Gas-phase synthesis and intense visible absorption of tryptophan-gold cations.
Gas-phase synthesis and intense visible absorption of tryptophan-gold cations.
复制标题
色氨酸-金阳离子的气相合成和强烈的可见光吸收。
DOI：
10.1002/anie.200902882
复制
发表时间：
2009
影响因子：
--
通讯作者：
V. Bonačić‐Koutecký
中科院分区：
文献类型：
--
作者：
R. Antoine;F. Bertorelle;M. Broyer;I. Compagnon;P. Dugourd;A. Kulesza;R. Mitrić;V. Bonačić‐Koutecký
金纳米颗粒(GNPs)由于在可见光区具有很强的表面等离子体共振，可以通过改变颗粒大小和表面环境以及形成具有分子单元的杂化产物来调节，因此受到了人们的广泛关注。GNP通常是通过“湿化学”过程制备的，即在表面覆盖配体存在的情况下形成金原子团簇。4]分子单元与GNPs的杂交可以进一步引入新的化学和生化功能。例如，在生物诊断和生物分子成像领域中，将GNPs连接到生物分子来生产高效光学探针的应用已经变得广泛。在这种背景下，GNPs与多肽或蛋白质的结合已被用于细胞靶向应用。GNPs的这种功能化不仅改变了表面等离子体共振，而且有利于能量转移现象的发生。这导致了特殊的发射特性，从生物分子的完全荧光猝灭到强烈的金属增强荧光。虽然这些研究开辟了一个令人振奋的新领域，这是由于纳米杂化材料独特的光学性质，但其中涉及的大量不可控参数使得完全理解这些现象的基本分子机制变得困难。最近，通过直接使用含有芳香族氨基酸的多肽或蛋白质作为还原剂来合成功能化金属纳米颗粒的新方法已有报道。例如，当金离子被加入到牛血清白蛋白水溶液中时，通过金离子的捕获和还原形成了高荧光的金纳米团簇。这种含有小纳米团簇的纳米杂化材料具有很强的荧光特性，这使得它们具有很强的应用吸引力。尽管与生物分子结合的GNPs在技术上具有重要意义，但控制其形状、大小和性质的尝试取得的成功有限。困难之一是，人们对它们的形成机制和前驱阶段知之甚少。具体地说，目前还不清楚生物分子存在下的前体盐如何被还原为中性原子，然后这些原子聚集形成纳米杂化。对能够作为形成具有光学性质的纳米团簇的成核种子的前体的性质的分子研究将使在纳米尺度上控制和预测纳米杂化的形成和性质成为可能。在这项实验和理论的联合贡献中，我们提出了由一个与色氨酸结合的单一金阳离子组成的最小可能的前体的合成，并报道了它的独特的光学性质--由于电荷转移激发而在可见光区的一个强吸收带。通过色氨酸-金络合物前体离子的碰撞激活解离(CAD)，在四极离子陷阱中合成了[TrpAu]阳离子。色氨酸、四氯金酸氢(III)三水合物(HAuCl4·3H2O)和抗坏血酸(C6H8O4)以1：1：1的比例溶解在乙腈/水(1：1：1)中，最终浓度约为500 mm。抗坏血酸表现出酮烯醇互变异构，其烯醇形式在水溶液中易电离，已被用作多种金属离子前驱体的多功能还原剂，用于制备金属纳米颗粒。在这种情况下，它作为一种弱还原剂将Au离子还原为Au离子[Eq。(1)]。然后Au离子就变成了AU3塔C6H8O4！Au塔式C6H6O4塔式2 H塔式独立1？
Gold nanoparticles (GNPs) have received considerable attention because of their strong surface plasmon resonance in the visible part of the spectrum, which can be tuned by changing the particle size and surface environment, and by the formation of hybrids with molecular units. GNPs are commonly prepared by “wet chemistry” procedures, in which clusters of gold atoms are formed in the presence of a surfacecapping ligand. 4] The hybridization of molecular units with GNPs can further introduce novel chemical and biochemical functionalities. For example, the application of GNPs linked to biomolecules to produce efficient optical probes in the fields of biodiagnostics and biomolecular imaging has become widespread. In this context, the conjugation of GNPs with peptides or proteins has been used for cell-targeting applications. Such functionalization of GNPs not only changes the surface plasmon resonance, but also favors the occurrence of energy-transfer phenomena. This results in specific emissive properties ranging from complete fluorescence quenching of “biomolecules” to strong metal-enhanced fluorescence. Although these studies have opened up an exciting new field spurred by the unique optical properties of nanohybrids, the large number of noncontrollable parameters involved makes complete understanding of the fundamental molecular mechanisms of these phenomena difficult. Recently, new alternative approaches for the synthesis of functionalized metal nanoparticles through the direct use of peptides or proteins containing aromatic amino acids as a reducing agent have been reported. For example, when Au ions were added to aqueous bovine serum albumin solutions, highly fluorescent gold nanoclusters were formed by the entrapment and reduction of Au ions. The strong fluorescence of such nanohybrids containing small nanoclusters makes them highly attractive for applications. Despite the technological importance of GNPs conjugated with biomolecules, attempts to control their shape, size, and properties have met with limited success. One difficulty is that little is known about the mechanism and the precursor stage involved in their formation. Specifically, it is still unclear how a precursor salt in the presence of biomolecules is reduced to neutral atoms, which then subsequently aggregate to form nanohybrids. A molecular study of the nature of the precursor capable of acting as a nucleation seed for forming nanoclusters with optical properties would make it possible to control and predict the formation and properties of nanohybrids at the nanoscale. In this joint experimental and theoretical contribution, we present the synthesis of the smallest possible precursor consisting of a single gold cation bound to tryptophan and report on its unique optical properties—a strong absorption band in the visible spectral region attributed to chargetransfer excitations. [TrpAu] cations were synthesized in a quadrupole ion trap by collision-activated dissociation (CAD) of tryptophan– gold complex precursor ions. Tryptophan, hydrogen tetrachloroaurate(III) trihydrate (HAuCl4·3 H2O), and ascorbic acid (C6H8O4) were dissolved in acetonitrile/water (1:1) at a ratio of 1:1:1 to provide a final concentration of approximately 500 mm. Ascorbic acid exhibits keto–enol tautomerism, and its enol form is susceptible to ionization in aqueous solution and has been used as a versatile reducing agent for a variety of metal ion precursors to prepare metal nanoparticles. In this case, it acts as a weak reducing agent to reduce Au ions to Au ions [Eq. (1)]. The Au ions are then Au3þ þ C6H8O4 ! Auþ þ C6H6O4 þ 2 Hþ ð1Þ
影响因子：
10.8
作者：
Choi Y;Kang T;Lee LP
通讯作者：
Lee LP