Hollow mesoporous silica particles

Recently, hollow silica nanoparticles with mesoporous shells have attracted much attention for the capabihty of molecules to interdifftise through the shells and for their enhanced surface area and porosity, which give the particles an increased drug storage capacity and lower refractive index. 

Surfactant assemblies are generally utilized as a template to form mesoporous shell. Vesicle-like hollow sihca particles can be prepared by sol-gel reactions in the presence of surfactants. Although most of the materials reported so far have multilamellar structures, hollow mesoporous silica particles with a single-walled vesicle structure have been prepared by the reaction of TEOS in the presence of a fluorinated surfactant (lH,lH,2//,2//-perfluorodecylpyridinium chloride). With 

To better control the ordering of mesopores in the silica shell, along with particle size and shape, the hard template method in combination with surfactant templating has been studied intensively. Typically, hollow particles with hexagonally ordered mesoporous shells can be obtained by using PS beads and CTAB in an aqueous ammonia solution. After the growth of a silica-surfactant meso-structured composite shell on the surfeice, the PS template is finally removed by calcination to form hollow spheres. Several reports have succeeded in 

Recently, a selective etching method has been developed as a simple and effective strategy to fabricate hollow mesoporous silica particles. Fang et al. reported the formation of hollow mesoporous sihca spheres with either a wormhole-like or an oriented pore structure by treatment of sohd silica spheres in a sodium 

---

Figure 11.5 TEM images of hollow mesoporous silica particles prepared using an anionic PS template (A40-an, A30-an, and A5-an) and the cationic PS template (A25-cat). Scale bar 100 nm. (Reproduced with permission from Ref. [37], Copyright 2008, American Chemical Society.)...

Figure 11.12 (a) Different release patterns of IBU from hollow mesoporous silica particles with and without the PAH/PSS coating, (b) Cumulative drug release from the two systems at different pH values. pH 1.4 from IBU-... 

The potential of hollow mesoporous silica nanoparticles as a drug carrier has been actively researched in vitro. For example, hollow mesoporous silica nanospheres with uniform sizes of 31-33 nm, prepared using PS-PVP-PEO triblock copolymer micelles, exhibited a higher storage capacity of a model drug (ibupro-fen) than the conventional mesoporous silica particles [111]. A more sustained release was achieved by propylamine functionalization, which is effective for controlled release of drug molecules. 

Zhu, Y., Meng, W., Gao, H., and Hanagata, N. (2011) Hollow mesoporous silica/poly(L-lysine) particles for codelivery of drug and gene with enzyme-triggered release property. 

CW/templated resin (TPR), 50 pm, is used for analysis of surfactants by HPLC. The templated resin in CW/TPR is a hollow, spherical DVB formed by coating DVB over a silica template. When the silica is dissolved, the hollow, spherical DVB particle formed has no micro- or mesopores [135],... 

Using SCF processes such as these, polymers and inorganic materials have been formed into films, fibres and spherical particles. For example, mesoporous silicate films and mesoporous silica hollow spheres have both been recently prepared using SCCO2 based technologies. ... 

Bayu, A., Nandiyanto, D., Akane, Y., Ogi, T., and Okuyama, K. (2012) Mesopore-free hollow silica particles with controllable diameter and shell thickness via additive-free synthesis. Langmuir, 28, 8616-8624. 

Tan, B., Lehmler, H.-J., Vyas, S.M., Knutson, B.L., and Rankin, S.E. (2005) Fluorinated-surfactant-templated synthesis of hollow silica particles with a single layer of mesopores in their shells. Adv. Mater, 17, 2368-2371. 

C., Sanchez, C, and Charleux, B. (2008) Elaboration of monodisperse spherical hollow particles with ordered mesoporous silica shells via dual latex/ surfrtctant templating radial orientation of mesopore channels. Langmuir, 24, 13132-13137. 

---