重金属由于其毒性而被认为是对人体有害的物质,持久性和生物蓄积性,血清水平是评估健康风险的重要因素,这取决于有效和灵敏的分析方法。这里,构建了基于金属依赖性DNAzyme的三重信号放大电化学传感平台,用于灵敏测定血清中的重金属(铜作为模型靶标)。在优化条件下,所提出的方法显示出良好的灵敏度(检测限,对于Cu2+为0.33fM)具有优异的选择性和稳定性,这归因于:(i)四面体DNA纳米结构(TDN),它被用作有前途的支架,以调整异质和均质反应之间的选择性转化,防止电极表面和DNA探针的非特异性结合;(ii)使用的磁珠(MB),由于其从复杂样品中提取等效靶标的优异特性,导致信号放大和背景降低;(iii)催化发夹组装(CHA)和杂交链反应(HCR)的两种信号放大策略。此外,通过电感耦合等离子体质谱(ICP-MS)和加标回收率分析(回收率,87.92-111.61%;RSD,4.89-8.85%),表明快速和灵敏检测Cu2+或其他金属离子的巨大潜力。
Heavy metals are considered as hazardous substances to human because of their toxicity, persistence and bioaccumulation, and the level in serum is an important factor to evaluate the caused health risk, which depends on efficient and sensitive analytical methods. Here, a triple signal-amplified electrochemical sensing platform based on metal-dependent
DNAzymes was fabricated for sensitive determination of heavy metals in serum (copper as a model target). Under the optimized conditions, the proposed method showed good sensitivity (limit of detection, 0.33 fM for Cu2+) with excellent selectivity and stability, which is ascribed to: (i) tetrahedral DNA nanostructures (TDNs) that was used as a promising scaffold to adjust the selective transformation between heterogeneous and homogeneous reactions, preventing the nonspecific binding of electrodes surface and DNA probes; (ii) the magnetic beads (MBs) used which led to signal amplification and decreased background owing to its excellent properties of extracting equivalent targets from the complex samples; (iii) two signal amplification strategy of catalytic hairpin assembly (CHA) and hybridization chain reaction (HCR). In addition, the proposed sensing platform displayed satisfactory accuracy through the validation with inductively coupled plasma-mass spectrometry (ICP-MS) and a spike-recovery analysis (recoveries, 87.92-111.61%; RSD, 4.89-8.85%), indicating the great potential for rapid and sensitive detection of Cu2+ or other metal ions.