Dual-Emissive Carbon Dots: Exploring Their Fluorescence Properties for Sensitive Turn-Off–On Recognition of Ferric and Pyrophosphate Ions and Its Application in Fluorometric Detection of the Loop-Mediated Isothermal Amplification Reaction

Abstract

In this study, dual-emissive carbon dots (CDs) were prepared using p-phenylenediamine (pPDA) and phytic acid (PA) precursors via a one-pot-hydrothermal method. The photophysical, morphological, and structural characterization of CDs was carried out using absorption, fluorescence, Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR), and high-resolution transmission electron microscopy (HR-TEM) analysis. The as-prepared CDs displayed dual-fluorescence peaks at 525 and 620 nm upon excitation at 450 nm. The CDs showed good photostability and exhibited solvent-dependent fluorescence properties. The solvatochromic behavior of CDs was utilized to detect water content in organic solvents. Furthermore, the dual-emissive property of CDs was utilized for the sequential detection of ferric (Fe 3+ ) and pyrophosphate ions (PPi) by a fluorescence turn-off−on mechanism. The proposed assay showed appreciable fluorescence response toward Fe 3+ and PPi with high selectivity and good tolerance for common interfering ions. The potential practical application of the CD probe was ascertained by carrying out the fluorometric detection of PPi to affirm the loop-mediated isothermal amplification (LAMP) reaction specific for Mycobacterium tuberculosis (negative and positive clinical samples).

Orange-Red-Emitting Carbon Dots for Bilirubin Detection and Its Antibacterial Activity Against Escherichia coli and Staphylococcus aureus

“…Further, a discernible signal at 3.63 ppm is attributed to the hydrogen vibrations of −NH or −CH 2 moieties. Additionally, the chemical shift observed at 2.51 ppm corresponds to the ArCH 2 (phenyl rings) protons Figure b, unveil a distinct signal within the range of 39.27–40.52 ppm, attributed to sp 3 carbon atoms.…”

Ultrasound-Assisted Hydrothermal Synthesis of Highly Fluorescent Sulfur Quantum Dots for Fe3+ Ion and Ascorbic Acid Detection in Real Samples

“…To assess the specificity of the SQDs/Fe 3+ system toward AA, a range of relevant compounds including cysteine (Cys), D-fructose (Fru), glycine (Gly), malic acid (MA), tartaric acid (TA), glutathione (GSH), citric acid (CA), glucose (Glu), methionine (Met), threonine (Thr), and homocysteine (Hcy), as well as S 2– , were tested using identical procedures. The limit of detection (LOD) was calculated by using the standard equation: LOD = 3σ/K, where σ represents the standard deviation of the blank sample, and K corresponds to the slope of the intensity-concentration linear equation …”