Serro A P, Fernandes A C, Saramago B, Lima J, Barbosa M A
Centro de Química Estrutural, Complexo I, Instituto Superior Técnico,Lisboa, Portugal.
Biomaterials. 1997 Jul;18(14):963-8. doi: 10.1016/s0142-9612(97)00031-8.
Titanium implant surfaces are known to spontaneously nucleate apatite layers when in contact with simulated body fluids. However, adsorption of proteins may influence the process of apatite layer formation. In this study the role of bovine serum albumin (BSA) adsorption in the process of apatite deposition on titanium substrates is investigated. Deposition of calcium phosphate was induced by immersing titanium substrates in a Hank's balanced salt solution (HBSS) for times ranging from 1 to 23 days. The resulting substrates were studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), wettability measurements and electrochemical impedance determinations. All these methods indicate the presence of a calcium phosphate layer. The same procedure was repeated substituting HBSS with a solution of BSA in HBSS. Although SEM, EDS and electrochemical impedance spectra do not reveal the presence of an apatite layer, XPS analysis strongly indicates that the inhibition of apatite formation by BSA is only partial. The competition between BSA adsorption and apatite deposition seems to lead to a mixed film where the protein co-exists with calcium phosphate. Wettability studies suggest that this surface film is heterogeneous and porous, similar to the thicker films formed in albumin-free HBSS.
已知钛植入物表面在与模拟体液接触时会自发形成磷灰石层。然而，蛋白质的吸附可能会影响磷灰石层的形成过程。在本研究中，研究了牛血清白蛋白（BSA）吸附在钛基底上磷灰石沉积过程中的作用。通过将钛基底浸入汉克平衡盐溶液（HBSS）中1至23天来诱导磷酸钙的沉积。通过扫描电子显微镜（SEM）、能量色散光谱（EDS）、X射线光电子能谱（XPS）、润湿性测量和电化学阻抗测定对所得基底进行研究。所有这些方法均表明存在磷酸钙层。用HBSS中的BSA溶液代替HBSS重复相同的步骤。尽管SEM、EDS和电化学阻抗谱未显示磷灰石层的存在，但XPS分析强烈表明BSA对磷灰石形成的抑制只是部分的。BSA吸附与磷灰石沉积之间的竞争似乎导致形成一种混合膜，其中蛋白质与磷酸钙共存。润湿性研究表明，这种表面膜是不均匀且多孔的，类似于在无白蛋白的HBSS中形成的较厚的膜。
