Modification of Honeybee Silk by the Addition of Antimicrobial Agents

Honeybee silk proteins can be produced at high levels in recombinant systems, fabricated into materials, and are tolerant of amino acid modifications: properties that make them exciting templates for designing new functional materials. Here, we explore the properties of materials either made from silk-antimicrobial peptide (AMP) fusion proteins or silk containing entrapped AMPs or silver nanoparticles. Inclusion of AMP within the silk protein sequence did not affect our ability to express the proteins or process them into films. When AMP-silk proteins and Escherichia coli cells were coincubated in solution, a reduction in cell numbers was observed after degradation of the chimeric protein to release a truncated version of the AMP. In films, the AMP was retained in the silk with leaching rates of <1% per day. Films containing silver nanoparticles were antimicrobial, with the silk preventing aggregation of nanoparticles and slowing the rate of dissolution of the particles.