Ordering of bacteriophages in the electric field: Application for bacteria detection

• We present the novel method for orientation of bacteriophages.
• The sensitivity increases four times for ordered over disordered layer of phages.
• The limit of detection of E. coli by T4 phages is in the range of 102–103 cfu/mL.
• The described protocol can be applied to variety of unsymmetrical phage species.

Only in USA the nosocomial infections cause around 100,000 deaths per year. Majority of them could have been avoided if the pathogens would be identified shortly after infection. However, classical approaches are laborious; can take up to even 72 h. Here we demonstrate a step towards a sensor for fast detection of bacteria. The sensor is based on layer of oriented T4 bacteriophages. The sensitivity of biosensors increases four times for ordered over disordered layer of bacteriophages. This results in the limit of detection of Escherichia coli in the range of 102–103 cfu/mL. Such value is much lower when compared to similar sensors based on physisorbed layer of phages and is of the same order of magnitude as probes with chemically immobilized bacteriophages described in the literature. Proper orientation of bacteriophages prevents receptor binding proteins from being blocked. For the purpose we utilized the electrostatic interactions upon application of electric potential to the surface on which phages are deposited.