Description
Among various carbon dot species, yellow carbon dots (YC-Dots) are a unique subspecies. YC-Dots are derived from citric acid and 1,2-phenylenediamine using a bottom-up approach mediated by ultrasonication. Property studies demonstrated that YC-Dots are nontoxic, biocompatible, and photoluminescent. Interestingly, unlike other C-Dot species, YC-Dots have shown robust excitation-independent yellow-emitting photoluminescence (PL). Morphology studies, including AFM and TEM, revealed that Y-CDs are spherical with a mean diameter of 3 nm.
As to the structure of YC-Dots, it has been confirmed that YC-Dots contain abundant carboxyl, amine, and hydroxyl groups on the surface. In addition, Y-CDs possess a high carbon content, which was rarely reported in other C-Dot species. Studies show that YC-Dots can cross diverse cell membranes and biological barriers (such as the Blood Brain Barrier) in research for drug delivery. To date, Y-CDs have been used in research for their capacity to enter the central nervous system (CNS) while greatly inhibiting the expression of amyloid precursor protein and beta-amyloid inside cells, which could be of great significance towards the treatment of Alzheimer’s disease. Moreover, when YC-Dots were conjugated with small molecules, their amphiphilicity and capability to cross the BBB were not affected. Thus, YC-Dots could be a promising versatile drug nanocarrier in research. Despite the fact that YC-Dots are more likely to be used in biological applications, the highly photoluminescent characteristics drive the YC-Dots to be used in other fields.