Title: Interactions of Tris with rutile surfaces and consequences for in vitro bioactivity testing Show Chinese title

Title: 三乙胺与金红石表面的相互作用及其对体外生物活性测试的影响

Abstract: Tris(hydroxymethyl)aminomethane (Tris) has been used as the buffer in bioactivity testing for over two decades and has become a standard choice for the scientific community. While it is believed to be non-interacting, the extent of its interactions with titanium oxide surfaces has not been systematically studied. Here, we use experimental (zeta potential measurements) and computational (molecular dynamics) approaches to evaluate the interaction of Tris with a rutile surface and how it affects the adsorption of other molecules relevant in biomedical in vitro testing. We show that the interaction of Tris with the rutile surface is strong and significantly affects the interaction of other organic residues with the surface. These strong interactions are compounded by the Tris concentration in the in vitro testing protocol which is much higher compared to other components. Our findings indicate that the kinetics observed in in vitro tests will be strongly influenced by the presence of Tris as a buffering agent when compared to the natural CO2 buffer in blood. These results reveal that considering the so-far neglected active role of Tris in in vitro testing is critically needed and that in vitro protocols using CO2 partial pressure as the buffering agent should yield more reliable results. Show Chinese abstract

Abstract: 三(羟甲基)氨基甲烷（Tris）已被用作生物活性测试中的缓冲剂超过二十年，并已成为科学界的首选。尽管人们认为它不参与相互作用，但其与氧化钛表面的相互作用程度尚未被系统研究。在此，我们使用实验（Zeta电位测量）和计算（分子动力学）方法来评估Tris与金红石表面的相互作用及其对其他在生物医学体外测试中相关的分子吸附的影响。我们表明，Tris与金红石表面的相互作用很强，并显著影响其他有机残基与表面的相互作用。这些强相互作用由于体外测试协议中Tris的浓度远高于其他成分而更加明显。我们的研究结果表明，与血液中的天然CO2缓冲剂相比，在体外测试中存在Tris作为缓冲剂时，观察到的动力学将受到强烈影响。这些结果表明，考虑到迄今为止被忽视的Tris在体外测试中的主动作用是至关重要的，使用CO2分压作为缓冲剂的体外协议应能产生更可靠的结果。