer猝灭常数为4.3×10³ L/mol。 当荧光猝灭的混合体系中加入巯基化合物时,巯基化合物与金纳米颗粒发生强相互作用阻断罗丹明B-金纳米颗粒之间的能量转移,罗丹明B荧光恢复。 基于罗丹明B-Au-SiO₂体系对巯基化合物的单一响应,建立了一种简单快速检测巯基化合物的方法;并且由于二氧化硅对金纳米颗粒的稳定作用,金纳米颗粒成为一种可以回收利用的检测探针。     

双重对象同时检测的新型荧光纳米粒子传感器的制备

报道了一种基于荧光共振能量转移理论合成的新型纳米粒子. 新型纳米粒子A中掺杂了由亲和素-生物素桥联并可发生荧光共振能量转移(FRET)的供体染料和受体染料; 新型纳米粒子B中只掺杂了供体染料. 在使用供体染料的特征激发波长同时激发纳米粒子A和B时, 纳米粒子A由于荧光共振能量转移而发射出受体染料的特征波长, 而纳米粒子B则只发射供体染料的特征波长. 这样, 在单一波长激发下, 可很容易地实现双重对象同时检测.     

银纳米粒子簇的设计、 制备和表面增强拉曼光谱

通过匹配激光光斑直径与胶体微球的尺寸, 设计制备了银纳米粒子的表面增强拉曼散射(SERS)基底, 并将其用于研究单个银纳米粒子簇的表面增强拉曼光谱. 在制备纳米粒子的过程中, 考察了等离子体刻蚀时间与银沉积厚度对“单”银纳米粒子结构与形貌的影响. 将吡啶、 巯基苯和罗丹明R6G作为SERS探针分子, 研究了其SERS效应, 通过荧光共振能量转移(FRET)机理, 实现了染料分子在单银纳米粒子簇上的SERS效应. SERS光谱测试与相关计算结果表明, 单个银纳米粒子簇的拉曼增强因子能够达到约10⁶.     

比率检测高/半胱氨酸荧光染料的合成及活细胞成像研究

经一步简单反应获得了一例长波长尼罗蓝衍生物荧光染料RB-S. 该染料分子RB-S对高/半胱氨酸具有明显的荧光响应,且随着高/半胱氨酸浓度（0.03～0.33 μmol/L）逐渐增加,染料荧光强度在685 nm处减弱,相应地在755 nm处增强,在685与755 nm处的荧光变化具有良好线性关系的比率荧光变化. 通过高效液相色谱-质谱联用技术以及核磁滴定氢谱研究了染料分子检测高/半胱氨酸的机理. 试验结果表明：染料分子中的醛基与高/半胱氨酸发生成环反应生成噻唑烷. 在体外溶液测试中（pH=7.4）,染料分子RB-S对高/半胱氨酸的检出限为0.025 μmol/L,且不存在其他物质干扰,成功用于血清样品中内高/半胱氨酸荧光比率检测. 染料分子RB-S具有良好的活细胞膜通透性,使其能够对活细胞内高/半胱氨酸荧光比率成像.     

g-C3N4/Ag纳米复合材料表面增强拉曼基底对婴幼儿糖果中的罗丹明B的痕量检测

近年来, 由婴幼儿食品中存在非法添加剂所引起的食品安全问题已经受到了广泛的关注. 表面增强拉曼散射(SERS)技术可以对食品中被禁止添加的常用染料分子罗丹明B (RhB)进行快速无损超灵敏的检测. 通过在类石墨相氮化碳(g-C₃N₄)纳米片上组装Ag纳米粒子的方式构筑了g-C₃N₄/Ag复合材料, 并采用透射电子显微镜(TEM)、紫外可见近红外分光光度计(UV-Vis)、X射线衍射仪(XRD)、荧光光谱仪和共聚焦显微拉曼光谱仪(Raman)对复合材料的形貌和结构进行了表征. g-C₃N₄纳米片不仅具有高度的离域π共轭体系和良好的吸附染料分子的性能, 而且可以作为Ag纳米粒子的载体, 使Ag纳米粒子均匀稳定地分散在其表面. 通过控制实验条件, 优化了测试过程中的pH及基底与RhB的结合时间, 详细探究pH对基底表面等离子共振的影响和对探针分子SERS强度的影响. 由于基底与探针分子之间的静电相互作用及π-π相互作用, 基底可以对阳离子染料进行大量地富集, 从而实现对其检测. 在最佳的实验条件下, 在1.0×10 ^–9~1.0×10 ^–6 mol/L浓度范围内, SERS强度与RhB浓度之间成线性关系, 最低检测限为0.39 nmol/L. 另外这种基底也可以对婴幼儿食用的棒棒糖中添加的RhB分子实现痕量检测. 总而言之, g-C₃N₄/Ag纳米复合物是一种均一、稳定、高灵敏的SERS基底, 可以简单快速地实现对罗丹明B的痕量检测.     

含有BaMoO4纳米粒子的反胶束溶液与罗丹明B的相互作用

在三种带有不同电荷的表面活性剂构建的反胶束体系中(AOT/异辛烷、Oπ-10/环已烷、CTAB/正已醇)合成了BaMoO₄的纳米粒子, 采用透射电镜(TEM)观察其粒子呈球形, 粒径在17～46 nm范围内, 分布均匀; 使用染料罗丹明B作为探针, 采用紫外-可见光谱(UV-vis)和荧光光谱研究反胶束水池中罗丹明B与BaMoO₄纳米粒子的相互作用; 由于反胶束水池的空间和极性的限定, 染料的光谱特征与其在纯水中发生很大变化, 不同的反胶束体系中, 由于染料分子所处的微观环境不同, 导致其光谱特征也有较大区别.     

采用纳米金和荧光标记的适配体检测凝血酶

将荧光染料分子标记的含29个碱基的可识别凝血酶的DNA适配体非特异吸附到纳米金表面,荧光发生猝灭,加入凝血酶后,凝血酶与适配体特异性结合,使适配体空间结构发生改变,荧光染料分子远离纳米金表面,荧光恢复,因此可以实现对凝血酶的检测。实验结果表明,这种检测方法简便、快速、特异性强,检出限为0.54 nmol/L(对应样品体积为200μL)。     

含有BaMoO4纳米粒子的反胶束溶液与罗丹明B的相互作用

在三种带有不同电荷的表面活性剂构建的反胶束体系中(AOT/异辛烷、Oπ-10,环已烷、CTAB／正已醇)合成了BaMoO4的纳米粒子,采用透射电镜(TEM)观察其粒子呈球形,粒径在17-46 nm范围内,分布均匀;使用染料罗丹明B作为探针,采用紫外-可见光谱(UV-vis)和荧光光谱研究反胶束水池中罗丹明B与BaMoO4纳米粒子的相互作用;由于反胶束水池的空间和极性的限定,染料的光谱特征与其在纯水中发生很大变化,不同的反胶束体系中,由于染料分子所处的微观环境不同,导致其光谱特征也有较大区别。     

罗丹明B与基因共负载纳米粒子的制备与性能

药物/基因共负载的智能微载体的制备是肿瘤多元复合治疗的关键科学问题。本文以疏水性荧光染料罗丹明B为模型药物,采用聚乙烯亚胺－接枝－胆固醇两亲聚合物作为药物载体,成功制备了罗丹明与基因共负载的超分子组装体。通过组装条件的调控,获得了尺寸为150 nm、表面电位33 mV的球形纳米粒子,并依然具有很好的DNA缔合特性。细胞培养结果表明：表面正电荷的罗丹明与基因共负载纳米粒子很容易被细胞内吞,并能有效转染细胞,为高效安全的药物/基因共负载微载体的制备提供了切实可行的途径。 关键词 非病毒基因载体;超分子组装;药物/基因共负载     

复合纳米材料Cu2O@Au对水体中罗丹明B的检测应用研究

制备了多面体Cu2 O纳米粒子,利用Cu2 O的还原性,在其表面原位生成了不同密度的Au纳米粒子,制备了Au、Cu共同增强拉曼信号的复合纳米粒子Cu2 O@Au.利用透射电镜(TEM)、扫描电镜(SEM)、X射线衍射(XRD)等对制备的Cu2 O和Cu2 O@Au的形貌、粒径、表面性能等进行了表征.研究了Cu2 O表面金纳米粒子的分布密度对水样中目标检测物罗丹明B的拉曼增强效果.结果表明,氯金酸浓度在1 mmol/L时制备的Cu2 O@Au表面均匀覆盖一层金纳米粒子,其表面增强拉曼效果最为显著,对水样中罗丹明B检测范围为1×10-2~5×10-6 mol/L.研究了此探针在PBS(1×)和酸性水溶液(0.01 mol/L HCl)中的稳定性,并将其用于沂河水样中靶标的检测实验,结果表明,其稳定性较好.     

Label-free detection of adenosine based on fluorescence resonance energy transfer between fluorescent silica nanoparticles and unmodified gold nanoparticles

A sensitive and convenient strategy was developed for label-free assay of adenosine. The strategy adapted the fluorescence resonance energy transfer property between Rhodamine B doped fluorescent silica nanoparticles (SiNPs) and gold nanoparticles (AuNPs) to generate signal. The different affinities of AuNPs toward the unfolded and folded aptamers were employed for the signal transfer in the system. In the presence of adenosine, the split aptamer fragments react with adenosine to form a structured complex. The folded aptamer cannot be adsorbed on the surface of AuNPs, which induces the aggregation of AuNPs under high ionic concentration conditions, and the aggregation of AuNPs leads to the decrease of the quenching ability. Therefore, the fluorescence intensity of Rhodamine B doped fluorescent SiNPs increased along with the concentration of adenosine. Because of the highly specific recognition ability of the aptamer toward adenosine and the strong quenching ability of AuNPs, the proposed strategy demonstrated good selectivity and high sensitivity for the detection of adenosine. Under the optimum conditions in the experiments, a linear range from 98 nM to 100 μM was obtained with a detection limit of 45 nM. As this strategy is convenient, practical and sensitive, it will provide a promising potential for label-free aptamer-based protein detection.     

Comment on "Multimodal coupling of optical transitions and plasmonic oscillations in rhodamine B modified gold nanoparticles" by M. Stobiecka and M. Hepel, Phys. Chem. Chem. Phys. 2011, 13, 1131

An article recently published in this journal claimed that a resonance enhanced light scattering (RELS) peak for 22 nm gold nanoparticles was observed at 653 nm, which was about 130 nm higher than the surface plasmon resonance maximum. They also claimed to observe RELS from dilute solutions of Rhodamine B, under conditions where it is expected to be in its monomeric form. This comment shows that the position of the RELS peak for the gold nanoparticles is an artefact of measurement and the RELS from Rhodamine B is simply fluorescence. These findings are likely to have a significant impact on the interpretation of the results in terms of interactions of dyes with gold nanoparticles as well as aggregation of gold nanoparticles, which has been reported elsewhere by the same authors.     

金纳米粒子与聚吡咯纳米管的复合及其SERS效应研究

通过柠檬酸盐与HAuCl4水溶液在微沸状态下反应制备的金纳米粒子因其特殊的表面与界面效应在光学、生物学和催化化学领域得到了广泛应用,而聚吡咯(PPy)具有环境稳定性好、电导率高且变化范围大、容易合成等优点,聚吡咯纳米管可用作导电材料、酶封装材料、抗静电材料,也可用于制备传感器、传动器、固体电解质电容器等。     

Excitation Energy Transfer from Semi‐Conducting Polymer Nanoparticles to Surface‐Bound Fluorescent Dyes

Summary: The first examples of the dye‐coated semi‐conducting polymer nanoparticles as well as experiments to demonstrate the excitation energy transfer from the excited chromophor of the nanoparticle to the fluorescent dye are described. We have demonstrated that the blue fluorescence of the dye‐coated polyfluorene nanoparticles is only slightly quenched after dye deposition. However, a new emission band of the surface‐bound dye (Rhodamine 6G or Rhodamine TM) appears in the wavelength region of 530–600 nm. These results clearly indicate an effective excitation energy transfer from the excited PF chromophores to the fluorescent dye.

Emission spectra of PF2/6 nanoparticle dispersion and of Rhodamine 6G‐coated nanoparticle dispersion.     

Preparation of a new core-shell Ag@SiO2 nanocomposite and its application for fluorescence enhancement

Ag@SiO₂ nanoparticles with different shell thicknesses were synthesized via modified Stöber method. Rhodamine B isothiocyanate was covalently bound onto the surface of Ag@SiO₂ nanoparticles to form fluorescent core-shell Ag@SiO₂ nanocomposites. Effects of shell thickness on the fluorescence enhancement were examined using the corresponding nanobubbles prepared by cyanide etching as a control. The result showed that the fluorescence enhanced as the shell thickness increased till the distance between fluorophore and metal core reached about 75 nm with the optimal enhancement factor of ∼5-folds. Further increasing of fluorophore-metal distance caused a decrease in the enhancement factor.     

Detection of glucose in synthetic tear fluid using dually functionalized gold nanoparticles

A simple fluorescent sensing of glucose in aqueous fluids (e.g. tear fluid) using dually functionalized gold nanoparticles is presented. As a first step gold nanoparticles (AuNPs) were synthesized using oxidised dextran which acted both as reducing and stabilizing agent. Aminophenyl boronic acid was conjugated onto AuNPs by Schiff's base formation and the formed Schiff's base was stabilized by sodium borohydride reduction. Rhodamine B isothiocyanate (RBITC) was then assembled onto the modified AuNPs. The fluorescence of RBITC was nearly quenched and found to be revived when glucose was added. It is reasoned that the glucose binding induces restructuring of the surface assembly resulting in an overall increase in the size and thereby enhancing the distance between the gold core and fluorophore. TEM image and size measurements using dynamic light scattering (DLS) in fact, reflected this possibility. The increase in fluorescence was proportional with the concentration of glucose enabling quantitative detection. A good linearity was observed between the fluorescence intensity and glucose concentration in a range of 0.025-0.125 μM with detection limit of 0.005 ± 0.002 μM. The potential of the method was demonstrated by measuring glucose in real tear fluids collected from volunteers. The method is extremely sensitive and can be employed to measure low concentration of glucose in aqueous fluids such as tear.     

Synthesis and characterization of photoswitchable fluorescent SiO2 nanoparticles

Switchable fluorescent silica nanoparticles have been prepared by covalently incorporating a fluorophore and a photochromic compound inside the particle core. The fluorescence can be switched reversibly between an on‐ and off‐state via energy transfer. The particles were synthesized using different amounts of the photoswitchable compound (spiropyran) and the fluorophore (rhodamine B) in a size distribution between 98 and 140 nm and were characterized in terms of size, switching properties, and fluorescence efficiency by TEM, and UV\Vis and fluorescence spectroscopy.     

Room‐Temperature Phosphorescence‐active Boronate Particles: Characterization and Ratiometric Afterglow‐sensing Behavior by Surface Grafting of Rhodamine B

We found that boronate particles ( BP ), as a self‐assembled system prepared by sequential dehydration of benzene‐1,4‐diboronic acid with pentaerythritol, showed greenish room‐temperature phosphorescence (RTP). This emission was observed in both solid and dispersion state in water. To understand the RTP properties, X‐ray crystallographic analysis, and density functional theory (DFT) and time‐dependent DFT at M06‐2X/6‐31G(d,p) level were performed using 3,9‐dibenzo‐2,4,8,10‐tetraoxa‐3,9‐diboraspiro[5.5]undecane ( 1 ) as a model compound. Our interest in functionalizing the RTP‐active particles led us to graft Rhodamine B onto their surface. The resulting system emitted a dual afterglow via a Förster‐type resonance energy transfer process from the BP in the excited triplet state to Rhodamine B acting as an acceptor fluorophore. This emission behavior was used for ratiometric afterglow sensing of water content in THF with a detection limit of 0.28 %, indicating that this study could pave the way for a new strategy for developing color‐variable afterglow chemosensors for various analytes.