College of Food Science and Engineering, Northwest A&F University, 22 Xinong Road, Yangling 712100, Shaanxi, China.
Qinghai Key Laboratory of Qinghai-Tibet Plateau Biological Resources, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, Qinghai, China.
Biosens Bioelectron. 2019 May 1;132:360-367. doi: 10.1016/j.bios.2019.02.061. Epub 2019 Mar 5.
Lateral flow immunoassay (LFIA) is a class and widespread applied point-of-care biosensor in the rapid monitoring field. To address the matched antibodies and antibody labeling dependence in the conventional LFIAs, in this work, an innovative label-free LFIA was proposed for the sensitive detection of Salmonella enteritidis (S. enteritidis) by introducing a new nanoparticles-bacteria-antibody sandwich strategy in the sensor. Surface positively charged nitrogen-rich carbon (pNC) nanoparticles, synthesized via calcination and etching reactions, were used as adsorbent to capture bacteria as well as for generating signals. In the presence of target pathogens, bacterial cells could combine with pNC through electrostatic interaction and hydrogen bonding, then the complex would be captured specifically by the anti-bacteria monoclonal antibody (McAb) coated on the test line (T-line). With the accumulation of nanoparticles-bacteria, the color on T-line would be gradually deepened from nearly colorless to deep black. Importantly, the pNC-based immunoassay could exhibit high sensitivity for target pathogens detection with a linear range of 10-10 cfu mL and a low detection limit of 10 cfu mL. Furthermore, this system was validated preliminarily to screen S. enteritidis in different food samples with recoveries ranging from 85% to 110%. Taking advantages of simplicity, label-free, convenience, and sensitivity, the pNC-based LFIA has the application potential for pathogenic microorganisms monitoring in food safety and early clinical diagnosis fields.
侧向流动免疫分析（LFIA）是一种应用广泛的即时检测生物传感器，在快速监测领域得到了广泛应用。为了解决传统 LFIA 中匹配抗体和抗体标记的依赖性问题，本工作提出了一种创新的无标记 LFIA，通过在传感器中引入新的纳米颗粒-细菌-抗体三明治策略，用于灵敏检测肠炎沙门氏菌（S. enteritidis）。通过煅烧和蚀刻反应合成的带正电荷的富氮碳（pNC）纳米颗粒作为吸附剂，不仅可以捕获细菌，还可以产生信号。在存在目标病原体的情况下，细菌细胞可以通过静电相互作用和氢键与 pNC 结合，然后复合物将被涂覆在测试线上（T 线）的抗细菌单克隆抗体（McAb）特异性捕获。随着纳米颗粒-细菌的积累，T 线的颜色会逐渐从几乎无色加深到深黑色。重要的是，基于 pNC 的免疫分析对目标病原体的检测具有高灵敏度，线性范围为 10-10 cfu/mL，检测限低至 10 cfu/mL。此外，该系统已初步验证可用于筛选不同食品样本中的肠炎沙门氏菌，回收率在 85%至 110%之间。基于 pNC 的 LFIA 具有简单、无标记、方便和灵敏的优点，在食品安全和早期临床诊断领域具有监测致病性微生物的应用潜力。
