Role of Citrate and NaBr at the Surface of Colloidal Gold Nanoparticles during Functionalization
Role of Citrate and NaBr at the Surface of Colloidal Gold Nanoparticles during Functionalization
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DOI：
10.1021/acs.jpcc.8b07897
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发表时间：
2018-12-06
影响因子：
3.7
通讯作者：
Peukert, Wolfgang
中科院分区：
文献类型：
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作者：
Dinkel, Rebecca;Jakobi, Jurij;Peukert, Wolfgang
对配体壳层和功能化过程的分子理解对于表面功能化金纳米颗粒（AuNPs）的发展至关重要。显然，来自合成的初始配体壳在该过程中起着至关重要的作用。在这里，在原位二次谐波散射应用于研究3巯基-1-丙磺酸盐（MPS）在激光烧蚀的NaBr和柠檬酸盐稳定的金纳米粒子的表面吸附的尺寸为5 nm。这种系统的比较是可能的，因为在微摩尔盐水中的激光烧蚀提供了在没有有机稳定剂的情况下获得窄分布的胶体AuNP的机会。对于两个AuNP批次，吸附的吉布斯自由能被确定为具有相似的量级（约100）。-40 kJ/mol）。然而，MPS的表面浓度差异很大，NaBr-稳定的AuNP比柠檬酸盐稳定的AuNP高出30%以上。与平面Au基底相比，NaBr-AuNP上MPS的表面浓度表明形成了完整的MPS单层，并证明了无配体AuNP的快速官能化直至单层覆盖。然而，在柠檬酸盐-AuNP上，观察到仅三分之二单层的MPS覆盖，这表明柠檬酸盐部分地抵抗官能化，并且主要在低配位的Au表面位点处交换。然而，高表面覆盖率通常与功能性密切相关，例如，当在缀合物受体相互作用期间利用亲合力效应时。
A molecular understanding of the ligand shell and the functionalization process is essential for the development of surface-functionalized gold nanoparticles (AuNPs). Obviously, the initial ligand shell from the synthesis plays a crucial role in this process. Here, in situ second harmonic scattering is applied to study the adsorption of a 3mercapto-1-propanesulfonate (MPS) at the surface of laser ablated NaBr- and citrate-stabilized AuNPs with sizes of 5 nm. This systeMatic comparison is possible due to the fact that laser ablation in micromolar saline water gives access to narrowly distributed colloidal AuNPs without organic stabilizers. The Gibbs free energy of adsorption was determined to be of similar order for both AuNP batches (ca. -40 kJ/mol). The surface concentration of MPS, however, differed strongly and was more than 30% higher for NaBr-stabilized AuNP than for citrate-stabilized AuNP. Compared to planar Au substrates, the surface concentration of MPS on NaBr-AuNP suggests formation of a complete monolayer of MPS and demonstrates the fast functionalization of ligand-free AuNP up to monolayer coverage. On citrate-AuNP, however, an MPS coverage of only two-thirds of a monolayer is observed, which indicates that citrate partially resists functionalization and is mostly exchanged at low-coordinated Au surface sites. High surface coverage, however, is often closely linked to functionality, for example, when avidity effects are exploited during conjugate receptor interactions.