Electron/energy co-transfer behavior and reducibility of Cu-chlorophyllin-bonded carbon-dots

Biocompatible Carbon Dot Decorated α-FeOOH Nanohybrid for an Effective Fluorometric Sensing of Cr (VI) in Wastewater and Living Cells

This article reports the fluorometric detection of toxic hexavalent chromium Cr (VI)) in wastewater and Cr (VI) contaminated living cells using in-situ grown carbon quantum dots into the goethite (α-FeOOH) nano-matrix. The synthesized nano-hybrid shows enormous potential in determining the chromium contamination levels in various types of water samples. This selective fluorometric probe is enormously sensitive (LOD 81 nM) toward hexavalent chromium, which makes it a dedicated chromium sensor. Moreover, the sensing mechanism has been assessed using Stern-Volmer's equation and fluorescence lifetime experiments showing the simultaneous occurrence of photoinduced electron transfer and the inner filter effect. This chromium sensor has also been employed to assess the contamination level in real-life industrial wastewater. The performance of this probe in a real-life wastewater sample is quite commendable. Further, this biocompatible fluorometric probe has been used to demonstrate the in-vitro sensing of Cr (VI) in HeLa cells. The rapid detection mechanism of hexavalent chromium in living cells has been validated using theoretical docking simulations. Henceforth, this fluorometric sensor material could open new avenues not only in wastewater monitoring but also in biomedical applications.

Carbon dots with polarity-tunable characteristics for the selective detection of sodium copper chlorophyllin and copper ions

Compared to water-soluble carbon dots (CDs) the properties and applications of hydrophobic CDs are rarely addressed. In this study, a one-pot, simple chemical oxidation approach has been applied to synthesize hydrophobic carbon dots (TO-CDs) at room temperature from triolein (TO) in concentrated sulfuric acid solution. Sodium copper chlorophyllin (SCC) quenches the fluorescence of TO-CDs by a photoinduced electron transfer process. Upon excitation at 400 nm, the fluorescence intensity of TO-CDs probe at 500 nm shows a linear response against the SCC concentration ranging from 1.0 to 10 μM, with a limit of detection (LOD) of 0.61 μM. Quantitation of SCC in flavored drinks shows percentage recovery (%R) vaues of 98-103% and relative standard deviation (RSD) values less than 6.5%. The hydrophobic TO-CDs can be converted into hydrophilic TO-CDs through hydrolysis in NaOH solution. The presence of sulfonyl groups on the hydrophilic TO-CDs enhances the coordination ability of the CDs toward Cu²⁺ ions, leading to fluorescence quenching which allows for the detection of Cu²⁺ ions with LOD of 0.21 μM and a linear range of 0.5-10 μM. The hydrophilic TO-CD probe possesses high selectivity toward Cu²⁺ ions (tolerance at least ten-fold comparative to other metal ions). The assay has been validated with the analysis of spiked soil samples, with %R values of Cu concentration of 97.8-99.0% and RSDs below 2.0%. The surface tunable CD probes demonstrate their potential for the rapid screening of Cu²⁺ ions in environmental samples and SCC in foods.