Silica nanoparticle size distributions were measured fromtransmission electron micrographs of bacterial cells in thin-sectioned hot spring sediment samples, as well as specimens from laboratory experiments on bacterial silicification. Diameters of silica nanoparticleson bacterial cells were smaller than corresponding values ofthose occurring away from bacteria in the same fields of view. Regression analysis of the particle size data and application of theLifshitz-van derWaals Acid-Base approach to evaluations of solid surface energy established that the size difference extends from a nearly 40 decrease in the mean interfacial energy of silica nanoparticles on bacteria (0.9 mJ/m2) as opposed to free in aqueous suspension (1.2 mJ/m2). In thermodynamic terms, the lower interfacial energy serves to reduce equilibrium solubility values, andenhance nucleation rates, of silica nanoparticles on bacteria cells.The well documented culmination of these events in hot spring sedimentsand experimental studies is rapid preferential silicificationand structural preservation of bacterial cells.
展开▼
