Water-soluble, lignin-derived carbon dots with high fluorescent emissions and their applications in bioimaging

• Published in: Journal of industrial and engineering chemistry (Seoul, Korea) Vol. 66; pp. 387 - 395
• Main Authors: Myint, Aye Aye, Rhim, Won-Kyu, Nam, Jwa-Min, Kim, Jaehoon, Lee, Youn-Woo
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 25.10.2018; 한국공업화학회
• Subjects: Bioimaging; Carbon dots; High photostability; Lignin; Tunable fluorescence properties; 화학공학; Lignin; Bioimaging; Tunable fluorescence properties; Carbon dots; High photostability
• ISSN: 1226-086X; 1876-794X
• DOI: 10.1016/j.jiec.2018.06.005

[Display omitted] •Water-soluble fluorescent carbon dots (CDs) synthesized from kraft lignin.•CDs exhibited pH-dependent fluorescence (FL) emission and high salt/photo stability.•FL emission intensities increased with longer reaction times.•A high quantum yield of 13% resulted in the CDs synthesized for 24h. We report the synthesis of water-soluble and environmentally friendly fluorescent carbon dots (CDs) using the renewable resource lignin as a precursor, which is a waste emitted from pulp and paper industries and lignocellulosic biofuel production, using a compressed liquid CO2 antisolvent method followed by carbonization and chemical oxidation with an acid mixture (H2SO4:HNO3=1:3, v/v) at 90°C for 8, 16, and 24h. The as-synthesized CDs emitted bright yellow fluorescence (FL) under argon laser excitation at 458nm with excitation-wavelength-independent and excitation-wavelength-dependent FL emission characteristics. Moreover, the CDs exhibited excellent stability in a highly concentrated NaCl solution, photostability with pH-dependent FL emission activities, and cellular imaging capability with very low cytotoxicity. Notably, the FL emission intensities of the as-synthesized CDs increased with longer reaction times, indicating high degree of oxidation on the CD surface and consequently, high quantum yield of 13% was achieved. Therefore, the as-synthesized CDs can be used as promising fluorescent probes for bioimaging applications in vitro and in vivo.