基于上转换纳米颗粒和金纳米颗粒的Cd2+免疫检测新方法

A Novel Immunoassay Method for Cd2+ Detection Based on Up-Conversion Nanoparticles and Gold Nanoparticles

摘要:

基于上转换纳米颗粒（UCNPs）和金纳米颗粒（AuNPs）间的荧光共振能量转移（FRET）和抗原抗体的识别作用构建了Cd²⁺的免疫检测平台。制备水溶性UCNPs表面修饰Cd-抗原作为能量供体探针，同时在AuNPs表面修饰Cd-抗体作为能量受体探针。抗原-抗体的免疫结合使得UCNPs和AuNPs发生FRET过程，引起UCNPs荧光猝灭；当检测体系中存在Cd²⁺时，Cd²⁺与UCNPs-抗原竞争性地结合AuNPs-抗体，从而抑制了FRET过程，荧光信号值随着Cd²⁺质量浓度的增加而增加。结果表明，该方法检测范围为0.01～10 ng/mL，检出限可达0.01 ng/mL。将该方法应用于自来水样品中Cd²⁺的检测，当加标水平为0.1、1、10 ng/mL时，回收率为98%~109%，相对标准偏差为3.4%~4.1%。

Abstract:

A immunoassay platform for Cd²⁺ was constructed based on fluorescence resonance energy transfer (FRET) between the up-conversion nanoparticles (UCNPs) and the gold nanoparticles (AuNPs) and the recognition of antigen and antibody. Water-soluble UCNPs modified with Cd-antigen were prepared as the energy donor probe, and AuNPs modified by Cd-antibody were synthesized as the energy receptor probe. The immune binding of antigen-antibody triggered FRET process of UCNPs and AuNPs, causing fluorescence quenching of UCNPs. In the presence of Cd²⁺, Cd²⁺ competitively bound to AuNPs-antibody with UCNPs-antigen, which inhibited the FRET process, and the fluorescence signal value enhanced with the increase of Cd²⁺ concentration. The results showed that the detection range was from 0.01 ng/mL to 10 ng/mL, and the detection limit was 0.01 ng/mL. The method was applied to the detection of Cd²⁺ in tap water samples. At the spiked level of 0.1, 1, 10 ng/mL, the recoveries for Cd²⁺ ranged from 98% to 109% with the relative standard deviations (RSDs) of 3.4% to 4.1%.