In situ preparation and protein delivery of silicate-alginate composite microspheres with core-shell structure.

Institute for Materials Science and Max Bergmann Center of Biomaterials, Dresden University of Technology, Germany.
Journal of The Royal Society Interface (Impact Factor: 3.86). 05/2011; 8(65):1804-14. DOI: 10.1098/rsif.2011.0201
Source: PubMed

ABSTRACT The efficient loading and sustained release of proteins from bioactive microspheres remain a significant challenge. In this study, we have developed bioactive microspheres which can be loaded with protein and then have a controlled rate of protein release into a surrounding medium. This was achieved by preparing a bioactive microsphere system with core-shell structure, combining a calcium silicate (CS) shell with an alginate (A) core by a one-step in situ method. The result was to improve the microspheres' protein adsorption and release, which yielded a highly bioactive material with potential uses in bone repair applications. The composition and the core-shell structure, as well as the formation mechanism of the obtained CS-A microspheres, were investigated by X-ray diffraction, optical microscopy, scanning electron microscopy, energy dispersive spectrometer dot and line-scanning analysis. The protein loading efficiency reached 75 per cent in CS-A microspheres with a core-shell structure by the in situ method. This is significantly higher than that of pure A or CS-A microspheres prepared by non-in situ method, which lack a core-shell structure. CS-A microspheres with a core-shell structure showed a significant decrease in the burst release of proteins, maintaining sustained release profile in phosphate-buffered saline (PBS) at both pH 7.4 and 4.3, compared with the controls. The protein release from CS-A microspheres is predominantly controlled by a Fickian diffusion mechanism. The CS-A microspheres with a core-shell structure were shown to have improved apatite-mineralization in simulated body fluids compared with the controls, most probably owing to the existence of bioactive CS shell on the surface of the microspheres. Our results indicate that the core-shell structure of CS-A microspheres play an important role in enhancing protein delivery and mineralization, which makes these composite materials promising candidates for application in bone tissue regeneration.

  • [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study is to prepare Ca, P and Si-containing ternary oxide nagelschmidtite (NAGEL, Ca7Si2P2O16) bioceramics and explore their in vitro bioactivity for potential bone tissue regeneration. We prepared dense NAGEL ceramics through high-temperature sintering of NAGEL ceramic powders. The apatite-mineralization ability, dissolution rate, and human osteoblast response (including cytotoxicity analysis, attachment, morphology, proliferation, and bone-related gene expression) to NAGEL ceramics have been systematically studied by comparing with conventional β-tricalcium phosphate (β-TCP) ceramics. The results showed that NAGEL ceramics possessed more obvious apatite mineralization and dissolution (degradation) and stimulated bone-related gene expression (OCN and OPN) of osteoblasts than β-TCP ceramics. NAGEL ceramics also showed no significant cytotoxicity. NAGEL ceramics supported osteoblast attachment, proliferation, and osteogenic gene expression, with a comparable cell proliferation activity with β-TCP ceramics. These results indicate that novel NAGEL bioceramics with the specific composition of Ca7Si2P2O16, are a promising biomaterial for bone tissue regeneration application.
    Journal of the American Ceramic Society 03/2013; 96(3). DOI:10.1111/jace.12059 · 2.43 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The advances in strategies for bone and cartilage regeneration have been centered on a concept that describes the close relationship between osteogenic cells, osteoconductive scaffolds, delivery growth factors and the mechanical environment. The dynamic nature of the tissue repair process involves intricate mimicry of signals expressed in the biological system in response to an injury. Recently, synergistic strategies involving hybrid delivery systems that provide sequential dual delivery of biomolecules and relevant topological cues received great attention. Future advances in tissue regeneration will therefore depend on multidisciplinary strategies that encompass the crux of tissue repair aimed at constructing the ideal functional regenerative scaffold. Here, functional scaffolds delivering therapeutics are reviewed in terms of their controlled release and healing capabilities.
    Drug discovery today 06/2014; 19(6):714-724. DOI:10.1016/j.drudis.2013.11.007 · 5.96 Impact Factor
  • Source
    Ceramics International 12/2014; 40(10):16595-16601. DOI:10.1016/j.ceramint.2014.08.017 · 2.09 Impact Factor