Multifunctional carbon dots for glutathione detection and Golgi imaging.

Glutathione (GSH) is present in almost every cell in the body and plays various integral roles in many biological processes. The Golgi apparatus is a eukaryotic organelle for the biosynthesis, intracellular distribution, and secretion of various macromolecules; however, the mechanism of GSH in the Golgi apparatus has not been fully elucidated. Here, specific and sensitive sulfur-nitrogen co-doped carbon dots (SNCDs) with orange-red fluorescence was synthesized for the detection of GSH in the Golgi apparatus. The SNCDs have a Stokes shift of 147 nm and excellent fluorescence stability, and they exhibited excellent selectivity and high sensitivity to GSH. The linear response of the SNCDs to GSH was in the range of 10-460 µM (LOD = 0.25 µΜ). More importantly, we used SNCDs with excellent optical properties and low cytotoxicity as probes, and successfully realized golgi imaging in HeLa cells and GSH detection at the same time.

Nitrogen-doped carbon dots with high selectivity for hydrosulfide sensing and their living cells imaging.

Hydrosulfuric acid is an aqueous solution of hydrogen sulfide (H2S). At physiological pH, approximately 80% of the total amount of H2S exists in the form of monoanionic HS-. Because HS- is both widely distributed and highly toxic to humans, it is necessary to design an efficient method to detect HS- with high sensitivity and selectivity. So, the nitrogen-doped carbon dots (NCDs) with green fluorescence are synthesized using a one-step hydrothermal method. The as-prepared NCDs show it can be effectively used as an indicator for monitoring HS-. And the NCD fluorescence intensity exhibits a linear relationship with HS- concentration. In addition, NCDs as a probe can be applied for fluorescence imaging in living cells to detect the presence of trace exogenous HS-.

Cd-free InP/ZnSeS quantum dots for ultrahigh-resolution imaging of stimulated emission depletion.

Stimulated emission depletion (STED) nanoscopy is a promising super-resolution imaging technique for microstructure imaging; however, the performance of super-resolution techniques critically depends on the properties of the fluorophores (photostable fluorophores) used. In this study, a suitable probe for improving the resolution of STED nanoscopy was investigated. Quantum dots (QDs) typically exhibit good photobleaching resistance characteristics. In comparison with CdSe@ZnS QDs and CsPbBr3 QDs, Cd-free InP/ZnSeS QDs have a smaller size and exhibit an improved photobleaching resistance. Through imaging using InP/ZnSeS QDs, we achieved an ultrahigh resolution of 26.1 nm. Furthermore, we achieved a 31 nm resolution in cell experiments involving InP/ZnSeS QDs. These results indicate that Cd-free InP/ZnSeS QDs have significant potential for application in fluorescent probes for STED nanoscopy.

Noval Dual-Emission Fluorescence Carbon Dots as a Ratiometric Probe for Cu2+ and ClO- Detection.

The use of carbon dots (CDs) with dual emission based on ratiometric fluorescence has been attracting attention in recent times for more accurate ion detection since they help avoid interference from background noise, probe concentration, and complexity. Herein, novel dual-emission nitrogen-doped CDs (NCDs) were prepared by a simple method for Cu2+ and ClO- detection. The NCDs showed excellent anti-interference ability and selectivity for different emissions. In addition, a good linear relationship was observed between the fluorescence intensity (FI) of the NCD solutions in different emissions with Cu2+ (0-90 µM) and ClO- (0-75 µM). The limits of both Cu2+ detection and ClO- were very low, at 17.7 and 11.6 nM, respectively. The NCDs developed herein also showed a good recovery rate in water for Cu2+ and ClO- detection. Hence, they are expected to have a more extensive application prospect in real samples.

A FRET-based ratiometric fluorescent probe for detection of intrinsically generated SO2 derivatives in mitochondria.

A mitochondria-targeted ratiometric fluorescent probe based on hemicyanine and pyrido[1,2-a]benzimidazole was presented. It shows high sensitivity and selectivity toward SO2 in pure water. The limit of detection (LOD) was as low as 26.7 nM, which is superior to most reported probes. Most importantly, the probe was successfully used for fluorescence imaging of endogenous bisulfite in mitochondria in Glioma cells.

A mitochondria-targeted and FRET-based ratiometric fluorescent probe for detection of SO2 derivatives in water.

A mitochondria-targeted ratiometric fluorescent probe based on the fluorophore pyrido[1,2-a]benzimidazole was developed. It showed high sensitivity and selectivity toward SO2 derivatives in water. The probe was also successfully applied to detect intrinsically generated SO2 derivatives in living glioma cells, which may be helpful in ascertaining the biological roles of SO2 in mitochondria.

A FRET based ratiometric fluorescent probe for detection of sulfite in food.

A new fluorophore pyrido[1,2-a]benzimidazole based ratiometric fluorescent probe for the selective detection of sulfite ions in water was investigated. It shows large (pseudo) Stokes shifts (260 nm), high FRET efficiency, high selectivity and sensitivity. A distinct color change from red to colorless was observed and importantly, it proves to be a convenient and efficient tool to detect the sulfite levels in sugar samples.

A ratiometric fluorescent probe for detection of exogenous mitochondrial SO2 based on a FRET mechanism.

A novel imidazo[1,5-a]pyridine-hemicyanine based ratiometric fluorescent probe for detection of mitochondrial SO2 was designed and synthesized. The probe is based on a fluorescence resonance energy transfer (FRET) mechanism. It exhibits high selectivity and sensitivity towards SO3 2- with a fast response time (3 min) and detection limit of 0.13 µM. Further, it showed low cytotoxicity and was successfully applied to image exogenous mitochondrial SO2 in cells.