Biocompatible fluorescence-enhanced ZrO₂-CdTe quantum dot nanocomposite for in vitro cell imaging.

With advances of quantum dots (QDs) in bioimaging applications, various materials have been used to coat QDs to reduce their nanotoxicity; however, the coating could introduce new toxic sources and quench the fluorescence in bioimaging applications. In this work, ZrO₂, an excellent ceramic material with low extinction coefficient and good biocompatibility, is utilized to coat CdTe QDs for the first time. Experimental results show that ZrO₂-QD nanocomposites with the size of ~30 nm possess enhanced fluorescence emission, lower nanotoxicity and gradually increased fluorescence under 350 nm light illumination. After functionalization with folic acid, they were applied to label cultured HeLa cells effectively. Therefore, the ZrO₂-QD nanocomposites could be promising biocompatible nanomaterials with strong fluorescence emission to replace or complement QDs in biomedical applications.