Nanomechanical Characterization of Bacillus anthracis Spores by Atomic Force Microscopy.

Unlabelled: The study of structures and properties of bacterial spores is important to understanding spore formation and biological responses to environmental stresses. While significant progress has been made over the years in elucidating the multilayer architecture of spores, the mechanical properties of the spore interior are not known. Here, we present a thermal atomic force microscopy (AFM) study of the nanomechanical properties of internal structures of Bacillus anthracis spores.

Thermal effects on surface structures and properties of Bacillus anthracis spores on nanometer scales.

Bacterial spores, one of the hardiest forms of life known, can survive severe environmental stresses such as high temperature. Using thermal atomic force microscopy (AFM), we show that the surface structures and properties of Bacillus anthracis spores when exposed to elevated temperatures undergo substantial changes on nanometer scales. Thermal-blister-like nanostructures, which grow in size with increasing temperature, are formed on the spore surface when it is heated by a thermal tip.

Glass transitions in nanoscale heated volumes of thin polystyrene films.

Glass transitions in confined polystyrene films on a silicon substrate were studied using atomic force microscopy incorporating a thermal tip. Three-dimensional spatial nanoconfinements were achieved by controlling size and boundary conditions of small heated volumes of polymer nanostrands drawn from the polymer surface with the thermal tip, using appropriate loads and temperatures at the tip-polymer contact. Finite element analysis was performed to model mechanical contact and thermal transport, including the effects of contact radius, film thickness, and load on temperature and pressure distributions in the confined volume at the contact.