Nanosensor Composed of Nitrogen-Doped Carbon Dots
and Gold Nanoparticles for Highly Selective Detection of Cysteine
with Multiple Signals
- Publication date
- Publisher
Abstract
Biological thiols play a critical
role in biological processes
and are involved in a variety of diseases. The discrimination detection
of biological thiols is of increasing importance in clinical diagnosis.
In this paper, a novel nanosensor was developed to discriminate cysteine
(Cys) from homocysteine (Hcy) and glutathione (GSH) with multiple
signals: colorimetric, photoluminescence (PL), and up-conversional
photoluminescence (UCP). The nanosensor (NC-dots/AuNPs) was constructed
by nitrogen-doped carbon dots (NC-dots) and gold nanoparticles (AuNPs)
through assembling NC-dots “shell” on AuNPs and showed
the obvious different response to Cys, Hcy, and GSH with colorimetric,
PL, and UCP signals. The discrimination effect for Cys is originated
from conformations and interaction difference of the thiols groups
in Cys and Hcy and/or GSH with AuNPs. Among them, only Cys can quickly
penetrate into the NC-dots “shell” of the composite
and induce the dispersing of the aggregated NC-dots/AuNPs, which lead to the color change from purple
to red and the recovery of PL and UCP of NC-dots. This assay was successfully
applied for the detection of Cys in human serum with the detection
limit of 4 nM