Article

Smart designing of new hybrid materials based on brushite-alginate and monetite-alginate microspheres: Bio-inspired for sequential nucleation and growth

Materials Science and Engineering C 01/2013; 35(1). DOI: 10.1016/j.msec.2013.11.012

ABSTRACT

In this report new hybrid materials based on brushite-alginate and monetite-alginate were prepared by self-assembling alginate chains and phosphate source ions via a gelation process with calcium ions. The alginate served as nanoreactor for nucleation and growth of brushite or/and monetite due to its gelling and swelling properties. The alginate gel framework, the crystalline phase and morphology of formed hybrid biomaterials were shown to be strongly dependent upon the concentration of the phosphate precursors. These materials were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDX).

Download full-text

Full-text

Available from: Walid Amer
  • [Show abstract] [Hide abstract]
    ABSTRACT: Strontium is known for efficient actions on bone formation and resorption. Strontium ranelate (SrR) is a commercial drug which maintains this balance during bone turnover, reducing the risks of vertebral fractures in the patients. Calcium phosphate bioceramics associated with alginate matrices containing strontium (Sr) could improve bone regeneration due to gradual Sr release. In this report, the strontium ranelate was incorporated on microspheres of alginate (ALG)/β-tricalcium phosphate in a single route of the production. Energy dispersive spectroscopy showed that strontium was incorporated on the surface of the microspheres produced. The dissolution behaviour into a buffer solution at pH 4.0 and at 7.4 was evaluated, measuring Sr content on the microspheres after in vitro assays by atomic absorption spectrometry. Dissolution tests showed a rapid strontium release in both assays, however, it was more pronounced at pH 4.0. Fourier transform infrared spectra indicated the presence of a new precipitated phase at pH 7.4 up after 14 days. Scanning electron microscopy of the microspheres submitted to in vitro revealed that the microspheres at pH 4.0 buffer underwent erosion up to 7 days, while the ones in pH 7.4 buffer, eroded in 48h. This behaviour is due to the high swelling rate of the microspheres in neutral pH. The solubility of the microspheres favors its use as a great material for a local strontium release and remodeling bone.
    No preview · Article · Jan 2015 · Key Engineering Materials
  • [Show abstract] [Hide abstract]
    ABSTRACT: By dropping a NaH2PO4·H2O precursor solution to a CaCl2 solution at 90°C under continuous stirring in presence of two biopolymers, i.e. gelatin (G) and chitosan (C), supramolecular calcium phosphate (CP) card house structures are formed. Light microscopic investigations in combination with scanning electron microscopy show that the GC-based flower-like structure is constructed from very thin CP platelets. Titration experiments indicate that H-bonding between both biopolymers is responsible for the synergistic effect in presence of both polymers. Gelatin-chitosan-water complexes play an important role with regard to supramolecular ordering. FTIR spectra in combination with powder X-ray diffraction show that after burning off all organic components (heating up >600°C) dicalcium and tricalcium phosphate crystallites are formed. From high resolution transmission electron microscopy (HR-TEM) it is obvious to conclude, that individual crystal platelets are dicalcium phosphates, which build up ball-like supramolecular structures. The results reveal that the GC guided crystal growth leads to nano-porous supramolecular structures, potentially attractive candidates for bone repair. Copyright © 2015 Elsevier B.V. All rights reserved.
    No preview · Article · May 2015 · Colloids and surfaces B: Biointerfaces
  • [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to point out the effect of porous clay heterostructure (PCH) and polymer concentration on thermal and dynamic mechanical properties of Sodium Alginate (SA) based hybrid films. New hybrid films based on SA and PCH were prepared by solvent casting method using different polymer concentrations and clay loadings. The interactions between nanofiller (PCH) and polymer matrix (SA), thermal stability and dynamic mechanical properties of neat SA and hybrid films were evaluated by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The obtained results showed the influence of PCH within SA on the storage modulus and a moderate change of thermal stability, the glass transition temperature being also recorded. The concentration of SA solution and PCH are significant factors which affect the thermal and mechanical properties of hybrid films.
    No preview · Article · Sep 2015 · MATERIALE PLASTICE