Application of an M13 bacteriophage displaying tyrosine on the surface for detection of Fe3+ and Fe2+ ions

Ferric and ferrous ion plays critical roles in bioprocesses, their influences in many fields have not been fully explored due to the lack of methods for quantification of ferric and ferrous ions in biological system or complex matrix. In this study, an M13 bacteriophage (phage) was engineered for use as a sensor for ferric and ferrous ions via the display of a tyrosine residue on the P8 coat protein. The interaction between the specific phenol group of tyrosine and Fe³⁺ / Fe²⁺ was used as the sensor. Transmission electron microscopy showed aggregation of the tyrosine-displaying phages after incubation with Fe³⁺ and Fe²⁺. The aggregated phages infected the host bacterium inefficiently. This phenomenon could be utilized for detection of ferric and ferrous ions. For ferric ions, a calibration curve ranging from 200 nmol/L to 8 μmol/L with a detection limit of 58 nmol/L was acquired. For ferrous ions, a calibration curve ranging from 800 nmol/L to 8 μmol/L with a detection limit of 641.7 nmol/L was acquired. The assay was specific for Fe³⁺ and Fe²⁺ when tested against Ni²⁺, Pb²⁺, Zn²⁺, Mn²⁺, Co²⁺, Ca²⁺, Cu²⁺, Cr³⁺, Ba²⁺, and K⁺. The tyrosine displaying phage to Fe³⁺ and Fe²⁺ interaction would have plenty of room in application to biomaterials and bionanotechnology.