The morphology of l-alanine can be controlled with additives to extend its application in medicine design and nonlinear material development. This study indicates the competitive mechanism of glycine-based oligopeptides, new types of green additives, on regulating the growth of an l-alanine crystal at room temperature and a supersaturation of 1.005. It is found that the morphology of l-alanine changes from rod-like to needle-like in the presence of glycine, which is quite different from a previous report. Meanwhile, this special case of the effect of weak hydrophilic tailor-made additives on the growth of l-alanine demonstrates the one-sidedness of analysis based on the single mechanism. However, in the presence of glycyl-glycine and glycyl-glycyl-glycine, which have a similar structure and the same weak hydrophilia as glycine, the l-alanine crystal grows as block-like morphology. The simulations and experiments reveal the competition between face adsorption, which reduces the kink sites, and face roughening, which increases kink sites on the (1 2 0) face in the presence of glycine, glycyl-glycine, and glycyl-glycyl-glycine. Differently, the controlling mechanism of glycine and these two oligopeptides on the growth of the (0 1 1) face of l-alanine can be changed from the competitive mechanism to single mechanism as the peptide chain length increases. Besides, relying on the fluorescence of oligopeptide, laser confocal technology is used creatively for the intuitive observation of the action sites of oligopeptide molecules in the l-alanine crystals, which verifies the incorporation of glycyl-glycine and the availability of the prediction based on the simulation.

中文翻译：

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l-丙氨酸与甘氨酸寡肽的晶体生长：竞争机制的启示

l-丙氨酸的形态可以用添加剂控制，以扩展其在药物设计和非线性材料开发中的应用。该研究表明了甘氨酸基寡肽（新型绿色添加剂）在室温和 1.005 过饱和度下调节l-丙氨酸晶体生长的竞争机制。可知的形态升丙氨酸更改自棒状到针状在甘氨酸存在，这是从先前的报告完全不同。同时，弱亲水性特制添加剂对l-丙氨酸证明了基于单一机制的分析的片面性。然而，在甘氨酰甘氨酸和甘氨酰-甘氨酰-甘氨酸存在，它具有相似的结构和相同的弱亲水性甘氨酸，该升丙氨酸晶体生长为块状形态。模拟和实验揭示了在甘氨酸、甘氨酰-甘氨酸和甘氨酰-甘氨酰-甘氨酸存在下，面部吸附（减少扭结位点）和面部粗糙（增加（1 2 0）面上的扭结位点）之间的竞争。不同的是，甘氨酸和这两种寡肽对l的(0 1 1)面生长的控制机制随着肽链长度的增加，-丙氨酸可以从竞争机制变为单一机制。此外，依靠寡肽的荧光，激光共聚焦技术创造性用于寡肽分子在作用位点的直观观察升丙氨酸结晶，从而验证甘氨酰甘氨酸的基础上，掺入和预测的可用性模拟。