In this work, we developed a microfluidic system for immunoassays where we combined the use of magnetic nanoparticles as immunosupport, a microfluidic magnetic trap, and a fluorogenic substrate in continuous flow for detection which, together with the optimization of the functionalization of surfaces to minimize nonspecific interactions, resulted in a detection limit in the order of femtomolar and a total assay time of 40 min for antibiotin antibody detection. A magnetic trap made of carbonyl-iron microparticles packaged inside a 200  μ m square microchannel was used to immobilize and concentrate nanoparticles. We functionalized the surface of the iron microparticles with a silica-polyethylene glycol (PEG) shell to avoid corrosion and unspecific protein binding. A new one-step method was developed to coat acrylic microchannels with an organofunctional silane functionalized with PEG to minimize unspecific binding. A model immunoassay was performed using nanoparticles decorated with biotin to capture antibiotin rabbit Immunoglobulin G (IgG) as target primary antibody. The detection was made using antirabbit IgG labeled with the enzyme alkaline phosphatase as a secondary antibody, and we measured fluorescence with a fluorescence microscope. All steps of the immunoassay were performed inside the chip. A calibration curve was obtained in which a detection limit of 8 pg/ml of antibiotin antibody was quantified. The simplicity of the device and the fact that it is made of acrylic, which is compatible with mass production, make it ideal for Point-Of-Care applications.

中文翻译：

---

微纳米粒子磁阱：迈向高灵敏度和快速的微流连续流酶免疫测定法。

在这项工作中，我们开发了一种用于免疫测定的微流体系统，在该系统中，我们将磁性纳米颗粒用作免疫支持物，微流体磁阱和荧光底物以连续流动相结合进行检测，并优化了表面功能化以最大程度地减少非特异性相互作用，导致检测极限为飞摩尔级，抗生物素抗体检测的总检测时间为40分钟。封装在200μm方形微通道内部的由羰基铁微粒制成的磁阱用于固定和浓缩纳米颗粒。我们用二氧化硅-聚乙二醇（PEG）壳功能化了铁微粒的表面，以避免腐蚀和非特异性蛋白质结合。开发了一种新的一步法，用丙烯酸官能团的有机官能硅烷覆盖丙烯酸微通道，以最大程度地减少非特异性结合。使用装饰有生物素的纳米颗粒进行模型免疫测定，以捕获抗生物素兔免疫球蛋白G（IgG）作为目标一抗。使用标记有碱性磷酸酶的抗兔IgG作为二抗进行检测，然后使用荧光显微镜测量荧光。免疫测定的所有步骤均在芯片内部进行。获得校准曲线，其中定量的抗生物素抗体检测限为8 pg / ml。该设备的简单性以及由丙烯酸制成的事实（可与批量生产兼容）使其成为护理点应用的理想选择。