134
S. A. Pauline
implant surface with high adhesion strength. The porosity of the developed coatings
could be close to that of the cortical bone which enhances osseointegration when the
orthopaedic implant comes into contact with the cortical bone [16].
Titania coatings of different thicknesses were developed on machined Ti Screw
shaped implants. New bone formation on the 120 nm coating was observed to be
higher at the bone-implant interface compared to the 1430 nm coating implying that
thinner PVD coating enhances a higher degree of bone growth soon after implantation
[17]. Titania/silver combined coating has been developed by PVD method and it is
reported to provide increased antimicrobial potency against microbial strains without
affecting its mechanical performance [18].
2.2 Spray Pyrolysis
Spray pyrolysis method is widely used for preparing metal and metal oxide powders
[19]. It involves formation of solid metal oxide particles by first converting the
reactants into micro-sized liquid droplets and spraying it onto a hot substrate in the
furnace. The precursor gets decomposed and the desired nanostructure is produced.
The size and shape of the nanostructure can be modified by controlling the reaction
conditions such as spray energy, droplet size of the precursors, distance between
the substrate and the spray gun, etc. [20]. Biocompatible nano calcium phosphate
(CaP) was synthesized by the aerosol-derived flame spray pyrolysis method. The
obtained nanoparticles have a particle size of 23 nm with increased crystallinity
and specific surface area. It showed reduced cytotoxicity at 5–50 μg/ml and higher
alkaline phosphatase (ALP) enzyme activity indicating that CaP synthesized by this
method can be used in biomedical applications [21]. Nano-sized HAp was produced
by ultrasonic spray pyrolysis using a salt-assisted decomposition method. The added
NaNO 3 salt interrupts agglomeration and results in the formation of rod-type, singlephase, nano-sized particles with high crystallinity [22].
2.3 Chemical Vapour Deposition (CVD)
Chemical vapour deposition is used to produce high-quality solid materials with
better performance characteristics. The deposit can be produced on the substrate by
depositing volatile precursors on its surface and then making them react or undergo
decomposition in the presence of heat, light or plasma. Many CVD processes have
been developed such as plasma-assisted chemical vapour deposition (PACVD), lowpressure chemical vapour deposition (LPCVD), laser-enhanced chemical vapour
deposition (LECVD), plasma-enhanced chemical vapour deposition (PECVD), etc.
Of these methods, PACVD is found to enhance biocompatibility, chemical stability
and also increase corrosion resistance [23]. Nanostructured titania coating was developed on pure Ti implants by a metal-organic chemical vapour deposition method.
S. A. Pauline
implant surface with high adhesion strength. The porosity of the developed coatings
could be close to that of the cortical bone which enhances osseointegration when the
orthopaedic implant comes into contact with the cortical bone [16].
Titania coatings of different thicknesses were developed on machined Ti Screw
shaped implants. New bone formation on the 120 nm coating was observed to be
higher at the bone-implant interface compared to the 1430 nm coating implying that
thinner PVD coating enhances a higher degree of bone growth soon after implantation
[17]. Titania/silver combined coating has been developed by PVD method and it is
reported to provide increased antimicrobial potency against microbial strains without
affecting its mechanical performance [18].
2.2 Spray Pyrolysis
Spray pyrolysis method is widely used for preparing metal and metal oxide powders
[19]. It involves formation of solid metal oxide particles by first converting the
reactants into micro-sized liquid droplets and spraying it onto a hot substrate in the
furnace. The precursor gets decomposed and the desired nanostructure is produced.
The size and shape of the nanostructure can be modified by controlling the reaction
conditions such as spray energy, droplet size of the precursors, distance between
the substrate and the spray gun, etc. [20]. Biocompatible nano calcium phosphate
(CaP) was synthesized by the aerosol-derived flame spray pyrolysis method. The
obtained nanoparticles have a particle size of 23 nm with increased crystallinity
and specific surface area. It showed reduced cytotoxicity at 5–50 μg/ml and higher
alkaline phosphatase (ALP) enzyme activity indicating that CaP synthesized by this
method can be used in biomedical applications [21]. Nano-sized HAp was produced
by ultrasonic spray pyrolysis using a salt-assisted decomposition method. The added
NaNO 3 salt interrupts agglomeration and results in the formation of rod-type, singlephase, nano-sized particles with high crystallinity [22].
2.3 Chemical Vapour Deposition (CVD)
Chemical vapour deposition is used to produce high-quality solid materials with
better performance characteristics. The deposit can be produced on the substrate by
depositing volatile precursors on its surface and then making them react or undergo
decomposition in the presence of heat, light or plasma. Many CVD processes have
been developed such as plasma-assisted chemical vapour deposition (PACVD), lowpressure chemical vapour deposition (LPCVD), laser-enhanced chemical vapour
deposition (LECVD), plasma-enhanced chemical vapour deposition (PECVD), etc.
Of these methods, PACVD is found to enhance biocompatibility, chemical stability
and also increase corrosion resistance [23]. Nanostructured titania coating was developed on pure Ti implants by a metal-organic chemical vapour deposition method.