Mesoporous silica

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SEM of mesoporous silica
General information
Name: Mesoprous silica
Appearance: fine white powder
Types: MCM-41, SBA-15, MSU-, KSW-, FSM-
Main Component : Amorphous Silica

Mesoporous silica is a recent development in nanotechnology. The most common types of mesoporous nanoparticles are MCM-41 and SBA-15.^[1] Research continues on the particles, which have applications in catalysis, drug delivery and imaging.^[2]

Contents 1 History 2 Synthesis 3 Drug delivery 4 Biosensors 5 References

[edit] History

Mesoporous silica nanoparticles (MSNs) were first synthesized in 1992 by researchers working for the Mobil Corporation. They had a uniform hexagonal array of pores which had sizes between 15 and 100 Angstroms.^[3] This material was named Mobil Crystalline of Materials, or MCM-41.^[4]

Six years later, researchers at the University of California in Santa Barbara announced that they had produced silica nanoparticles with much larger 46-300 angstrom pores.^[5] The material was named Santa Barbara Amorphous type material, or SBA-15. These particles also have a hexagonal array of pores. The researches who invented these types of particles planned to use them as molecular sieves. Today, mesoporous silica nanoparticles have many applications in medicine, biofuels, and imaging.

[edit] Synthesis

Mesoporous silica nanoparticles are synthesized by reacting Tetraethyl orthosilicate with a template made of micellar rods. The result is a collection of nano-sized spheres or rods that are filled with a regular arrangement of pores. The template can then be removed by washing with a solvent adjusted to the proper pH.^[2]

[edit] Drug delivery

The large surface area of the pores allows the particles to be filled with a drug or a cytotoxin. Like a Trojan Horse, the particles will be taken up by certain biological cells though endocytosis, depending on what chemicals are attached to the outside of the spheres. Some types of cancer cells will take up more of the particles than healthy cells will, giving researchers hope that MCM-41 will one day be used to treat certain types of cancer. ^[2]

[edit] Biosensors

The mesoporous structure of these particles allows them to be filled with a fluorescent dye that would normally be unable to pass through cell walls. The MSN material is then capped off with a molecule that is compatible with the target cells. When the MSNs are added to a cell culture, they carry the dye across the cell membrane. These particles are optically transparent, so the dye can be seen through the silica walls. The dye in the particles does not have the same problem with self-quenching that a dye in solution has. The types of molecules that are grafted to the outside of the MSNs will control what kinds of biomolecules are allowed inside the particles to interact with the dye. ^{[6] [7]}

[edit] References

1. ^ Katiyar, Amit; Yadav, Santosh; G, Panagiotis; Neville, Smirniotis; Pinto, G (2006). "Synthesis of ordered large pore SBA-15 spherical particles for adsorption of biomolecules". Journal of Chromatography (A. 1122): 13–20. 
2. ^ ^{a b c} Trewyn, Brian G; Nieweg, Jennifer A; Zhao, Yannan; Lin, Victor S.-Y. (2007). "Biocompatible mesoporous silica nanoparticles with different morphologies for animal cell membrane penetration". Chemical Engineering Journal (137): 23–29. 
3. ^ J. S. Beck; J. C. Vartuli; W. J. Roth; M. E. Leonowicz; C. T. Kresge; K. D. Schmitt; C. T-W. Chu; D. H. Olson; E. W. Sheppard; S. B. McCullen; J. B. Higgins; and J. L. Schlenkert (1992). "A New Family of Mesoporous Molecular Sieves Prepared with Liquid Crystal Templates". American Chemical Society 114 (114): 10834–10843. doi:10.1021/ja00053a020. 
4. ^ Brian Trewyn, et al. (2007). "Synthesis and Functionalization of a Mesoporous Silica Nanoparticle Based on the Sol–Gel Process and Applications in Controlled Release". Accounts of Chemical Research (40): 846–853. 
5. ^ Dongyuan Zhao, et al. (1998). "Triblock Copolymer Syntheses of Mesoporous Silica with Periodic 50 to 300 Angstrom Pores". Science (279): 548. 
6. ^ Trewyn, Brian G; Supratim, Giri; Slowing, Igor I; Lin, Victor S.-Y. (2007). "Mesoporous silica nanoparticle based controlled release, drug delivery, and biosensor systems". Chemical communications: 3236–3245. doi:10.1039/b701744h. 
7. ^ Radu, Daniela R; Lai, Chen-Yu; Jeftinija, Ksenija; Rowe, Eric W; Jeftinija, Srdija; and Lin, Victor S.-Y. (2004). "A Polyamidoamine Dendrimer-Capped Mesoporous Silica Nanosphere-Based Gene Transfection Reagent". Journal of the Americal Chemical Society 126 (126): 13216–13217. doi:10.1021/ja046275m.