SiO2 encapsulated nanofluorophor: Photophysical properties, aggregation induced emission and its application for cell mitochondria imaging

An organic fluorescent 1,8-naphthalimide derivative (NI-1) was designed and synthesized. Its photo physical properties were systematically investigated by a series of spectroscopic and theoretical methods. The twisted intramolecular charge transfer (TICT) was proved within NI-1 in various solutions. After adding H2O into its CH3CN solution, the aggregation induced emission (AIE) of NI-1 occurred, during which the enhanced green-yellow fluorescence and quantum yield up to 0.62 were monitored. In addition, SiO2 was used to coat on the surface of NI-1 to fabricate the composite nano structure (NI-1@SiO2). This nanomaterial not only qualifies AIE-active characteristic, but also exhibits remarkable anti-photobleaching ability and good biocompatibility. The NI-1@SiO2 can go through the cell membrane and specifically light up the mitochondria. The cellular uptake mechanism studies revealed that the energy dependent cell uptake mechanism was responsible for the NI-1@SiO2 entering cells. The NI-1@SiO2 could be utilized as an efficient AIE-active fluorescent material and mitochondria imaging reagent. (C) 2016 Elsevier Ltd. All lights reserved.