Adhesion of microbes using 3-aminopropyl triethoxy silane and specimen stabilisation techniques for analytical transmission electron microscopy

A variety of adhesive support-films were tested for their ability to adhere various biological specimens for transmission electron microscopy. Support films primed with 3-amino-propyl triethoxy silane (APTES), poly-L-lysine, carbon and ultraviolet-B (UV-B)-irradiated carbon were tested for their abi lity to adhere a variety of biological specimens including axenic cultures of Bacillus subtilis and Escherichia coli and wild-type magnetotactic bacte ria. The effects of UV-B irradiation on the support film in the presence of air and electrostatic charge on primer deposition were tested and the stab ility of adhered specimens on various surfaces was also compared. APTES-pri med UV-B-irradiated Pioloform(TM) was consistently the best adhesive, espec ially for large cells, and when adhered specimens were UV-B irradiated they became remarkably stable under an electron beam. This assisted the acquisi tion of in situ phase-contrast lattice images from a variety of biominerals in magnetotactic bacteria, in particular metastable greigite magnetosomes. Washing tests indicated that specimens adhering to APTES-primed UV-B-irrad iated Pioloform(TM) were covalently coupled. The electron beam stability wa s hypothesised to be the result of mechanical strengthening of the specimen and support film and the reduced electrical resistance in the specimen and support film due to their polymerization and covalent coupling.