Silk microfibrous mats with long-lasting antimicrobial function

The controlled release of antibiotic drugs to injured sites has great advantages over the conventional intravenous administration of antibiotics, which is associated with systemic toxicity, for wound care. Electrospun nanofibrous/microfibrous mats, with a similar structure to the native extracellular matrix, is a promising wound dressing. Herein, drug-loaded halloysite nanotubes (HNTs) incorporated into regenerated silk fibroin (RSF) microfibrous mats were prepared by electrospinning to achieve sustained drug release and long-lasting antimicrobial protection. A broad-spectrum antibiotic, tetracycline hydrochloride (TCH), was selected as the model drug. Transmission electron microscopic images revealed that the TCH-loaded HNTs were homogeneously embedded in the RSF electrospun microfibers without significant changes in morphology. The drug release profiles showed that the RSF microfibrous mats with TCH-loaded HNTs exhibited a significantly reduced burst phase and a long release time over two weeks compared to the pure TCH-loaded HNTs and the TCH-loaded RSF microfibrous mats without HNTs. These results were attributed to the two-step release of TCH first from the HNTs and then RSF matrix in the electrospun mats. Finally, the antimicrobial properties of the RSF microfibrous mats with TCH-loaded HNTs were evaluated using both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. The results demonstrated long-lasting antimicrobial activity for at least one week, showing the great potential of TCH-loaded RSF microfibrous mat as a wound dressing material. Therefore, these TCH-loaded RSF microfibrous mats with excellent biocompatibility and sustained antimicrobial protection are extremely attractive systems for clinical applications.