For example, proteins that possess the ellipsoidal shape two types of orientation of adsorbed molecules may occur: side- and end-on adsorption if major axis is parallel and perpendicular to solid surface, respectively [23]. Conformational change or change in lateral interaction may run concurrently with the adsorption process. Discontinuities in the adsorption isotherms as observed in this work may indicate different concentration-dependent orientation of adsorbed click here molecules at interface due to a non-spherical protein shape [24]. The ability of BSA to establish strong molecule-molecule interaction when in contact

with HA surface was confirmed by AFM analyses performed in sintered discs (1 cm2 in diameter) before and after the protein adsorption. For BSA initial concentration of 0.05 mg/mL with 24 hours incubation time, the AFM images revealed a thin BSA film covering the HA disc surface still maintaining visible the HA grain boundaries (Fig. 3b). The protein was homogenously distributed over the HA disc surface but small aggregates of protein could be detected at grains surface. The adsorption

pattern changed drastically when higher BSA concentrations were used (2.0 mg/mL). In that case, the adsorption was not homogeneous and large aggregates of protein were formed in different parts of discs surface as shown in Fig. 3d and f. These agglomerates can be produced when surface coverage exceeds a saturation value as suggested by Xu et al. [14]. The reactivity of HA + BSA surface was evaluated by Selleckchem TSA HDAC its capability to induce the crystallization of a new calcium phosphate when the surface was in contact with a simulating body fluid solution (n-SBF). For this evaluation, HA discs were coated Rutecarpine with a high BSA concentration (1.42 × 10−6 mmol/cm2) in order to cover the whole HA surface with protein layers and to promote a strong protein–protein interaction on HA surface. In such condition the stability of BSA film on

HA surface was assured for periods up to 7 days. After 7 days soaking in n-SBF, HA discs with BSA (HA + BSA/SBF) and without BSA (HA/SBF) were both fully covered by a thick layer of crystalline particles as observed by SEM, Fig. 4a and b. That thick layer was further characterized as a poorly crystalline calcium phosphate phase (CaP) by FTIRM-ATR and GIXRD measurements. The new layer presented similar crystal morphology in discs with and without BSA. In order to investigate the influence of BSA on the formation of the apatite layer the precipitation rate of calcium and phosphorous onto discs surface were followed by ICP. As shown in Fig. 5, calcium and phosphorous concentration on n-SBF solution decreased gradually with time confirming the precipitation of a new calcium phosphate on HA and HA + BSA discs surface.