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: 3.92). 05/2011; 8(65):1804-14. DOI: 10.1098/rsif.2011.0201
Source: PubMed


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.

Download full-text


Available from: Yin Xiao
  • Source
    • "Since this mechanism depends on the cations diffusion, only small unities (from hundreds of microns up to few millimeters of diameter) can be produced. However, since they exhibit very controlled and reproducible microstructure and properties , such beads have been investigated for several applications , as drug delivery carriers and bone replacement substrates [3] [6] [8] [11] [13] [14] [19] [26]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Gelcasting consolidating processes often employ natural polymers as binder agents to reduce the generation of toxic volatiles at the handling of the raw materials, mixing of the suspension during the calcination step. Sodium alginate (SA) is one of the most used binders, amongst many others, such as chitosan, casein, and starch. Its gelling mechanism can be activated by the crosslinking the polyvalent cations (such as Ca2+ and Al3+) produce amongst its macromolecules. The present study employed this mechanism to prepare porous alumina beads of tailored geometry. Droplets of alumina SA suspension were dripped inside an Al(NO3)(3) coagulation bath and generated a soft core rigid shell structure. By varying the coagulation time, drying and sintering conditions, the initial spherical shape of the structures was controllably deformed and generated curious geometries. Large variations in apparent porosity and specific surface area were also obtained, which suggests that this system can be applied as proppants for shale gas extraction, implants, and scaffolds for the growth of biological tissues.
    Full-text · Article · Dec 2014 · Ceramics International
  • [Show abstract] [Hide abstract]
    ABSTRACT: Pure calcium alginate (CA), CA composite beads containing 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (CA-P507), core–shell structural calcium silicate-alginate (CS-A) and CS-A containing P507 (CS-A-P507) have been synthesized and their adsorption properties towards rare earths (III) have been investigated. The order of their adsorption capacities is as follows: CA-P507 > CS-A-P507 > CA > CS-A. The effect of ionic radii of rare earths on the adsorption distribution ratio has also been examined. Adsorption mechanism could mainly be proposed to be cation exchange. The pseudo-second-order kinetics model and Langmuir isotherm equation are used to describe the adsorption process very well. The adsorption capacity, selectivity and reusability have been improved owing to the introduction of P507 ionophore and CaSiO3 crust, respectively. As far as adsorption properties are concerned, CS-A-P507 is generally superior to the other three kinds of beads and shows its potential industrial application for the separation and recovery of rare earths. Graphical abstract Schematic illustration for in situ preparation of core–shell structural calcium silicate-alginate containing 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (CS-A-P507). Core: Calcium alginate (CA); Shell: Calcium silicate (CS).
    No preview · Article · Sep 2012
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The impact of bone diseases and trauma in the whole world has increased significantly in the past decades. Bioactive glasses are regarded as an important bone regeneration material owing to their generally excellent osteoconductivity and osteostimulativity. A new class of bioactive glass, referred to as mesoporous bioglass (MBG), was developed 7 years ago, which possess a highly ordered mesoporous channel structure and a highly specific surface area. The study of MBG for drug/growth factor delivery and bone tissue engineering has grown significantly in the past several years. In this article, we review the recent advances of MBG materials, including the preparation of different forms of MBG, composition-structure relationship, efficient drug/growth factor delivery and bone tissue engineering application. By summarizing our recent research, the interaction of MBG scaffolds with bone-forming cells, the effect of drug/growth factor delivery on proliferation and differentiation of tissue cells and the in vivo osteogenesis of MBG scaffolds are highlighted. The advantages and limitations of MBG for drug delivery and bone tissue engineering have been compared with microsize bioactive glasses and nanosize bioactive glasses. The future perspective of MBG is discussed for bone regeneration application by combining drug delivery with bone tissue engineering and investigating the in vivo osteogenesis mechanism in large animal models.
    Preview · Article · Jun 2012 · Interface focus: a theme supplement of Journal of the Royal Society interface
Show more