Abstract
A facile one-step hydrothermal synthesis approach was proposed to prepare nitrogen and chlorine co-doped carbon dots (CDs) using l-ornithine hydrochloride as the sole precursor. The configuration and component of CDs were characterized by transmission electron microscopy and X-ray photoelectron and Fourier transform infrared spectroscopies. The obtained CDs (Orn-CDs) with a mean diameter of 2.1 nm were well monodispersed in aqueous solutions. The as-prepared CDs exhibited a bright blue fluorescence with a high yield of 60%, good photostability and low cytotoxicity. The emission of Orn-CDs could be selectively and effectively suppressed by Fe3+. Thus, a quantitative assay of Fe3+ was realized by this nanoprobe with a detection limit of 95.6 nmol l−1 in the range of 0.3–50 µmol l−1. Furthermore, ascorbic acid could recover the fluorescence of Orn-CDs suppressed by Fe3+, owing to the transformation of Fe3+ to Fe2+ by ascorbic acid. The limit of detection for ascorbic acid was 137 nmol l−1 in the range of 0.5–10 µmol l−1. In addition, the established method was successfully applied for Fe3+ and ascorbic acid sensing in human serum and urine specimens and for imaging of Fe3+ in living cells. Orn-CD-based sensing platform showed its potential to be used for biomedicine-related study because it is cost-effective, easily scalable and can be used without additional functionalization and sample pre-treatment.
Highlights
In recent years, carbon dots (CDs) have drawn tremendous attention because of their high photostability, low toxicity and& 2019 The Authors
The shape and structure of the Orn-CDs were characterized by transmission electron microscopy (TEM) and are displayed in figure 1
Based on the statistical analysis of 100 particles from the TEM results, the obtained Orn-CDs showed a mean diameter of 2.9 + 0.6 nm in the range from 1.3 to 4.0 nm
Summary
Carbon dots (CDs) have drawn tremendous attention because of their high photostability, low toxicity and. Hydrothermal method is one of the most often used techniques because it is a single-step process, easy to manipulate, cost-effective and has controlled reaction conditions Another significant factor is the selection of appropriate precursor to prepare fluorescent CDs. It is well known that nitrogen-containing organic compounds are often used in the fabrication of CDs to improve their fluorescent properties. Many reports described probes for selective detection of Fe3þ by fluorescence methods due to their high sensitivity, user-friendliness and on-site testing, such as organic dyes [22,23], semiconductor quantum dots [24], and metal nanoclusters [25]. Based on a selective fluorescence off – on mechanism, a novel nanoprobe platform was developed for sensitive detection of Fe3þ (off ) and ascorbic acid (on) with detection limits of 95.6 nmol l21 and 137 nmol l21, respectively. This chemosensor was used for the determination of Fe3þ and ascorbic acid in real serum and urine samples
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