Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
Department of General Education, Army Engineering University of PLA, Nanjing, 211101, China.
Mikrochim Acta. 2024 Mar 21;191(4):213. doi: 10.1007/s00604-024-06293-5.
Strontium-90 (Sr) is a major radioactive component that has attracted great attention, but its detection remains challenging since there are no specific energy rays indicative of its presence. Herein, a biosensor that is capable of rapidly detecting Sr ions is demonstrated. Simple colorimetric method for sensitive detection of Sr with the help of single-stranded DNA was developed by preparing MnO nanorods as oxidase mimic catalysis 3,3',5,5'-tetramethylbenzidine (TMB). Under weakly acidic conditions, MnO exhibited a strong oxidase-mimicking activity to oxidize colorless TMB into blue oxidation products (oxTMB) with discernible absorbance signals. Nevertheless, the introduction of a guanine-rich DNA aptamer inhibited MnO-mediated TMB oxidation and reduced oxTMB formation, resulting in blue fading and diminished absorbance. Upon the addition of strontium ions to the system, the aptamers formed a stable G-quadruplex structure with strontium ions, thereby restoring the oxidase-mimicking activity of MnO. Under the best experimental conditions, the absorbance exhibits a linear relationship with the Sr concentration within the range 0.01-200 μM, with a limit of detection of 0.0028 µM. When the concentration of Sr from 10 to 10 mol L, a distinct color change gradient could be observed in paper-based sensor. We successfully applied this approach to determine Sr in natural water samples, obtaining recoveries ranging from 97.6 to 103% with a relative standard deviation of less than 5%. By providing technical solutions for detection, our work contributed to the effective monitoring of transportation of radioactive Sr in the environment.
锶-90（Sr）是一种主要的放射性成分，引起了广泛关注，但由于其不存在特定的能量射线来指示其存在，因此检测仍然具有挑战性。在此，展示了一种能够快速检测 Sr 离子的生物传感器。通过制备 MnO 纳米棒作为氧化酶模拟物来催化 3,3',5,5'-四甲基联苯胺（TMB），开发了一种简单的比色法，用于在单链 DNA 的帮助下灵敏检测 Sr。在弱酸性条件下，MnO 表现出很强的氧化酶模拟活性，可将无色 TMB 氧化为蓝色氧化产物（oxTMB），具有可识别的吸收信号。然而，引入富含鸟嘌呤的 DNA 适体抑制了 MnO 介导的 TMB 氧化并减少了 oxTMB 的形成，导致蓝色褪色和吸光度降低。当向体系中加入锶离子时，适体与锶离子形成稳定的 G-四链体结构，从而恢复了 MnO 的氧化酶模拟活性。在最佳实验条件下，吸光度在 0.01-200 μM 范围内与 Sr 浓度呈线性关系，检测限为 0.0028 μM。当 Sr 的浓度从 10 到 10 mol L 时，在基于纸的传感器上可以观察到明显的颜色变化梯度。我们成功地将这种方法应用于天然水样中 Sr 的测定，回收率在 97.6%至 103%之间，相对标准偏差小于 5%。通过为检测提供技术解决方案，我们的工作有助于有效监测环境中放射性 Sr 的迁移。
