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Title: Chiral Graphene Quantum Dots

Abstract

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-GQDsmore » 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. Finally, emergence of nanoscale chirality in GQDs decorated with biomolecules is expected to be a general stereochemical phenomenon for flexible sheets of nanomaterials.« less

Authors:
 [1];  [2];  [3];  [4];  [5];  [4];  [6];  [7];  [5];  [2];  [8];  [9];  [10]
  1. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Chemical Engineering; Univ. of Michigan, Ann Arbor, MI (United States). Biointerfaces Inst.; Nara Inst. of Science and Technology, Ikoma, Nara (Japan)
  2. Univ. of Michigan, Ann Arbor, MI (United States). Biointerfaces Inst.; Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Biomedical Engineering
  3. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Biomedical Engineering; Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Mechanical Engineering
  4. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Chemical Engineering
  5. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Chemical Engineering; Univ. of Michigan, Ann Arbor, MI (United States). Biointerfaces Inst.
  6. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Mechanical Engineering
  7. Univ. of Michigan, Ann Arbor, MI (United States). Biointerfaces Inst.; Pusan National Univ., Miryang (Korea, Republic of). Dept. of Cogno-Mechatronics Engineering
  8. Pusan National Univ., Miryang (Korea, Republic of). Dept. of Cogno-Mechatronics Engineering
  9. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Biomedical Engineering; Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Mechanical Engineering; Univ. of Michigan, Ann Arbor, MI (United States). Dept.of Macromolecular Science and Engineering, Biophysics Program
  10. Univ. of Michigan, Ann Arbor, MI (United States). Biointerfaces Inst., Dept. of Biomedical Engineering, Dept. of Mechanical Engineering, and Dept. of Materials Science and Engineering
Publication Date:
Research Org.:
Univ. of Michigan, Ann Arbor, MI (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
OSTI Identifier:
1435721
Grant/Contract Number:  
SC0002619; 2510001; DMR-9871177
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
ACS Nano
Additional Journal Information:
Journal Volume: 10; Journal Issue: 2; Journal ID: ISSN 1936-0851
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; biological activity; chiral excitons; chirality; circular dichroism; graphene quantum dots

Citation Formats

Suzuki, Nozomu, Wang, Yichun, Elvati, Paolo, Qu, Zhi-Bei, Kim, Kyoungwon, Jiang, Shuang, Baumeister, Elizabeth, Lee, Jaewook, Yeom, Bongjun, Bahng, Joong Hwan, Lee, Jaebeom, Violi, Angela, and Kotov, Nicholas A. Chiral Graphene Quantum Dots. United States: N. p., 2016. Web. doi:10.1021/acsnano.5b06369.
Suzuki, Nozomu, Wang, Yichun, Elvati, Paolo, Qu, Zhi-Bei, Kim, Kyoungwon, Jiang, Shuang, Baumeister, Elizabeth, Lee, Jaewook, Yeom, Bongjun, Bahng, Joong Hwan, Lee, Jaebeom, Violi, Angela, & Kotov, Nicholas A. Chiral Graphene Quantum Dots. United States. doi:10.1021/acsnano.5b06369.
Suzuki, Nozomu, Wang, Yichun, Elvati, Paolo, Qu, Zhi-Bei, Kim, Kyoungwon, Jiang, Shuang, Baumeister, Elizabeth, Lee, Jaewook, Yeom, Bongjun, Bahng, Joong Hwan, Lee, Jaebeom, Violi, Angela, and Kotov, Nicholas A. Fri . "Chiral Graphene Quantum Dots". United States. doi:10.1021/acsnano.5b06369. https://www.osti.gov/servlets/purl/1435721.
@article{osti_1435721,
title = {Chiral Graphene Quantum Dots},
author = {Suzuki, Nozomu and Wang, Yichun and Elvati, Paolo and Qu, Zhi-Bei and Kim, Kyoungwon and Jiang, Shuang and Baumeister, Elizabeth and Lee, Jaewook and Yeom, Bongjun and Bahng, Joong Hwan and Lee, Jaebeom and Violi, Angela and Kotov, Nicholas A.},
abstractNote = {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. Finally, emergence of nanoscale chirality in GQDs decorated with biomolecules is expected to be a general stereochemical phenomenon for flexible sheets of nanomaterials.},
doi = {10.1021/acsnano.5b06369},
journal = {ACS Nano},
issn = {1936-0851},
number = 2,
volume = 10,
place = {United States},
year = {2016},
month = {1}
}

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