Anatomical considerations

The reactivity of surface modification of hydroxyapatite particles depends on their shape

“…Figure 2 illustrates the FTIR spectra of s-HA-PDLLA (A) and r-HA-PDLLA (B) together with those of pure PDLLA (C), pure s-HA (D), and r-HA (E). As expected, both the pure s-HA and r-HA particles have the characteristic peaks of PO 4 3− at 550 and 1050 cm −1 , the peaks of associated water at 1620 and 3411 cm −1 , and the peak of hydroxyl groups at 3557 to 3571 cm −1 . [13,21] s-HA seems to have more content of associated water than r-HA, which was also observed by TGA results (see Figure 4).…”

“…Further simulating the crystal faces by using Materials Studio 7.0, we can see that crystal faces (211) and (112) have less OH groups and more Ca ions than crystal faces (002) and (300) (Figure 7). It was said that water prefers binding with Ca ion by using its oxygen atom and forming H-bond with the nearby surface oxygen atoms belonging to PO 4 3− or OH groups. [15] Accordingly, s-HA particles rich in exposed crystal faces (211) and (112) should contain higher content of associated water than r-HA, which has been confirmed by FTIR ( Figure 2) and TGA results (Figure 4).…”

“…Lack of strong adhesion between HA and polymer matrix usually results in stress concentration, fast dissolution and early failure at the interface of HA/polymer. [4,5] Covalently grafting polymers onto HA surfaces is an effective way to enhance the interfacial bonding between HA and polymers. [6] For instance, polyethylene glycol (PEG), [7] PEG/PBT copolymer, [8] polyacrylates, [9] poly(ε-caprolactone), [10] or polylactide (PLA) [11] were grafted onto HA particles by using hexamethylene diisocyanate or aminopropyltriethoxysilane as the coupling agents.…”