单颗粒计数策略定量检测癌胚抗原

Quantification of Carcinoembryonic Antigen by Single Particle Inductively Coupled Plasma Mass Spectrometry

该文提出了一种基于单颗粒电感耦合等离子体质谱(spICP-MS)的计数策略,用于癌胚抗原(CEA)的灵敏检测。该策略采用50 nm的金纳米颗粒(AuNPs)作为免疫识别和单颗粒计数的探针,以磁性纳米颗粒(MBs)作为免疫识别的捕获中心,基于夹心免疫反应,应用抗体标记的MBs捕获CEA和AuNPs探针。通过磁铁分离后,捕获有AuNPs的MBs在离心管底部富集,而上清液中剩余的AuNPs探针通过spICP-MS进行计数。样品中的CEA越多,在MBs表面捕获的AuNPs探针越多,而在上清液中未被捕获的残留AuNPs探针数量则越少。实验分别对免疫分析中MBs的用量和样品检测之前的稀释倍数进行优化。在最佳条件下,该策略对CEA的检测提供了3个数量级的线性范围(0.05~20 ng/mL,r^(2)=0.997),检出限(LOD)低至0.017 ng/mL。该方法选择性良好,并成功应用于血清样品的分析,在癌症诊断中显示出巨大潜力。

Cancer ranks as the leading threat to life expectancy all over the world,based on the latest estimations.Timely diagnosis and treatment of malignancies are still essential procedures to control the growing burden of cancer incidence and mortality.Single particle inductively coupled plasma mass spectrometry(spICP-MS)is a detection method for single par⁃ticles in time-resolved mode.Inheriting the advantages of ICP-MS,spICP-MS ensures the single-particle counting with high sensitivity and high element resolutions.For immunoassays by this mode,there are breakthroughs not only in improv⁃ing the detection limits of heterogeneous immunoassay but also in achieving multiplex homogeneous immunoassays with a simpler procedure.In this work,a single particle counting strategy was achieved by spICP-MS for sensitive carcinoem⁃bryonic antigen(CEA)evaluation.Gold nanoparticles(AuNPs)with a diameter of 50 nm were synthesized by one-step so⁃dium citrate reduction,which were further applied to CEA-specific capturing.Anti-CEA antibody labeled AuNPs were syn⁃thesized by electrostatic adsorption between disulfide bonds exposed on the anti-CEA antibodies and the surface of AuNPs.The strategy was based on sandwich immunoassay where anti-CEA antibody labeled magnetic beads(MBs)were applied to capture CEA and antibody labeled AuNPs.After separation by a magnet,MBs were enriched at the bottom of the centrifu⁃gal tube,while the remaining AuNPs in the supernatant were counted by spICP-MS.The more CEA occurred in the sam⁃ple,the more AuNPs probes were captured on the surface of MBs,and the fewer numbers of detectable remaining AuNPs were found in the supernatant.The proposed method was more direct and facile without washing steps,compared with the traditional MBs strategy.The experimental conditions were optimized,including magnetic beads volume applied in immu⁃noassay and dilution ratio of the sample in spICP-MS.Under the optimal conditions,spICP-MS could accurately deter⁃mine the change of AuNPs numbers in the process of CEA immunoassay,with an efficiency of 2.1%.The proposed meth⁃od provided a three-orders-of-magnitude linear range(0.05-20 ng/mL,r^(2)=0.997)with a limit of detection(LOD)as low as 0.017 ng/mL forCEA quantification.The method was also successfully utilized in serum sample analysis with good selectiv⁃ity,exhibiting a great potential in cancer diagnosis.