Rajendra Kumar Singh

Evaluation of CaO–SiO2–P2O5–Na2O–Fe2O3 bioglass-ceramics for hyperthermia application

Magnetic bioglass ceramics (MBC) are being considered for use as thermoseeds in hyperthermia treatment of cancer. While the bioactivity in MBCs is attributed to the formation of the bone minerals such as crystalline apatite, wollastonite, etc. in a physiological environment, the magnetic property arises from the magnetite [Fe3O4] present in these implant materials. A new set of bioglasses with compositions 41CaOxa0·xa0(52xa0−xa0x)SiO2xa0·xa04P2O5xa0·xa0xFe2O3xa0·xa03Na2O (2xa0≤xa0xxa0≤xa010 mol% Fe2O3) have been prepared by melt quenching method. The as-quenched glasses were then heat treated at 1050°C for 3xa0h to obtain the glass-ceramics. The structure and microstructure of the samples were characterized using X-ray diffraction and microscopy techniques. X-ray diffraction data revealed the presence of magnetite in the heat treated samples with xxa0≥xa02 mol% Fe2O3. Room temperature magnetic property of the heat treated samples was investigated using a Vibrating Sample Magnetometer. Field scans up to 20 kOe revealed that the glass ceramic samples had a high saturation magnetization and low coercivity. Room temperature hysteresis cycles were also recorded at 500 Oe to ascertain the magnetic properties at clinically amenable field strengths. The area under the magnetic hysteresis loop is a measure of the heat generated by the MBC. The coercivity of the samples is another important factor for hyperthermia applications. The area under the loop increases with an increase in Fe2O3 molar concentration and the. coercivity decreases with an increase in Fe2O3 molar concentration The evolution of magnetic properties in these MBCs as a function of Fe2O3 molar concentration is discussed and correlated with the amount of magnetite present in them.

Evolution of Magnetic Properties of

Magnetic hysteresis loss and the resulting local heating in implanted thermoseed (magnetic biocompatible material) can be used to selectively destroy cancerous tissue. We have prepared magnetic bioglass ceramics (MBC) by annealing 41CaO·44 SiO₂·4P₂O₅·8Fe₂O₃·3Na₂O glass at temperatures ( TA) ranging from 750 ^°C to 1150 ^°C for 1 h. X-ray diffraction patterns confirm the presence of bone mineral (hydroxyapatite and wollastonite) and magnetite ( Fe₃O₄) phases in nanocrystalline form in the MBCs. Average crystallite size ( d_av) of all the phases increased with increasing T_A. Magnetization ( M-H) curves of all MBCs were recorded up to 20 kOe at 300 K to understand the evolution of magnetism in the nonmagnetic glass upon heat treatment. Magnetic properties correlated with d_{av(magnetite)} for samples annealed up to 1050 ^°C. Electron paramagnetic resonance study was carried out to understand the behavior of sample annealed at 1150 ^°C and the evolution of magnetic properties in the MBCs. This study also reveals a methodology to control the magnetic properties of this MBC and its potential application in hyperthermia treatment of bone cancer.

{\hbox{CaO}}\hbox{-}{\hbox{P}}_{2}{\hbox{O}}_{5}\hbox{-}{\hbox{Na}}_{2}{\hbox{O}}\hbox{-}{\hbox{Fe}}_{2}{\hbox{O}}_{3}\hbox{-}{\hbox{SiO}}_{2}

We report the evolution of magnetism in bioglass ceramics 41CaO.(52-x)SiO2.4P2O5. xFe2O3.3Na2O (2 ≤ x ≤ 10 mole % Fe2O3) prepared by melt quenching technique followed by heat treatment at 1050 oC. The structural investigation revealed the presence of magnetite phase in the heat treated samples with x ≥ 2 mole % Fe2O3. Room temperature magnetic measurements showed a very weak ferrimagnetic behaviour for the sample with x = 2 mole % of Fe2O3. Samples with x > 2 mole % of Fe2O3 exhibited magnetic behavior similar to soft magnetic materials with low coercivity. The evolution of magnetic properties in these samples as a function of Fe2O3 molar concentration is correlated with the amount of magnetite phase present in them.