Department of Electrical Engineering & Computer Science, University of Tennessee, Knoxville, TN 37996, United States.
Colloids Surf B Biointerfaces. 2012 Apr 1;92:271-6. doi: 10.1016/j.colsurfb.2011.11.052. Epub 2011 Dec 8.
The adhesion of spores of Bacillus anthracis - the cause of anthrax and a likely biological threat - to solid surfaces is an important consideration in cleanup after an accidental or deliberate release. However, because of safety concerns, directly studying B. anthracis spores with advanced instrumentation is problematic. As a first step, we are examining the electrostatic potential of Bacillus thuringiensis (Bt), which is a closely related species that is often used as a simulant to study B. anthracis. Scanning surface potential microscopy (SSPM), also known as Kelvin probe force microscopy (KPFM), was used to investigate the influence of relative humidity (RH) on the surface electrostatic potential of Bt that had adhered to silica, mica, or gold substrates. AFM/SSPM side-by-side images were obtained separately in air, at various values of RH, after an aqueous droplet with spores was applied on each surface and allowed to dry before measurements. In the SSPM images, a negative potential on the surface of the spores was observed compared with that of the substrates. The surface potential decreased as the humidity increased. Spores were unable to adhere to a surface with an extremely negative potential, such as mica.
炭疽杆菌孢子的黏附性——炭疽病的病因，也是一种可能的生物威胁——对固体表面的黏附性是事故或故意释放后的清理工作中的一个重要考虑因素。然而，由于安全问题，直接用先进仪器研究炭疽杆菌孢子存在问题。作为第一步，我们正在检查苏云金芽孢杆菌（Bt）的静电势，这是一种密切相关的物种，通常被用作研究炭疽杆菌的模拟物。扫描表面电势显微镜（SSPM），也称为 Kelvin 探针力显微镜（KPFM），用于研究附着在二氧化硅、云母或金基底上的 Bt 对相对湿度（RH）的表面静电势的影响。在每种表面上施加含有孢子的水滴并在测量前让其干燥后，在空气中以不同的 RH 值分别获得 AFM/SSPM 并排图像。与基底相比，在 SSPM 图像中观察到孢子表面的负电势。随着湿度的增加，表面电势降低。孢子无法附着在电势非常负的表面上，例如云母。
