Fabrication of multifunctional monometallic nanohybrids for reactive oxygen species-mediated cell apoptosis and enhanced fluorescence cell imaging

Novel fluorescent monometallic Ag nanohybrids (Ag NHs) have been synthesized via polycytosine-mediated biomineralization on Ag nanoparticles (Ag NPs). Thiolated polycytosine dC(12) was anchored on the Ag NPs, followed by dC(12)-templated synthesis of the Ag nanoclusters (Ag NCs). The Ag NHs exhibited strong fluorescence emission and improved resistance to dissolved oxygen in solution as compared to the Ag NCs. As an efficient therapeutic agent, the delivery of aptamer-functionalized Ag NHs into target cells induced reactive oxygen species (ROS) generation and cell apoptosis. The ROS-mediated apoptotic effect of the Ag NHs was stronger than that of the Ag NCs. For cell imaging, the target cells treated with aptamer-functionalized Ag NHs exhibited a higher fluorescence brightness than those treated with Ag NCs. Due to the fluorescence quenching of Ag NHs by the intracellularly generated ROS, the Ag NHs served as a fluorescent indicator for real-time monitoring of ROS-mediated cell apoptosis. The In vivo antitumor efficacy of the Ag NHs was also evaluated.