Chunxing Li

Bio: Chunxing Li is an academic researcher from Guangxi University. The author has contributed to research in topics: Luminescence & Nanoprobe. The author has co-authored 2 publications. Previous affiliations of Chunxing Li include Gulf University.

Study on luminescence mechanism of nitrogen-doped carbon quantum dots with different fluorescence properties and application in Fe 3+ detection

Abstract: Carbon quantum dots surface doped with nitrogen (N-CQDs) were synthesized with quantum yield (24.9–66.4%) via an easy hydrothermal route while using citric acid as a precursor for carbon and varying concentrations of DL-Alaninol as the dopant. The as-prepared N-CQDs with adjustable fluorescence emission transformed from weak excitation-dependent to excitation-dependent and then to excitation-independent. After a detailed characterization and investigation, the N-CQDs were found to have a uniform particle size (1.76–3.07 nm) and good monodispersion. They were bearing similar functional groups on their surfaces but with different contents. The N/C ratio of N-CQDs increased gradually with the increasing contents of dopant, while the O/C ratio gradually decreased. The photoluminescence (PL) of (N-CQDs) has been explained by a proposed PL mechanism that involved quantum size effect and the energy levels by the surface state. When further investigated as a fluorescent probe for Fe3+ ion detection, the synthesized N-CQDs were found to be selectively and sensitively detecting Fe3+ ions. The N-CQD-based fluorescent probe was capable of detecting in a wider linear detection range and lower limits of detection (LODs).

Manganese and dysprosium codoped carbon quantum dots as a potential fluorescent/T1/T2/CT quadri-modal imaging nanoprobe

Abstract: It has been challenging to integrate various medical imaging modalities into an ultra-small nanoparticle with good biocompatibility to build highly efficient multimodal imaging nanoprobes. A new manganese and dysprosium codoped carbon quantum dots (Mn,Dy-CQDs) with a mean diameter of 1.77 nm was synthesized for fluorescence imaging,T1/T2-weighted magnetic resonance imaging (T1/T2-weighted MRI), and x-ray computed tomography (CT) imaging using a simple one-step hydrothermal approach. The obtained Mn,Dy-CQDs showed good water solubility, long-term stability, strong stable fluorescence property (fluorescence quantum yield of 31.62%), and excellent biocompatibility. The cell imaging verified that the Mn,Dy-CQDs have high efficiency of fluorescence imaging. The Mn,Dy-CQDs, on the other hand, had a superior x-ray absorption performance (47.344 HU l g-1), a higher longitudinal relaxivity (r1 = 7.47 mM-1s-1), a higher transverse relaxivity (r2 = 42.686 mM-1s-1).In vitroT1/T2-weighted MRI and CT imaging showed that Mn,Dy-CQDs can produce a strong contrast enhancement impact. To summarise, the Mn,Dy-CQDs may be used as aT1/T2-weighted MRI/CT/fluorescent quadri-modal imaging nanoprobe, indicating that they have a lot of uses in biomedical multimode imaging and clinics.

Yellow fluorescent carbon dots sensitive detection of Hg2+ and its detection mechanism

Abstract: In this paper, yellow fluorescent carbon dots (Y-CDs) were successfully synthesized by carbonization of o-phenylenediamine and p-aminobenzoic acid with hydrogen peroxide. The as-prepared Y-CDs possess excellent photoluminescence, high photostability, good water solubility and are rich in various functional groups on the surface by the analysis of transmission electron microscope, Fourier transform infrared spectrum, X-ray photoelectron spectroscopy, fluorescence spectrophotometer and ultraviolet-visible absorption spectrum. With these superior properties, Y-CDs have been used as sensing probes for the detection of Hg2+ ions and show a high selectivity for Hg2+. There is a good linear relationship between the fluorescence intensity of Y-CDs and the concentration of Hg2+ between 20 μM and 150 μM, and the minimum detection limit reach to 0.12 μM. Furthermore, the detection method was applied to the recovery test of Hg2+ in real water samples and the ideal recovery rate was obtained. Based on above researches, the fluorescent test paper which is convenient to carry is prepared. In order to explore the mechanism of fluorescence quenching, Y-CDs was combined with zeolite imidazole skeleton-8 to synthesize [email protected] composites. After adding Hg2+, the fluorescence of [email protected] was no longer quenched. By analyzing the fluorescence lifetime, UV–vis absorption spectra and Fourier transform infrared spectra of Y-CDs before and after adding Hg2+, the mechanism of fluorescence quenching was finally determined to be static quenching.