For the first time, scientists have achieved controllable orderly modification of carbon nanotubes

Single-walled carbon nanotubes with controlled orderly modifications. Courtesy of the research team

The reporter learned from South China University of Technology a few days ago that Professor Lin Zhiwei of the School of Frontier Soft Matter of the University and Ming Zheng, a researcher at the National Institute of Standards and Technology (NIST), used DNA to achieve the controllable and orderly modification of single-walled carbon nanotubes (SWCNTs) for the first time. The study was published in Science. The reviewers spoke highly of the relevant research results, believing that the work had accomplished the ambitious goals that many researchers had tried but had little success in the past, and was a major progress in the field.

According to reports, the paper has caused great repercussions after publication, and many media at home and abroad have carried out highlight reports on the work. Science published a Review review of the work: “The materials designed in this paper are an important step towards the realization of room-temperature superconducting materials and are landmark discoveries. ”

The work opens up a whole new line of thought for controlled chemical modifications in SWCNTs through simple DNA sequence design and sophisticated structural characterization. South China University of Technology is the cooperative unit of the paper, Lin Zhiwei is the first author and corresponding author, and doctoral student Yinong Li has made important contributions to the molecular simulation and color map design of the paper; Ming Zheng is the co-corresponding author and NIST is the main communicator.

SWCNTs are one-dimensional tubular nanomaterials composed of single-layer carbon atoms, with excellent optical, electrical, mechanical, thermal and other properties, and are widely used in many fields, including electronic devices, optical instruments, disease detection and so on. The chemical modification of SWCNTs can change their lattice structure, thereby changing the electrical and optical properties, which is of great significance to the development of new materials such as organic superconducting materials and quantum materials, and is an international frontier research direction. But because all carbon atoms in SWCNTs have the same chemical environment, controlled chemical modification of SWCNTs is a major long-standing challenge in the field.

Lin Zhiwei said, “The precise and controllable modification method makes it possible for scientists to design the chemical structure of SWCNTs according to their own ideas like clothing designers to achieve special properties, such as superconductivity and quantum performance, and then achieve cutting-edge applications in aerospace, quantum computers, quantum communications, next-generation biomedicine and other fields.” ”

Specifically, the authors wound DNA sequences containing guanine bases (Guanine, G) around the surface of a variety of one-handed SWCNTs to achieve pre-customized reaction sites by modulating SWCNTs species, DNA sequences, and conformations. Rose Bengal is excited under 525 nm light to produce unlinear oxygen, which in turn triggers a reaction between G and SWCNTs. The structure of the product was then characterized by absorption spectroscopy, photoluminescence spectroscopy (PL), and Raman spectroscopy.

Schematic and spectral characterization of SWCNTs’ reactions with DNA. Courtesy of the research team

In order to delve into the reaction mechanism and the spatial distribution of reaction sites in the WCNTs lattice after the reaction, the researchers designed a series of DNA (2G-n) with the same G content but different relative positions of G, and unexpectedly found that the reaction products of C3GC7GC3 (2G-7) and (8,3) SWCNTs appeared to have extremely small peak strengths associated with SWCNTs lattice defects in raman and fluorescence spectra, indicating that an orderly arrangement of lattice defects was formed in SWCNTs. That is, an orderly arrangement of reaction sites.

The structure of C3GC7GC3-(8,3) was characterized and reconstructed using cryo-ELECTRON microscopy (Cryo-EM), confirming the ordered DNA helix structure. The theoretical model constructed by computer simulation and the reconstructed model of cryo-EM are mutually verified, which clearly reveals the reaction mechanism and further proves the orderly arrangement of lattice defects (G reaction sites) at equal spacing on the surface of SWCNTs. Based on the precise and controllable SWCNTs modification method, it is expected to reshape the original lattice structure and photoelectric properties of SWCNTs in a customizable manner, and provide an important theoretical and experimental basis for the development of transformative materials such as organic superconducting materials and topological materials.

Science Daily in the United States reported on the research results, pointing out: “Scientists have used DNA to overcome previously almost insurmountable obstacles and design materials that are expected to bring revolutionary effects to electronic products.” (Source: China Science Daily Zhu Hanbin)

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