Ratiometric Multimode Detection of pH and Fe³⁺ by Dual-Emissive Heteroatom-Doped Carbon Dots for Living Cell Applications

Abstract

Dual-emissive carbon dots (D-CDs) are in high demand for multipurpose applications. Herein, nitrogen-doped carbon dots possessing inherent dual emissions at green (490 nm) and yellow (570 nm) are synthesized hydrothermally from 3,4-diaminobenzoic acid and hydrazine hydrate. The relative intensity of the two emission bands is dependent markedly on the pH of medium, making the D-CDs a robust pH sensor within the pH range of 2.0−7.6. The ratiometric emission of D-CDs is sensitive to trace amounts of Fe 3+ ; the 490 nm emission intensity diminishes with simultaneous amplification of the 570 nm emission intensity. A discernible color change from light green to bright yellow is evident under an ultraviolet (UV) lamp with increasing Fe 3+ concentrations, and the CIE color coordinate shifts from (0.33, 0.43) to (0.47, 0.50). Primarily, the complexation between D-CDs and Fe 3+ and the accompanying aggregation play a dominant role in the ratiometric change of the emission intensities. For the on-spot detection of Fe 3+ , smartphone-based and solid-phase sensing is accomplished. The D-CDs also display decent anticancer properties against the breast cancer cell line MCF-7 and effectively detect the intracellular pH and exogenous Fe 3+ inside the MCF-7 cells. KEYWORDS: N-doped carbon dots, ratiometric detection of pH and Fe 3+ , pH and Fe 3+ sensing inside cells, solid-phase and smartphone-based Fe 3+ detection

MOF-Fabric Composites Based on a Multi-Functional MOF as Luminescent Sensors for a Neurotransmitter and an Anti-Cancer Drug

“…There are several phenomena [e.g., Förster resonance energy transfer (FRET), inner-filter effect (IFE), and ground-state complexation] reported in the literature that can cause quenching of the fluorescence intensity of a fluorophore . The above-mentioned events can be categorized into two parts: static and dynamic quenching. , Excited-state collisions between the quencher and the fluorophore can cause dynamic quenching, and if they are tightly bound, then static quenching occurs . These two quenching processes can be differentiated by measuring the fluorescence lifetimes of the fresh and analyte-treated fluorophores.…”

“…The huge difference between the observed and the corrected quenching efficiencies strongly suggested that the IFE contribution is required to explain the observed quenching efficiency in the presence of 6-MP. Although the IFE was once thought to be a flaw in fluorescence measurement, it has now been discovered to be a non-irradiative energy transformation model in the spectroscopic technique and has been utilized in the creation of numerous photoluminescent-based detection systems. ,− Moreover, this sensing mechanism has been reported in many of the previously reported literature studies for 6-MP and other analytes’ sensing. ,− …”

Rose Bengal‐Derived Carbon Quantum Dots as a Fluorescence Probe for the Highly Sensitive Detection of Fe3+ Ions

“…We have cited additional references within the Supporting Information [51–88] . The Supporting Information includes: 1.…”

Development of graphitic-N-based carbon dots using solid-state synthesis for fingerprinting, LEDs, and anticounterfeiting

“…[1][2][3] Since their discoveries, CDs have widened their application in LEDs, fingerprinting, room-temperature phosphorescence, solar cells, sensing, etc. [4][5][6][7] On the one hand, to date, most of the reported CDs showed fluorescence only in dispersed states, which restricts their applicability. 8,9 The dispersed CDs generate aggregationcaused quenching when it turns into solid powder due to p-p stacking interactions, Fo ¨rster resonance energy transfer, and intermolecular hydrogen bonding.…”