DeMarco D R, Saaski E W, McCrae D A, Lim D V
Department of Biology, University of South Florida, Tampa 33620, USA.
J Food Prot. 1999 Jul;62(7):711-6. doi: 10.4315/0362-028x-62.7.711.
A portable fiber-optic biosensor was used to detect Escherichia coli O157:H7 in seeded ground beef samples. The principle of the system is a sandwich immunoassay using cyanine 5 dye-labeled polyclonal anti-E. coli O157:H7 antibodies for generation of a specific fluorescent signal. Signal acquisition is effected by launching light from a 635-nm diode laser into a dual tapered 600-microm silica fiber. Fluorescent molecules within approximately 100 nm of the fiber surface are excited by the evanescent field, and a portion of the emission recouples into the fiber. A photodiode allows for quantitation of the collected emission light at wavelengths of 670 to 710 nm. Biotin-avidin interactions are used to attach polyclonal antibodies specific for E. coli O157:H7 to the final 7.5 cm of the fiber probe. The biosensor was able to detect E. coli O157:H7 to 3 to 30 CFU/ml in seeded ground beef samples. The reaction was highly specific. Signals with Listeria monocytogenes, Salmonella Typhimurium, or E. coli nonO157:H7 were 2 to 3% of those observed with a similar concentration of E. coli O157:H7. Assays were conducted at or near real-time with results obtained within 20 min of sampling.
一种便携式光纤生物传感器被用于检测接种在绞碎牛肉样本中的大肠杆菌O157:H7。该系统的原理是一种夹心免疫测定法，使用花青5染料标记的抗大肠杆菌O157:H7多克隆抗体来产生特定的荧光信号。信号采集是通过将来自635纳米二极管激光器的光发射到双锥形600微米石英光纤中来实现的。光纤表面约100纳米内的荧光分子被倏逝场激发，一部分发射光重新耦合到光纤中。一个光电二极管用于对在670至710纳米波长处收集的发射光进行定量。生物素-抗生物素蛋白相互作用被用于将针对大肠杆菌O157:H7的多克隆抗体连接到光纤探针的最后7.5厘米处。该生物传感器能够在接种的绞碎牛肉样本中检测到3至30 CFU/ml的大肠杆菌O157:H7。该反应具有高度特异性。单核细胞增生李斯特菌、鼠伤寒沙门氏菌或非O157:H7大肠杆菌产生的信号是相同浓度大肠杆菌O157:H7所观察到信号的2%至3%。检测在接近实时的情况下进行，在采样后20分钟内获得结果。
