纳米金增强SPR铅离子检测器构建

为满足采用简便方法检测痕量铅离子（Pb²⁺）的需求，构建了新型的超灵敏、高特异性表面等离子体共振（SPR）生物传感器，用于水中Pb²⁺检测.以硫醇化GR-5脱氧核酶（DNAzyme）为Pb²⁺特异性识别探针，并自组装到芯片金膜表面，底物官能化的纳米金（S-AuNPs）用于信号增强，并与DNAzyme杂交形成传感薄膜.AuNPs不仅增加了质量变化，其局部表面等离子体共振（LSPR）与芯片表面传播SPR的耦合作用也可产生信号放大的效果.在Pb²⁺离子存在下，DNAzyme催化底物裂解，导致AuNPs的去除并引起SPR信号显著变化.通过X射线光电子能谱和扫描电镜对芯片表面的表征分析验证了传感薄膜构建过程和检测原理.Pb²⁺检测实验结果表明，1 μmol/L DNAzyme修饰的传感器检测效果最好，检测限为80pmol/L，并在100nmol/L范围内与Pb²⁺浓度的对数呈线性关系（R²=0.992）.该传感器对10倍浓度的其他金属离子无明显响应，说明其具有良好的Pb²⁺特异性；检测自来水和地下水中Pb²⁺的结果与ICP-MS方法有良好的一致性.研究建立的Pb²⁺检测方法具有高灵敏度和特异性，且操作简便，具有现场检测的应用前景.

Characterization of AuNP-enhanced SPR biosensor for Pb2+ detection

In order to cope with the challenge of simple methods for Pb²⁺ detection, a novel ultra-sensitive, highly specific surface plasmon resonance (SPR) biosensor was developed. Thiolated GR-5DNAzyme was used for specific recognition of Pb²⁺ and immobilized on the SPR sensor surface. Substrate functionalized gold nanoparticles (S-AuNPs) were used for signal enhancement and hybridized with DNAzyme for the formation of the Pb²⁺ sensing layer. The enhancement of SPR signal was induced by the mass of AuNPs and the coupling effect between their local surface plasmon resonance (LSPR) and the SPR propagated on the chip surface. In the presence of Pb²⁺ ions, the substrate cleavage was catalyzed by DNAzyme, resulting in the removal of AuNPs and the significant weakening of SPR signal. The sensor surface was characterized and analyzed using X-ray photoelectron spectrometer and field emission scanning electron microscope, and the detection mechanism was verified. The biosensor incorporating 1 μmol/L DNAzyme showed the best Pb²⁺ detection performance. Its detection limit was 80pmol/L, and the SPR angle shift demonstrated a linear relationship with the logarithm of Pb²⁺ concentration in the range of 10~100nmol/L. It also showed good specificity against highly concentrated other metal ions. These results of Pb²⁺ detection in tap water and ground water showed good consistency with the ICP-MS measurements. This Pb²⁺ detection method features high sensitivity and specificity, and may have application prospects for onsite detection due to its simplicity.