On–Off–On Fluorescent Carbon Dot Nanosensor for Recognition of Chromium(VI) and Ascorbic Acid Based on the Inner Filter Effect

Abstract

Chromium(VI) [Cr(VI)] is considered as a severe environmental pollutant, due to its highly toxic and carcinogenic properties. Therefore, low cost, highly sensitive sensors for the determination of Cr(VI) are highly demanded. It is well-known that highly luminescent carbon dots (CDs) have been successfully applied as fluorescent nanosensors for pH, ions, and molecular substances. In the present work, we have demonstrated an on-off fluorescent CD probe for detecting Cr(VI) based on the inner filter effect (IFE) because the absorption bands of Cr(IV) fully covered the emission and excitation bands of CDs. This CD-based nanosensor provides obvious advantages of simplicity, convenience, rapid response, high selectivity, and sensitivity, which have potential application for the detection of Cr(VI) in the environmental industry. In addition, because Cr(VI) can be reduced to low valent chromium species easily by reductant, resulting in the elimination of the IFE and recovery of CD fluorescence, the CD-Cr(VI) mixture could behave as an off-on type fluorescent probe for reductant. We employed ascorbic acid (AA) as an example molecule to demonstrate this off-on type fluorescent probe.

Tailoring color emissions from N-doped graphene quantum dots for bioimaging applications

“…In this report, CA is still chosen as carbon source and DETA as N source for synthesis of N-GQDs. When the reaction is carried out in the water solution, the as-obtained N-GQDs show the blue emission (named as N-GQDs-B) as previous reports 27,28 . Instead of the water with DMF, the N-GQDs exhibit strong green light emission under excitation wavelength of 460 nm (denoted as N-GQDs-G).…”

Characterization and Analytical Separation of Fluorescent Carbon Nanodots

“…When the X-rays interacts with a crystallite C-dots sample, the constructive interference is produced, and these diffracted X-rays are then detected, processed, and counted, revealing the average structure of C-dots [86,87,89,[130][131][132][133][134][135][136]. Figure 3(A) displays a typical XRD pattern of polyethylenimine (PEI) functionalized C-dots (C-dots-PEI) derived from microwave-assisted pyrolysis of glycerol in the presence of branched PEI [86].…”

Autofluorescent Hyperbranched Poly(amide amine) as Effective Fluorescent Probe for Label-free Detection of Copper(II) Ions

“…It has been reported that the decreased fluorescence intensity of fluorophore was attributed to the absorption spectrum of the absorber, which has an overlap with the excitation and/or emission spectrum of the fluorophore, i.e., inner filter effect. 32,34 The amino groups of the HPAMAM were able to interact with Cu 2+ to form cupric amine complexes that acted as an absorber, leading to a selective quenching of the fluorescence intensity of HPAMAM by the inner filter effect.…”

“…As shown in Scheme 1, Cu 2+ ions could bind to the amino groups of the HPAMAM to form cupric amine complexes, resulting in the fluorescence intensity of HPAMAM quenching by the inner filter effect, 31 caused by the absorption of the excitation and/or emission light by absorbers in the detection system. [32][33][34] Based on this, we designed a label-free, rapid, selective and sensitive fluorometric method to detect Cu 2+ ions in aqueous media by using HPAMAM. Furthermore, the practicality of this novel method based on the HPAMAM probe to detect Cu 2+ ions in real water samples also proved successful.…”