The development and application of portable and user-friendly biosensing technology for rapid detection of pathogenic bacteria are essential for human and environmental care. In this work, based on the phenomenon that the filter membrane can selectively separate MnO₂ nanosheets (MnO₂ NSs) and Mn²⁺, a novel label-free sensing platform was developed to detect the Escherichia coli (E. coli) using β-galactosidase (β-Gal) as a marker. MnO₂ NSs were utilized as a dual-mode signal molecule of smartphone-based colorimetric analysis and inductively coupled plasma mass spectrometry (ICP-MS). β-Gal can catalyze the 4-Aminophenyl β-D-galactopyranoside (PAPG) to produce p-aminophenol (PAP), which could reduce MnO₂ NSs to Mn²⁺. After selective separation of MnO₂ NSs and Mn²⁺ by the filter, colorimetric detection was achieved with a smartphone by identifying the RGB value of the MnO₂ NSs coated membrane, while the Mn²⁺ in the filtrate was detected by ICP-MS. Under optimal conditions, the limits of detection (LODs) of E. coli by smartphone-based RGB analysis and ICP-MS were 5.6 × 10³ CFU mL⁻¹ and 35 CFU mL⁻¹, respectively. This method was successfully used for E. coli assay in meat, vegetables, and fruit samples with the advantages of sensitivity, simplicity, and short incubation time (within 1 h).

用于快速检测病原菌的便携式和用户友好的生物传感技术的开发和应用对于人类和环境保健至关重要。本工作基于滤膜可以选择性分离MnO ₂纳米片（MnO ₂ NSs）和Mn ²⁺的现象，开发了一种新型无标记传感平台，利用β-检测大肠杆菌（E.coli ） 。半乳糖苷酶（β - Gal）作为标记。MnO ₂ NSs 被用作基于智能手机的比色分析和电感耦合等离子体质谱 (ICP-MS) 的双模信号分子。β-Gal可催化4-氨基苯基β -D-吡喃半乳糖苷(PAPG)生成对氨基苯酚(PAP)，可将MnO ₂ NSs还原为Mn ²⁺。经过滤器选择性分离MnO ₂ NSs和Mn ²⁺后，通过智能手机识别MnO ₂ NSs包膜膜的RGB值实现比色检测，而滤液中的Mn ²⁺则通过ICP-MS检测。在最佳条件下，基于智能手机的 RGB 分析和 ICP-MS 对大肠杆菌的检测限 (LOD)为 5.6 × 10 ³  CFU mL ^-1和 35 CFU mL ^-1， 分别。该方法成功地用于肉类、蔬菜和水果样品中的大肠杆菌检测，具有灵敏度高、操作简单、孵育时间短（1小时以内）的优点。