Development of a Detection Kit Based on G-Quadruplex DNAzyme for Detection of Lead(II) Ion in Food Samples
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Development of a Detection Kit Based on G-Quadruplex DNAzyme for Detection of Lead(II) Ion in Food Samples Tao Liu & Gang Nie & Xiao Zhang & Wei Liu & Wentao Zhang & Yashan Wang & Daohong Zhang & Jianlong Wang
Received: 22 June 2014 / Accepted: 2 September 2014 # Springer Science+Business Media New York 2014
Abstract The biocatalytic function of G-quadruplex DNAzyme has been first used to design a detection kit for colorimetric detection of Pb2+ in food samples by coupling guaiacol (GA) as an effective and ideal colorimetric signal indicator. Addition of Pb2+ enabled the G-rich DNA to bind hemin to fabricate the Pb2+-promoted DNAzyme, which can catalyze the H2O2-mediated oxidation of colorless GA to produce amber tetraguaiacol, causing a visible color change. Both standard curve and colorimetric card were constructed in the present detection kit for the quantitative analysis of Pb2+. Under optimum conditions, the working range of the kit was 10–100 nM with a detection limit of 1 nM Pb2+. And the performance of the colorimetric card method of the kit could discriminate Pb2+ from 5 to 80 nM. The shelf-life of the kit was 6 months at 4 °C, and the effectiveness and reliability of the kit on the determination of Pb2+ were evaluated in real food samples. Therefore, the good performance characteristics of the DNAzyme-based detection kit indicate that it holds a promising application for sensitive and low-cost detection of Pb2+ ions in foods. Keywords Lead(II) ion . Kit . Colorimetric method . DNAzyme . Guaiacol
Introduction Detection of lead(II) ions (Pb2+) in food samples remains an active area of research because Pb2+ has severe adverse effects Both Tao Liu and Gang Nie rank as the first authors. T. Liu : G. Nie : X. Zhang : W. Liu : W. Zhang : Y. Wang : D. Zhang (*) : J. Wang (*) College of Food Science and Engineering, Northwest A&F University, 712100 Yangling, Shaanxi, China e-mail: [email protected] e-mail: [email protected]
on human health and the environment. For examples, even exposure to very low levels of Pb2+ ions can damage the nervous system and brain function, and cause neurological, cardiovascular, and developmental disorders (Winder et al. 1982). Besides, studies have shown that food may be a potential source of heavy metals such as Pb2+ (Hague et al. 2008; Szymczycha-Madeja and Welna 2013). Therefore, the safe limit of Pb2+ in fruit juice that was recommended by the World Health Organization (WHO) is 0.01 mg/L (Ofori et al. 2013), and the maximum level of Pb2+ has also been strictly defined by Commission Regulation (EC) No. 1881/2006 (EC, 2006) amended by EC 629/2008 (EC, 2008) (Millour et al. 2011) or other organizations (Ataro et al. 2008). To avoid the risk of Pb2+ consumption, it is of prime importance to determine the concentration of Pb2+ in food samples. At present, majority of the detection and quantification methods of Pb2+ are instrumental analysis including atomic absorption spectrometry (AAS) (Bagheri et al. 2012), inductively coupled plasma mass spectrometry (ICP-MS) (Ataro et al.
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