Key Laboratory of Agricultural Information Acquisition Technology, Ministry of Agriculture and Rural Affairs, China Agricultural University, 17 East Qinghua Road, Beijing, 100083, China.
Department of Electronic Engineering, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
Biosens Bioelectron. 2020 Jun 1;157:112160. doi: 10.1016/j.bios.2020.112160. Epub 2020 Mar 20.
Screening of pathogenic bacteria plays a crucial role in preventing foodborne disease outbreaks. In this study, an ultrasensitive biosensor was developed for fast detection of Salmonella using self-assembled magnetic nanoparticle (MNP) chains for continuous-flow separation of Salmonella from large-volume sample, urease coated gold nanoparticles (GNPs) for specific labelling of Salmonella and efficient amplification of signal, and linear scan voltammetry for sensitive detection of catalysate. First, MNP chains were formed and distributed in a 3D spiral channel using mutually repelling cylindrical magnets and ring iron gears to control anti-Salmonella monoclonal antibody coated MNPs. After bacterial sample was continuous-flow drawn into the channel, bacteria-MNP complexes (magnetic bacteria) were formed on the chains, resulting in specific separation of target bacteria from sample background. Then, anti-Salmonella polyclonal antibodies and urease coated GNPs were drawn to label the magnetic bacteria, resulting in the formation of enzymatic bacteria. After washing to remove residual GNPs, urea was drawn and catalyzed by urease on enzymatic bacteria, resulting in the produce of catalysate (ammonium carbonate). Finally, the catalysate was transferred into a microfluidic chip with a thin-film Ag/AgCl reference electrode array for linear scan voltammetric measurement, and the resistance of catalysate was obtained to determine the amount of target bacteria. This biosensor could quantitatively detect Salmonella from 1.0 × 10 to 1.0 × 10 CFU/mL in 1 h with low detection limit of 10 CFU/mL. The mean recovery for Salmonella in spiked milk was about 104.3%.
筛选病原菌对于预防食源性疾病爆发至关重要。在本研究中，开发了一种超灵敏的生物传感器，用于快速检测沙门氏菌，该传感器使用自组装的磁性纳米粒子（MNP）链从大量样品中连续分离沙门氏菌，用脲酶包覆的金纳米粒子（GNPs）对沙门氏菌进行特异性标记并对信号进行有效放大，用线性扫描伏安法对催化产物进行灵敏检测。首先，通过相互排斥的圆柱形磁铁和环形铁齿轮在 3D 螺旋通道中形成和分布 MNP 链，以控制抗沙门氏菌单克隆抗体包覆的 MNP。在将细菌样品连续吸入通道后，在链上形成细菌-MNP 复合物（磁性细菌），从而实现目标细菌与样品背景的特异性分离。然后，将抗沙门氏菌多克隆抗体和脲酶包覆的 GNPs 吸入以标记磁性细菌，形成酶细菌。在洗涤以去除残留的 GNPs 后，将尿素吸入并在酶细菌上被脲酶催化，产生催化产物（碳酸铵）。最后，将催化产物转移到带有薄膜 Ag/AgCl 参比电极阵列的微流控芯片中进行线性扫描伏安测量，并获得催化产物的电阻以确定目标细菌的数量。该生物传感器可在 1 小时内定量检测浓度范围在 1.0×10 至 1.0×10 CFU/mL 的沙门氏菌，检测限低至 10 CFU/mL。在添加牛奶中的沙门氏菌的平均回收率约为 104.3%。
