Early cancer diagnosis is critically important for early intervention and it can significantly enhance the treatment efficacy and the chance of cure. Herein, for the first time, the cyanine fluorophore namely, SLSO₃, was synthesized and found to possess a high binding affinity towards a typical biomarker, carcinoembryonic antigen (CEA) in which it served as an excellent turn-on labelling fluorophore for the detection of CEA. On this basis, the target CEA antigen is captured by a primary antibody conjugated on magnetic silica coated iron oxide nanoparticles and then followed by secondary antibody-loaded SiO₂ nanoparticles, which provide more binding sites for the labelling dyes resulting in 6-fold increase in fluorescence and thus heightened sensitivity. The immunosensor is capable of differentiating target analyte from other cancer-associated proteins and has been applied to quantify CEA in human serum sample and the result was consistent to that obtained from a commercial ELISA kit. This simple and direct detection assay has achieved a low limit of detection in the pg mL⁻¹ regime with small sample consumption (only 10 μL) and without any sample pre-treatment and purification.

早期癌症诊断对于早期干预至关重要，它可以显着提高治疗效果和治愈机会。在此，首次合成了花青荧光团即SLSO ₃，并发现其对典型的生物标志物癌胚抗原（CEA）具有很高的结合亲和力，在其中它是用于检测的极好的开启标记荧光团CEA。在此基础上，目标CEA抗原被偶联在磁性二氧化硅涂层的氧化铁纳米颗粒上的一抗捕获，然后被负载有_二抗的SiO ₂捕获纳米颗粒，它为标记染料提供了更多的结合位点，导致荧光增加了6倍，从而提高了灵敏度。该免疫传感器能够将目标分析物与其他与癌症相关的蛋白质区分开，并已被用于定量人类血清样品中的CEA，其结果与从商业ELISA试剂盒获得的结果一致。这种简单而直接的检测分析方法在pg mL ^-1范围内的检测限很低，样品消耗量小（仅10μL），并且无需任何样品预处理和纯化。