Development of silver/α-lactalbumin nanocomposites: a new approach to reduce silver toxicity

The current use of silver is limited to certain medical applications owing to two major toxicity concerns, namely low haemocompatibility and silver release-induced skin discoloration, both of which have been attributed to the interaction between silver and blood cysteine. To address these challenges, in this study silver/protein nanocomposites were prepared using α-lactalbumin (ALA), a high-cysteine protein. The effect of the cysteine redox state of ALA on physicochemical characteristics was evaluated, and the nanocomposites were formed by Ag–S or Ag–N coordination bonds and electrostatic attractions. The optimum balance between antimicrobial efficacy and toxicity was achieved by treating freshly prepared silver and reduced ALA (ALAred) nanocomposite with ultraviolet radiation, which resulted in a dramatic reduction in toxicity and maintenance of antimicrobial activity. We anticipate that these promising results may have a great impact on broadening the clinical application of silver-based antimicrobial agents.