In this paper, the conformational changes of tryptophan (Trp) on the corroded 316 L stainless steel (SS) surface obtained under controlled simulated inflammatory conditions have been studied by Raman (RS) and Fourier-transform infrared (FT-IR) spectroscopy methods. The corrosion behavior and protective efficiency of the investigated samples were performed using the potentiodynamic polarization (PDP) technique in phosphate-buffered saline (PBS) solution acidified to pH 3.0 at 37 °C in the presence and absence of 10⁻² M Trp, with different immersion times (2 h and 24 h). The amino acid is adsorbed onto the corroded SS surface mainly through the lone electron pair of the nitrogen atom of the indole ring, which adopts a more/less tilted orientation, and the protonated amine group. The visible differences in the intensity of the Fermi doublet upon adsorption of Trp onto the corroded SS surface, which is a sensitive marker of the local environment, suggested that a stronger hydrophobic environment is observed. This may result in an improvement of the corrosion resistance, after 2 h than 24 h of exposure time. The electrochemical results confirm this statement—the inhibition efficiency of Trp, acting as a mixed-type inhibitor, is made drastically higher after a short period of immersion.

中文翻译：

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在模拟炎症条件下对 316L 不锈钢进行植入物应用的光谱研究：色氨酸作为腐蚀抑制剂/疏水性标志物的作用

在本文中，通过拉曼 (RS) 和傅里叶变换红外 (FT-IR) 光谱方法研究了在受控模拟炎症条件下获得的腐蚀 316 L 不锈钢 (SS) 表面上色氨酸 (Trp) 的构象变化。使用动电位极化 (PDP) 技术在磷酸盐缓冲盐水 (PBS) 溶液中，在 37 °C 存在和不存在 10 ^-2M Trp，具有不同的浸泡时间（2 小时和 24 小时）。氨基酸主要通过吲哚环氮原子的孤电子对（采用多/少倾斜取向）和质子化的胺基团吸附在腐蚀的SS表面上。Trp 吸附到腐蚀的 SS 表面后，费米双峰强度的可见差异，这是局部环境的敏感标记，表明观察到更强的疏水环境。这可能会导致在 2 小时后比 24 小时的暴露时间提高耐腐蚀性。电化学结果证实了这一说法——作为混合型抑制剂的 Trp 的抑制效率在短时间浸泡后显着提高。