A Facile Approach for Doxorubicine Delivery in Cancer Cells by Responsive and Fluorescent Core/Shell Quantum Dots

Biocompatible thermoresponsive copolymers based on 2-(2-methoxyethoxy) ethyl methacrylate (MEO₂MA) and oligo (ethylene glycol) methacrylate (OEGMA) were grown from the surface of ZnO quantum dots (QDs) by surface initiated atom transfer radical polymerization with activators regenerated by electron transfer (SI-ARGET ATRP) in order to design smart and fluorescent core/shell nanosystems to be used toward cancer cells. Tunable lower critical solution temperature (LCST) values were obtained and studied in water and in culture medium. The complete efficiency of the process was demonstrated by the combination of spectroscopic and microscopic studies. The colloidal behavior of the ZnO/copolymer core/shell QDs in water and in physiological media with temperature was assessed. Finally, the cytotoxicity toward human colon cancer HT29 cells of the core/shell QDs was tested. The results showed that the polymer-capped QDs exhibited almost no toxicity at concentrations up to 12.5 μg.mL^–1, while when loaded with doxorubicin hydrochloride (DOX), a higher cytotoxicity and a decreased HT29 cancer cell viability in a short time were observed