Bio-Assembly of Bactericidal Inorganic Nanostructures Using M13 Bacteriophage Filaments, Rods and Spheroids

In recent years, the bacteriophage has been used as a versatile template to create inorganic nanomaterials and as a potential bactericidal agent to fight multidrug resistant bacteria. The M13 bacteriophage is a viable platform for bactericidal materials with an innate ability to target bacteria. The phage itself is a micron long, filamentous biological molecule. Extensive research has shown that this phage can be genetically modified to bind and biomineralize various inorganic nanostructures. Furthermore, unlike other viruses, the M13 bacteriophage has been shown to drastically change shape and aspect ratio upon contact with chloroform, morphing from its filamentous form to either rods 100s of nanometers long or sub 100 nm spheroids. These different geometries could provide an excellent platform to deliver bactericidal materials due to their compactness. In this study, we investigated the M13 bacteriophage as a template for bactericidal ZnO and gold nanoparticles and as a E. coli targeting platform. A filamentous genetically modified M13 bacteriophage, with the DRQVDATA peptide insert, was shown to have synthesize amorphous ZnO nanoparticles. Due to the low particle count and the phage agglomerates, the ZnO was found to be unsuitable for bactericidal purposes. No further investigation into the phage geometry was performed. A different avenue was explored with gold templated phage. To create a suitable gold platform, a gold-binding phage morphology was tailored to maximize contact of gold nanoparticles to the E. coli membrane. The binding and biomineralization properties of the transformed was examined and it was found that the templates retained its binding and mineralization properties. Furthermore, the gold mineralized on the spheroids differed from the gold grown on the filaments, where spike-like structures extended outward while isotropic particles grew on the latter. These gold/phage platforms were then studied for their targeting and photothermal bactericidal properties. It was found that the Au/template was able to target the E. coli and via the photothermal effect, kill off more than 63% of the bacteria under 532 nm irradiation. These Au/templates were shown to be effective photothermal bactericide and could be further expanded to target other bacteria and to be used in near infrared wavelengths