近年来, 重金属污染引起了人们广泛关注。 传统的重金属检测方法需要依赖大型仪器, 预处理繁琐耗时, 因此急需发展重金属的快速高灵敏检测技术。 基于金纳米颗粒(AuNPs)的比色法传感器具有分析操作简单、 灵敏度高、 成本低等特点, 在环境监测、 食品安全以及化学和生物分析领域得到了广泛关注和应用。 本文基于纳米金(AuNPs)特性与Fenton反应原理, 构建了一种用于水中Cu2+检测的简单快速、 高灵敏检测方法。 该方法利用Cu2+与抗坏血酸钠（sodium ascorbate, SA）发生Fenton反应, 生成具有强氧化性的羟基自由基（·OH）, ·OH将附着在纳米金表面的单链DNA（ssDNA）裂解, 使得金纳米粒子失去保护, 容易在一定的盐浓度下发生聚集, 从而引起吸光度值的变化。 实验结果表明, 最优的反应条件为pH 7.9, 11 mg·L-1 ssDNA, 8 mmol·L-1 SA以及70 mmol·L-1 NaCl, 金纳米粒子在700和525 nm处的吸光度比值（A700/A525）与Cu2+浓度成线性关系。 该方法对Cu2+检测线性范围为0.1～10.0 μmol ·L-1, 检出限为24 nmol·L-1(3σ)。 对饮用水, 自来水及湖水的Cu2+加标回收率可以达到87%～120%, 表明该方法能够用于实际水样的Cu2+检测。

Heavy metal pollution has received great attentions in recent years. The traditional methods for heavy metal detection rely on the expensive laboratory instruments and need time-consuming preparation steps; therefore, it is urgent to develop quick and highly sensitive new technologies for heavy metal detection. The colorimetric method based on the gold nanoparticles (AuNPs) features with simple operation, high sensitivity and low cost, therefore, enabling it widely concerned and used in the environmental monitoring, food safety and chemical and biological sensing fields. This work developed a simple, rapid and highly sensitive strategy based on the Fenton reaction and unmodified AuNPs for the detection of Cu2+ in water samples. The hydroxyl radical (·OH) generated by the Fenton reaction between the Cu2+ and sodium ascorbate (SA) oxidized the single stranded DNA (ssDNA) attached on the AuNPs surface into variable sequence fragments. The cleavage of ssDNA induced the aggregation of AuNPs in a certain salt solution, therefore, resulting in the changes on the absorbance of solution. The assay conditions were optimized to be pH value of 7.9, 11 mg·L-1 ssDNA, 8 mmol·L-1 SA and 70 mmol·L-1 NaCl. Results showed that the absorbance ratio values at the wavelengths of 700 and 525 nm (A700/A525) were linearly correlated with the Cu2+ concentrations. The linear detection range was 0.1～10.0 μmol·L-1 with a detection limit of 24 nmol·L-1 (3σ). Spiked recoveries ranged from 87%～120% in three sorts of water, including drinking water, tap water and lake water, which confirmed that the potentials of the proposed assay for Cu2+ detection in reality.