Department of Biomedical Engineering, University Medical Center Groningen and University of Groningen, P.O. Box 196, 9700 AD Groningen, The Netherlands.
Langmuir. 2010 Jul 6;26(13):11113-7. doi: 10.1021/la100896a.
Studies in flow displacement systems have shown that the reversibility of bacterial adhesion decreases within seconds to minutes after initial contact of a bacterium with a substratum surface. Atomic force microscopy (AFM) has confirmed that the forces mediating bacterial adhesion increase over a similar time span. The interfacial rearrangements between adhering bacteria and substratum surfaces responsible for this bond maturation have never been studied. Quartz crystal microbalance with dissipation (QCM-D) senses the interfacial region in real time and nondisruptively up to 250 nm from the sensor surface. In this paper, QCM-D is combined with real-time observation of bacterial adhesion in a flow displacement system, in order to analyze resident-time-dependent changes in dissipation. Three different Streptococcus salivarius strains showed a nonlinear relation between total dissipation shift (DeltaD) and number of adhering bacteria, whereas inert and rigid silica particles demonstrated a linear relation between DeltaD and the number of adhering particles. This suggests removal of interfacial water due to residence time dependent deformation of the nonrigid bacterium-substratum interface during bond maturation. Dissipation could be described by an exponentially decaying function, which combined with adhesion data allowed extraction of the dissipation shifts per bacterium upon initial contact (DeltaD(0)), after bond maturation (DeltaD(infinity)), as well as a characteristic time constant (tau(bm)). All bacterial strains showed significant bond maturation within one minute after their arrival at the substratum surface, which was not observed for silica particles. Dissipation analysis at the level of individually adhering bacteria would have been impossible without the simultaneous real-time analysis of bacterial adhesion numbers.
在流动置换系统中的研究表明，细菌与基质表面初始接触后的几秒钟到几分钟内，细菌黏附的可逆性降低。原子力显微镜（AFM）已经证实，介导细菌黏附的力在相似的时间范围内增加。负责这种键合成熟的黏附细菌和基质表面之间的界面重排从未被研究过。石英晶体微天平（QCM-D）实时检测界面区域，在传感器表面 250nm 范围内无干扰。在本文中，QCM-D 与流动置换系统中细菌黏附的实时观察相结合，以分析耗散的驻留时间依赖性变化。三种不同的唾液链球菌（Streptococcus salivarius）菌株表现出总耗散位移（DeltaD）与黏附细菌数量之间的非线性关系，而惰性和刚性二氧化硅颗粒则表现出耗散与黏附颗粒数量之间的线性关系。这表明，由于非刚性细菌-基质界面在键合成熟过程中的驻留时间依赖性变形，界面水被去除。耗散可以用指数衰减函数来描述，该函数与黏附数据相结合，允许提取初始接触时（DeltaD(0)）、键合成熟后（DeltaD(infinity)）以及特征时间常数（tau(bm)）每个细菌的耗散位移。所有细菌菌株在到达基质表面后的一分钟内都表现出明显的键合成熟，而二氧化硅颗粒则没有观察到。如果没有对单个黏附细菌的实时黏附数量进行同时分析，就不可能进行耗散分析。
