Ostruszka Radek, Zoppellaro Giorgio, Tomanec Ondřej, Pinkas Dominik, Filimonenko Vlada, Šišková Karolína
Department of Experimental Physics, Faculty of Science, Palacký University, tř. 17. Listopadu 12, 77900 Olomouc, Czech Republic.
Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacký University, tř. 17. Listopadu 12, 77900 Olomouc, Czech Republic.
Nanomaterials (Basel). 2022 Apr 22;12(9):1425. doi: 10.3390/nano12091425.
Bovine serum albumin-embedded Au nanoclusters (BSA-AuNCs) are thoroughly probed by continuous wave electron paramagnetic resonance (CW-EPR), light-induced EPR (LEPR), and sequences of microscopic investigations performed via high-resolution transmission electron microscopy (HR-TEM), scanning transmission electron microscopy (STEM), and energy dispersive X-ray analysis (EDS). To the best of our knowledge, this is the first report analyzing the BSA-AuNCs by CW-EPR/LEPR technique. Besides the presence of Au(0) and Au(I) oxidation states in BSA-AuNCs, the authors observe a significant amount of Au(II), which may result from a disproportionation event occurring within NCs: 2Au(I) → Au(II) + Au(0). Based on the LEPR experiments, and by comparing the behavior of BSA versus BSA-AuNCs under UV light irradiation (at 325 nm) during light off-on-off cycles, any energy and/or charge transfer event occurring between BSA and AuNCs during photoexcitation can be excluded. According to CW-EPR results, the Au nano assemblies within BSA-AuNCs are estimated to contain 6-8 Au units per fluorescent cluster. Direct observation of BSA-AuNCs by STEM and HR-TEM techniques confirms the presence of such diameters of gold nanoclusters in BSA-AuNCs. Moreover, in situ formation and migration of Au nanostructures are observed and evidenced after application of either a focused electron beam from HR-TEM, or an X-ray from EDS experiments.
通过连续波电子顺磁共振（CW-EPR）、光诱导电子顺磁共振（LEPR）以及一系列借助高分辨率透射电子显微镜（HR-TEM）、扫描透射电子显微镜（STEM）和能量色散X射线分析（EDS）进行的微观研究，对牛血清白蛋白包埋的金纳米团簇（BSA-AuNCs）进行了全面探究。据我们所知，这是首篇运用CW-EPR/LEPR技术分析BSA-AuNCs的报告。除了在BSA-AuNCs中存在Au(0)和Au(I)氧化态外，作者还观察到大量的Au(II)，这可能源于纳米团簇内发生的歧化反应：2Au(I) → Au(II) + Au(0)。基于LEPR实验，并通过比较在紫外光照射（325 nm）下BSA与BSA-AuNCs在光开-关循环过程中的行为，可排除光激发过程中BSA与金纳米团簇之间发生的任何能量和/或电荷转移事件。根据CW-EPR结果，估计BSA-AuNCs内的金纳米聚集体每个荧光团簇含有6-8个金单元。通过STEM和HR-TEM技术对BSA-AuNCs进行直接观察，证实了BSA-AuNCs中存在这种直径的金纳米团簇。此外，在应用HR-TEM的聚焦电子束或EDS实验的X射线后，观察并证明了金纳米结构的原位形成和迁移。
