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Keywords:

  • antibacterial applications;
  • bacteriophages;
  • Kevlar;
  • phage fibers;
  • silver

Abstract

Multifunctionality can be imparted to protein-based fibers and coatings via either synthetic or biological approaches. Here, potent antimicrobial functionality of genetically engineered, phage-based fibers and fiber coatings, processed at room temperature, is demonstrated. Facile genetic engineering of the M13 virus (bacteriophage) genome leverages the well-known antibacterial properties of silver ions to kill bacteria. Predominant expression of negatively charged glutamic acid (E3) peptides on the pVIII major coat proteins of M13 bacteriophage enables solution-based, electrostatic binding of silver ions and subsequent reduction to metallic silver along the virus length. Antibacterial fibers of micrometer-scale diameters are constructed from such an E3-modified phage via wet-spinning and glutaraldehyde-crosslinking of the E3-modified viruses. Silverization of the free-standing fibers is confirmed via energy dispersive spectroscopy and inductively coupled plasma atomic emission spectroscopy, showing ∼0.61 µg cm−1 of silver on E3–Ag fibers. This degree of silverization is threefold greater than that attainable for the unmodified M13–Ag fibers. Conferred bactericidal functionality is determined via live–dead staining and a modified disk-diffusion (Kirby–Bauer) measure of zone of inhibition (ZoI) against Staphylococcus epidermidis and Escherichia coli bacterial strains. Live–dead staining and ZoI distance measurements indicate increased bactericidal activity in the genetically engineered, silverized phage fibers. Coating of Kevlar fibers with silverized E3 phage exhibits antibacterial effects as well, with relatively smaller ZoIs attributable to the lower degree of silver loading attainable in these coatings. Such antimicrobial functionality is amenable to rapid incorporation within fiber-based textiles to reduce risks of infection, biofilm formation, or odor-based detection, with the potential to exploit the additional electronic and thermal conductivity of fully silverized phage fibers and coatings.