Abstract: Excessive heavy metal residues is one of the major food safety issues. To quickly and accurately determine the amount of heavy metals, this paper reported a colorimetric sensor for the quantification of Cd²⁺ and Pb²⁺. The peroxidase activity of Fe₃O₄ was used as the signal output tool and aptamer as the target specific recognition element. First, the detection method was determined by the feasibility analysis and the condition optimization, and the sensor performance was evaluated by sensitivity and specificity experiments. Under the optimum conditions, the sensor has a high selectivity over other competitive ions with the detection limits as low as 0.108 μmol/L for Cd²⁺ and 0.117 μmol/L for Pb²⁺. The method has the advantages of low cost, fast and simple detection process, visible to the naked eye, and the quantitative analysis can be realized by hand-held photometer. The establishment of the sensor would make it possible to detect heavy metals in real time and quickly, and provide a strong guarantee for food safety detection in China.

Key words: Fe₃O₄, peroxidase, nucleic acid, heavy metal, biosensor

摘要： 重金属残留超标是重大食品安全问题之一。为建立一种快速简单的Cd²⁺和Pb²⁺重金属离子检测法，以磁性Fe₃O₄纳米粒子(MNPs)的过氧化物酶活性作为传感信号输出工具，以核酸适配体的特异性识别功能作为靶标识别元件，建立了一个比色传感器。通过可行性分析和条件优化确定检测方法，再通过灵敏度和特异性实验对传感器性能进行评估。在最优条件下，Cd²⁺和Pb²⁺的最低检测线分别为0.108 μmol/L和0.117 μmol/L。该检测方法检测成本低、检测过程快速简单、检测结果肉眼可见，凭借手持式光度计即可实现定量分析。此外，该方法受其他离子干扰相对较小，特异性较强。该传感器的建立将使重金属的现场实时快速检测成为可能，为我国食品安全检测提供了有力保障。

关键词: Fe₃O₄, 过氧化物酶, 核酸, 重金属, 生物传感器