Hidden Properties of Carbon Dots Revealed After HPLC Fractionation

• Published in: The journal of physical chemistry letters 2013-01, Vol.4 (2), p.239-243
• Main Authors: Vinci, John C, Ferrer, Ivonne M, Seedhouse, Steven J, Bourdon, Allen K, Reynard, Justin M, Foster, Barbara A, Bright, Frank V, Colón, Luis A
• Format: Article
• Language: English
• Subjects: Physical Processes in Nanomaterials and Nanostructures
• ISSN: 1948-7185; 1948-7185
• DOI: 10.1021/jz301911y

Carbon dots (C-dots) are often synthesized, modified, and studied as a mixture. Unfortunately, the spectroscopic and biological properties measured for such C-dots assume that there is a high degree of homogeneity in the produced sample. By means of high-resolution separation techniques, we show that “as-synthesized” C-dots exist as a relatively complex mixture and that an unprecedented reduction in such complexity can reveal fractions of C-dots with unique luminescence properties. The wavelength-dependent photoluminescence commonly assigned as an inherent property of C-dots is not present in fractionated samples. While ultraviolet–visible absorption profiles reported for C-dots are typically featureless, we have found fractions of C-dots possessing unique absorption bands, with different fractions possessing specific emission wavelengths. Furthermore, fractionated C-dots showed profound differences in emission quantum yield, allowing for brighter C-dots to be isolated from an apparent low quantum yield mixture. These more luminescent fractions of C-dots displayed improved biological compatibility and usefulness as cellular imaging probes.