Fluorescent Core-shell Silica Nanoparticles Research Articles

Site-Specific Labeling of Surface Proteins on Living Cells Using Genetically Encoded Peptides that Bind Fluorescent Nanoparticle Probes

We report a highly specific, robust, and generic method for noncovalent labeling of cellular proteins with highly fluorescent core-shell silica nanoparticles termed C dots. Our approach uses short genetically engineered peptides with affinity for silica (GEPS) that are site-specifically introduced at the termini or in loops of cellular proteins. Because GEPS are absent from native cell surface proteins, GEPS-tagged recombinant proteins can be selectively and rapidly labeled with fluorescent C dots. To demonstrate the versatility of our method, we targeted 30 nm C dots to two structurally distinct integral outer membrane proteins in Escherichia coli, FhuA and OmpX. Efficient labeling was achieved in 15 min or less and was observed to be highly sensitive and specific. This strategy provides a powerful technique, comparable to other chemical and biological labeling strategies, for efficient and quantitative investigation of protein function in live biological cells.

Dye structure–optical property correlations in near-infrared fluorescent core-shell silica nanoparticles

In this paper we report on dye structure–optical property correlations for a range of near-infrared emitting (NIR, 650–900 nm) fluorescent dyes in a 9–14 nm diameter core-shell silica particle architecture (C dots), including Cy5, Alexa Fluor 700, DY730, Alexa Fluor 750, and DY780. For each dye an apparent per-dye enhancement in fluorescence is observed over free dye in aqueous solution ranging from 1.2× to 6.6×, highlighting the versatility of the silica encapsulation approach. For the Cy5 and DY730 dye/particle sample pairs photobleaching was undertaken and revealed that the particles photobleach slower than the dyes. For a particular NIR dye series with identical chemical backbone, DY730, DY731, DY732, and DY734, we demonstrate that with increasing number of sulfonated substituent groups the per-dye brightness enhancement decreases. Finally, we show that in special cases, like Cy5, brightness enhancement of dyes in dots over free dye may be a combination of effects from dye conjugation chemistry and immobilization in the silica matrix. These results provide powerful design criteria for next generation optical probes for applications ranging from bioimaging to security.

Fluorescent core-shell silicananoparticles as tunable precursors: towards encoding and multifunctional nano-probes

Core-shell silica nanoparticles comprised of a RuBpy doped silica core and a Pas-DTPA doped silica shell were synthesized and post-functionalized with an encoding fluorescence combination and multiplex imaging function.

Intracellular delivery of core–shell fluorescent silica nanoparticles

Highly fluorescent core–shell silica nanoparticles made by the modified Stöber process (C dots) are promising as tools for sensing and imaging subcellular agents and structures but will only be useful if they can be easily delivered to the cytoplasm of the subject cells. This work shows that C dots can be electrostatically coated with cationic polymers, changing their surface charge and enabling them to escape from endosomes and enter the cytoplasm and nucleus. As an example of cellular delivery, we demonstrate that these particles can also be complexed with DNA and mediate and trace DNA delivery and gene expression.

Core-shell silica nanoparticles as fluorescent labels for nanomedicine

Progress in biomedical imaging depends on the development of probes that combine low toxicity with high sensitivity, resolution, and stability. Toward that end, a new class of highly fluorescent core-shell silica nanoparticles with narrow size distributions and enhanced photostability, known as C dots, provide an appealing alternative to quantum dots. Here, C dots are evaluated with a particular emphasis on in-vivo applications in cancer biology. It is established that C dots are nontoxic at biologically relevant concentrations, and can be used in a broad range of imaging applications including intravital visualization of capillaries and macrophages, sentinel lymph node mapping, and peptide-mediated multicolor cell labeling for real-time imaging of tumor metastasis and tracking of injected bone marrow cells in mice. These results demonstrate that fluorescent core-shell silica nanoparticles represent a powerful novel imaging tool within the emerging field of nanomedicine.

Functionalized fluorescent core-shell nanoparticles used as a fluorescent labels in fluoroimmunoassay for IL-6

Nanoparticle labels conjugated with biomolecules are used in a variety of different assay applications. In this paper, a sensitive fluoroimmunoassay for recombinant human interleukin-6 (IL-6) with the functionalized Rubpy-encapsulated fluorescent core-shell silica nanoparticles labeling technique has been proposed. IL-6 was measured based on the specific interaction between captured IL-6 antigen and functionalized fluorescent core-shell nanoparticles-labeled anti-IL-6 monoclonal antibody. The calibration graph for IL-6 was linear over the range 20–1250 pg ml −1 with a detection limit of 7 pg ml −1 (3 σ). The regression equation of the working curve is I F = 7.665 + 32.499 [IL-6] (ng ml −1) ( r = 0.9980). The relative standard deviation (R.S.D.) for 11 parallel measurements of 78 pg ml −1 IL-6 was 3.2%. Furthermore, the application of fluorescence microscopy imaging in the study of the antibody labeling and sandwich fluoroimmunoassay with the functionalized fluorescent core-shell silica nanoparticles was also explored. This proposed method has the advantage of showing the specificity of immunoassay and sensitivity of fluorescent nanoparticle labels technology. The results demonstrate that the method offers potential advantages of sensitivity, simplicity and reproducibility for the determination of IL-6, and is applicable to the determination of IL-6 in serum samples and enabling fluorescence microscopy imaging for the determination of IL-6.

Fluorescent Core—Shell Silica Nanoparticles: Towards “Lab on a Particle” Architectures for Nanobiotechnology

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

A novel sensitive staphylococcal enterotoxin C 1 fluoroimmunoassay based on functionalized fluorescent core-shell nanoparticle labels

A highly sensitive fluoroimmunoassay for the determination of staphylococcal enterotoxin C 1 (SEC 1) is proposed. It is based on the functionalized fluorescent core-shell nanoparticles as the labels coated with anti-SEC 1 monoclonal antibodies in “sandwich” fluoroimmunoassay. With the simple, inverse microemulsion polymerisation method, the functionalized fluorescent core-shell nanoparticles were prepared easily. The preparation process produces a silica shell on the surface of the Ru(bpy) 3Cl 2 (Rubpy) dye with one step cohydrolysis of tetraethylorthosilicate (TEOS), and the coupling agent (3-aminopropy1)triethoxysilane (APS) provided the amine groups that can be used for biological conjugation. The nanoparticles were then labeled with the anti-SEC 1 monoclonal antibodies and the antibody-labeled nanoparticles were successfully used for the determination of SEC 1. The calibration graph for SEC 1 was linear over the range 1.0–75.0 ng ml −1 with a detection limit of 0.3 ng ml −1. The regression equation of the working curve was I F = 24.583 + 0.6426[SEC 1] (ng ml −1) ( r = 0.9991). The relative standard deviation (RSD) for five parallel measurements of 25.0 ng ml −1 SEC 1 was 2.5%. Furthermore, the application of fluorescence microscopy imaging in the study of the antibody labeling and sandwich fluoroimmunoassay with the functionalized fluorescent core-shell silica nanoparticles was also explored. The results demonstrate that the method offers potential advantages of easily labeling to the antibody, sensitivity, simplicity and reproducibility for the determination of SEC 1 and is applicable to the determination of SEC 1 in real samples and enables fluorescence microscopy imaging for the determination of SEC 1.

Fluorescent core–shell silica nanoparticles: towards “Lab on a Particle” architectures for nanobiotechnology

Novel nanoscale fluorescent materials are integral to the progress of emergent fields such as nanobiotechnology and facilitate new research in a variety of contexts. Sol-gel derived silica is an excellent host material for creating fluorescent nanoparticles by the inclusion of covalently-bound organic dyes. Significant enhancements in the brightness and stability of organic dye emission can be achieved for silica-based core-shell nanoparticle architectures at length scales down to tens of nanometers with narrow size distributions. This tutorial review will highlight these findings and describe the evolution of the fluorescent core-shell silica nanoparticle concept towards integration of multiple functionalities including mesoporosity, metal nanoshells and quantitative chemical sensing. These developments point towards the development of "lab on a particle" architectures with promising prospects for nanobiotechnology, drug development and beyond.