Wang Jun, Liu Guodong, Wu Hong, Lin Yuehe
Pacific Northwest National Laboratory, Richland, WA 99352, United States.
Anal Chim Acta. 2008 Mar 3;610(1):112-8. doi: 10.1016/j.aca.2008.01.024. Epub 2008 Jan 18.
We present a poly(guanine)-functionalized silica nanoparticle (NP) label-based electrochemical immunoassay for sensitively detecting 2,4,6-trinitrotoluene (TNT). This immunoassay takes advantage of magnetic bead-based platform for competitive displacement immunoreactions and separation, and use electroactive nanoparticles as labels for signal amplification. For this assay, anti-TNT-coated magnetic beads interacted with TNT analog-conjugated poly(guanine)-silica NPs and formed analog-anti-TNT immunocomplexes on magnetic beads. The immunocomplexes coated magnetic beads were exposed to TNT samples, which resulted in displacing the analog conjugated poly(guanine) silica NPs into solution by TNT. In contrast, there are no guanine residues releasing into the solution in the absence of TNT. The reaction solution was then separated from the magnetic beads and transferred to the electrode surface for electrochemical measurements of guanine oxidation with Ru(bpy)3(2+) as mediator. The sensitivity of this TNT assay was greatly enhanced through dual signal amplifications: (1) a large amount of guanine residues on silica nanoparticles are introduced into the test solution by displacement immunoreactions and (2) a Ru(bpy)3(2+)-induced guanine catalytic oxidation further enhances the electrochemical signal. Some experimental parameters for the nanoparticle label-based electrochemical immunoassay were studied and the performance of this assay was evaluated. The method is found to be very sensitive and the detection limit of this assay is approximately 0.1 ng mL(-1) TNT. The electrochemical immunoassay based on the poly[guanine]-functionalized silica NP label offers a new approach for sensitive detection of explosives.
我们展示了一种基于聚鸟嘌呤功能化二氧化硅纳米颗粒（NP）标记的电化学免疫分析法，用于灵敏检测2,4,6-三硝基甲苯（TNT）。这种免疫分析法利用基于磁珠的平台进行竞争性置换免疫反应和分离，并使用电活性纳米颗粒作为信号放大的标记。在该分析中，抗TNT包被的磁珠与TNT类似物偶联的聚鸟嘌呤-二氧化硅纳米颗粒相互作用，并在磁珠上形成类似物-抗TNT免疫复合物。将包被有免疫复合物的磁珠暴露于TNT样品中，这导致TNT将偶联的聚鸟嘌呤二氧化硅纳米颗粒置换到溶液中。相比之下，在没有TNT的情况下，没有鸟嘌呤残基释放到溶液中。然后将反应溶液与磁珠分离，并转移到电极表面，以钌（联吡啶）3（2+）作为介质对鸟嘌呤氧化进行电化学测量。通过双重信号放大，大大提高了这种TNT分析的灵敏度：（1）通过置换免疫反应将大量二氧化硅纳米颗粒上的鸟嘌呤残基引入测试溶液中，（2）钌（联吡啶）3（2+）诱导的鸟嘌呤催化氧化进一步增强了电化学信号。研究了基于纳米颗粒标记的电化学免疫分析法的一些实验参数，并评估了该分析方法的性能。发现该方法非常灵敏，该分析方法的检测限约为0.1 ng mL（-1）TNT。基于聚[鸟嘌呤]功能化二氧化硅NP标记的电化学免疫分析法为爆炸物的灵敏检测提供了一种新方法。
