近一次在美國爆發(fā)的大腸桿菌流行影響了12個西部州和600萬磅的肉類。這表明我們急需一種更好的進(jìn)行探測的設(shè)備。
來自Drexel大學(xué)化工系的教授Raj Mutharasan發(fā)明了一種可以在10分鐘內(nèi)檢測出肉類中大腸桿菌的感應(yīng)器。他目前正在和一家公司合作，計劃將這一產(chǎn)品商業(yè)化。與此同時，此種探測器還能在醫(yī)學(xué)診斷（如前列腺癌）以及檢測生物武器方面得到應(yīng)用。在醫(yī)療上，它能被用于分析4種常見的體液：血液、尿液、唾液和腦脊液。
目前的檢測食物中大腸桿菌的測試需要大約24小時，并且需要在實(shí)驗(yàn)室進(jìn)行。而Mutharasan的儀器能實(shí)現(xiàn)手提，且容易操作。目前市場上沒有快速測試少量蛋白的設(shè)備，在Analytical Chemistry的文章中，利用Mutharasan的儀器可以檢測出低濃度大腸桿菌。
Mutharasan的設(shè)備達(dá)到了在千分之一升溶液中4個細(xì)胞的檢測靈敏度。感應(yīng)器使用了大腸桿菌抗體來進(jìn)行探測，這類似于我們身體的工作機(jī)制?？贵w和一窄條玻璃結(jié)合，玻璃另一端是陶瓷層，它將通過產(chǎn)生電壓對機(jī)械壓力產(chǎn)生反應(yīng)。
在陶瓷層施加電壓后，會導(dǎo)致其膨脹和收縮，從而震蕩玻璃。感應(yīng)器通過探測玻璃的共振頻率的改變來確定是否有大腸桿菌的存在以及其濃度。
此外感應(yīng)器還可以探測液體和固體樣本，它能搭載各種不同的抗體來實(shí)現(xiàn)多種抗原的檢測，并且此感應(yīng)器可以實(shí)現(xiàn)對于有害**的極微量的測量。 （引自教育部科技發(fā)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.
