Hollow mesoporous spheres with cubic pore network as a potential carrier for drug storage and its in vitro release kinet
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The hollow mesoporous spheres (HMS) with cubic pore network have been synthesized via a simple two-step method. Two drugs of different molecules size, Aspirin and Gentamicin, were tested by one simple adsorption process. Up to 336 mg Aspirin molecules can be stored in 1.0 g HMS, while Gentamicin molecules of much larger size are much more difficult to be introduced into the pore channels of HMS. The same results can be obtained by using MCM-48 and MCM-41 as comparative mesoporous carriers. The HMS shows significantly higher storage amount of Aspirin than conventional MCM-48 and MCM-41 due to its hollow core structure. The release process of HMS-Aspirin, MCM-48-Aspirin and MCM-41-Aspirin are found to have a sustained-release property and follow a Fickian diffusion mechanism. Moreover, the HMS is suitable for storage of drug molecules of much smaller size.
I. INTRODUCTION
The discovery of ordered mesoporous silica of the MCM-41S family by Mobil researchers in 19921 has opened a new field for host-guest chemistry. Many potential applications of the materials have been investigated, especially for catalysis,2 adsorptions,3 and nanotechnology.4 Recently, hollow mesoporous spheres with ordered pore structures have attracted much attention, because these materials have more advantages than the conventional mesoporous materials in drug storage and release, confined-space catalysis, chromatography, and large biomolecular-release systems.5–9 Several reports have described the synthesis of hollow spherical materials with mesoporous network.10–13 A general approach for preparing hollow spheres of mesoporous materials was based on sol-gel/emulsion technologies or the use of organic polymer beads as the templates that control the void formation and its volume. However, the pore structures of these hollow spherical mesoporous materials were hexagonally ordered within the shells of the spheres along latitude directions, which prevented the diffusion of the guest molecules into the cores of the spheres. Undoubtedly, with the cubic pore network within the shells of the spheres one can avoid this problem, which is
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Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2005.0035 54
http://journals.cambridge.org
J. Mater. Res., Vol. 20, No. 1, Jan 2005 Downloaded: 21 May 2014
because the channels are cross-linked in three-dimension space, the guest molecules can diffuse into the cores of the spheres through the channels. The regular and tunable pore size together with the large surface area, mesoporous volume, and the nontoxic nature of amorphous silica1,14 have led many research groups to investigate the potential of these materials for the storage and release of drug.15–22 They all used the conventional mesoporous particles with hexagonal structure as carriers, for the investigation of hosting ibuprofen, pentagastrin, vancomycin, adenosine triphosphate, taxol, and so on. The results indicated that the mesoporous materials-drug systems have a sustained-release property. However, most researc
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