Concentration-dependent color tunability of nitrogen-doped carbon dots and their application for iron(III) detection and multicolor bioimaging

• Published in: Journal of colloid and interface science 2018-07, Vol.521, p.33-41
• Main Authors: Wang, Chan, Hu, Tantan, Wen, Zhuoqi, Zhou, Jingdan, Wang, Xioajie, Wu, Qian, Wang, Chuanxi
• Format: Article
• Language: English
• Subjects: Biosensing and cellular imaging; Biosensing Techniques; Carbon - chemistry; Color; Concentration-dependent fluorescence; Fluorescent Dyes - chemistry; HeLa Cells; High quantum yield; Humans; Iron - analysis; Microscopy, Confocal; Microwaves; Multicolor fluorescence; Nitrogen - chemistry; Nitrogen-doped carbon dots; Optical Imaging; Oxygen - chemistry; Particle Size; Quantum Dots - chemistry; Spectrometry, Fluorescence; Surface Properties
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2018.03.021

The N-doped CDs with high quantum yield and stability are synthesized by rapid microwave route. As-prepared CDs exhibit multicolor fluorescence via adjusting their concentrations and could be used for biosensing and bioimaging. [Display omitted] Nitrogen doping can effectly adjust the compositions and structures of carbon dots and hence enhance their fluorescence. In this work, we report a fast and low-cost route for synthesis of nitrogen-doped carbon dots (N-CDs) by microwave pyrolysis of citric acid and ammonium within 7 min. The as-prepared N-CDs contain plentiful oxygen and nitrogen functional groups, and dispaly intense fluorescence with high quantum yield of ca. 44.3% and have an average size of 1.8 nm. The obtained N-CDs exhibit highly stable against photobleaching, ionic strengths, and can be used for selective and sensitive detection of Fe(III). It is postulated that the Fe3+-mediated fluorescence quenching is attributed to the charge transfer between N-CDs and Fe3+. In particular, the emission peaks from blue to red region can be tuned by interparticle distance of N-CDs, simply by increasing the concentration of N-CDs in aqueous solution, which indicates its potential applications as a promising optical image probe in multicolor cellular imaging.