Chemiluminescence of doped carbon dots with H2O2-KMnO4 system for the detection of Cu2+ and tannin

Enhanced chemiluminescence by carbon dots for rapid detection of bisphenol A and nitrite

Herein, a novel chemiluminescence (CL) sensor was successfully developed based on chlorine doped carbon dots (Cl/CDs) for the rapid determination of bisphenol A (BPA) and nitrite. The Cl/CDs were synthesized through a hydrothermal method, using ascorbic acid as the precursor and hydrochloric acid as the dopant. It was found that Cl/CDs significantly enhanced the CL intensity of the acid-KMnO4 system, while BPA and nitrite quenched the CL intensity of the Cl/CDs-sensitized acid-KMnO4 system. Under optimal conditions, BPA exhibited a linear detection range of 0.05-10 μM, with limits of detection (LOD) and quantification (LOQ) of 0.86 nM and 2.8 nM, respectively. Nitrite showed a linear detection range of 0.7-100 μM, with LOD and LOQ of 22.5 nM and 75 nM, respectively. The CL sensor was successfully use to determine BPA in water samples and nitrite in pickles, ham and celery, with spike recovery rates of 96.3 %-104.8 % and 96.0 %-104.9 %, respectively.

Mn, N co-doped CDs as a fluorescent nanosensing platform for the detection of tannic acid and hafnium ion and in vitro fluorescence imaging of U2OS osteosarcoma cells

Multi-wavelength emission fluorescent manganese-nitrogen co-doped carbon dots (Mn, N co-doped CDs) were synthesized by solvothermal method using β-cyclodextrin, O-phenylenediamine, and manganese chloride as raw materials. The prepared Mn, N co-doped CDs were used as fluorescent nanosensing platforms for the detection of metal ions and biomolecules and were found to be capable of fluorescence detection of tannic acid (TA) and hafnium (Hf) ion at 320, 380, and 480 nm excitation wavelengths with multi-response linear ranges of 0.7 ~ 1.2 µM and 6.35 ~ 13 µM and detection limits of 0.45 µM and 6.3 µM, respectively. The wide linear ranges and low detection limits may be due to the fluorescence resonance energy transfer effect between the platform and TA and Hf ions. In addition, it was found that Mn, N co-doped CDs had good photostability, biocompatibility, and low cytotoxicity, which could be used for in vitro fluorescence imaging of exogenous TA and Hf ion imaging in U2OS osteosarcoma cells. Thus, the probe has a promising application in biomedical fields as a new multi-responsive fluorescence nanosensing platform member.

Vanillin-Catalyzed highly sensitive luminol chemiluminescence and its application in food detection

Among various chemiluminescence (CL) systems, luminol-H₂O₂ system is used extensively due to its cheapness and sensitivity. Herein, 4-hydroxy-3-methoxybenzaldehyde, known as vanillin, was firstly found to be able to catalyze H₂O₂ very efficiently to produce ^•OH and O₂^•-, which can be used to enhance the CL of luminol-H₂O₂ as Co⁺. In alkaline aqueous solution, vanillin catalyzed the dissociation of H₂O₂ into active ^•OH and O₂^•- radicals and accelerated luminol-H₂O₂ reaction to emit strong CL signal. Combining the stabilizing function of β-CD, CL intensity of luminol-H₂O₂ was enhanced further. Thus, dual-signal amplification of luminol-H₂O₂ chemiluminescence based on the catalyzing function of vanillin and the stabilizing function of β-CD was proposed and its mechanism was explored deeply in the manuscript. Interestingly, vanillin is a highly prized flavor compound broadly used as food additive, however, the excessive intake of vanillin is harmful to human and thus the determination of vanillin is very important. On the basis of the luminol-β-CD-H₂O₂/vanillin reaction, a low-cost, rapid and simple CL sensor has been established to detect vanillin. The sensor was able to detect vanillin in the range of 1.0 μM ∼ 75 μM with a detection limit of 0.89 μM (S/N = 3). It can also be used for CL imaging detection with satisfactory results.