The Synthesis of Magnetic and Fluorescent Bi-functional Silica Composite Nanoparticles via Reverse Microemulsion Method

In this paper, a simple synthesis method of small-size( about 50 nm in diameter), high magnetic and fluorescent bi-functional silica composite nanoparticles were developed, in which water-soluble Fe₃O₄ magnetic nanoparticlels (MNs) and CdTe quantum dots (QDs) were directly incorporated into a silica shell by reverse microemulsion method. The high luminescent QDs can be used as luminescent marker, while the high magnetic MNs allow the manipulation of the bi-functional silica composite nanoparticles by external magnetic field. Poly (dimethyldiallyl ammonium chloride) was used to balance the electrostatic repulsion between CdTe QDs and silica intermediates to enhance the fluorescence intensity of MNs-QDs/SiO₂ composite nanoparticles. The optical property, magnetic property, size characterization of the bi-functional composite nanoparticles were studied by UV-Vis and PL emission spectra, VSM, TEM, SEM. The stabilities toward time, pH and ionic strength and the effect of MNs on the fluorescence properties of bi-functional silica composite nanoparticles were also studied in detail. By modifying the surface of MNs-QDs/SiO₂ composite nanoparticles with amino and methylphosphonate groups, biologically functionalized and monodisperse MNs-QDs/SiO₂composite nanoparticles can be obtained. In this work, bi-functional composite nanoparticles were conjugated with FITC labeled goat anti-rabbit IgG, to generate novel fluorescent-magnetic-biotargeting tri-functional composite nanoparticles, which can be used in a number of biomedical application.     

Semiconducting Polymer Nanoparticles as Fluorescent Probes for Biological Imaging and Sensing

In recent years, semiconducting polymer nanoparticles have emerged as a new class of extraordinarily bright fluorescent probes. These polymer nanoparticles, which are primarily composed of π‐conjugated polymers, exhibit a variety of outstanding features, including exceptional fluorescence brightness, fast radiative rate, good photostability, facile surface functionalization, and low cytotoxicity. These advantageous characteristics make polymer nanoparticles highly promising for applications in biological imaging and sensing. This progress report highlights recent advances in the synthesis, characterization, and applications as bio‐labels or sensors of these highly emissive organic nanoparticles.     

Fluorescent Characteristics of Rheumatoid Arthritis Patients Blood Lymphocytes

A fluorescent probe, ABM, aminoderivative of benzanthrone, synthesized in the Department of Organic Chemistry of the Riga Technical University (Latvia), has been successfully used to characterize changes in the structural and functional properties of cell membranes during different pathologies. In the present study the physicochemical properties and the functional activity of the peripheral blood mononuclear cells (lymphocytes—Ly) in patients with rheumatoid arthritis (RA) were studied using the ABM probe. Intensity of the ABM fluorescence in the celi suspension, functional activity of the ly anisotropy of the membranes differ patients with different titres of rheumatoid factor in blood. Patients with seropositive RA had decreased proliferative activity and lower number of iy in blood plasma indicating greater alterations of the immunoregulating processes in these patients as compared to patients with seronegative RA. In the latter the Ly deficiency is compensated to some extent by increased proliferation activity of these cells. The ABM fluorescence intensity correlated not only with membrane anisotropy (r = 0.97, but also with the proliferation activity of the Ly (r = 0.98). The above parameters correlated with the clinical manifestations of the disease. The results indicate that the fluorescent probe ABM is useful for screening the physicochemical status of Ly membranes and the proliferation activity of these cells in RA patients.     

Modification-Free Fluorescent Biosensor for CEA Based on Polydopamine-Coated Upconversion Nanoparticles

Journal of Fluorescence - Upconversion nanoparticles (UCNPs) have achieved considerable success in protein sensing in vitro. And aptamer is one of the most frequently used biomolecules to modify...     

磁免疫和荧光免疫传感器的构建及其在检测甲胎蛋白中的应用

甲胎蛋白(AFP)是常见的肝癌肿瘤标志物,在早期诊断方面起到重要作用。分别设计构建了磁免疫和荧光免疫传感器并将其应用于AFP的定量检测。在磁免疫传感器中,采用免疫磁珠代替传统固相载体,实现了目标物的快速分离;利用标记抗体上的辣根过氧化物酶(HRP)催化底物显色,根据底物吸光度值的大小进行定量检测。构建的AFP检测方法的检出限为3.6 ng·mL-1,线性范围为10~80 ng·mL-1。在荧光免疫传感器中,将碲化镉量子点(CdTe QDs)的荧光作为信号输出,并通过同时将多个CdTe QDs连接在纳米硅球表面实现信号放大,通过测量量子点荧光强度实现定量检测。该方法AFP检出限为4.2 ng·mL-1,线性范围为5~150 ng·mL-1。所设计的两种传感器均具有特异性强、灵敏度高的特点,为AFP的检测提供了新的思路和方法。     

Imaging the Magnetic Structure of Thin Films and Nanoparticles

Hyperfine Interactions - Nuclear resonant scattering of synchrotron radiation is applied to investigate the magnetic spin structure of nanoscale systems. The outstanding brilliance of modern...     

Preparation and Fluoroimmunoassay Application of New Red-Region Fluorescent Silica Nanoparticles

This is the first report on the preparation and utilization of a novel red-region fluorescent dye (tetracarboxy aluminum phthalocyanine) doped silica nanoparticles. In these nanoparticles, the tetracarboxy aluminum phthalocyanine molecules were covalently bound to silica matrix to protect the dye leaking from nanoparticles in bio-applications. The surface of the nanoparticles was modified by amino groups and easily bioconjugated with goat anti-human IgG antibody. By employing these nanoparticles as fluorescent probe, a sensitive fluoroimmunoassay method has been developed for the determination of trace level of human IgG. The calibration graph for human IgG was linear over the range of 0–500 ng mL⁻¹ with a detection limit of 1.6 ng mL⁻¹. Compared with the corresponding system using free AlC₄Pc as a probe for determining human IgG, the sensitivity of the proposed system was notably increased. The method was applied to the analysis of human IgG in human sera with satisfactory results.     

Protein Binding on the Surface of Magnetic Nanoparticles

Magnetic nanoparticles (MNPs) are widely used in the areas of biology and biomedicine. The interaction between MNPs and proteins plays a crucial role in the bioapplication of MNPs, and the binding affinity of protein–MNPs is the manifestation of this interaction. The binding affinity of some proteins with MNPs modified in various ways is determined by fluorescence quenching. The results show that the binding affinity depends on the properties of both the MNPs and the proteins. The higher the surface curvature of MNPs, the larger the MNP, and the higher the binding affinity. No significant difference is found in binding affinity between MNPs with different modification methods. For proteins, the binding affinity depends on the properties of individual proteins, such as the amino acid sequence, the native protein conformation in solution, the isoelectric point, and surface potential. In general, the binding affinity is higher for proteins with cysteine residues on the surface. In addition, pH affects the binding affinity between proteins and MNPs; positively charged proteins and lower pH are more suitable for MNP binding due to electrostatic forces.     

不同表面结构的金纳米粒子荧光性质.

"研究了具有不同表面结构的金纳米粒子：裸金纳米粒子、三苯基膦修饰的金纳米粒子、巯基丙酸表面取代的金纳米粒子的荧光性质,及其对CdSe纳米粒子的荧光猝灭作用．发现不同的金纳米粒子荧光信号受粒子表面一价金离子与配体分子之间相互作用的影响,其荧光强度对其表面分子具有强烈的敏感性;具有不同表面结构的金纳米粒子对CdSe纳米粒子的荧光猝灭作用不同,与其吸收光谱和CdSe纳米粒子发射光谱的重叠程度相关."     

稀磁ZnO纳米颗粒的生长和性能

利用Zn、Fe、Mn、Co的铜铁试剂盐为前驱体,胺为表面包裹剂,在200℃N2保护下生长了2%的过渡金属离子掺杂的ZnO稀磁纳米晶体,研究了纳米晶体的结构、形态、光学和磁学性能。所有ZnO纳米晶体均为近圆形的颗粒,晶体结构为六角纤锌矿结构,无其他氧化物相的析出,但过渡金属离子的掺入使纳米颗粒的尺寸增大。在掺杂纳米颗粒的吸收谱和发射谱中均可以观察到明显的激子吸收和发射峰,所有纳米颗粒在温度高于43K时只有顺磁性。     

Magnetic Composite Thin Films of FexOy Nanoparticles and Photocrosslinked Dextran Hydrogels

Magnetic hydrogel composites are promising candidates for a broad field of applications from medicine to mechanical engineering. Here, surface-attached composite films of magnetic nanoparticles (MNP) and a polymeric hydrogel (HG) were prepared from magnetic iron oxide nanoparticles and a carboxymethylated dextran with photoreactive benzophenone substituents. A blend of the MNP and the dextran polymer was prepared by mixing in solution, and after spin-coating and drying the blend film was converted into a stable MNP-HG composite by photocrosslinking through irradiation with UV light. The bulk composite material shows strong mobility in a magnetic field, imparted by the MNPs. By utilizing a surface layer of a photoreactive adhesion promoter on the substrates, the MNP-HG films were covalently immobilized during photocrosslinking. The high stability of the composite was documented by rinsing experiments with UV-Vis spectroscopy, while surface plasmon resonance and optical waveguide mode spectroscopy was employed to investigate the swelling behavior in dependence of the nanoparticle concentration, the particle type, and salt concentration.     

Preparation,Characterization and Application of Fluorescent Terbium Complex-Doped Zirconia Nanoparticles

Novel zirconia-based fluorescent terbium nanoparticles have been prepared as a fluorescent nanoprobe for time-resolved fluorescence bioassay. The nanoparticles were prepared in a water-in-oil (W/O) microemulsion consisting of a strongly fluorescent Tb³⁺ complex, N,N,N¹, N¹-[2,6-bis(3′-aminomethyl-1′-pyrazolyl)-phenylpyridine]tetrakis(acetate)-Tb³⁺(BPTA-Tb³⁺), Triton X-100, hexanol, and cyclohexane by controlling co-condensation of Zr(OCH₂CH₃)₄ and ZrOCl_2. The characterizations by transmission electron microscopy and fluorometric methods indicate that the nanoparticles are uniform in size, 33± 4 nm in diameter, and have a fluorescence quantum yield of 8.9% and a long fluorescence lifetime of 2.0 ms. The zirconia-based fluorescent terbium nanoparticles show high stability against basic dissolution in a high pH aqueous buffer compared to the silica-based nanoparticles. A surface modification and bioconjugation method for the fluorescent nanoparticles was developed, and the nanoparticle-conjugated streptavidin (SA) was used for time-resolved floroimmunoassy (TR-FIA) of human prostate specific antigen (PSA). The result shows that the zirconia-based fluorescent terbium nanoparticles are useful as a fluorescent nanoprobe for time-resolved fluorescence bioassay.     

Synthesis of Fluorescent Silica Nanoparticles and Their Applications as Fluorescence Probes

This paper presents the synthesis of organic dye molecules embedded silica nanoparticles by Stöber method and their applications as fluorescence probes in cell imaging. By modifying the surface of fluorescent silica nanoparticles (FSNs) with amino, biologically functionalized and monodisperse FSNs can be obtained. In this work, FSNs were conjugated with monoclonal anti-Carcinoembryonic Antigen (anti-CEA) antibody via covalent binding. The antibody-conjugated FSNs can be used to label the SPCA-1 cells successfully, demonstrating that the application of FSNs as fluorescence probes in fluorescence imaging and bioassay would be feasible.     

A Novel Fluorescent Biosensor for Detection of Silver Ions Based on Upconversion Nanoparticles

In this paper, we report a simple and sensitive fluorescent biosensor for the quantitative analysis of silver ions (Ag⁺) by using NaYF₄:Yb³⁺, Tm³⁺ upconversion nanoparticles (UCNPs). Ag⁺ could oxidize o-phenylenediamine (OPD) to the oxidized OPD (oxOPD) directly. The fluorescence of UCNPs can be significantly quenched by oxOPD through inner filter effects (IFE). Under the optimized conditions, the Ag⁺ concentration is proportional to the changes of the fluorescence intensity of UCNPs. The proposed method shows high selectivity and Ag⁺ could be quantitatively detected in the range of 0 to 0.5 mM with a low detection limit of 33 nM for Ag⁺. The selectivity and sensitivity of the detection can also be satisfactory. More importantly, this method has potential in practical application to detect Ag⁺ in real samples without interference.     

Facile Fabrication of Dendritic Mesoporous SiO2@CdTe@SiO2 Fluorescent Nanoparticles for Bioimaging

A seeded watermelon‐like mesoporous nanostructure (mSiO₂@CdTe@SiO₂, mSQS) composed of a novel dendritic mesoporous silica core, fluorescent CdTe quantum dots (QDs), and a protective solid silica shell is successfully fabricated by loading QDs into dendritic mesoporous silica nanoparticles through electrostatic interaction, and then coating with a solid silica shell by the modified Stöber method. The shell thickness of mSQS can be tuned from 0 to 32 nm as desired by controlling the reaction parameters, including the amount of silica precursor, tetraethyl orthosilicate, that is introduced, the solvent ratio (H₂O:ethanol), and the amount of catalyst (NH₃?H₂O). These fluorescent mSiO₂@QDs@SiO₂ nanoparticles possess excellent stability and thickness‐dependent cytotoxicity, and are successfully applied to bioimaging.     

Synthesis and Characterization of Oxazine-doped Silica Nanoparticles for Their Potential Use as Stable Fluorescent Reagents

The synthesis process to obtain silica nanoparticles (NPs) doped with two oxazine dyes, nile blue and cresyl violet, has been investigated using a modification of the reverse micelle microemulsion method and a procedure based on the Stöber method. A micellar medium provided by the non-ionic surfactant Triton X-100 in a hexanol:water mixture and an ethanol:water mixture, have been used to provide the synthesis medium in each case. Tetraethoxysilane has been used as the initiator of the polymerization and condensation reactions after its hydrolysis in basic medium using ammonium hydroxide. Dye-silane precursor NPs have been also synthesized in order to compare their potential advantages against the NPs obtained by the direct encapsulation of the oxazine dyes. Size distribution and fluorescence of the synthesized NPs, which were monitored using Transmision Electron Microscopy (TEM) and a microplate reader, respectively, depend on the molar ratio and total concentration of the reagents involved in the synthesis. NPs obtained using the developed synthesis procedures had sizes below 400 nm in most instances and the best luminescent properties were observed for NPs with sizes ranging from 100 to 300 nm. Lower sizes result in a decrease in the fluorescence intensities of these nanomaterials. Parameters related with the luminescence features of these NPs were calculated in order to compare the feasibility of both synthesis approaches. The repeatability of the reverse-micelle microemulsion procedure performed in different days gave a relative standard deviation of 10% for the fluorescence intensity values.     

Bioconjugated Fluorescent Polymeric Nanoparticles for Imaging and Targeted Therapy of HER2-Overexpressing Cancer Cells

We report the development of Herceptin-conjugated fluorescent polymeric nanoparticles (PNp) probes. Synthesis of fluorescent conjugated polymer as the core, preparation of the core/shell PNp, the ability of immobilizing Herceptin on PNp, targeting and imaging of bioconjugated PNp toward HER2-overexpressing cancer cells, and therapeutic effect on cell cycle, together with the expression of apoptosis related proteins, were investigated. We have achieved active tumor targeting by rapid PNp-antibody binding to tumor-specific antigens. Besides, Herceptin-conjugated PNp can suppress the growth of HER2-overexpressing cancer cells.     

SiO_2/Ag核壳结构纳米粒子的制备及其表面荧光增强

以罗丹明B掺杂的SiO2球为核,通过化学还原的方法制备了二氧化硅/银核壳结构复合纳米粒子。采用透射电镜(TEM)、紫外-可见-近红外(UV-Vis-NIR)分光光度计和荧光分光光度计对二氧化硅/银核壳结构纳米粒子的表面形貌、表面等离子共振和表面荧光增强特性进行了研究和表征。结果表明,二氧化硅/银核壳结构纳米粒子的表面等离子共振峰具有明显的可调谐性,且其表面荧光增强强烈依赖于银壳层的表面等离子共振,随银壳层厚度的增大而增强。     

三聚氰胺-铜(Ⅱ)配合物抑制AT-双链铜纳米颗粒合成荧光检测三聚氰胺

基于三聚氰胺与铜离子配位反应并抑制A T-双链铜纳米颗粒合成,构建了一种新型的"turn-off"策略检测三聚氰胺.当三聚氰胺存在时,与铜离子发生配位反应,使得后期合成铜纳米颗粒的铜离子浓度不够,导致铜纳米颗粒荧光减弱.在最优化实验条件下,对三聚氰胺检测的线性范围为1~150μmol·L-1,检出限达0.5μmol·L-1.此外,该方法还可以检测牛奶样品中的三聚氰胺,回收率良好.