Elasticity of Pseudomonas putida KT2442 surface polymers probed with single-molecule force microscopy
Elasticity of Pseudomonas putida KT2442 surface polymers probed with single-molecule force microscopy
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DOI：
10.1021/la015695b
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发表时间：
2002-05-14
期刊：
影响因子：
3.9
通讯作者：
Camesano, TA
中科院分区：
文献类型：
--
作者：
Abu-Lail, NI;Camesano, TA
利用单分子力显微镜研究了溶剂极性和离子强度对细菌表面聚合物弹性的影响。利用原子力显微镜（AFM）测量恶臭假单胞菌KT 2442细菌细胞与氮化硅针尖之间的粘附力。分析力延伸曲线以确定聚合物链在几种溶剂（水、甲酰胺、甲醇、0.1 M KCl和0.01 M KCl）中的弹性。将粘附峰拟合到基于熵的统计机械随机游走公式（自由连接链（FJC）和蠕虫状链（WLC）模型）。实验数据显示与FJC（平均R-2 = 0.86 +/-0.20）的一致性优于WLC模型（平均R-2 = 0.76 +/-0.22）。使用FJC模型，在所有五种溶剂中的链段长度为0.18 - 1.0 nm，其中约60%的链段长度为0.154 - 0.20 nm。使用WLC模型的持续长度为0.18 - 0.83 nm，约78%的链具有0.154 - 0.20 nm的持续长度。WLC模型不能代表<11 nm的链的聚合物性质（4%的数据），因为获得的持久长度短于C-C键。WLC模型也未能预测KCl溶液和甲醇中的高量级粘附力。考虑了可扩展自由连接链模型（FJC+），因为后者考虑了FJC模型中忽略的交叉效应，但它并没有比FJC模型更好地代表数据。在这些溶剂中的生物聚合物和AFM针尖之间的粘附相互作用进行了比较。在极性最小的溶剂甲醇中粘附性最高。在水和甲酰胺中的粘附力大致相同，并且小于在甲醇中观察到的力。虽然生物聚合物的轮廓长度在很宽的范围内变化（数十至数百纳米），在所有溶剂中，观察到较短的长度时，盐的存在，表明聚合物链在盐的存在下延伸较少。
Single-molecule force microscopy was used to study the effect of solvent polarity and ionic strength on the elasticity of bacterial surface polymers. Adhesion forces were measured between Pseudomonas putida KT2442 bacterial cells and silicon nitride tips of an atomic force microscope (AFM). Force-extension profiles were analyzed to determine the elasticity of the polymer chains in several solvents (water, formamide, methanol, 0.1 M KCl, and 0.01 M KCl). Adhesion peaks were fit to entropic-based, statistical mechanical, random walk formulations (the freely jointed chain (FJC) and the wormlike chain (WLC) models). The experimental data showed better agreement with the FJC (average R-2 = 0.86 +/- 0.20) than the WLC model (average R-2 = 0.76 +/- 0.22). The segment length was 0.18-1.0 nm in all five solvents using the FJC model, with about 60% of the chains having a segment length of 0.154-0.20 nm. The persistence length was 0.18-0.83 nm using the WLC model, with about 78% of chains having a persistence length of 0.154-0.20 rim. The WLC model was not able to represent polymer properties for chains of < 11 nm (4% of the data), since persistence lengths shorter than the C-C bond were obtained. The WLC model also failed to predict the high-magnitude adhesion forces in KCl solutions and methanol. The extensible freely jointed chain model (FJC+) was considered since the latter accounts for enthalpic effects neglected in the FJC model, but it did not represent the data better than the FJC model. Adhesive interactions between the biopolymer and the AFM tip were compared in these solvents. Adhesion was highest in the least polar solvent, methanol. Adhesion forces in water and formamide were about the same and less than forces observed in methanol. Although biopolymer contour lengths varied over a wide range (tens to hundreds of nanometers) in all solvents, shorter lengths were observed when salt was present, indicating that the polymer chains were less extended in the presence of salt.