Optimized synthesis of luminescent silica nanoparticles by a direct micelle-assisted method (original) (raw)
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Journal of colloid and interface science, 2017
The encapsulation of fluorescent dyes inside silica nanoparticles is advantageous to improve their quality as probes. Inside the particle, the fluorophore is protected from the external conditions and its main emission parameters remains unchanged even in the presence of quenchers. On the other hand, the amine-functionalized nanoparticle surface enables a wide range of applications, as amino groups could be easily linked with different biomolecules for targeting purposes. This kind of nanoparticle is regularly synthesized by methods that employ templates, additional nanoparticle formation or multiple pathway process. However, a one-step synthesis will be an efficient approach in this sort of bifunctional hybrid nanoparticles. A co-condensation sol-gel synthesis of hybrid fluorescent silica nanoparticle where developed. The chemical and morphological characterization of the particles where investigated by DRIFTS, XPS, SEM and SAXS. The nanoparticle fluorescent properties were also as...
Dye-doped silica-based nanoparticles for bioapplications
Advances in Natural Sciences: Nanoscience and Nanotechnology, 2013
This paper presents our recent research results on synthesis and bioapplications of dye-doped silica-based nanoparticles. The dye-doped water soluble organically modified silicate (ORMOSIL) nanoparticles (NPs) with the size of 15-100 nm were synthesized by modified Stöber method from methyltriethoxysilane CH 3 Si(OCH 3 ) 3 precursor (MTEOS). Because thousands of fluorescent dye molecules are encapsulated in the silica-based matrix, the dye-doped nanoparticles are extremely bright and photostable. Their surfaces were modified with bovine serum albumin (BSA) and biocompatible chemical reagents. The highly intensive luminescent nanoparticles were combined with specific bacterial and breast cancer antigen antibodies. The antibody-conjugated nanoparticles can identify a variety of bacterium, such as Escherichia coli O157:H7, through antibody-antigen interaction and recognition. A highly sensitive breast cancer cell detection has been achieved with the anti-HER2 monoclonal antibody-nanoparticles complex. These results demonstrate the potential to apply these fluorescent nanoparticles in various biodetection systems.
The present paper describes the synthesis of silica nanoparticles via the sol–gel method assisted by reverse micelle microemulsion, using reagents as Triton x-100/Cyclohexane/Methanol/H 2 O, and also the effect on particle size of some synthesis parameters such as the water-surfactant molar ratio (R), Co-surfactant-surfactant (q), and synthesis time (t). The structure, morphology, and size of the silica nanoparticles were characterized with transmission electron microscopy and scanning electron microscopy. A variation of q = [Methanol]/[Triton X-100] affects the size, morphology, and dispersion of the particles. An increase in the concentration of methanol produces a decrease in particle size. The condition that resulted in smaller particle size, better spherical morphology, and monodispersity was when q = 7.6, which generated an approximate size of 83 ± 7 nm. The parameter R = [H 2 O]/[Triton X-100] affects not only the size of the particles, but also their morphology. Higher values of R result in a decrease in the amount of catalyst present in the interior of the micelle, but in turn generate a greater amount of water, which results in a decrease in particle size and polydispersity. Time is a parameter that directly affects the size of the silica particles. The optimal time for the synthesis of nanoparticles was 2 h, resulting in silica nanoparticles of 25 ± 3 nm, monodisperse, with spherical morphology and without the presence of agglomerations.
Luminescent chemosensors based on silica nanoparticles
2011
The field of nanoparticles is amazingly many-sided and consequently their applications range between many different areas from industry to bio-analysis and catalysis. In particular, luminescent nanoparticles attract close attention in the areas of biology, medical diagnosis and therapy, where they already find many applications. In this so fascinating and wide framework we have focussed our attention on luminescent silica nanoparticles able to act as sensing materials. We highlight here the importance, especially with the aim of sensing, of gaining precise knowledge and control of their structures; the performance of a chemosensor is, in fact, totally dependent on its design. We then briefly present the state of the art and the progress both in the synthetic protocols and in the application of luminescent silica nanoparticles as chemosensors. We present many recent examples, organized into two main sections, the first dealing with systems presenting the signalling units on the surface (dye coated silica nanoparticles, DCSNs) and the second with systems entrapping the dyes inside the silica matrix (dye doped silica nanoparticles, DDSNs).
Ultrabright Fluorescent Mesoporous Silica Nanoparticles
Small, 2010
The fi rst successful approach to synthesizing ultrabright fl uorescent mesoporous silica nanoparticles is reported. Fluorescent dye is physically entrapped inside nanochannels of a silica matrix created during templated sol-gel self-assembly. The problem of dye leakage from open channels is solved by incorporation of hydrophobic groups in the silica matrix. This makes the approach compatible with virtually any dye that can withstand the synthesis. The method is demonstrated using the dye Rhodamine 6G. The obtained 40-nm silica particles are about 30 times brighter than 30-nm coated water-soluble quantum dots. The particles are substantially more photostable than the encapsulated organic dye itself.
Photoluminescent Silica Nanotubes and Nanodisks Prepared by the Reverse Micelle Sol−Gel Method
Langmuir, 2010
The reverse micelle sol-gel method was used earlier to prepare silica nanotubes, in aerosol OT/ n-heptane/water microemulsions containing FeCl 3. The present communication reports the remarkable effect of the amount of water in the microemulsions on the shape, size, and spectral properties of the silica nanostructures formed. Nanotubes are formed, as expected, at lower water contents. However, for higher water contents, nanodisks form in predominance. This rather surprising observation indicates the formation of flat, disklike water pools in this medium. Notably, a phase separation occurs at higher water contents, and this appears to be essential for the formation of the disklike nanostructures. Hence, we propose that flat water pools form at the interface of the two liquid phases. The nanotubes and nanodisks exhibit blue photoluminescence. The photoluminescence of the nanotubes is more susceptible to quenching by moisture than that of the nanodisks. Luminescence is restored by heating or purging nitrogen or oxygen. Time-resolved photoluminescence studies conform to a model in which the luminescence is ascribed to a particular kind of defect center, with some contribution from surface-associated defects.
Preparation of dye-loaded SiO2 nanoparticles
Journal of Non-Crystalline Solids, 2007
A room temperature method for the encapsulation of pyrene in SiO 2 nanoparticles is described. The relation between alkoxysilane surfactant chain length, reactant molar ratios and the uptake of dye, sample morphology, photophysical properties, and the ability of the silicate matrix to protect the encapsulated dye was examined. The synthesis can easily be adapted for the encapsulation of other hydrophobic and thermolabile substances, and used in the development of nanostructured optically active coatings, films and monoliths.