Ethylene glycol and alanine anhydride based nitrogen doped fluorescent carbon nanoparticles as probe for detection of epinephrine, nor-epinephrine and dopamine

Abstract

Here we present highly ordered nitrogen doped fluorescent carbon nanoparticles (N–CNPs) as fluorescent probe prepared by controlled heating of ethylene glycol and alanine anhydride at 170 °C for 120 min. The probe exhibits bluish fluorescence at λemission = 452 nm when excited at λexcitation = 380 nm, with fluorescence quantum yield of 7.6% and average lifetime of 5.8 ns The structural and compositional studies of N–CNPs by Raman Spectroscopy, Fourier transformed infrared spectroscopy, X-ray photoelectron spectroscopy, 1H and 13C NMR and higher resolution transmission electron microscopy indicated formation of highly ordered N-CNPs via oligomerization of ethylene glycol with alanine anhydride. The probe has been optimized for detecting trace level of important biomarkers as analytes, e.g., norepinephrine epinephrine and dopamine via fluorescence recovery mechanism. Here, MnO4‾ is used for quenching the fluorescence intensity of the probe while the analytes were instrumental in recovering the fluorescence. The fluorescence recovery index is linear with the concentration of the analytes of interest and satisfied the Stern-Volmer equation. The Limit of detection (LoD) of epinephrine (88 nM) and norepinephrine (91 nM) are better than the LoD of dopamine (140 nM). The selectivity towards detection of epinephrine, norepinephrine and dopamine has been established with respect to several biologically relevant molecules as interfering agents. The feasibility of this analytical methodology in detection of epinephrine, nor-epinephrine and dopamine in real sample has been demonstrated by spike analysis in human urine samples.