Yizhong Shen,Shaopu Liu,Jidong Yang,Linlin Wang,Xuanping Tan,Youqiu He
A novel and sensitive turn-on fluorescent biosensor for herring sperm DNA (hsDNA) detecting was designed based on hsDNA-induced fluorescence enhancement of Sm 3+ -modulated glutathione (GSH)-capped CdTe quantum dots (QDs). The fluorescent biosensor was based on the following two properties. First, the high fluorescence of GSH-capped CdTe QDs could be effectively quenched by Sm 3+ due to the binding of Sm 3+ to the GSH on the surface of the QDs and the electron transfer from the photoexcited GSH-capped CdTe QDs to Sm 3+ . Second, the high affinity of hsDNA to Sm 3+ enabled Sm 3+ to be dissociated from the surface of GSH-capped CdTe QDs to form more stable complex with hsDNA in aqueous solution, thereby enhancing the fluorescence of Sm 3+ -modulated GSH-capped CdTe QDs. Experimental results showed that the enhanced fluorescence intensity of Sm 3+ -modulated GSH-capped CdTe QDs was directly proportional to the concentration of hsDNA in the range from 0.012 to 14.0 μg mL −1 with a good correlation coefficient of 0.9977, and the detection limit (3 σ / S ) was 3.61 ng mL −1 . To further investigate perfect analysis performance, the developed biosensor was applied to the determination of hsDNA in synthetic samples and human fresh serum samples with satisfactory results.
Li Sun,Xueliang Wang,Na Zou,Hongying Li,Zhangyu Yu
The interaction of formononetin (FN) with herring sperm DNA has been studied by electrochemical methods, UV-Vis spectroscopy and fluorescence. On a poly L-cysteine film modified electrode (PLC/GCE), FN showed a couple of well-defined voltammetric peaks in 0.1 M acetate buffer of pH 5.3. As adding the herring sperm DNA into above solution, the peak current of FN decreased and no new peaks appeared. Based on the electrochemical results, the binding constant and binding ratio between FN and herring sperm DNA were determined to be 1.98×10 4 M -3 and 1:3, respectively. The UV-Vis spectroscopy indicated that the maximum absorption of FN had obviously hyperchromic effect and red shift after the interaction of DNA and FN. The interaction of DNA and FN can also make the fluorescence intensity of FN enhancement. The electrochemical and spectroscopic results indicated that the interaction of FN to DNA was an intercalative mode.
Xin Zhao,Hao Guo,Rui Xue,Mingyue Wang,Qixia Guan,Tian Fan,Wenhu Yang,Wu Yang
Alteration in the concentrations of guanine (G) and adenine (A) leads to various abnormalities in the metabolic process which causes various diseases. Therefore, it still remains a challenge to establish an accurate, simple and accurate method for simultaneous detection of guanine and adenine. In this paper, using covalent organic frameworks (COFs) as a carrier and the amino functionalized reduced graphene oxide as charge transfer accelerator, layer molybdenum disulfide (MoS 2 ) nanosheets are deposited on glassy carbon electrode (GCE) by simple physical stacking to fabricate a dual-signal amplification biosensor for simultaneous detection of adenine and guanine. Under optimized conditions, the electrochemical behaviors of guanine and adenine on the COFS/NH 2 -rG/MoS 2 modified electrode were studied by cyclic voltammetry and differential pulse voltammetry. The sensor performs well in determining G and A at the same time with wide linear ranges of 0.5–150.0 μM and 1.0–280 μM and low detection limits of 0.51 μM(S/N = 3) and 0.44 μM(S/N = 3), respectively. The sensor was successfully used to assay G and A in thermally denatured herring sperm DNA, and the G/A ratio was calculated to be 0.79. The biosensor has the advantages of simplicity, speed, high sensitivity, good reproducibility, and long-term stability.
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