Browsing by Author "Rahaman, MN"

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    Direct-write assembly of silicate and borate bioactive glass scaffolds for bone repair
    Deliormanli, AM; Rahaman, MN
    Silicate (13-93) and borate (13-93B3) bioactive glass scaffolds were created by robotic deposition (robocasting) of organic solvent-based suspensions and evaluated in vitro for potential application in bone repair. Suspensions (inks) were developed, characterized, and deposited layer-by-layer to form three-dimensional scaffolds with a grid-like microstructure (porosity approximate to 50%; pore width 420 +/- 30 mu m). The mechanical response of the scaffolds was tested in compression, and the conversion of the glass to hydroxyapatite (HA)-like material in a simulated body fluid (SBF) was evaluated. As fabricated, the 13-93 scaffolds had a compressive strength 142 +/- 20 MPa, comparable to the strength of human cortical bone, while the strength of the 13-93B3 scaffolds (65 +/- 11 MPa), was far higher than that for trabecular bone. When immersed in SBF, the borate 13-93B3 scaffolds converted faster than the silicate 13-93 scaffolds to an HA-like material, but they also showed a sharper decrease in strength with immersion time. Based on their high compressive strength and bioactivity, the scaffolds fabricated in this work by robocasting could have potential application in the repair of load-bearing bone. (C) 2012 Elsevier Ltd. All rights reserved.
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    Evaluation of borate bioactive glass scaffolds with different pore sizes in a rat subcutaneous implantation model
    Deliormanli, AM; Liu, X; Rahaman, MN
    Borate bioactive glass has been shown to convert faster and more completely to hydroxyapatite and enhance new bone formation invivo when compared to silicate bioactive glass (such as 45S5 and 13-93 bioactive glass). In this work, the effects of the borate glass microstructure on its conversion to hydroxyapatite (HA) invitro and its ability to support tissue ingrowth in a rat subcutaneous implantation model were investigated. Bioactive borate glass scaffolds, designated 13-93B3, with a grid-like microstructure and pore widths of 300, 600, and 900 mu m were prepared by a robocasting technique. The scaffolds were implanted subcutaneously for 4 weeks in Sprague Dawley rats. Silicate 13-93 glass scaffolds with the same microstructure were used as the control. The conversion of the scaffolds to HA was studied as a function of immersion time in a simulated body fluid. Histology and scanning electron microscopy were used to evaluate conversion of the bioactive glass implants to hydroxyapatite, as well as tissue ingrowth and blood vessel formation in the implants. The pore size of the scaffolds was found to have little effect on tissue infiltration and angiogenesis after the 4-week implantation.