本项目拟构建一种高灵敏、快速和简便的磁弛豫时间免疫传感器，并将其应用于细菌感染生物标志物的检测。主要研究内容为：1）通过click可控反应将纳米小磁颗粒和抗体同时组装在聚苯乙烯微球的不同表层，制备同时具有免疫识别和磁信号放大的多功能磁探针，实现免疫识别和多重信号放大的一步完成；2）将该多功能磁探针和免疫磁分离技术相结合，改变磁信号获取模式，使得磁信号和目标分析物的浓度直接相关，进而从检测原理上克服传统磁弛豫时间免疫传感器稳定性和操作性不佳的缺点，实现磁富集和磁传感于一步完成。该方法将有效的免疫磁富集模式和高效的信号放大策略（层层组装磁信号放大和纳米材料信号放大）结合起来，实现高灵敏和快速检测的统一，可显著提高磁弛豫时间免疫传感器的性能，进而为细菌感染等重大疾病的早期诊断提供新的思路和手段。

We propose a simple, rapid and sensitive magnetic relaxation switching (MRS) immunosensor for detection of the biomarkers for bacterial infection in human serum samples. The main contents are: 1) The magnetic nanoparticles (MNPs) and antibody (Ab) are simultaneously conjugated to the surface of polystyrene (PS) microspheres layer by layer using click chemistry. This multi-functional magnetic probes can not only recognize target from samples but also be used as an magnetic signal amplification system. More importantly, the immunosensor can achieve immuno recognition and multi-step signal amplification in one step. 2) Combined with immunomagnetic separation and the multi-functional magnetic probes, this immunosensor can change acquisition mode of the magnetic signal. The magnetic signal is directly related to the amount of target, thus this immunosensor can realize immunomagnetic enrichment and magnetic sensing within one step, meanwhile eliminate the drawbacks of traditional MRS sensor such as instability and complex manipulation. This MRS immunosensor combines immunomagnetic enrichment and efficient signal amplification strategy (magnetic signal amplification through layer-by-layer assembly and nanomaterials-based signal amplification) to achieve ultra-high sensitivity and speediness, which significantly improves the performance of the MRS immunosensor and further provides a powerful and novel strategy for early diagnosis of diseases like bacterial infection.