Highly luminescent covalently bonded layered double hydroxide-fluorescent dye nanohybrids

Incorporation of fluorescein dye molecules into layered double hydroxide (LDH) nanoparticles to form nanocomposites has great potential for optical and biological applications. Herein, we report a novel highly luminescent covalently bonded LDH-sodium fluorescein dye nanohybrid. This nanocomposite shows a significantly higher quantum yield (QY) of 55.1% than the nanohybrids prepared using the previously reported anion exchange (3.0%) and coprecipitation (12.4%) approaches. Our LDH-sodium fluorescein nanohybrid is superior to the pure fluorescent dye from a number of perspectives. Firstly, the nanohybrid exhibits excellent linearity between the fluorescence intensity and the concentration in a certain range. Secondly, the nanohybrid remains fluorescent even in a dry powder form. Thirdly, the nanohybrid can self-assemble into a transparent and free-standing film which is fluorescent under UV, which will lead to important applications in optical devices.