Research on mesoporous materials for biomedical purposes has experienced an outstanding increase during recent years. Since 2001, when MCM-41 was first proposed as drug-delivery system, silica-based materials, such as SBA-15 or MCM-48, and some metal-organic frameworks have been discussed as drug carriers and controlled-release systems. Mesoporous materials are intended for both systemic-delivery systems and implantable local-delivery devices. The latter application provides very promising possibilities in the field of bone-tissue repair because of the excellent behavior of these materials as bioceramics. This Minireview deals with the advances in this field by the control of the textural parameters, surface functionalization, and the synthesis of sophisticated stimuli-response systems.

A new application of MCM-41 mesoporous materials has been developed. Two kinds of surfactants, C16TAB and C12TAB, have been employed to get different pore sizes. The samples were disk-shaped conformed before and after charging with ibuprofen, an antiinflammatory drug. In all the cases the weight percent ratio of drug/MCM-41 was 30%. The drug release plots show a different behavior depending on the method for charging the drug in the material but not on the employed surfactant.

Flexible nanoporous chromium or iron terephtalates (BDC) MIL-53(Cr, Fe) or M(OH)[BDC] have been used as matrices for the adsorption and in vitro drug delivery of Ibuprofen (or alpha- p-isobutylphenylpropionic acid). Both MIL-53(Cr) and MIL-53(Fe) solids adsorb around 20 wt % of Ibuprofen (Ibuprofen/dehydrated MIL-53 molar ratio = 0.22(1)), indicating that the amount of inserted drug does not depend on the metal (Cr, Fe) constitutive of the hybrid framework. Structural and spectroscopic characterizations are provided for the solid filled with Ibuprofen. In each case, the very slow and complete delivery of Ibuprofen was achieved under physiological conditions after 3 weeks with a predictable zero-order kinetics, which highlights the unique properties of flexible hybrid solids for adapting their pore opening to optimize the drug-matrix interactions.

Fill 'em up: The metal carboxylates MIL‐100 and MIL‐101 act as porous matrices (see picture; MIL=Materials of Institut Lavoisier) for drug‐delivery systems using Ibuprofen as a model substrate. Very large amounts of the drug could be incorporated, up to an unprecedented capacity of 1.4 g of drug per gram of porous solid for MIL‐101, and the total release of Ibuprofen was achieved under physiological conditions in 3 (MIL‐100) and 6 days (MIL‐101).

Pack sie voll: Die Metallcarboxylate MIL‐100 und MIL‐101 fungieren als poröse Matrices (siehe Bild) in Wirkstofftransportsystemen mit Ibuprofen als Modellsubstrat. Sie konnten sehr große Mengen Wirkstoff aufnehmen (bis zu bisher unerreichten 1.4 g Wirkstoff pro Gramm MIL‐101), und Ibuprofen wurde unter physiologischen Bedingungen in 3 (MIL‐100) bzw. 6 Tagen (MIL‐101) vollständig freigesetzt.

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Bioactive glasses react chemically with the body fluids. The reaction product is an apatite, which, with the intervention of biological drivers, assists the generation of bone matrix and bone growth. The main application of these bioactive glasses in the clinical field is the filling of osseous cavities, manufacture of small parts for middle ear bone replacement and maxilofacial reconstruction and dental applications. Thanks to advances in related medical technologies, bioactive glasses are now undergoing a new stage of development, resulting in different mechanical properties, drug delivery capabilities, bioactive coating of metallic implants, protein and/or cell activation for tissue regeneration and tissue engineering, and are also finding use in biomimetics, nanotechnology, production of hybrid organic‐inorganic materials and as bioactivity accelerators of mineral apatites or as bioactivity inductors of magnetic materials for hyperthermia treatment of osseous tumours. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Organic modification with aminopropyl group of two MCM-41 materials having different pore sizes (obtained from trimethylalkylammonium surfactants with different chain sizes (16 and 12 carbon atoms)) has been carried out in order to control the delivery rate of ibuprofen from the siliceous matrix. This functionalization was performed by two different methods: the as-synthesized MCM-41 sample was treated with aminopropyltrimethoxysilane (method a), and the MCM-41 was first calcined and then funtionalized by reaction with aminopropyltrimethoxysilane (method b). The amount of ibuprofen adsorbed from hexane solution is lower for the C12 derived materials. A slower delivery rate has been observed for method b, whereas a minor influence of the pore size on the delivery rate has been found.