In-field screening of foodborne pathogens plays an important role in ensuring food safety. Thus, a microfluidic biosensor was developed for rapid and sensitive detection of Salmonella using manganese dioxide nanoflowers (MnO₂ NFs) for amplifying the biological signal, a microfluidic chip with a convergence–divergence spiral micromixer for performing automatic operations, and a smartphone app with a saturation calculation algorithm for processing the image. First, immune magnetic nanoparticles (MNPs), the sample, and immune MnO₂ NFs were fully mixed and sufficiently incubated in the spiral micromixer to form MNP–bacteria–MnO₂ sandwich complexes, which were magnetically captured in a separation chamber in the microfluidic chip. Then, a 3,3′,5,5′-tetramethylbenzidine (TMB) substrate was injected and catalyzed by a MnO₂ NF nanomimetic enzyme on the complexes, resulting in the production of yellow catalysate. Finally, the catalysate was transferred into a detection chamber and its image was measured and processed using the smartphone app to determine the number of bacteria. This biosensor was able to detect Salmonella from 4.4 × 10¹ to 4.4 × 10⁶ CFU/mL in 45 min with a detection limit of 44 CFU/mL, and has the potential to provide a promising platform for on-site detection of foodborne bacteria.

中文翻译：

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基于二氧化锰纳米酶和收敛-发散螺旋微混合器的微流体比色生物传感器，用于沙门氏菌的快速灵敏检测

食源性病原体的现场筛查在确保食品安全方面发挥着重要作用。因此，开发了一种使用二氧化锰纳米花 (MnO ₂ NFs) 放大生物信号的微流控生物传感器，用于快速灵敏地检测沙门氏菌，微流控芯片具有用于执行自动操作的收敛-发散螺旋微混合器，以及具有处理图像的饱和度计算算法。首先，免疫磁性纳米粒子（MNPs）、样品和免疫MnO ₂ NFs在螺旋微混合器中充分混合并充分孵育以形成MNP-细菌-MnO ₂夹心复合物，它们被磁性捕获在微流控芯片的分离室中。然后，注入 3,3',5,5'-四甲基联苯胺 (TMB) 底物并由 MnO ₂ NF 纳米模拟酶在复合物上催化，产生黄色催化剂。最后，将催化剂转移到检测室中，使用智能手机应用程序测量和处理其图像以确定细菌数量。该生物传感器能够在 45 分钟内检测4.4 × 10 ¹至 4.4 × 10 ⁶ CFU/mL 的沙门氏菌，检测限为 44 CFU/mL，有可能为现场检测食源性细菌提供一个有前景的平台.