Oxidized nanocellulose facilitates preparing photoluminescent nitrogen-doped fluorescent carbon dots for Fe3+ ions detection and bioimaging

A major challenge in preparing nitrogen-doped carbon dots (N-CDs) from the world's most abundant material, cellulose, is its limited chemical accessibility, which results in low yield and low quantum yield (QY) of the obtained N-CDs. Herein, we showed that the overall yield and QY of N-CDs from dissolving pulp were significantly improved from 2.9% and 9.7% to 16.1% and 30.3% with an oxidation treatment. The efficient synthesis of N-CDs from dissolving pulp was attributed to the enhanced chemical accessibility of cellulose by the oxidation process. The obtained N-CDs showed a graphite-like structure rich in carboxyl and amino functional groups. They were well monodispersed spherical nanoparticles with a mean diameter of 1.86 nm. Also, the asprepared N-CDs showed excellent selective and sensitive response to Fe3+ ions with the detection limit of 1.14 mu M. In addition, vitro cytotoxicity test indicated the non-toxicity of N-CDs which enabled their success as fluorescent probe for bio-imaging of Vero cells. Summarily, this study presented an improved strategy to synthesize advanced materials with potential application in sensor, bioimaging and biomedical from the world's most abundant, cheapest, green and renewable materials-cellulose.