Eco-friendly synthesis of tunable fluorescent carbon nanodots from Malus floribunda for sensors and multicolor bioimaging

In this work, green and economical synthesis of highly fluorescent nitrogen-doped carbon nanodots (N-CNDs) is reported using Malus floribunda (M. floribunda) fruit and aqueous ammonia as carbon and nitrogen source, respectively by a simple hydrothermal method. The synthesized N-CNDs show exceptional advantages including acceptable fluorescent quantum yield (18 %) and N-CNDs sizes are around 3.5 nm. The fluorescence of N-CNDs based nanosensor can be selectively and sensitively quenched by ferric ions in the aqueous medium. This phenomenon was used to develop a fluorescent method for facile detection of ferric ions within a linear range of 10-50 mu M with a detection limit of 2.5 mu M (S/N = 5) having linear regression value (R-2) of 0.994. The synthesized N-CNDs incubated with human colon cancer (HCT-116) cells which did not stimulate cell death, indicating that the N-CNDs have good biocompatibility. Hence, the N-CNDs was used as a fluorescent probe for in vitro imaging of HCT-116.TheN-CNDswereuniformly internalized into the whole body of cells and displays the multicolor fluorescence imaging. To best of the authors' knowledge, this is the earliest report on the selective sensing of ferric ions and live-cell imaging using M. floribunda fruit-derived N-CNDs by fluorescent quenching mechanism.