Ebrahimi Maryam, Raoof Jahan Bakhsh, Ojani Reza
Eletroanalytical Chemistry Research Laboratory, Department of Analytical Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar, Mazandaran, 47416-1467, Iran.
Anal Bioanal Chem. 2017 Aug;409(20):4729-4739. doi: 10.1007/s00216-017-0416-5. Epub 2017 Jun 7.
An electrochemical DNA biosensor based on a G-quadruplex (G4) for the sensitive determination of Pb was reported using a carbon paste electrode (CPE) or a multi-walled carbon nanotube paste electrode (MWCNTPE) as working electrodes, ethyl green (EG) as a new G4 intercalator, and a single-stranded nucleic acid sequence rich in guanine (G) as DNA probe. Electrochemical determination of Pb relied on probe structural changes from single - stranded to the stabilized intramolecular G4 in the presence of Pb, which caused a change in the current of the EG reduction peak due to the intercalation of EG into the G4 structure. The change in the reduction peak of EG before and after its intercalation into the stabilized G4 (∆I) had a linear correlation to the concentration of Pb ions. The linear ranges of 4.0 × 10-5.0 × 10 M and 2 × 10-1 × 1 M with a detection limit (LOD) of 1.04 × 10 M were obtained using CPE, while improved linear ranges of 4.0 × 10-1.0 × 10 M and 2 × 10-1 × 10 M with a lower LOD of 2.64 × 10 M were achieved using the MWCNTPE biosensor. The biosensors exhibited satisfactory results in terms of selectivity and practical applicability in the analysis of real samples. Graphical abstract The principle of the electrochemical sensing of Pb based on intramolecular G-quadruplex using EG.
报道了一种基于G-四链体（G4）的电化学DNA生物传感器，用于灵敏测定铅。该生物传感器以碳糊电极（CPE）或多壁碳纳米管糊电极（MWCNTPE）作为工作电极，以乙基绿（EG）作为新型G4嵌入剂，以富含鸟嘌呤（G）的单链核酸序列作为DNA探针。铅的电化学测定依赖于在铅存在下探针结构从单链转变为稳定的分子内G4，这由于EG嵌入G4结构而导致EG还原峰电流发生变化。EG嵌入稳定的G4前后还原峰的变化（∆I）与铅离子浓度呈线性相关。使用CPE时，线性范围为4.0×10⁻⁵.0×10⁻⁵M，检测限（LOD）为1.04×10⁻⁶M；而使用MWCNTPE生物传感器时，线性范围得到改善，为4.0×10⁻⁷.0×10⁻⁷M，检测限更低，为2.64×10⁻⁸M。该生物传感器在实际样品分析中的选择性和实际适用性方面表现出令人满意的结果。图形摘要：基于使用EG的分子内G-四链体的铅电化学传感原理。
