We conducted a related study on the determination of Hg 2+ in water by surface-enhanced Raman scattering (SERS). It is based on acriflavine as a signal probe with the assistance of aggregation agent MgSO 4 for the SERS investigation. Moreover, the density functional theory (DFT) calculations of acriflavine were performed for interpreting the assignments of the vibrational normal modes. The interaction of acriflavine with AgNPs was inhibited because the citrate reduced Hg 2+ to Hg and formed Ag amalgam on the AgNPs surface. The formation of Ag-Hg alloys reduced the SERS intensity of acriflavine. This sensing system displayed excellent sensitivity and a detection limit as low as 1.4 mol L − 1 . The relationship between the SERS intensity and Hg 2+ concentration was found in the range of 0.1–8.0 × 10 −7 mol L − 1 . This method for detecting Hg 2+ is inexpensive, facile and sensitive.
Fang Fang,Cao Hongyu,Lu Jialu,Chen Nannan,Zhang Lu,Chen Yang
Carbon dots (CDs)-based ratiometric fluorescence strategies have attracted considerable attention. In this study, we developed a facile ratiometric fluorescent biosensor for DNA detection by utilizing the blue-emitting carbon dots (BCDs) as the fluorophore and acriflavine (AF), a fluorescent biological stain reagent, as both the response and recognition molecules. When AF was added, the fluorescence of BCDs decreased effectively and accompanied by a hypsochromic shift from 448 to 425 nm, whereas the fluorescence of AF at about 500 nm appeared due to the synergistic effect of Förster resonance energy transfer (FRET) and the inner filter effect (IFE) between the BCDs and AF. In the presence of DNA, the intercalative binding of AF into the DNA helix resulted in the fluorescence quenching of AF and the fluorescence restoration of BCDs at the same time. Therefore, the quantitative detection of DNA can be carried out vis evaluating the fluorescence intensity ratio of F 425 /F 500 . Under optimized conditions, the developed fluorescence method had an excellent linear range from 0 to 90 µM and a low detection limit of 0.52 µM. In addition, satisfactory results were obtained for the analysis of DNA in synthetic and real samples, with spiked recoveries ranging from 90.1 to 101.3%, demonstrating the enormous potential of the developed sensing platform for bioanalysis and biodetection. Graphical
Adenine detection is important in biomedicine. Here, we report acriflavine-based carbon dots prepared via a one-step synthesis that can detect adenine in aqueous solution via fluorescence. Titration experiments show that the fluorescence intensity of carbon dots increases by up to 35% as the concentration of adenine increases. High-resolution transmission electron microscopy images show that carbon dots have a recognizable lattice structure. Based on this, we built a theoretical model using the DFT method to explain the mechanism by which adenine enhances fluorescence on the carbon dots.
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