We have developed a virtual filter that quickly and efficiently captures and detects pathogenic bacteria in large amounts of water. The virtual filter comprised magnetic nanoparticle chains (MNCs) obtained by cross-linking alginate-coated magnetic nanoparticles (MNPs). When the MNC solution in a disposable plastic tube was exposed to an external magnetic field, the MNCs were aligned along the magnetic field lines, forming a filter similar to a whale’s baleen filtering system. A Halbach ring that increased the magnetic field inside the ring was used as the source of an external magnetic field. The Halbach ring produced a more uniform and denser alignment of MNCs than any other ring array. To demonstrate the performance of the virtual filter comprising MNCs, Escherichia coli (E. coli) O157-spiked water was injected into the virtual filter comprising polyethyleneimine-coated MNCs, and the concentration of E. coli O157 captured by electrostatic interaction was determined using qPCR analysis. The bacterial capture efficiency using MNCs was 90% at a flow rate of 5 mL/min, and the detection limit after 10 min of preconcentration of bacteria was 10 cfu/mL, which is 100 times lower than that obtained using qPCR alone.

中文翻译：

---

仿人虚拟过滤器，用于利用磁性纳米粒子链和Halbach环快速检测水中的病原细菌

我们开发了一种虚拟过滤器，可以快速有效地捕获和检测大量水中的致病细菌。虚拟过滤器包括通过交联涂覆有藻酸盐的磁性纳米颗粒（MNP）获得的磁性纳米颗粒链（MNC）。当一次性塑料管中的MNC溶液暴露于外部磁场时，MNC沿着磁场线对齐，形成类似于鲸鱼的baleen过滤系统的过滤器。将增加环内部磁场的Halbach环用作外部磁场源。与任何其他环阵列相比，Halbach环产生的MNC排列更加均匀和密集。为了演示包含MNC的虚拟过滤器的性能，大肠杆菌（E. coli将O157掺加的水注入包含聚乙烯亚胺涂层的MNC的虚拟过滤器中，并通过qPCR分析确定通过静电相互作用捕获的大肠杆菌O157的浓度。使用MNC的细菌捕获效率在5 mL / min的流速下为90％，细菌预浓缩10分钟后的检出限为10 cfu / mL，这比单独使用qPCR所获得的检出限低100倍。