石墨烯
手性(物理)
材料科学
量子点
圆二色性
密度泛函理论
共价键
纳米技术
化学物理
计算化学
结晶学
化学
物理
有机化学
量子力学
手征对称破缺
Nambu–Jona Lasinio模型
夸克
作者
Nozomu Suzuki,Yichun Wang,Paolo Elvati,Zhibei Qu,Kyoungwon Kim,Shuang Jiang,Elizabeth Baumeister,Jae‐Wook Lee,Bongjun Yeom,Joong Hwan Bahng,Jaebeom Lee,Angela Violi,Nicholas A. Kotov
出处
期刊:ACS Nano
[American Chemical Society]
日期:2016-01-08
卷期号:10 (2): 1744-1755
被引量:328
标识
DOI:10.1021/acsnano.5b06369
摘要
Chiral nanostructures from metals and semiconductors attract wide interest as components for polarization-enabled optoelectronic devices. Similarly to other fields of nanotechnology, graphene-based materials can greatly enrich physical and chemical phenomena associated with optical and electronic properties of chiral nanostructures and facilitate their applications in biology as well as other areas. Here, we report that covalent attachment of l/d-cysteine moieties to the edges of graphene quantum dots (GQDs) leads to their helical buckling due to chiral interactions at the "crowded" edges. Circular dichroism (CD) spectra of the GQDs revealed bands at ca. 210-220 and 250-265 nm that changed their signs for different chirality of the cysteine edge ligands. The high-energy chiroptical peaks at 210-220 nm correspond to the hybridized molecular orbitals involving the chiral center of amino acids and atoms of graphene edges. Diverse experimental and modeling data, including density functional theory calculations of CD spectra with probabilistic distribution of GQD isomers, indicate that the band at 250-265 nm originates from the three-dimensional twisting of the graphene sheet and can be attributed to the chiral excitonic transitions. The positive and negative low-energy CD bands correspond to the left and right helicity of GQDs, respectively. Exposure of liver HepG2 cells to L/D-GQDs reveals their general biocompatibility and a noticeable difference in the toxicity of the stereoisomers. Molecular dynamics simulations demonstrated that d-GQDs have a stronger tendency to accumulate within the cellular membrane than L-GQDs. Emergence of nanoscale chirality in GQDs decorated with biomolecules is expected to be a general stereochemical phenomenon for flexible sheets of nanomaterials.
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