Effects of glutamic acid shelled PAMAM dendrimers on the crystallization of calcium phosphate in diffusion systems

Second generation poly(amidoamine) (PAMAM) dendrimers were synthesized and peripherally modified with glutamic acid (PAMAM-MG) as a shell. The effect of the dendrimers on the crystallization of different calcium phosphate compounds was investigated in both double and one way diffusion systems. It was found that the crystals of calcium phosphate showed tape-like morphology in the presence of PAMAM-MG, and the crystals' thickness and width decreased compared to those grown without dendritic molecules. Such a result might be due to the interaction of electric charges between dendritic molecules and octacalcium phosphate (Ca8H2(PO4)(6)center dot 5H(2)O, OCP), which led to the adsorption of PAMAM-MG in the 100 and 010 surfaces of OCP. Moreover, PAMAM-MG showed an affinity for gelatin, and it could cause the formation of amorphous calcium phosphate (Ca-9(PO4)(6)center dot nH(2)O, ACP) at a concentration of 5 mg/mL of PAMAM-MG. These results suggest that PAMAM-MG could be used for regulating the morphology of OCP and changing the composition of minerals in gels.