Carbon-dots from sugars and ascorbic acid: Role of the precursors on morphology, properties, toxicity and drug uptake

There is the need for reproducible, simple, high-yielding synthetic protocols aimed at obtaining Carbon Dots (CDs) with controlled surface properties, fluorescence, photothermal and photochemical behavior, biocompatibility, tumor targeting ability, drug absorption biodistribution and tumor uptake. This paper describes a systematic study on the effect of glucose, fructose and ascorbic acid as starting materials for the preparation of highly luminescent CDs, characterized by a blue emission. Their composition and morphology are investigated by titration of OH surface groups, spectroscopic techniques, high-resolution-transmission electron microscopy (HR-TEM) and their toxicity was tested toward HeLa cells. CDs made using fructose were toxic while CDs made from glucose and ascorbic acid showed good biocompatibility. The reproducible and simple synthetic procedure yields luminescent biomass-derived CDs for combined cancer therapy and diagnostics. Their doxorubicin (DOX) drug loading capabilities were measured by spectrofluorimetry indicating a crucial role of the morphologies of the CDs in controlling DOX uptake. The glucose derived CDs showed up to 28 %w/w of DOX loading.