Nanocenter synthesis of nitrogen-doped graphene quantum dots

Abstract Two-photon fluorescence imaging technology has the advantages of near-infrared excitation, avoiding phototoxicity and photobleaching, weak autofluorescence interference and deep tissue penetration depth, and has received great attention in the field of biomedicine research. Develop materials with high two-photon absorption cross section and good biocompatibility as...
Two-photon fluorescence imaging technology has the advantages of near-infrared excitation, avoiding phototoxicity and photobleaching, weak autofluorescence interference and deep tissue penetration depth, and has received great attention in the field of biomedicine research. The development of a material with high two-photon absorption cross section and good biocompatibility as a two-photon fluorescent probe is a key and hot spot in the research field of living cells and deep tissue imaging.


The National Nanoscience Center Gong Jianru research group synthesized nitrogen-doped graphene quantum dots (N-GQD) by using graphene oxide as precursor and N,N-dimethylformamide as nitrogen source. The N-GQD nanomaterial emits strong fluorescence under the excitation of near-infrared femtosecond laser. The two-photon absorption cross section is as high as 48000 GM, far exceeding the organic dye molecules, which is the highest value reported in carbon materials, and semiconductor quantum dot materials. quite. N-GQD's remarkable quantum effect and rigid π-π conjugate structure make it have strong two-photon absorption. At the same time, the doped nitrogen is bonded to the aromatic ring of N-GQD in the form of alkylamine, and the strong electron donating effect of the alkylamine further enhances the two-photon absorption of N-GQD. Two-photon imaging studies of N-GQD in tissue models have shown that tissue penetration depth can reach 1800 microns, breaking the limits of traditional two-photon fluorescence imaging depth. In addition, N-GQD has good dispersibility in water, phosphate buffer and cell culture medium, almost no cytotoxicity, and is not prone to photobleaching, indicating its long-term bio-tissue imaging and related applications, such as biological tissues. Potential application value in structural observation, disease diagnosis, etc. The above work was published in Nano Lett. (2013, 13, 2436-2441).

The latest series of research results of this group have been published in Adv. Mater. (2013, DOI: 10.1002/adma.201301207), Nano Lett. (2012, 12, 4584), J. Am. Chem. Soc. (2011, 133 , 10878).

The above research work has received strong support from the Chinese Academy of Sciences, the National Natural Science Foundation of China and the Ministry of Science and Technology.

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