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Recent advances in ceramic implants as drug delivery systems for biomedical applications.

Colilla M, Manzano M, Vallet-Regí M - Int J Nanomedicine (2008)

Bottom Line: Second, their capability of acting as delivery systems of a large variety of biologically active molecules, including drugs to treat bone infection, inflammation or diseases, and molecules that promote bone tissue regeneration, such as peptides, proteins, growth factors, and other osteogenic agents.The recent chemical and technological advances in the nanometer scale has allowed the design of mesoporous silicas with tailored structural and textural properties aimed at achieving a better control over molecule loading and release kinetics.Moreover organic modification of mesoporous silica walls has been revealed as a key strategy to modulate molecule adsorption and delivery rates.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Química Inorgánica y Bioinorgánica, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain.

ABSTRACT
Research in the development of new bioceramics with local drug delivery capability for bone regeneration technologies is receiving great interest by the scientific biomedical community. Among bioceramics, silica-based ordered mesoporous materials are excellent candidates as bone implants due to two main reasons: first, the bioactive behavior of such materials in contact with simulated body fluids, ie, a carbonate hydroxyapatite similar to the mineral phase of bone is formed onto the materials surfaces. Second, their capability of acting as delivery systems of a large variety of biologically active molecules, including drugs to treat bone infection, inflammation or diseases, and molecules that promote bone tissue regeneration, such as peptides, proteins, growth factors, and other osteogenic agents. The recent chemical and technological advances in the nanometer scale has allowed the design of mesoporous silicas with tailored structural and textural properties aimed at achieving a better control over molecule loading and release kinetics. Moreover organic modification of mesoporous silica walls has been revealed as a key strategy to modulate molecule adsorption and delivery rates.

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Related in: MedlinePlus

Schematic representation of the structure of different proteins with diverse dimensions (RCSB 2008) compared to thiol-functionalized SBA-15.
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f2-ijn-3-403: Schematic representation of the structure of different proteins with diverse dimensions (RCSB 2008) compared to thiol-functionalized SBA-15.

Mentions: Pore diameter is a limiting factor in molecule adsorption when the confinement of really large molecules, such as proteins and other biologically active molecules, is targeted. Therefore, the adsorption of globular proteins on mesoporous MCM-41 (with pore diameters ranging from 2 to 5 nm) has been reported in the literature (Deere et al 2002). In general, proteins with hydrodynamic dimensions larger than the mesopore diameter were adsorbed on the outer surface of MCM-41 (Katiyar et al 2005). For this reason, when the confinement of proteins into mesoporous matrices is targeted, large pore mesoporous materials should be employed. The group of Prof. Wright (Yiu et al 2001b) investigated the influence of protein dimensions on the adsorption into SBA-15 mesoporous molecular sieve, whose silica walls were organically modified using thiol groups. For this purpose, a series of proteins with molecular weights ranging from 12000 to 76000 u were used to investigate adsorption on SBA-15 materials. The structures of the employed proteins together with their dimensions in nanometers (RCSB 2008) are displayed in Figure 2. Further adsorption studies revealed that the proteins with the smallest sizes, ie, cytochrome c, lysozyme, myoglobin, and β-lactoglobulin, showed significant adsorption. On the contrary, the proteins with the largest sizes, ie, conalbumin, serum albumin and ovalbumin were excluded from the internal surfaces of thiol-functionalized SBA-15. This fact agrees with the sieving expected from the 5.1 nm pore size of thiol-functionalized SBA-15 when compared to the proteins dimensions. Moreover, the exclusion of ovalbumin (4.0 × 5.0 × 7.0 nm), with dimensions quite close to thiol-functionalized SBA-15 matrix, indicates that this size selectivity is rigorous and that there are very few pores appreciably larger than the average pore size. It should be remarked that the maximum amounts of protein loaded, expressed as a volume percent of the available internal pore volume (5% for β-lactoglobulin, 15% for myoglobin, and 43% for cytochrome c) showed that the protein molecules were adsorbed within the mesopores and not only on the external surfaces.


Recent advances in ceramic implants as drug delivery systems for biomedical applications.

Colilla M, Manzano M, Vallet-Regí M - Int J Nanomedicine (2008)

Schematic representation of the structure of different proteins with diverse dimensions (RCSB 2008) compared to thiol-functionalized SBA-15.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2636592&req=5

f2-ijn-3-403: Schematic representation of the structure of different proteins with diverse dimensions (RCSB 2008) compared to thiol-functionalized SBA-15.
Mentions: Pore diameter is a limiting factor in molecule adsorption when the confinement of really large molecules, such as proteins and other biologically active molecules, is targeted. Therefore, the adsorption of globular proteins on mesoporous MCM-41 (with pore diameters ranging from 2 to 5 nm) has been reported in the literature (Deere et al 2002). In general, proteins with hydrodynamic dimensions larger than the mesopore diameter were adsorbed on the outer surface of MCM-41 (Katiyar et al 2005). For this reason, when the confinement of proteins into mesoporous matrices is targeted, large pore mesoporous materials should be employed. The group of Prof. Wright (Yiu et al 2001b) investigated the influence of protein dimensions on the adsorption into SBA-15 mesoporous molecular sieve, whose silica walls were organically modified using thiol groups. For this purpose, a series of proteins with molecular weights ranging from 12000 to 76000 u were used to investigate adsorption on SBA-15 materials. The structures of the employed proteins together with their dimensions in nanometers (RCSB 2008) are displayed in Figure 2. Further adsorption studies revealed that the proteins with the smallest sizes, ie, cytochrome c, lysozyme, myoglobin, and β-lactoglobulin, showed significant adsorption. On the contrary, the proteins with the largest sizes, ie, conalbumin, serum albumin and ovalbumin were excluded from the internal surfaces of thiol-functionalized SBA-15. This fact agrees with the sieving expected from the 5.1 nm pore size of thiol-functionalized SBA-15 when compared to the proteins dimensions. Moreover, the exclusion of ovalbumin (4.0 × 5.0 × 7.0 nm), with dimensions quite close to thiol-functionalized SBA-15 matrix, indicates that this size selectivity is rigorous and that there are very few pores appreciably larger than the average pore size. It should be remarked that the maximum amounts of protein loaded, expressed as a volume percent of the available internal pore volume (5% for β-lactoglobulin, 15% for myoglobin, and 43% for cytochrome c) showed that the protein molecules were adsorbed within the mesopores and not only on the external surfaces.

Bottom Line: Second, their capability of acting as delivery systems of a large variety of biologically active molecules, including drugs to treat bone infection, inflammation or diseases, and molecules that promote bone tissue regeneration, such as peptides, proteins, growth factors, and other osteogenic agents.The recent chemical and technological advances in the nanometer scale has allowed the design of mesoporous silicas with tailored structural and textural properties aimed at achieving a better control over molecule loading and release kinetics.Moreover organic modification of mesoporous silica walls has been revealed as a key strategy to modulate molecule adsorption and delivery rates.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Química Inorgánica y Bioinorgánica, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain.

ABSTRACT
Research in the development of new bioceramics with local drug delivery capability for bone regeneration technologies is receiving great interest by the scientific biomedical community. Among bioceramics, silica-based ordered mesoporous materials are excellent candidates as bone implants due to two main reasons: first, the bioactive behavior of such materials in contact with simulated body fluids, ie, a carbonate hydroxyapatite similar to the mineral phase of bone is formed onto the materials surfaces. Second, their capability of acting as delivery systems of a large variety of biologically active molecules, including drugs to treat bone infection, inflammation or diseases, and molecules that promote bone tissue regeneration, such as peptides, proteins, growth factors, and other osteogenic agents. The recent chemical and technological advances in the nanometer scale has allowed the design of mesoporous silicas with tailored structural and textural properties aimed at achieving a better control over molecule loading and release kinetics. Moreover organic modification of mesoporous silica walls has been revealed as a key strategy to modulate molecule adsorption and delivery rates.

Show MeSH
Related in: MedlinePlus