Background: Water soluble nitrogen and phosphorus doped carbon dots (CD) have been synthesized
using citric acid, tris(2-aminoethyl)amine and orthophosphoric acid via one step microwave assisted
Methods: The CD synthesized has been characterized using FTIR, UV-Vis, fluorescence spectroscopy and
EDAX coupled with SEM techniques.
Results: SEM study has shown the formation of nanosized CD with an average size of ~18 nm. Elemental
analysis via EDAX has confirmed successful incorporation of nitrogen (30.8% wt) and phosphorus (5.7%
wt) atoms in it. The steady state and 3D fluorescence spectroscopic studies have shown its efficient fluorescence
emission with emission maxima in the region of ~450 nm. It has shown efficient “turn off” fluorescence
behaviour towards transition metal ions like Fe2+ and Co2+ ions and toxic nitrophenolic compounds
like p-nitrophenol and picric acid. Its efficient interaction with BSA has been revealed in terms of fluorescence
quenching of BSA by steady state, synchronous and 3D fluorescence spectroscopy. It has shown
very good in vitro biocompatibility and enhanced cell adhesion properties towards NIH 3T3 fibroblast
cells. Moreover, fluorescence microscopy has shown significant uptake of CD by the tested cell line.
Conclusion: Such bio-compatible nitrogen and phosphorous doped CD can be potentially useful to estimate
metal ions, p-nitrophenol and picric acid using fluorescence spectroscopy and for fluorescence based