Preparation of nitrogen-doped carbon dots with high quantum yield from Bombyx mori silk for Fe(III) ions detection

Nitrogen-doped carbon dots (CDs) have attracted increasing attention in the field of biochemistry and biosensors due to their high emission efficiency. Herein, Bombyx mori silk, natural fibres composed by two fibroin brins and conglutinated by sericin binder, has a high content of nitrogen, was used as raw material in the coupling of citric acid to prepare nitrogen-doped CDs using a facile one-step hydrothermal route. The as-prepared nitrogen-doped CDs are uniform with an average particle size of 5.6 nm, emit blue fluorescence with the quantum yield of 61.1%, and maintain photochemical stability in high salt concentrations and in most organic solvents. Binding experiments of the as-prepared CDs with metal ions show that the hydroxyl groups on their surface play very important role in the blue fluorescence emission, which can easily bind with Fe3+ as the consequence of fluorescence quenching, making a method for Fe3+ detection developed with high selectivity and sensitivity.