Abstract:
Nitric oxide (NO) is a ubiquitous, gaseous, free radical signaling molecule which plays a key role in physiological
and pathological processes. Literature reports revealed that the conventional methods such as colorimetry,
electron paramagnetic resonance (EPR), electrochemical etc. to detect NO are costly, time consuming and lack
resolution, particularly in aqueous or biological system. Thus, in this context, herein we have developed cova-
lently linked biomass derived carbon quantum dots (CQDs) and naphthalimide based nano sensor system for
FRET based ratiometric detection of nitric oxide (NO) in pure aqueous media. The CQDs derived from orange
peels were characterized using UV–visible absorption, fluorescence spectroscopy, PXRD, TEM, FT-IR and zeta
potential studies. Further, the obtained CQDs were functionalized with amine functionality, and subsequently
linked with naphthalimide derivative (5) using terephthaldehyde through covalent bond formation. The
conjugation of naphthalimide (5) and functionalized CQDs was studied using DLS, zeta potential, FT-IR and time
resolved fluorescence spectroscopy. The excitation of developed nano sensor system at λex 360 nm results in
fluorescence emission at λem 530 nm which establishes the FRET pair between the CQDs and naphthalimide unit.
However, in the presence of NO, the observed FRET pair abolishes due to the cleavage of NO susceptible imine
bond. The developed sensor demonstrates high selectivity towards NO with limit of detection (LOD) and limit of
