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S. T. Aruna and M. Shilpa
far- red wavelength fluorescence under UV excitation with emission at 696 nm and
excitation at 350 nm. They are of promise for multicolor imaging applications as
relatively narrow emission bands are observed in their fluorescence spectra [35].
Hydroxyapatite, fluorapatite (FAp) and chlorapatite (ClAp) were synthesized by the
SCS method by employing reagent grade Ca(NO 3 ) 2 ·4H 2 O, (NH 4 ) H 2 PO 4 , NH 4 F
and NH 4 Cl as sources of Ca, P, F and Cl, respectively. The powders synthesized by
using citric acid and NH 4 NO 3 respectively as oxidizer and accelerant were annealed
at 800 °C after combustion [36]. Crystalline nano-sized powders of calcium hydroxyapatite and hydroxyapatite/tricalcium phosphate composites were produced by the
SCS method using fuel-rich conditions. It was found that by varying the contents
of calcium nitrate and diammonium hydrogen orthophosphate the phase composition of the composite products could be controlled. Considering the dependence of
thermal stability of the HAp phase on the Ca/P atom ratio in the range of 1.45–1.67,
it is proposed that the initially formed HAp transforms to TCP and results in the
formation of composite material during solution combustion process [37].
The team at CSIR-CGCRI, India has carried out pioneering work on solution
combustion synthesized calcium phosphates. Nanosized HAp with particle size in the
range of 20–120 nm was synthesized by combustion method using urea and glycine
as fuels and calcium nitrate–diammonium hydrogen orthophosphate as oxidizers
[38]. The team has explored SCS method for synthesizing calcium phosphates and
in particular HAp and carried out extensive studies on modeling the flame temperature during SCS and optimization of SCS parameter using Taguchi method [39],
in vivo studies of calcium phosphate [40] and studies on the implantable delivery
system [41]. The effectiveness of SCS synthesized porous calcium phosphates such as
HAp and bi-phasic calcium phosphate (BCP) with predominantly β-tricalcium phosphate (β-TCP) impregnated with cefuroxime axetil for the treatment of experimental
osteomyelitis was investigated and compared with parenteral treatment [41]. The
study revealed that biphasic calcium phosphate with predominately β-TCP content
was a potent carrier material for antibiotic compounds and also for refractory infections by S. aureus [41]. Porous struts were prepared using SCS synthesized pure
hydroxyapatite (HAp) and a biphasic calcium phosphate-containing 90% β-TCP
and 10% HAp along with bioglass. The struts were implanted to the lateral side
of the radius bone of 24 black Bengal goats and to act as a control, a blank hole
was left empty in a group of six specimens. β-TCP/bioglass-based implants exhibited higher bone in-growth and improved strength compared to HAp [40]. Solution
combustion synthesized porous hydroxyapatite (HAp) powder was scrutinized as a
bone substitute in healing bone defects in vivo and as determined by radiologic and
histopathologic methods, oxytetracycline labeling, and angiogenic features. Porous
HAp ceramic promoted bone formation over the defect, vouching for its biologic
osteoconductive property [42].
The studies on solution combustion synthesized HAp powders were not limited
to powder synthesis and evaluation of properties but also used for making scaffolds
and coatings. Microporous HAp scaffolds were prepared by the slip casting method
using the nanosized HAp powder synthesized by the SCS method using glycine as
fuel [43]. The sintered (1250 °C for 1 h) product exhibited a bulk density in the range
S. T. Aruna and M. Shilpa
far- red wavelength fluorescence under UV excitation with emission at 696 nm and
excitation at 350 nm. They are of promise for multicolor imaging applications as
relatively narrow emission bands are observed in their fluorescence spectra [35].
Hydroxyapatite, fluorapatite (FAp) and chlorapatite (ClAp) were synthesized by the
SCS method by employing reagent grade Ca(NO 3 ) 2 ·4H 2 O, (NH 4 ) H 2 PO 4 , NH 4 F
and NH 4 Cl as sources of Ca, P, F and Cl, respectively. The powders synthesized by
using citric acid and NH 4 NO 3 respectively as oxidizer and accelerant were annealed
at 800 °C after combustion [36]. Crystalline nano-sized powders of calcium hydroxyapatite and hydroxyapatite/tricalcium phosphate composites were produced by the
SCS method using fuel-rich conditions. It was found that by varying the contents
of calcium nitrate and diammonium hydrogen orthophosphate the phase composition of the composite products could be controlled. Considering the dependence of
thermal stability of the HAp phase on the Ca/P atom ratio in the range of 1.45–1.67,
it is proposed that the initially formed HAp transforms to TCP and results in the
formation of composite material during solution combustion process [37].
The team at CSIR-CGCRI, India has carried out pioneering work on solution
combustion synthesized calcium phosphates. Nanosized HAp with particle size in the
range of 20–120 nm was synthesized by combustion method using urea and glycine
as fuels and calcium nitrate–diammonium hydrogen orthophosphate as oxidizers
[38]. The team has explored SCS method for synthesizing calcium phosphates and
in particular HAp and carried out extensive studies on modeling the flame temperature during SCS and optimization of SCS parameter using Taguchi method [39],
in vivo studies of calcium phosphate [40] and studies on the implantable delivery
system [41]. The effectiveness of SCS synthesized porous calcium phosphates such as
HAp and bi-phasic calcium phosphate (BCP) with predominantly β-tricalcium phosphate (β-TCP) impregnated with cefuroxime axetil for the treatment of experimental
osteomyelitis was investigated and compared with parenteral treatment [41]. The
study revealed that biphasic calcium phosphate with predominately β-TCP content
was a potent carrier material for antibiotic compounds and also for refractory infections by S. aureus [41]. Porous struts were prepared using SCS synthesized pure
hydroxyapatite (HAp) and a biphasic calcium phosphate-containing 90% β-TCP
and 10% HAp along with bioglass. The struts were implanted to the lateral side
of the radius bone of 24 black Bengal goats and to act as a control, a blank hole
was left empty in a group of six specimens. β-TCP/bioglass-based implants exhibited higher bone in-growth and improved strength compared to HAp [40]. Solution
combustion synthesized porous hydroxyapatite (HAp) powder was scrutinized as a
bone substitute in healing bone defects in vivo and as determined by radiologic and
histopathologic methods, oxytetracycline labeling, and angiogenic features. Porous
HAp ceramic promoted bone formation over the defect, vouching for its biologic
osteoconductive property [42].
The studies on solution combustion synthesized HAp powders were not limited
to powder synthesis and evaluation of properties but also used for making scaffolds
and coatings. Microporous HAp scaffolds were prepared by the slip casting method
using the nanosized HAp powder synthesized by the SCS method using glycine as
fuel [43]. The sintered (1250 °C for 1 h) product exhibited a bulk density in the range