Hidden Properties of Carbon Dots Revealed After HPLC Fractionation.
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.
†Department of Chemistry, Natural Sciences Complex, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States.
John C
JC
Vinci
†Department of Chemistry, Natural Sciences Complex, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States.
Ivonne M
IM
Ferrer
‡Department of Pharmacology, Roswell Park Cancer Institute, Buffalo, New York 14263, United States.
Steven J
SJ
Seedhouse
†Department of Chemistry, Natural Sciences Complex, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States.
Allen K
AK
Bourdon
†Department of Chemistry, Natural Sciences Complex, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States.
Justin M
JM
Reynard
‡Department of Pharmacology, Roswell Park Cancer Institute, Buffalo, New York 14263, United States.
Barbara A
BA
Foster
†Department of Chemistry, Natural Sciences Complex, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States.|§Materials Science and Engineering Program, Natural Sciences Complex, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States.
Frank V
FV
Bright
†Department of Chemistry, Natural Sciences Complex, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States.|§Materials Science and Engineering Program, Natural Sciences Complex, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States.
Luis A
LA
Colón
HPLC; carbon dots; carbon nanoparticles; graphene quantum dots; ion exchange chromatography; nanomaterial fractionation; photoluminescence