Nitrogen-Doped Carbon Nanoparticles Derived from Silkworm Excrement as On–Off–On Fluorescent Sensors to Detect Fe(III) and Biothiols

Abstract

On–off–on fluorescent sensors based on emerging carbon nanoparticles (CNPs) or carbon dots (CDs) have attracted extensive attention for their convenience and efficiency. In this study, dumped silkworm excrement was used as a novel precursor to prepare fluorescent nitrogen-doped CNPs (N-CNPs) through hydrothermal treatment. The obtained N-CNPs showed good photoluminescent properties and excellent water dispersibility. Thus, they were applied as fluorescence “on–off–on” probes for the detection of Fe(III) and biothiols. The “on–off” process was achieved by adding Fe(III) into N-CNP solution, which resulted in the selective fluorescence quenching, with the detection limit of 0.20 μM in the linear range of 1–500 μM. Following this, the introduction of biothiols could recover the fluorescence efficiently, in order to realize the “off–on” process. By using glutathione (GSH) as the representative, the linear range was in the range of 1–1000 μM, and the limit of detection was 0.13 μM. Moreover, this useful strategy was successfully applied for the determination of amounts of GSH in fetal calf serum samples.

Highly Fluorescent Green Carbon Dots as a Fluorescent Probe for Detecting Mineral Water pH

“…At the same time, the response of CDs to common metal ions (Ba 2+ , Ca 2+ , Cr 2+ , Cu 2+ , Fe 2+ , Fe 3+ , K + , Na + , Mg 2+ , Mn 2+ , Pb 2+ ) has also been investigated. It can be concluded from Figure 3d that the fluorescence intensity of the CDs does not substantially change in the aqueous solutions of metal ions of 0.5 mM concentration, except for a slight response to iron ions, which can be attributed to the interactions between iron ions and amino or carboxyl groups on the surface of CDs [25,33]. So we can rule out the interference of typical ions in the practical applications of CDs such as cell imaging and water detection.…”

Fluorescence sensing by carbon nanoparticles

“…Cao and co-workers used silkworm droppings as the starting material to obtain fluorescent nitrogen-doped CNPs (N-CNPs) via hydrothermal treatment. 70 These N-CNPs exhibited good optical properties, showing bright blue emission under ultraviolet excitation and good water solubility, and were used for the detection of Fe 3+ via the “on–off–on” mechanism. This mechanism is due to the presence of Fe 3+ ions, which led to the quenching of the nanoparticle emission, with a detection limit of 0.20 μM in the linear range of 1–500 μM.…”

Cross-Linked Polyamide Chains Enhanced the Fluorescence of Polymer Carbon Dots

“…Carbon dots (CDs) are a special kind of fluorescent nanoparticles with a diameter less than 10 nm. , CDs have attracted great attention in recent years for their unique properties, such as high aqueous solubility, good biocompatibility, and resistance to photobleaching, − and have been intensively studied in the fields of sensors, − light-emitting devices, electrochemical analysis, bioimaging, − drug delivery, and photocatalysis. , Great effort has been devoted to synthesizing CDs with photostability and photoluminescence (PL). ,, However, a comprehension of the general fluorescence phenomenon still remains unclear, which hinders advances in the design, preparation, and application of CDs. − …”