To study the in vitro behavior, nanopowders were immersed individually in SBF

in polystyrene bottles and were stored in a biological incubator for 30 days at 37 ^C.

Digital pH meter was used for recording changes in pH of SBF solution at regular

intervals. Nanopowders were dried at 70 ^C for 4 h in a hot air oven after 30 days.

Dried nanopowders were analyzed for apatite formation on their surfaces using FTIR

and TEM.

In vitro analysis of nanopowders on immersion in SBF for 30 days almost showed

a similar trend of alternate decrease and increase of pH in SBF confirming the

bioactive behavior of the nanopowders (Fig. 23.8). However, the variation in pH

of SBF with time decreased with an increase in heat treatment temperature,

indicating reduced bioactivity of heat-treated nanopowders than as-synthesized

nanopowders. The FTIR spectra displayed a significant decrease in the relative

transmittance of nanopowders after immersion in SBF, indicating the deposition of

an apatite layer on the surface of nanopowders (Fig. 23.9). TEM micrographs also

revealed that there was a growth of an apatite layer on the surface of nanopowders

(Fig. 23.10), exhibiting bioactive nature of nanopowders upon immersion in SBF.

Table 23.10 Ionic composition of human blood plasma and SBF (Fatehi et al. 2009)

Ion

Na⁺

K⁺

Ca²⁺

Mg²⁺

HCO3

HPO4

Cl

SO4

2

SBF (mmol/L)

142.0

5.0

2.5

1.5

4.2

1.0

147.8

0.5

Human blood plasma

(mmol/L)

142.0

5.0

2.5

1.5

27.0

1.0

103.0

0.5

Fig. 23.8 pH change in SBF with time of immersion of as-synthesized nanopowders

23

Unleashing Potential of Bone Mimicking Nanodimensional Hydroxyapatites and. . .

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