A new method is described for characterizing the physicochemical properties of native microbial cells by using atomic force microscopy (AFM) with chemically functionalized probes. Adhesion forces were measured, under deionized water, between probes and model substrata functionalized with alkanethiol self-assembled monolayers terminated with OH and CH(3) groups. These were found to be 6 +/- 2 nN (n = 1024), 0.9 +/- 0.4 nN, and approximately 0 nN, for CH(3)/CH(3), CH(3)/OH, and OH/OH surfaces, respectively, and were not significantly influenced by changes of ionic strength (0.1 M NaCl versus deionized water). This shows that functionalized probes are very sensitive to changes of surface hydrophobicity. Using OH- and CH(3)-terminated probes, patterns of rodlets, approximately 10 nm in diameter, were visualized, under physiological conditions, at the surface of spores of Phanerochaete chrysosporium. Multiple (1024) force-distance curves recorded over 500 x 500-nm areas at the spore surface, either in deionized water or in 0.1 M NaCl solutions, always showed no adhesion for both OH- and CH(3)-terminated probes. Control experiments indicated that the lack of adhesion is not due to transfer of cellular material onto the probe, but to the hydrophilic nature of the spore surface.
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机译:描述了一种通过使用具有化学功能化探针的原子力显微镜(AFM)来表征天然微生物细胞的理化特性的新方法。在去离子水下,测量探针和模型基层之间的粘附力,该模型基层由烷硫醇自组装单分子层以OH和CH(3)基团终止。对于CH(3)/ CH(3),CH(3)/ OH和OH /,发现这些为6 +/- 2 nN(n = 1024),0.9 +/- 0.4 nN和大约0 nN。 OH表面分别不受离子强度变化的影响(0.1 M NaCl与去离子水相比)。这表明功能化的探针对表面疏水性的变化非常敏感。使用OH和CH(3)终止的探针,在生理条件下,在Phanerochaete chrysosporium的孢子表面上,观察到直径约10 nm的小棒的模式。在去离子水或0.1 M NaCl溶液中,在孢子表面500 x 500 nm区域记录的多个(1024)力-距离曲线始终显示对OH-和CH(3)终止的探针均无粘附力。对照实验表明缺乏粘附不是由于细胞材料转移到探针上,而是由于孢子表面的亲水性。
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