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.