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UV–Vis–NIR Full‐Range Responsive Carbon Dots with Large Multiphoton Absorption Cross Sections and Deep‐Red Fluorescence at Nucleoli and In Vivo
Author(s) -
Jiang Lei,
Ding Haizhen,
Xu Mingsheng,
Hu Xiaolong,
Li Shengli,
Zhang Mingzhu,
Zhang Qiong,
Wang Qiyang,
Lu Siyu,
Tian Yupeng,
Bi Hong
Publication year - 2020
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.202000680
Subject(s) - fluorescence , absorption (acoustics) , photochemistry , materials science , conjugated system , photon upconversion , near infrared spectroscopy , quantum yield , absorption band , quantum dot , analytical chemistry (journal) , chemistry , doping , optoelectronics , optics , polymer , organic chemistry , physics , composite material
Carbon dots (CDs), with excellent optical property and cytocompatibility, are an ideal class of nanomaterials applied in the field of biomedicine. However, the weak response of CDs in the near‐infrared (NIR) region impedes their practical applications. Here, UV–vis–NIR full‐range responsive fluorine and nitrogen doped CDs (N‐CDs‐F) are designed and synthesized that own a favorable donor‐π‐acceptor (D‐π‐A) configuration and exhibit excellent two‐photon (λ ex = 1060 nm), three‐photon (λ ex = 1600 nm), and four‐photon (λ ex = 2000 nm) excitation upconversion fluorescence. D‐π‐A‐conjugated CDs prepared by solvothermal synthesis under the assistance of ammonia fluoride are reported and are endowed with larger multiphoton absorption (MPA) cross sections (3PA: 9.55 × 10 −80 cm 6 s 2 photon −2 , 4PA: 6.32 × 10 −80 cm 8 s 3 photon −3 ) than conventional organic compounds. Furthermore, the N‐CDs‐F show bright deep‐red to NIR fluorescence both in vitro and in vivo, and can even stain the nucleoli of tumor cells. A plausible mechanism is proposed on the basis of the strong inter‐dot and intra‐dot hydrogen bonds through NH···F that can facilitate the expanding of conjugated sp 2 domains, and thus not only result in lower highest occupied molecular orbital‐lowest unoccupied molecular orbital energy level but also larger MPA cross sections than those of undoped CDs.