Constraints related to sample preparation are some of the primary obstacles to widespread deployment of molecular diagnostics for rapid detection of trace quantities (≤10³ CFU/mL) of food-borne pathogens. In this research, we report a sample preparation method using a novel handheld electroflotation system to concentrate and recover dilute quantities (10²−10³ CFU/mL) of Escherichia coli (E. coli) 25922 in artificially contaminated samples for reliable, rapid detection by loop-mediated isothermal amplification (LAMP). To protect suspended cells from shear stresses at bubble surfaces, a non-ionic surfactant (Pluronic-F68) and flocculant (chitosan oligosaccharide) were used to aggregate cells and reduce their surface hydrophobicity. Effective conditions for recovery were determined through multifactorial experiments including various concentrations of Pluronic-F68 (0.001, 0.01, 0.1, 1 g L^-1), chitosan oligosaccharide (0.01, 0.1, 1, 10 g L^-1), bacteria (10², 10³, 10⁴ CFU/mL E. coli 25922), recovery times (10, 15 and 20 minutes), and degrees of turbulent gas flux (“high” and “low”). The automated electroflotation system was capable of concentrating effectively all of the bacteria from a large sample (380 mL 0.1 M potassium phosphate buffer containing 10² CFU/mL E. coli) into a 1 mL recovered fraction in less than 30 minutes. This enabled detection of bacterial contaminants within 2 hours of collecting the sample, without a specialized laboratory facility or traditional enrichment methods, with at least a 2–3 order of magnitude improvement in detection limit compared to direct assay with LAMP.

与样品制备相关的限制是广泛部署分子诊断以快速检测痕量（≤10 ³ CFU/mL）食源性病原体的一些主要障碍。在这项研究中，我们报告了一种样品制备方法，使用新型手持式电浮选系统来浓缩和回收人工污染样品中稀释量（10 ² −10 ³ CFU/mL）的大肠杆菌 (E . coli) 25922，以实现可靠、快速的检测通过环介导等温扩增（LAMP）。为了保护悬浮细胞免受气泡表面剪切应力的影响，使用非离子表面活性剂（Pluronic-F68）和絮凝剂（壳寡糖）来聚集细胞并降低其表面疏水性。通过多因素实验确定了有效的回收条件，包括不同浓度的Pluronic-F68（0.001、0.01、0.1、1 g L ^-1）、壳寡糖（0.01、0.1、1、10 g L ^-1）、细菌（10 ²、10 ³、10 ⁴ CFU /mL大肠杆菌25922）、恢复时间（10、15 和 20 分钟）以及湍流气体通量程度（“高”和“低”）。自动电浮选系统能够在不到 30 分钟的时间内将大样品（含有 10 ² CFU/mL大肠杆菌的380 mL 0.1 M磷酸钾缓冲液）中的所有细菌有效浓缩为 1 mL回收级分。这使得在收集样品后 2 小时内即可检测出细菌污染物，无需专门的实验室设施或传统的富集方法，与 LAMP 直接检测相比，检测限至少提高了 2-3 个数量级。