β-Cyclodextrin/glycyrrhizic acid functionalised quantum dots selectively enter hepatic cells and induce apoptosis

The use of active components from important medical herbs has proved effective in treating various cancers. Glycyrrhizic acid (GA) is one of the many interesting triterpenoic acids with anticancerogenic potential, and is known to trigger apoptosis in hepatocarcinoma cells. In this study we combined quantum dots (QDs) with GA in the presence of β-cyclodextrin (β-CD), and prepared β-CD/GA-functionalised QDs, which led to improved antitumor activity and induced apoptosis in hepatocarcinoma cells. These compounds showed a better selectivity for hepatic cells compared to HeLa and ECV-304 cells. Hoechst and annexin V-FITC staining and mitochondrial membrane potential (MMP) experiments proved an apoptotic effect of these compounds on HepG2 cells. At the same time, transmission electron microscopy (TEM) showed obvious features of apoptosis, for example, irregularities of nuclear shapes, mitochondria swelling, clumping and peripheral chromatin condensation, zeiosis or blebbing of the plasma membrane and formation of apoptotic bodies. It is notable that β-CD/GA-functionalised QDs showed effective cell growth inhibition by triggering G0/G1 phase arrest and inducing apoptosis through an reactive oxygen species mediated mitochondrial dysfunction pathway. β-CD/GA-functionalised QDs primarily induced apoptotic response in a time- and dose-dependent manner, but little apoptosis appeared with L-Cys-β-CD-functionalised QDs or GA alone. These studies suggest that β-CD/GA-functionalised QDs have therapeutic potential against cancer.