Bioactive glass/polymer composite scaffolds mimicking bone tissue

Article (PDF Available)inJournal of Biomedical Materials Research Part A 100(10):2654-67 · October 2012with123 Reads
DOI: 10.1002/jbm.a.34205 · Source: PubMed
Abstract
The aim of this work was the preparation and characterization of scaffolds with mechanical and functional properties able to regenerate bone. Porous scaffolds made of chitosan/gelatin (POL) blends containing different amounts of a bioactive glass (CEL2), as inorganic material stimulating biomineralization, were fabricated by freeze-drying. Foams with different compositions (CEL2/POL 0/100; 40/60; 70/30 wt %/wt) were prepared. Samples were crosslinked using genipin (GP) to improve mechanical strength and thermal stability. The scaffolds were characterized in terms of their stability in water, chemical structure, morphology, bioactivity, and mechanical behavior. Moreover, MG63 osteoblast-like cells and periosteal-derived stem cells were used to assess their biocompatibility. CEL2/POL samples showed interconnected pores having an average diameter ranging from 179 ± 5 μm for CEL2/POL 0/100 to 136 ± 5 μm for CEL2/POL 70/30. GP-crosslinking and the increase of CEL2 amount stabilized the composites to water solution (shown by swelling tests). In addition, the SBF soaking experiment showed a good bioactivity of the scaffold with 30 and 70 wt % CEL2. The compressive modulus increased by increasing CEL2 amount up to 2.1 ± 0.1 MPa for CEL2/POL 70/30. Dynamical mechanical analysis has evidenced that composite scaffolds at low frequencies showed an increase of storage and loss modulus with increasing frequency; furthermore, a drop of E' and E″ at 1 Hz was observed, and for higher frequencies both moduli increased again. Cells displayed a good ability to interact with the different tested scaffolds which did not modify cell metabolic activity at the analyzed points. MTT test proved only a slight difference between the two cytotypes analyzed.

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    • "The FTIR analysis performed for the composite scaffolds after SBF treatment showed three main bands (1035 cm À 1 , 600 cm À 1 , 561 cm À 1 ) attributed to phosphate group of the precipitated hydroxyapatite and a significant increase in intensity was found between day 1 (Fig. 11(d)) and day 28 (Fig. 11(e)). Likewise, peaks were observed at 1530–1400 cm À 1 and 880 cm À 1 that were attributed to the C-O stretching vibrations and C-O out of plane vibrations respectively [37]. Fig. 11(c) shows the FTIR spectra of silk scaffolds after 28 days of SBF immersion where no characteristic phosphate peaks are shown. "
    File · Data · Jul 2016 · Materials Science and Engineering C
    • "3.6 [102] PMMA epoxy 15.5 wt% 1109 (Y) [97] Epoxy/bioactive glass 1wt% 298.51 (F) 2.78 (GPa) Flexural modulus [115] Chitosan/gelatine [85] PCL 20 wt% 10 (T) 150 (Y) [86] Gelatine 50 wt% 5.6 Yield strength 78 1.2 (MPa) [9] "
    [Show abstract] [Hide abstract] ABSTRACT: Bones are nanocomposites consisting of a collagenous fibre networks, embedded with calcium phosphates mainly hydroxyapatite (HA) nanocrystallites. As bones are subjected to continuous loading and unloading process every day, they often tend to become prone to fatigue and breakdown. Therefore, this review addresses the use of nanocomposites particularly polymers reinforced with nanoceramics that can be used as load bearing bone implants. Further, nanocomposite preparation and dispersion modification techniques have been highlighted along with thorough discussion on the influence that various nanofillers have on the physico-mechanical properties of nanocomposites in relation to that of natural bone properties.This review up to dates the nanocomposites that meet the physico-mechanical properties (strength and elasticity) as well as biocompatibility requirement of a load bearing bone implant and also attempts to highlight the gaps in the reported studies to address the fatigue and creep properties of the nanocomposites.
    Full-text · Article · May 2016
    • "In preparing gelatin hydrogels, these residues allow for the partial reformation of triple helices into secondary helix structures [4], which are considered the driving force behind the sol–gel transition of gelatin. While porous gelatin materials (e.g., scaffolds) have been created and studied primarily for tissue engineering applications (e.g., biomineralization [5][6][7][8]) using a variety of fabrication methods, freeze-drying (or modified versions) has been the most widely employed [9][10][11][12][13][14] . In this method, the water in gelatin solutions is frozen , then subsequently lyophilized, yielding an open pore structure. "
    [Show abstract] [Hide abstract] ABSTRACT: Gelatin-based foams with aligned tubular pore structures were prepared via liquid-to-gas vaporization of tightly bound water in dehydrated gelatin hydrogels. This study elucidates the mechanism of the foaming process by investigating the secondary (i.e., helical) structure, molecular interactions, and water content of gelatin films before and after foaming using X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry and thermogravimetric analysis (TGA), respectively. Experimental data from gelatin samples prepared at various gelatin-to-water concentrations (5–30 wt.%) substantiate that resulting foam structures are similar in pore diameter (approximately 350 μm), shape, and density (0.05–0.22 g/cm3) to those fabricated using conventional methods (e.g., freeze-drying). Helical structures were identified in the films but were not evident in the foamed samples after vaporization (~ 150 °C), suggesting that the primary foaming mechanism is governed by the vaporization of water that is tightly bound in secondary structures (i.e., helices, β-turns, β-sheets) present in dehydrated gelatin films. FTIR and TGA data show that the foaming process leads to more disorder and reduced hydrogen bonding to hydroxyl groups in gelatin and that no thermal degradation of gelatin occurs before or after foaming.
    Full-text · Article · Jan 2016 · Materials Science and Engineering C
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