[7]). “
“Albumin is the most abundant protein in the circulatory system, possessing low content of tryptophan and methionine and a high content of cystine and charged amino acids, aspartic and glutamic acids, lysine, and arginine. Its great affinity to hydroxyapatite could be explained by the presence of charged residues that can bind to phosphate and calcium sites on hydroxyapatite surface. The aspartic and glutamic acids residues could bind to calcium site while lysine and arginine could bind to phosphate groups [1]. The

proteins adhesion onto biomaterial surface is a key point in bioengineering because of the fundamental role that GSI-IX purchase proteins play in the contact between inorganic surface and a biological environment. For applications involving hard and soft tissues regeneration an excellent adhesion of

selected proteins allows, in most cases, a better biocompatibility and a better recovery of the biological function of the implants. In this sense, the protein may play two important roles: the first due to its specific biological activity, the second due to its importance in the processes of biomineralization as inhibiting or promoting [2] the calcium phosphate formation. In vivo studies support GSK2118436 cost that serum proteins are adsorbed immediately on the surface of HA after implantation and the initial cellular response are dependent on the proteins adsorbed by the implant surfaces [3]. The first protein layer adsorbed on to the implant surface affects the cellular adhesion [4] and [5], differentiation and extracellular matrix production. It also affects dissolution, nucleation and crystal growth of HA [6] and [7]. Therefore,

the kinetic study of protein adsorption onto biomaterials is primordial to understand the nature of interactions between surfaces and proteins and in some cases allow us to assess the arrangement, and the conformation of the proteins onto the biomaterial surface. In general, the protein adsorption occurs in two steps [8]: first, the protein is rapidly adsorbed and forms a strongly bonded denatured monolayer due to a multiple site binding. The proteins of the first monolayer lose their tertiary structure and consequently biological activity. A second protein layer begins to be formed slowly and leads to a monolayer of nondenaturated with biological activity. Information concerning the surface coverage could be obtained by adsorption isotherms. The Langmuir isotherms have been used to explain the protein monolayer formation on biomaterial surface. However, many factors could also influence the adsorption process such as (i) multiple-site binding for protein, which often results in irreversible adsorption and denaturation, (ii) the heterogeneous nature of most solid surfaces, and (iii) lateral and other cooperative interactions.