Calcium phosphate biomaterials from marine algae. Hydrothermal synthesis and characterisation

Abstract

Recebido em 18/2/99; aceito em 27/1/00Calcium phosphate compounds such as Hydroxyapatite (HAp) were prepared by hydrothermal synthesis with phycogenic CaCO 3 as starting material. Material obtained was characterised by usual methods (XRD, FTIR, TG, N 2 -adsorption, SEM and EDX) in order to study its physical-chemical characteristics. The prepared HAp showed that it may be suitable for use as a biomaterial.

Synthesis of calcium-phosphate and chitosan bioceramics for bone regeneration

“…Calcium phosphate based bioceramics have recently received special attention as bone replacement materials, as they behave similarly to the mineral constituent of bones (Martin and Brown 1995, Felício-Fernandes and Laranjeira 2000, Pereira et al 1999, Kawachi et al 2000, Shareef et al 1993, Sivakumar et al 1996.…”

“…Chitosan is insoluble in water and, consequently, in physiological environments. HAp can act as a reticular modifier agent (due to the presence of calcium and phosphorous) and its use as bone former (Felício-Fernandes and Laranjeira 2000), has also been appraised. Its superior osteoconductive properties render HAp a vast potential to be used in implants as bone substitute (Sivakumar et al 1996).…”

Design of experiments (DOE) for the optimization of hydrothermal synthesis of hydroxyapatite nanoparticles

“…9-432) and all peaks correspond to the hexagonal crystal form of HAp. 1,10,17,33,[47][48][49][50] From Figure 7, it can be seen that a decreasing degree of crystallinity leads to a decrease in intensity and an increase in width of the diffraction peaks. Moreover, the relative intensity of the peak (300) grows with the increase in the crystallinity degree, which shows that HAp may be oriented along the c-axis.…”

“…The peaks at 3437 and 1637 cm -1 are relative to the bending modes of the hydroxyl group in the adsorbed water, while the peaks at 3571 and 633 cm -1 are assigned to the stretching vibration of the hydroxyl group in the crystalline structure of HAp. 33,35,40,[50][51][52][53][54][55][56][57] From Figure S1, it can be seen that, with decreasing degree of crystallinity, the intensity of the absorption bands appearing at 3437 and 1637 cm -1 increases, while the intensity of the bands at 3571 and 633 cm -1 decreases. Therefore, according to the results presented here, the change in the intensity of the aforementioned peaks could be used as an alternative to the XRD patterns for determination of the degree of crystallinity.…”

“…This method enables the synthesis of HAp powders with high degree of crystallinity which are relatively stable in physiological medium. 33 The HAp prepared by this method is homogeneous and easily sinterable, with Ca/P molar ratios close to the stoichiometric value, owing to the effects of high temperature and high pressure on the aqueous solutions. 4,10,[17][18][19][20][21][22][23][24][25][26][27]34 However, many different studies have resulted in discrepancies in the optimum experimental conditions.…”