Facile synthesis of red-emitting carbon dots from pulp-free lemon juice for bioimaging

• Published in: Journal of materials chemistry. B, Materials for biology and medicine Vol. 5; no. 26; pp. 5272 - 5277
• Main Authors: Ding, Hui, Ji, Yuan, Wei, Ji-Shi, Gao, Qing-Yu, Zhou, Zi-Yuan, Xiong, Huan-Ming
• Format: Journal Article
• Language: English
• Published: England 14.07.2017
• Subjects: Carbon; carbon quantum dots; Citrus limon; cytotoxicity; ethanol; Juices; lemon juice; Lemons; light emitting diodes; luminescence; Medical imaging; Nanoparticles; optical properties; photostability; physical properties; Sodium; sodium borohydride; Synthesis; Toxicity
• ISSN: 2050-750X; 2050-7518; 2050-7518
• DOI: 10.1039/C7TB01130J

In this work, red-emitting carbon dots (R-CDs) with a high quantum yield (QY) of 28% in water were synthesized for the first time by heating an ethanol solution of pulp-free lemon juice. The obtained R-CDs were mono-dispersed with an average diameter of 4.6 nm, and exhibited excitation-independent emission at 631 nm. Meanwhile, these R-CDs featured low cytotoxicity and good photostability, which allow R-CDs to be employed as luminescent probes for in vitro / in vivo bioimaging. In addition, a detailed study on the physical properties and structural compositions of the sodium borohydride (NaBH 4 ) reduced R-CDs with orange emission suggested that surface states on the R-CD surfaces and nitrogen-derived structures in the R-CD cores synergistically caused their intense red luminescence. The low-cost and eco-friendly synthesis method and favorable optical properties of R-CDs make these carbon dots promising for further applications, such as bioimaging and light-emitting diodes.