Mondal Bhairab, Ramlal Shylaja, Lavu Padma S, N Bhavanashri, Kingston Joseph
Microbiology Division, Defence Food Research Laboratory, Mysore, India.
Front Microbiol. 2018 Feb 13;9:179. doi: 10.3389/fmicb.2018.00179. eCollection 2018.
A simple, sensitive and selective colorimetric biosensor for the detection of Staphylococcal enterotoxin B (SEB) was developed using SEB-binding aptamer (SEB2) as recognition element and unmodified gold nanoparticles (AuNPs) as colorimetric probes. The assay is based on color change from red to purple due to conformational change of aptamer in the presence of SEB, and the phenomenon of salt-induced AuNPs aggregation which could be monitored by naked eye or UV-vis spectrometer. Results showed that the AuNPs can effectively differentiate the SEB induced conformational change of the aptamer in the presence of a given high salt concentration. A linear response in the range of 50 μg/mL to 0.5 ng/mL of SEB concentration was obtained. The assay was highly specific to SEB as compared to other related toxins. The limit of detection (LOD) of SEB achieved within few minutes was 50 ng/mL visually and spectrometric method improved it to 0.5 ng/mL. Robustness of the assay was tested in artificially spiked milk samples and cross-checked using in house developed sandwich ELISA (IgY as capturing and SEB specific monoclonal as revealing antibody) and PCR. This colorimetric assay could be a suitable alternative over existing methods during biological emergencies due to its simplicity, sensitive and cost effectiveness.
一种用于检测葡萄球菌肠毒素B（SEB）的简单、灵敏且具选择性的比色生物传感器被开发出来，该传感器使用SEB结合适体（SEB2）作为识别元件，未修饰的金纳米颗粒（AuNPs）作为比色探针。该检测方法基于在SEB存在时适体构象变化导致的从红色到紫色的颜色变化，以及盐诱导的AuNPs聚集现象，这一现象可用肉眼或紫外可见光谱仪监测。结果表明，在给定的高盐浓度下，AuNPs能够有效区分SEB诱导的适体构象变化。获得了在50 μg/mL至0.5 ng/mL的SEB浓度范围内的线性响应。与其他相关毒素相比，该检测方法对SEB具有高度特异性。在几分钟内实现的SEB检测限，肉眼检测为50 ng/mL，光谱法将其提高到0.5 ng/mL。在人工加标的牛奶样品中测试了该检测方法的稳健性，并使用内部开发的夹心ELISA（以IgY作为捕获抗体，以SEB特异性单克隆抗体作为检测抗体）和PCR进行了交叉检验。由于其简单、灵敏且成本效益高，这种比色检测方法在生物紧急情况下可能是现有方法的合适替代方法。
