Imaging fluorescent silica nanoparticles

S. Santra, Fluorescent silica nanoparticles for cancer imaging. Methods Mol. Biol. 624 (2010) 151-162. 

A series of silica nanoparticles doped with cyanine dye DY-635 (Dyomics) were also prepared, characterized, and investigated in flow cytometry and fluorescence imaging applications [77]. Also these dye-nanoparticles demonstrate high, stable, and tunable fluorescence intensity and are useful for multicolor detection. 

Fig. 34 Example of mechanized mesoporous silica nanoparticles (MSNPs). SEM (a) and TEM (b) images show the structure and morphology of the MSNP platform [238]. (c) Structural formula of the a-cyclodextrin-based snap-top rotaxane that blocks the pores of an enzyme-cleavable mechanized MSNP. The stopper is connected to the stalk (dumbbell) by an ester or an amide bond [254]. (d) Release profile of rhodamine B from the snap-top MSNP. The addition of an esterase enzyme cleaves the ester bond, releasing the stopper, a-cyclodextrin, and cargo from the nanoparticles, which is monitored by the fluorescence intensity of rhodamine B. Controls employing an amide bond snap-top or deactivated enzyme do not release significant amounts of cargo...

Fig. 6 An overview of the versatility of the fluorescent core-shell silica nanoparticle platform illustrations of single and dual-emission particles as well as gold-nanoshell encapsulated core-shell particles are shown at the centre of the figure, while a variety of applications including bio-imaging, drug delivery, sensing and therapeutics are shown in the periphery. Reproduced with permission from [55]...

Fig. 8 Left TEM picture of the fluorescait silica nanoparticles. Right size distribution of the nanoparticles obtained from TEM images (bars) absorbance at 500 nm during the FIFFF elution of the nanoparticles (dashed line) numtaical size distribution curve calculated liom FIFFF (continuous curve) fluorescence intensities of the fraction n with a diameter betwetm 3n - 1 and 3n (squares). Adapted with permission from [74]...

Fig. 24 Left evolution of the fluorescence spectra of NBD-(NH2)-silica nanoparticles with increasing TNT concentrations (the inset shows the fluorescence images before and after addition of TNT with excitation by a 365 nm UV lamp). Right variation in fluorescence intensity with increasing TNT concentrations for NBD-(NH2)-silica nanoparticles with different ratios of NBD to amino groups 1 40 (a), 1 10 b), 3 1 (c), and free NBD-APTES conjugates (d). Adapted with permission from [125]...

Telomerase expression, specific to cancer cells, is responsible for their uncontrolled division [ 175]. Ju ef al. described an elegant platform for fluorescence imaging of telomerase activity in cancer cells, an approach amenable to evaluate both tumor load and response to treatment [176]. Fluorescein and black hole quencher were loaded in meso-porous silica nanoparticles, the pores were then sealed by a telomerase DNA template probe. Telomerase detection was achieved by telomerase-induced detachment of the probe for its amplification, followed by liberation of the fluorophore. Interestingly, this probe allowed intracellular quantitation of telomerase activity. Signal was decreased after treatment with telomerase inhibitors, suggesting its usefulness as a disease monitoring tool in vivo. 

R. Qian, L. Ding, and H. Ju, Switchable fluorescent imaging of intracellular telomerase activity using telomerase-responsive mesoporous silica nanoparticle, J Am Chem Soc, 135 (36), 13282-5,2013. 

The internal biofunctionalization of silica nanoparticles with functional molecules, such as fluorescent dyes and drugs, is also very important for bioassays, imaging and drug delivery. Internally biofunctionalized silica nanoparticles that can provide strong and stable signals for imaging are particularly useful. 

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