Papers by Author: S. Dhara

Abstract: By modifying the sequences in preparation of aqueous ceramic slurries, starch was successfully employed to improve the microstructural controllability of alumina foams fabricated through protein coagulation casting technique. Open porosity was increased and the uniform distribution of microstructures was improved by the dual functions of starch as pore former and wet foam stabilizer. The viscosity of slurry was affected by the increasing amount of starch additive due to the total solid loading increase and the water uptake of starch. A well controlled pore structure will benefit multifunctional applications of these porous foams.

Abstract: Chemical treatment of polycaprolactone was carried out to bioactivite the biodegradable polymer for bone tissue engineering application. The results show that surface modifications are necessary to introduce functional groups such as carboxylic groups for the effective induction of apatite nucleation, prior to SBF treatment. The functional groups, acting as anchors between the polymer and the apatite nuclei, dictate the duration of the induction period need for apatite nucleation. After the surface treatment with sodium hydroxide solution, the apatite nuclei will form and grow spontaneously into a dense and uniform layer of apatite, by taking up Ca2+ and PO4 2- ions that are present in the SBF, as SBF is supersaturated with respect to apatite. Similar surface treatment was applied to electrospun PCL nanofibres. Biomimetic apatite/PCL nanofibres were formed which can potentially be used as bone tissue engineering scaffolds.

Abstract: An environmentally friendly direct foaming method was investigated to produce porous alumina ceramics. Egg white protein was used as a binder and foaming agent. The microstructures show that pores are interconnected with pore size of a few hundreds μm and pore window size of ca. 50 μm. The compressive strength of alumina foam is up to 100 MPa depending on porosity. Bioactivation of alumina was carried out using an alkaline solution treatment. Hydroxylation of alumina was achieved using 5M NaOH at 80°C for 4 days. In vitro assessments of the alumina in a human osteoblast cell-like cell (MG63) culture showed that the bioactivated alumina foams exhibited better cellularity and alkaline phosphatase (ALP) activity compared to untreated alumina foams. The results indicate that it is possible to improve the osseointgration of alumina ceramics by structural and surface modifications and to extend the applications of biocompatible alumina ceramics in biomedical implants and tissue engineering scaffolds.