New labels and assay techniques are needed to improve the sensitivity and quantitativeness of point-of-care immunotesting while sustaining the rapidity and ease of use of the assays. We synthesized a novel, intrinsically fluorescent nonadentate europium chelate with two chromophores and hydrophilic α-galactose side groups. The chelate is highly fluorescent, soluble in water, and provides effective shielding of Eu from water. The performance of the nonadentate chelate was compared with a heptadentate chelate in a dry reagent immunoassay for human chorionic gonadotropin (hCG). After 15-min incubation and washing, time-resolved fluorescence was measured directly from a wet or dried well surface. Contrary to the heptadentate label, the effect of aqueous quenching on the nonadentate label was found to be insignificant, with calculated analytical detection limits (background + 3 SD) of 0.9 and 0.7 IU/L hCG for wet and dry measurements, respectively, and a linear range up to 5000 IU/L. The CVs for the new label were <8% at the cutoff of 25 IU/L and above in both whole blood and plasma. The novel nonadentate label facilitates short turnaround times and simple instrumentation due to the absence of all signal development steps, at the same time retaining an excellent immunoassay performance.
需要新的标签和检测技术来提高现场免疫检测的灵敏度和定量性,同时保持检测的快速性和易用性。我们合成了一种新型的内源性荧光非九齿
铕配合物,具有两个色基和亲
水性的α-半
乳糖侧基。该配合物具有高度荧光性,易溶于
水,并有效地保护
铕不受
水的影响。在对人绒毛膜
促性腺激素(hCG)的干试剂免疫检测中,将非九齿配合物的性能与七齿配合物进行了比较。经过15分钟的孵育和洗涤后,从湿或干的孔表面直接测量了时间分辨荧光。与七齿标签相比,发现
水相猝灭对非九齿标签的影响微乎其微,计算出的分析检测限(背景+3倍标准差)分别为湿测和干测的0.9和0.7 IU/L hCG,线性范围可达5000 IU/L。新标签在25 IU/L及以上的切割点处的变异系数(CV)均小于8%,适用于全血和血浆。该新型非九齿标签由于省略了所有信号开发步骤,促进了短周转时间和简单仪器的使用,同时保持了优异的免疫检测性能。