Incorporation of the
antimicrobial peptide LL-37 (LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES), as well as low molecular weight antimicrobial
chlorhexidine, into mesoporous
silica was obtained using an EISA one-pot synthesis method. FTIR confirmed efficient encapsulation of both LL-37 and
chlorhexidine into mesoporous
silica, while XRD and TEM showed that
antimicrobial agent incorporation can be achieved without greatly affecting the structure of the mesoporous
silica. The modified mesoporous
silica released LL-37 and
chlorhexidine slowly, reaching maximum release after about 200 h. The release rate could also be controlled through incorporation of SH groups in the pore walls, adding to pore hydrophobicity and reducing the release rate by about 50% compared to the unmodified mesoporous
silica. Mesoporous
silica containing either LL-37 or
chlorhexidine displayed potent bactericidal properties against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. While
chlorhexidine-loaded mesoporous
silica displayed an accompanying high toxicity, as judged from
hemolysis, LDH release, and MTT assay, the corresponding material containing LL-37 showed very low toxicity by all these assays, comparable to that observed for mesoporous
silica in the absence of antibacterial drug, as well as to the negative controls in the respective assays. Mesoporous
silica containing LL-37 therefore holds potential as an implantable material or a surface coating for such materials, as it combines potent bactericidal action with low toxicity, important features for controlling implant-related
infections, e.g., for multi-resistant pathogens or for cases where access to the
infection site of systemically administered
antibiotics is limited due to
collagen capsule formation or other factors.