Carbon dots have garnered attention for their strong multi-color luminescence properties and unprecedented biocompatibility. Despite significant progress in the recent past, a fundamental understanding of their photoluminescence and structure-properties relationships, especially at the bulk vs. single-particle level, has not been well established. Here we present a comparative study of bulk-and single-particle properties as a function of precursor composition and reaction temperature. The synthesis and characterization of multicolored inherently functionalized carbon dots were achieved from a variety of carbon sources, and at synthesis temperatures of 150 degrees C and 200 degrees C. Solvothermal synthesis at 200 degrees C led to quantum yields as high as 86%, smaller particle sizes, and a narrowed fluorescence emission, while synthesis at 150 degrees C resulted in a greater UV-visible absorbance, increase in nanoparticle stability, red-shifted fluorescence, and a greater resistance to bulk photobleaching. These results suggest the potential for synthesis temperature to be utilized as a simple tool for modulating carbon dot photophysical properties. Single-particle imaging resolved that particle brightness was determined by both the instantaneous intensity and the on-time duty cycle. Increasing the synthesis temperature caused an enhancement in blinking frequency, which led to an increase in on-time duty cycle in three out of four precursors. (c) 2019 Elsevier Ltd. All rights reserved.
[1]Univ Illinois, Dept Bioengn, Urbana, IL 61801 USA;
[2]Univ Illinois, Dept Mat Sci & Engn, Urbana, IL 61801 USA;
[3]Univ Illinois, Beckman Inst, Urbana, IL 61801 USA;
[4]Carle Fdn Hosp, Mills Breast Canc Inst, Urbana, IL 61801 USA;
[5]NIST, Phys Measurement Lab, Microsyst & Nanotechnol Div, Biomed Technol Grp, Gaithersburg, MD 20899 USA;
[6]Univ Illinois, Sch Mol & Cellular Biol, Dept Biochem, Urbana, IL 61801 USA;
[7]Fudan Univ, Dept Chem, Shanghai, Peoples R China
(8.0+极速模式)