近一次在美国爆发的大肠杆菌流行影响了12个西部州和600万磅的肉类。这表明我们急需一种更好的进行探测的设备。
来自Drexel大学化工系的教授Raj Mutharasan发明了一种可以在10分钟内检测出肉类中大肠杆菌的感应器。他目前正在和一家公司合作，计划将这一产品商业化。与此同时，此种探测器还能在医学诊断（如前列腺癌）以及检测生物武器方面得到应用。在医疗上，它能被用于分析4种常见的体液：血液、尿液、唾液和脑脊液。
目前的检测食物中大肠杆菌的测试需要大约24小时，并且需要在实验室进行。而Mutharasan的仪器能实现手提，且容易操作。目前市场上没有快速测试少量蛋白的设备，在Analytical Chemistry的文章中，利用Mutharasan的仪器可以检测出低浓度大肠杆菌。
Mutharasan的设备达到了在千分之一升溶液中4个细胞的检测灵敏度。感应器使用了大肠杆菌抗体来进行探测，这类似于我们身体的工作机制。抗体和一窄条玻璃结合，玻璃另一端是陶瓷层，它将通过产生电压对机械压力产生反应。
在陶瓷层施加电压后，会导致其膨胀和收缩，从而震荡玻璃。感应器通过探测玻璃的共振频率的改变来确定是否有大肠杆菌的存在以及其浓度。
此外感应器还可以探测液体和固体样本，它能搭载各种不同的抗体来实现多种抗原的检测，并且此感应器可以实现对于有害**的极微量的测量。 （引自教育部科技发展中心）
原文摘要：
The latest outbreak of E. coli cases — now in 12 western states and involving 6 million pounds of fresh and frozen meat — shows a need for better detection in food processing exists.
Abstract:
A sensitive and reliable method for the detection of Bacillus anthracis (BA; Sterne strain 7702) spores in presence of large amounts of Bacillus thuringiensis (BT) and Bacillus cereus (BC) is presented based on a novel PZT-anchored piezoelectric excited millimeter-sized cantilever (PAPEMC) sensor with a sensing area of 1.5 mm2. Antibody (anti-BA) specific to BA spores was immobilized on the sensing area and exposed to various samples of BA, BT, and BC containing the same concentration of BA at 333 spores/mL, and the concentration of BT + BC was varied in concentration ratios of (BA:BT + BC) 0:1, 1:0, 1:1, 1:10, 1:100, and 1:1000. In each case, the sensor responded with an exponential decrease in resonant frequency and the steady-state frequency changes reached were 14 ± 31 (n = 11), 2742 ± 38 (n = 3), 3053 ± 19 (n = 2), 2777 ± 26 (n = 2), 2953 ± 24 (n = 2), and 3105 ± 27 (n = 2) Hz, respectively, in 0, 27, 45, 63, 154, and 219 min. The bound BA spores were released in each experiment, and the sensor response was nearly identical to the frequency change during attachment. These results suggest that the transport of BA spores to the antibody immobilized surface was hindered by the presence of other Bacillus species. The observed binding rate constant, based on the Langmuir kinetic model, was determined to be 0.15 min-1. A hindrance factor is defined to describe the reduced attachment rate in the presence of BT + BC and found to increase exponentially with BT and BC concentration. The hindrance factor increased from 3.52 at 333 BT + BC spores/mL to 11.04 at 3.33 × 105 BT + BC spores/mL, suggesting that is a strong function of BT and BC concentration. The significance of these results is that anti-BA functionalized PEMC sensors are highly selective to Bacillus anthracis spores and the presence of other Bacillus species, in large amounts, does not prevent binding but impedes BA transport to the sensor.
