Department of Condensed Matter Physics and Materials Sciences, S. N. Bose National Centre for Basic Sciences, JD Block, Sector-III, Salt Lake City, Kolkata 700106, India.
Langmuir. 2020 Sep 29;36(38):11255-11261. doi: 10.1021/acs.langmuir.0c01527. Epub 2020 Sep 17.
Despite the key roles of l-glutathiones (GSHs) inbiology and nano-biotechnology, understanding their labile structures and hydrogen bond interactions with nanoparticles has posed a critical challenge to the scientific community. The structural conformation of GSH as a capping layer on gold nanoparticle (AuNP) and silver nanoparticle (AgNP) surfaces is investigated. In this report, we attempt to explore the material-dependent interaction of GSH with different spherical nanoparticle surfaces by employing Fourier transform infrared (FTIR) spectroscopy. The infrared signal of amide I of GSH is studied as a function of different materials' spherical nanoparticles with comparable size. We revealed the β-sheet secondary structure of GSH on AgNPs and the random structure on AuNPs even though both the nanoparticles have comparable shapes and sizes and belong to the same group of the periodic table. The GSH is firmly anchored on the gold and silver surface via the thiol of the cys part. However, our experimental data designate a further interaction with the AgNP surface via the carboxylic acid group of the gly- and glu- end of the molecule. It is observed that enhancement of IR absorption of amide I of GSH is pronounced by a factor of 10 on AuNP but, in contrast, on the same-sized AgNP, the suppression is perceived by a factor of 2, even though both are plasmonic materials with respect to free GSH. This study can be used as a point of reference for understanding the structural conformation of the capping layer on nanoparticle surfaces as well as surface enhancement of the IR absorption of amide I. We would like to emphasize that molecular self-assembly on the nanoparticle surfaces is definitely of very broad interest for chemists working in nearly any subdiscipline, spanning from the nanoparticle-based medicine to surface-enhanced spectroscopy to heterogeneous catalysis, etc.
尽管 l-谷胱甘肽（GSHs）在生物学和纳米生物技术中起着关键作用，但了解它们不稳定的结构以及与纳米粒子的氢键相互作用，对科学界来说仍是一项重大挑战。本研究调查了 GSH 作为金纳米粒子（AuNP）和银纳米粒子（AgNP）表面的封端层的结构构象。在本报告中，我们试图通过傅里叶变换红外（FTIR）光谱来探索 GSH 与不同球形纳米粒子表面的材料依赖性相互作用。研究了 GSH 的酰胺 I 红外信号作为不同材料的球形纳米粒子的函数，这些纳米粒子具有可比的尺寸。我们揭示了 GSH 在 AgNPs 上的β-折叠二级结构和在 AuNPs 上的无规结构，尽管这两种纳米粒子具有可比的形状和尺寸，并且属于元素周期表的同一组。GSH 通过半胱氨酸部分的巯基牢固地锚定在金和银表面上。然而，我们的实验数据表明，GSH 与 AgNP 表面的进一步相互作用是通过分子的甘氨酸和谷氨酸末端的羧酸基团进行的。可以观察到，GSH 的酰胺 I 的 IR 吸收增强因子在 AuNP 上显著为 10，但在相同尺寸的 AgNP 上，抑制因子为 2，尽管两者相对于游离 GSH 都是等离子体材料。这项研究可以作为理解纳米粒子表面封端层的结构构象以及酰胺 I 的表面增强 IR 吸收的参考点。我们要强调的是，分子在纳米粒子表面的自组装对于从事几乎任何子学科的化学家都具有非常广泛的兴趣，涵盖了基于纳米粒子的医学、表面增强光谱学、多相催化等。
