Sridhar Dalai

Preparation of Hollow Glass Microspheres (HGMs) from Amber Coloured and Borosilicate Glass Frits

Hollow glass microspheres (HGMs) are a unique class of materials with interconnected pores in the microsphere walls, which can adsorb, retain and release hydrogen and other gases. In this study, HGMs was prepared from amber coloured and borosilicate glass frits. The glass frits after the preliminary washing and drying was sized to particles below 120 μm. The hollow glass microspheres were successfully fabricated from the glass powder by flame spheroidisation using air-acetylene flame. Effect of glass feed particle size as well as feed rate, in the formation of HGMs was studied. Glass feed particle size >75 μm and that <45 μm were found to give very poor yield of HGMs, whereas particles 50-75 μm gave very good yield for HGMs. Further study of the process parameters and constant monitoring to regulate the process are being carried out in our laboratory to arrive at a correct figure for the yield of HGMs. Characterisation of the HGMs prepared was done using Image analysing system, SEM, and XRD. The composition of the raw material and the product HGMs were determined using ICP-AES.

Development of high strength hydroxyapatite for bone tissue regeneration using nanobioactive glass composites

With an increasing demand of biocompatible bone substitutes for the treatment of bone diseases and bone tissue regeneration, bioactive glass composites are being tested to improvise the osteoconductive as well as osteoinductive properties. Nanobioactive glass (nBG) composites, having composition of SiO2 70 mol%, CaO 26 mol % and P2O5 4 mol% were prepared by Freeze drying method using PEG-PPG-PEG co-polymer. Polymer addition improves the mechanical strength and porosity of the scaffold of nBG. Nano Bioactive glass composites upon implantation undergo specific reactions leading to the formation of crystalline hydroxyapatite (HA). This is tested in vitro using Simulated Body Fluid (SBF). This high strength hydroxyapatite (HA) layer acts as osteoconductive in cellular environment, by acting as mineral base of bones, onto which new bone cells proliferate leading to new bone formation. Strength of the nBG composites as well as HA is in the range of cortical and cancellous bone, thus proving significant for bone tissue regeneration substitutes.With an increasing demand of biocompatible bone substitutes for the treatment of bone diseases and bone tissue regeneration, bioactive glass composites are being tested to improvise the osteoconductive as well as osteoinductive properties. Nanobioactive glass (nBG) composites, having composition of SiO2 70 mol%, CaO 26 mol % and P2O5 4 mol% were prepared by Freeze drying method using PEG-PPG-PEG co-polymer. Polymer addition improves the mechanical strength and porosity of the scaffold of nBG. Nano Bioactive glass composites upon implantation undergo specific reactions leading to the formation of crystalline hydroxyapatite (HA). This is tested in vitro using Simulated Body Fluid (SBF). This high strength hydroxyapatite (HA) layer acts as osteoconductive in cellular environment, by acting as mineral base of bones, onto which new bone cells proliferate leading to new bone formation. Strength of the nBG composites as well as HA is in the range of cortical and cancellous bone, thus proving significant for bone...

Preparation and Characterization of Zinc Loaded Hollow Glass Microspheres (HGMs) from Amber Coloured Glass Frits

Hollow glass microspheres loaded with ZnO nanoparticles were fabricated from amber colored glass powder blended with zinc acetate salt, by flame spheroidisation method. The morphology and the microstructure of the samples were observed using SEM, TEM, FTIR and XRD techniques, whereas the composition of the feed glass and product HGMs were determined using EDX and ICP. The results showed that HGMs with surface coating of zinc oxide nanoparticles can be successfully synthesized using this single step process. Effect of zinc acetate percentage (0-10%) in the glass feed on the formation of zinc oxide coated HGMs and the nature of the ZnO coating were studied. A continuous thin coating of ZnO nanoparticles on the HGMs surface were obtained when the zinc acetate content in the feed glass powder was 2-5%. Further increase of the zinc acetate in the feed glass led to uneven coating on the surface of HGMs. A clear cut diffraction pattern for crystalline ZnO was observed at the thick patches observed on the HGMs samples with 10% loading of zinc. The thickness of the ZnO coating increased from 10 nm to 500 nm when the zinc content in the feed glass increased from 2 to 10%.