Nitrogen doped fluorescent carbon dots from Delonix regia for Fe(III) and cysteine sensing, DNA binding and bioimaging

Abstract

The current work primarily deals with the synthesis of nitrogen rich carbon dots from Delonix regia along with characterisation using several analytical techniques for fluorescent sensing of Fe(III) and cysteine, electrochemical sensing of hydrogen peroxide and DNA binding. The average particle size of the spherical N-CDs is calculated to be 2.23 nm with a quantum yield of 33.5%. The SAED pattern from HR-TEM confirms the slight graphitisation of the N-CDs along with the amorphous carbon core. The synthesised N-CDs served as an efficient turn off sensor for Fe(III) with a detection limit of 5.76 × 10-7 M and turn on sensor for L-Cysteine with a detection limit of 3.76 × 10-4 M. The nature and extent of binding of the N-CDs with ctDNA was evaluated and the binding constant from the Benesi Hildebrand plot is calculated to be 6.49 (mg/mL)-1. The limit of detection was found to be 71 µM for electrochemical sensing of hydrogen peroxide. The less cytotoxic and excellent biocompatible nature of the N-CDs have been taken advantage to image L6 cells and SKMEL cells.