Gold templated on spheroidal M13 bacteriophage as a photothermal bactericide

Antibiotic resistant bacteria have increasingly become a health issue. Photothermal lysis using plasmonic metal nanostructures is effective against bacteria, regardless of drug resistance. Viruses provide an approach to the synthesis of bacteria-targeting metal nanoshells. A virus can be genetically programmed to both serve as a scaffold for metal nanostructure assembly and have an affinity for a specific bacterial host. In this work, we used an Au-binding M13 virus to create a photothermal bactericide for e coli. The virus geometry was converted from filament to spheroid via chloroform treatment. Au nanoshells were formed by (1) binding Au NPs to the spheroid for visible light absorption and (2) synthesizing an Au shell on the spheroid for NIR absorption. TEM and spectrophotometry were used to assess morphology and optical absorption, respectively. Nanoshell photothermal activity was quantified under either green or NIR illumination. Antibacterial activity was measured via titer count. Au/M13 nanoshells acted as photothermal bactericide. This potentially powerful approach can be generalized to target a variety of bacteria through the use of different affinity peptides.