Carbon dots (CDs) possess unique optical properties such as tunable photoluminescence (PL) and excitation dependent multicolor emission. The quenching and recovery of the fluorescence of CDs can be utilized for detecting analytes. The PL mechanisms of CDs have been discussed in previous articles, but the quenching mechanisms of CDs have not been summarized so far. Quenching mechanisms include static quenching, dynamic quenching, Forster resonance energy transfer (FRET), photoinduced electron transfer (PET), surface energy transfer (SET), Dexter energy transfer (DET) and inner filter effect (IFE). Following an introduction, the review (with 88 refs.) first summarizes the various kinds of quenching mechanisms of CDs (including static quenching, dynamic quenching, FRET, PET and IFE), the principles of these quenching mechanisms, and the methods of distinguishing these quenching mechanisms. This is followed by an overview on applications of the various quenching mechanisms in detection and imaging.

The quenching of the fluorescence of carbon dots: A review on mechanisms and applications

Nature provides an almost limitless supply of sources that inspire scientists to develop new materials with novel applications and less of an environmental impact. Recently, much attention has been focused on preparing natural-product-derived carbon dots (NCDs), because natural products have several advantages. First, natural products are renewable and have good biocompatibility. Second, natural products contain heteroatoms, which facilitate the fabrication of heteroatom-doped NCDs without the addition of an external heteroatom source. Finally, some natural products can be used to prepare NCDs in ways that are very green and simple relative to traditional methods for the preparation of carbon dots from man-made carbon sources. NCDs have shown tremendous potential in many fields, including biosensing, bioimaging, optoelectronics, and photocatalysis. This Review addresses recent progress in the synthesis, properties, and applications of NCDs. The challenges and future direction of research on NCD-based materials in this booming field are also discussed.

Natural‐Product‐Derived Carbon Dots: From Natural Products to Functional Materials

Over the span of the past decade, carbon dots (CDs) synthesized from renewable organic resources (organic CDs) have gathered a considerable amount of attention for their photoluminescent properties. This review will focus on organic CDs synthesized using clean chemistry and conventional synthetic chemistry from organic sources and their fluorescence mechanisms, such as quantum confinement effect and surface/edge defects, before outlining their performance in electronic applications, including organic photovoltaic devices, organic light-emitting devices, biosensors, supercapacitors, and batteries. The various organic resources and methods of organic CDs synthesis are briefly covered. Many challenges remain before the adoption of CDs can become widespread; their characterization, structure, functionality, and exact photoluminescent mechanism all require additional research. This review aims to summarize the current research outcomes and highlight the area where further research is needed to fully use these materials.

Future Perspectives and Review on Organic Carbon Dots in Electronic Applications.

N,S co-doped carbon dots based fluorescent “on-off-on” sensor for determination of ascorbic acid in common fruits

Recent progress on the development of glutathione (GSH) selective fluorescent and colorimetric probes

Formation of N, S-codoped fluorescent carbon dots from biomass and their application for the selective detection of mercury and iron ion.

Construction of carbon nanodots/tungsten trioxide and their visible-light sensitive photocatalytic activity.

Carbon nanodots prepared for dopamine and Al(3+) sensing, cellular imaging and logic gate operation.

A simple one-step hydrothermal method was designed to synthesize fluorescent carbon nanodots (CNDs). The resulting CNDs exhibited excellent properties such as good solubility, superior photo-stability and low toxicity. Significantly, the CNDs were found to be an effective fluorescence sensing platform for turn-on detection of glutathione (GSH). The initial fluorescence of CNDs was quenched through an electron transfer process in the presence of dopamine, while the quenched fluorescence was enhanced with the further addition of GSH. Moreover, it showed a good linear relationship between GSH concentration and the relative fluorescence intensity of the system. Significantly, this sensing platform successfully detected GSH in biological fluids, indicating its potential applications in the field of biology.

Yinyin Wang

Papers

Formation of N, S-codoped fluorescent carbon dots from biomass and their application for the selective detection of mercury and iron ion.

Construction of carbon nanodots/tungsten trioxide and their visible-light sensitive photocatalytic activity.

Carbon nanodots prepared for dopamine and Al(3+) sensing, cellular imaging and logic gate operation.

Carbon nanodots prepared for cellular imaging and turn-on detection of glutathione