Bacteriophages have recently been viewed as an important tool in the fight against antibiotic-resistant bacteria. However, bacteriophages are viruses whose biology is not fully understood and which replicate and evolve directly within the host organism. Some view these properties of phages as a significant advantage over synthetic agents, while others expect greater predictability and controllability from these drugs. For example, a recent study used bacteriophages to attack pathogenic bacteria but were immediately destroyed afterwards.

To bring the bacterial killing process under tight control, scientists from the University of California (USA) combined bacteriophages with gold nanoparticles. The bacteriophages were chimeric—created through genetic manipulation to specifically interact with several Gram-negative bacteria, including Escherichia coli, Pseudomonas aeruginosa , and Vibrio cholerae , which are pathogenic to humans, as well as Xanthomonas campestris, which is pathogenic to plants.

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Chimeric phages conjugated to gold nanoparticles precisely located target bacteria. Upon exposure to infrared waves, the nanoparticles heated up and began to intensely generate heat, which killed the target bacteria. This process is called photothermal ablation. The heat generated by the nanoparticles was so localized that the epithelial cells hosting P. aeruginosa biofilms suffered minimal damage. The phages were killed along with the bacteria, preventing their further reproduction.

The authors believe that combining the specificity of phages in recognizing bacteria with the photothermal properties of gold nanoparticles is an effective and well-controlled approach to combating pathogenic bacteria.

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* Peng H, Borg RE, Dow LP, Pruitt BL, Chen IA. Controlled phage therapy by photothermal ablation of specific bacterial species using gold nanorods targeted by chimeric phages // PNAS, 2020, 201 913 234; DOI: 10.1073/pnas.1913234117