Single-Cell Detection: Test of Microbial Contamination Using Capillary Electrophoresis

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• 作者：Andrew W. Lantz ; Ye Bao ; Daniel W. Armstrong
• 刊名：Analytical Chemistry
• 出版年：2007
• 出版时间：February 15, 2007
• 年：2007
• 卷：79
• 期：4
• 页码：1720 - 1724
• 全文大小：102K
• 年卷期：v.79,no.4(February 15, 2007)
• ISSN：1520-6882

文摘

Single cells of bacteria and fungi were detected using acapillary electrophoresis-based test for microbial contamination in laboratory samples. This technique utilizesa dilute cationic surfactant buffer to sweep microorganisms out of the sample zone and a small plug of "blockingagent" to negate the cells' mobility and induce aggregation.Analysis times are generally under 10 min. Previously, anutrient broth media was reported as an effective blockingagent; however, the natural background fluorescence fromthe nutrient broth limited the detection sensitivity to ~50cells. In order to enhance the sensitivity of the techniquedown to a single cell, an alternative synthetic blockingagent was sought. Various potential blocking agents werescreened including salts, polypeptides, small organiczwitterions, and surfactants. Zwitterionic surfactants areshown to be attractive alternatives to a nutrient brothblocker and mimic the nutrient broth's effects on cellularaggregation and mobility. Specifically, caprylyl sulfobetaine provided the sharpest cell peaks. By substitutingcaprylyl sulfobetaine in place of the nutrient broth, thefluorescence of the blocker plug was reduced by as muchas 40×. This reduction in background noise enablesdetection of a single microorganism in a sample andallows this technique to be potentially used as a rapidsterility test. All single cells analyzed using this techniquedisplayed signal-to-noise ratios between 5 and 9.