Synthesis, characterization, and pharmacological evaluation of dextrin capped cadmium sulfide quantum dots conjugated with temozolomide for drug delivery and imaging application

Abstract

Quantum dots (QDs) of cadmium sulfide semiconductor capped with dextrin and bioconjugated with temozolomide (CdS/Dx+TMZ) were used to target and provide imaging of glioma cells. CdS/Dx+TMZ QDs were in the range of 6.5 nm in size and exhibited an intense fluorescence emission in the green spectrum, which allowed us to monitor fluorescence imaging in a rat glioma cell line. The results showed that glioma cells efficiently took up the CdS/Dx+TMZ QDs, which had a large accumulation time in cells and were distributed in both the cytoplasm and nucleus, where the pharmacological drug effects were enhanced. CdS/Dx+TMZ QDs were more cytotoxic than TMZ and CdS/Dx alone. Glioma cells treated with 100 µM CdS/Dx+TMZ QDs showed both an increase in size (cytoplasm and nucleus) and in the number of cell deaths by apoptosis. The morphological analysis showed the presence of binucleated cells and membrane blebbing, as well as apoptotic bodies. This study confirmed the effective cellular uptake of CdS/Dx QDs bioconjugated with TMZ and their pharmacological effects in a glioma cell line. Our conclusion is that CdS/Dx+ TMZ QDs could be simultaneously used as drug delivery and cell monitoring system for the treatment of GBM and other brain tumors.