Non-Redox Modulated Fluorescence Strategy for Sensitive
and Selective Ascorbic Acid Detection with Highly Photoluminescent
Nitrogen-Doped Carbon Nanoparticles via Solid-State Synthesis
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Abstract
Highly photoluminescent nitrogen-doped
carbon nanoparticles (N-CNPs)
were prepared by a simple and green route employing sodium alginate
as a carbon source and tryptophan as both a nitrogen source and a
functional monomer. The as-synthesized N-CNPs exhibited excellent
water solubility and biocompatibility with a fluorescence quantum
yield of 47.9%. The fluorescence of the N-CNPs was intensively suppressed
by the addition of ascorbic acid (AA). The mechanism of the fluorescence
suppression of the N-CNPs was investigated, and the synergistic action
of the inner filter effect (IFE) and the static quenching effect (SQE)
contributed to the intensive fluorescence suppression, which was different
from those reported for the traditional redox-based fluorescent probes.
Owing to the spatial effect and hydrogen bond between the AA and the
groups on the N-CNP surface, excellent sensitivity and selectivity
for AA detecting was obtained in a wide linear relationship from 0.2
μM to 150 μM. The detection limit was as low as 50 nM
(signal-to-noise ratio of 3). The proposed sensing systems also represented
excellent sensitivity and selectivity for AA analysis in human biological
fluids, providing a valuable platform for AA sensing in clinic diagnostic
and drug screening