Mesoporous silica
Mesoporous silica is a form of
A compound producing mesoporous silica was patented around 1970.[5][6][7] It went almost unnoticed[8] and was reproduced in 1997.[9] Mesoporous silica nanoparticles (MSNs) were independently synthesized in 1990 by researchers in Japan.[10] They were later produced also at Mobil Corporation laboratories[11] and named Mobil Composition of Matter (or Mobil Crystalline Materials, MCM).[12]
Six years later, silica nanoparticles with much larger (4.6 to 30 nanometer) pores were produced at the University of California, Santa Barbara.[13] The material was named Santa Barbara Amorphous type material, or SBA-15. These particles also have a hexagonal array of pores.
The researchers who invented these types of particles planned to use them as
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.[3]
Mesoporous particles can also be synthesized using a simple sol-gel method[1] such as the Stöber process, or a spray drying method.[17] Tetraethyl orthosilicate is also used with an additional polymer monomer (as a template).
However, TEOS is not the most effective precursor for synthesizing such particles; a better precursor is (3-Mercaptopropyl)trimethoxysilane, often abbreviated to MPTMS. Use of this precursor drastically reduces the chance of aggregation and ensures more uniform spheres.[18]
Drug delivery
The large surface area of the pores allows the particles to be filled with a drug or a
Ordered mesoporous silica (e.g. SBA-15,[21] TUD-1,[22] HMM-33,[1] and FSM-16[23]) also show potential to boost the in vitro and in vivo dissolution of poorly water-soluble drugs. Many drug-candidates coming from drug discovery suffer from a poor water solubility. An insufficient dissolution of these hydrophobic drugs in the gastrointestinal fluids strongly limits the oral bioavailability. One example is itraconazole which is an antimycoticum known for its poor aqueous solubility. Upon introduction of itraconazole-on-SBA-15 formulation in simulated gastrointestinal fluids, a supersaturated solution is obtained giving rise to enhanced transepithelial intestinal transport.[24] Also the efficient uptake into the systemic circulation of SBA-15 formulated itraconazole has been demonstrated in vivo (rabbits and dogs).[25] This approach based on SBA-15 yields stable formulations[26] and can be used for a wide variety of poorly water-soluble compounds.[27]
Biosensors
The 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.[28][29]
See also
- Mesoporous material
- Mesoporous silicates
References
- ^ .
- PMID 16716334.
- ^ .
- S2CID 245147740.
- ^ Chiola, V.; Ritsko, J. E. and Vanderpool, C. D. "Process for producing low-bulk density silica." Application No. US 3556725D A filed on 26-Feb-1969; Publication No. US 3556725 A published on 19-Jan-1971
- ^ "Porous silica particles containing a crystallized phase and method" Application No. US 3493341D A filed on 23-Jan-1967; Publication No. US 3493341 A published on 03-Feb-1970
- ^ "Process for producing silica in the form of hollow spheres"; Application No. US 342525 A filed on 04-Feb-1964; Publication No. US 3383172 A published on 14-May-1968
- ISBN 978-0-470-82233-3.
- .
- .
- .
- PMID 17645305.
- PMID 9438845.
- PMID 27960352.
- .
- S2CID 139146490.
- .
- .
- PMID 24871552.
- PMID 28536462.
- PMID 17377687.
- PMID 17046183.
- PMID 16079530.
- PMID 18325700.
- PMID 18164930.
- .
- PMID 19072861.
- PMID 17668088.
- PMID 15479063.