Indian Institute of Technology Indore, Discipline of Chemistry, Indore 453552, Madhya Pradesh, India.
J Phys Chem B. 2021 Nov 18;125(45):12436-12445. doi: 10.1021/acs.jpcb.1c07392. Epub 2021 Nov 4.
Metal ions are known to strongly bind with different proteins and peptides, resulting in alteration of their different physicochemical properties. In this work, we investigate the effect of metal ions of different nuclear charges and sizes on the intrinsic blue luminescence of the self-assembled structures formed by aromatic amino acids, namely, phenylalanine and tryptophan, using spectroscopic and imaging techniques. The study reveals that the intrinsic blue fluorescence of amino acid assemblies is influenced by metal ions and the pH of the medium. The metal ions with a higher charge to radius ratio promote clusterization which results in the enhancement of the intrinsic fluorescence, an effect known as "clusteroluminescence" of the amino acids aggregates. The imaging study reveals that metal ions with a higher charge to size ratio inhibit the large fibrillation of aromatic amino acids by promoting the formation of small nonfibrillar aggregates through increased hydrophobicity in the medium. The nanoaggregates are assumed to be responsible for the enhancement in the blue "clusteroluminescence".
金属离子与不同的蛋白质和肽强烈结合，导致它们的不同物理化学性质发生改变。在这项工作中，我们使用光谱和成像技术研究了不同核电荷和大小的金属离子对由芳香族氨基酸（即苯丙氨酸和色氨酸）形成的自组装结构的固有蓝色发光的影响。研究表明，氨基酸组装体的固有蓝色荧光受金属离子和介质 pH 的影响。具有更高电荷半径比的金属离子促进团聚，从而增强固有荧光，这种效应称为氨基酸聚集体的“团簇发光”。成像研究表明，具有更高电荷半径比的金属离子通过增加介质中的疏水性，促进小的非纤维状聚集体的形成，从而抑制芳香族氨基酸的大纤维化。假设纳米聚集体是增强蓝色“团簇发光”的原因。
