An all-in-one nanosensor was developed for the magnetic enrichment and ratiometric surface-enhanced Raman scattering (SERS) detection of Escherichia coli (E. coli). The all-in-one nanosensor was constructed through the chemical integration of four components into a single nanoparticle, which include a manganese ferrite nanoparticle serving as the magnetic core, a thin silver shell as the SERS substrate, a self-assembled layer of 4-mercaptobenzoic acid (MBA) molecules as the SERS internal standard, and a MBA-conjugated layer of aptamer sequences as the capture probe of E. coli. In the detection of E. coli in food, the target cells were first captured by the nanosensors and magnetically enriched in a short time of 15 min, and then the ratiometric SERS was performed through the Raman intensity ratio between two specific SERS peaks produced by the captured E. coli and the internal MBA. The pre-concentration and ratiometry enabled the nanosensor to detect E. coli with a detection limit down to 10 CFU/mL. The all-in-one nanosensor was successfully applied for the detection of E. coli in various liquid foods including milk, juice, tea, and coffee, with recoveries ranging from 89 to 110% and relative standard deviation lower than 1.7%. In comparison with the previous sandwich strategy adopted by most SERS sensors, this nanosensor endowed with an easier use and a lower cost is more sensitive and reproducible, leading to a great potential in practical applications.

开发了一种一体化纳米传感器，用于大肠杆菌（E.coli）的磁性富集和比率表面增强拉曼散射 (SERS) 检测。一体化纳米传感器是通过将四种成分化学整合成单个纳米颗粒而构建的，其中包括作为磁芯的锰铁氧体纳米颗粒、作为 SERS 基底的薄银壳、4-自组装层。巯基苯甲酸 (MBA) 分子作为 SERS 内标，MBA 共轭的适体序列层作为大肠杆菌的捕获探针。在检测大肠杆菌在食品中，靶细胞首先被纳米传感器捕获并在 15 分钟的短时间内磁性富集，然后通过捕获的大肠杆菌产生的两个特定 SERS 峰与内部工商管理硕士。预浓缩和比率测定使纳米传感器能够以低至 10 CFU/mL 的检测限检测大肠杆菌。多合一纳米传感器成功应用于大肠杆菌检测在牛奶、果汁、茶、咖啡等各种流质食品中，回收率89%～110%，相对标准偏差小于1.7%。与之前大多数SERS传感器采用的夹心策略相比，这种纳米传感器使用更容易，成本更低，更灵敏和可重复，在实际应用中具有很大的潜力。