An impedance biosensor using rotary magnetic separation and cascade reaction was developed for rapid and ultrasensitive detection of Salmonella typhimurium. First, magnetic nanoparticles (MNPs) modified with anti-Salmonella monoclonal antibodies were injected into a capillary at the presence of a rotary high gradient magnetic field, which was rotated by a stepper motor. Then, a bacterial sample was injected into the capillary and the target bacteria were continuous-flow captured onto the MNPs. After organic-inorganic hybrid nanoflowers were prepared using manganese dioxide (MnO₂), glucose oxidase (GOx) and anti-Salmonella polyclonal antibodies (pAbs), they were injected to label the bacteria, resulting in the formation of MNP-bacteria-nanoflower sandwich complexes. Finally, glucose (low conductivity) was injected and oxidized by GOx on the complexes to produce H₂O₂ (low conductivity) and gluconic acid (high conductivity), leading to impedance decrease. Besides, the produced H₂O₂ triggered a cascade reduction of MnO₂ into Mn²⁺, leading to further impedance decrease. The impedance changes were measured using an interdigitated microelectrode and used to determine the concentration of target bacteria. This biosensor was able to detect Salmonella ranging from 10¹ to 10⁶ CFU/mL in 2 h with a low detection limit of 10¹ CFU/mL and a mean recovery of 100.1% for the spiked chicken samples.

阻抗生物传感器的旋转磁分离和级联反应的发展，用于快速和超灵敏的检测鼠伤寒沙门氏菌。首先，在存在旋转高梯度磁场的情况下，将用抗沙门氏菌单克隆抗体修饰的磁性纳米颗粒（MNP）注入毛细管中，该磁场由步进电机旋转。然后，将细菌样品注入毛细管中，并将目标细菌连续流捕获到MNP上。使用二氧化锰（MnO ₂），葡萄糖氧化酶（GOx）和抗沙门氏菌制备有机-无机杂化纳米花后多克隆抗体（pAbs），将其注射以标记细菌，导致形成MNP-细菌-纳米花三明治复合物。最后，注入葡萄糖（低电导率）并通过GOx在配合物上氧化，生成H ₂ O ₂（低电导率）和葡萄糖酸（高电导率），导致阻抗降低。此外，产生的H ₂ O ₂触发了MnO ₂的级联还原为Mn ²⁺，从而进一步降低了阻抗。使用叉指式微电极测量阻抗变化，并用于确定目标细菌的浓度。这种生物传感器能够检测沙门氏菌，范围从10 ¹ 在2小时内达到10 ⁶ CFU / mL，低检出限为10 ¹  CFU / mL，加标鸡肉样品的平均回收率为100.1％。