Electrostatic assembly of anti-listeria bacteriophages on a self-assembled monolayer of aminoundecanethiol: film morphology, charge transfer studies, and infectivity assays

The integration of bacteriophages, a particular class of viruses that specifically infect bacteria and archaea, in biosensors for the monitoring of pathogens in foods and beverages is highly desirable. To this end, an increasing focus has been set on the exploration of covalent and physical methods for the immobilization of phages on solid surfaces. This work investigates the electrostatic assembly of tailed phages, specifically anti-Listeria monocytogenes P100 phages, on an ultrathin self-assembled monolayer (SAM) of 11-amino-1-undecanethiol (AUT). The cationic properties of AUT may allow for the electrostatic capture of P100 in a capsid-down fashion, thereby exposing the specific receptor-binding proteins on their tails to the corresponding pathogens in the analytical samples. The morphology and charge transfer behavior of the assembled films were studied with atomic force microscopy, scanning electron microscopy and electrochemical techniques. These methods provided valuable insights into the orientation of the phages and the relevant role of the pH. Biological plaque assays revealed that the immobilized phages remain active towards the target bacterium. Overall, this research portrays SAMs of amino-akylthiols as a valid platform for the oriented immobilization of bacteriophages on surfaces for electroanalytical purposes.