Adsorption Mechanism Of BMP-7 On Hydroxyapatite Surfaces

With the development of medicinal science, material science and biotechnology, the adsorption behavior of biomacromolecule onto hydroxyapatite (HAP) surfaces have received much attention due to its importance on the control of interfacial behavior of molecule and the design of materials with special performance and biocompatability. In this paper, molecular dynamics (MD) combined with steered molecular dynamics (SMD) simulations are employed to study the adsorption mechanism of BMP-7 onto HAP surfaces. This paper is mainly composed of the following four parts:Chapter 1: The development of biomaterials, as well as the background and the framework of the research were briefly introduced.Chapter 2: The simulation methods of molecular dynamics and the steered molecular dynamics were introduced.Chapter 3: The adsorption mechanism of BMP-7 onto hydroxyapatite (001) surfaces was studied. It shows that the adsorption residues could be divided into two categories: Glu/Asp and Arg/Lys. Both of them play important roles in the adsorption of BMP-7 onto the HAP surfaces. However, their adsorption mechanisms are remarkably different. For Glu/Asp, the adsorptive interaction is caused by the electrostatic attractive force which exists between their carboxylate groups and Cal cations on the HAP surface. While for Arg/Lys, the adsorption mainly comes from the intermolecular H-bonds between their N-containing group and the phosphate on the HAP surface. These results revealed the adsorption mechanism of BMP-7 onto hydroxyapatite (001) surfaces from atomic level. Chapter 4: The effect of different textures of hydroxyapatite surfaces on the adsorption behavior of BMP-7 was studied. And the HAP surfaces included four extreme surfaces and two natural surfaces. It is found that both the type and the number of adsorptive residues are dependent on the texture of HAP surface. In addition, the conformation of BMP-7 just slightly changes after being adsorbed onto the natural surfaces; however, for the extreme surfaces with higher interfacial ion density, both the conformation and secondary structure of BMP-7 change obviously. Correspondingly, the potential energies of adsorbed BMP-7 on these HAP surfaces are different. These results revealed that the effect of different textures of HAP surfaces on the adsorption of BMP-7 is important.