College of Chemistry, Jilin University, Qianjin Street 2699, Changchun 130012, PR China.
College of Chemistry, Jilin University, Qianjin Street 2699, Changchun 130012, PR China.
Biosens Bioelectron. 2017 Oct 15;96:288-293. doi: 10.1016/j.bios.2017.05.023. Epub 2017 May 12.
An ultrasensitive surface plasmon resonance (SPR) immunoassay was developed for the specific detection of human cardiac troponin I (cTnI), a principle diagnostic marker for myocardial damage. The thin gold film evaporated on a glass slate, which was employed as the SPR sensing film, was modified by hollow gold nanoparticles (HGNPs) and polydopamine (PDA) sequentially, and then was immobilized with antibodies for specific recognition of target analyte. Electronic coupling of the surface plasmon waves originating from the HGNPs and the gold film leads to the remarkable amplification of SPR response. The PDA film modified on the gold film via self-polymerization of dopamine (DA) facilitates the direct immobilization of capture antibodies (cAb). To separate and enrich the target analyte, PDA-wrapped magnetic multi-walled carbon nanotubes (MMWCNTs-PDA) were conjugated with detection antibodies (dAb) and used as the extracting agent for the magnetic extraction of cTnI in sample. Large surface area of MMWCNTs-PDA ensures its loading capacity for dAb, as well as its extraction efficiency for cTnI. By serving as the "vehicles" for fast delivering the concentrated analyte to the SPR sensing surface, MMWCNTs-PDA-dAb also overcomes the disadvantage of slow diffusion-limited mass transfer and matrix interference effect in regular patterns. The combination of the above improvements results in the significant sensitivity enhancement of the SPR immunoassay. The concentration of cTnI with minimum detectable SPR response obtained by the present assay is 1.25ngmL, which is 1000-fold lower than that obtained by the traditional SPR immunoassay based on PDA-modified gold film.
一种超灵敏的表面等离子体共振（SPR）免疫分析方法被开发出来，用于特异性检测心肌损伤的主要诊断标志物——人心肌肌钙蛋白 I（cTnI）。将蒸发在玻璃石板上的薄金膜作为 SPR 传感膜，依次用中空金纳米粒子（HGNPs）和聚多巴胺（PDA）进行修饰，然后固定抗体用于对靶标分析物进行特异性识别。源自 HGNPs 和金膜的表面等离子体波的电子耦合导致 SPR 响应的显著放大。通过多巴胺（DA）的自聚合在金膜上修饰的 PDA 膜有利于捕获抗体（cAb）的直接固定。为了分离和浓缩目标分析物，用 PDA 包裹的多壁碳纳米管（MMWCNTs-PDA）与检测抗体（dAb）偶联，并用作样品中 cTnI 的磁性萃取提取剂。MMWCNTs-PDA 的大表面积确保了其对 dAb 的负载能力，以及对 cTnI 的萃取效率。作为将浓缩分析物快速输送到 SPR 传感表面的“载体”，MMWCNTs-PDA-dAb 还克服了常规模式中扩散限制的质量转移和基质干扰效应的缓慢缺点。上述改进的结合导致 SPR 免疫分析的灵敏度显著提高。本测定法获得的最小可检测 SPR 响应的 cTnI 浓度为 1.25ngmL，比基于 PDA 修饰金膜的传统 SPR 免疫分析低 1000 倍。
