State Key Laboratory of Virology & Key Laboratory of Analytical Chemistry for Biology and Medicine (MOE), College of Chemistry and Molecular Sciences, Wuhan University , Wuhan 430072, People's Republic of China.
College of Chemistry and Material Science, Guangxi Teachers Education University , Nanning 530001, People's Republic of China.
Langmuir. 2017 May 30;33(21):5108-5116. doi: 10.1021/acs.langmuir.7b00196. Epub 2017 May 18.
Noble metal nanoclusters (NCs) show great promise as nanoprobes for bioanalysis and cellular imaging in biological applications due to ultrasmall size, good photophysical properties, and excellent biocompatibility. In order to achieve a comprehensive understanding of possible biological implications, a series of spectroscopic measurements were conducted under different temperatures to investigate the interactions of Au NCs (∼1.7 nm) with three model plasmatic proteins (human serum albumin (HSA), γ-globulins, and transferrin). It was found that the fluorescence quenching of HSA and γ-globulins triggered by Au NCs was due to dynamic quenching mechanism, while the fluorescence quenching of transferrin by Au NCs was a result of the formation of a Au NC-transferrin complex. The apparent association constants of the Au NCs bound to HSA, γ-globulins, and transferrin demonstrated no obvious difference. Thermodynamic studies demonstrated that the interaction between Au NCs and HSA (or γ-globulins) was driven by hydrophobic forces, while the electrostatic interactions played predominant roles in the adsorption process for transferrin. Furthermore, it was proven that Au NCs had no obvious interference in the secondary structures of these three kinds of proteins. In turn, these three proteins had a minor effect on the fluorescence intensity of Au NCs, which made fluorescent Au NCs promising in biological applications owing to their chemical and photophysical stability. In addition, by comparing the interactions of small molecules, Au NCs, and large nanomaterials with serum albumin, it was found that the binding constants were gradually increased with the increase of particle size. This work has elucidated the interaction mechanisms between nanoclusters and proteins, and shed light on a new interaction mode different from the protein corona on the surface of nanoparticles, which will highly contribute to the better design and applications of fluorescent nanoclusters.
贵金属纳米团簇（NCs）由于其超小尺寸、良好的光物理性质和优异的生物相容性，在生物分析和细胞成像等生物应用中作为纳米探针具有广阔的应用前景。为了全面了解可能的生物学意义，我们在不同温度下进行了一系列光谱测量，以研究 Au NCs（约 1.7nm）与三种模型血浆蛋白（人血清白蛋白（HSA）、γ-球蛋白和转铁蛋白）的相互作用。结果发现，Au NCs 猝灭 HSA 和 γ-球蛋白的荧光是由于动态猝灭机制，而 Au NCs 猝灭转铁蛋白的荧光则是由于形成了 Au NC-转铁蛋白复合物。Au NCs 与 HSA、γ-球蛋白结合的表观结合常数没有明显差异。热力学研究表明，Au NCs 与 HSA（或 γ-球蛋白）之间的相互作用是由疏水作用力驱动的，而静电相互作用在转铁蛋白的吸附过程中起主导作用。此外，还证明 Au NCs 对这三种蛋白质的二级结构没有明显干扰。反过来，这三种蛋白质对 Au NCs 的荧光强度影响较小，这使得荧光 Au NCs 由于其化学和光物理稳定性而在生物应用中具有广阔的应用前景。此外，通过比较小分子、Au NCs 和大纳米材料与血清白蛋白的相互作用，发现结合常数随着粒径的增加而逐渐增加。这项工作阐明了纳米团簇与蛋白质之间的相互作用机制，并揭示了一种不同于纳米粒子表面蛋白冠的新相互作用模式，这将有助于更好地设计和应用荧光纳米团簇。
