Data from: Gramicidin and chlorhexidine encapsulated in bicontinuous microemulsions: Antimicrobial activity performance and their impact on self-assembly

The utility of bicontinuous microemulsions (BMEs) as carriers of the
antimicrobial peptide (AMP) gramicidin D and antiseptic chlorhexidine was
investigated for possible topical delivery to chronic wounds. The two
water-insoluble solutes dissolved in pre-formed one-phase BMEs of Water/
Polysorbate 80/ Limonene/ Ethanol/ Glycerol and Water/ Aerosol-OT (AOT)/
Polysorbate 85/ Isopropyl Myristate and an AOT/ Polysorbate 85 Winsor-III
system, achieving gramicidin and chlorhexidine concentrations of 1.0 (wt)%
and 0.5% individually and 0.5% and 0.3% in mixtures at 22oC, respectively.
Small-angle neutron scattering measurements demonstrated that both solutes
decreased surfactant interfacial activity and increased interfacial
fluidity for the Polysorbate 80 system. For the AOT/ Polysorbate systems,
ellipsoidal aggregates consisting of gramicidin and likely adsorbed
surfactant and oil formed, while chlorhexidine enhanced the surface
activity of surfactants. According to bioassays performed on artificial
skin, the incorporation of melittin, gramicidin, and chlorhexidine
enhanced the bioactivity of BMEs for 24 h treatment against relevant
antibiotic-resistant bacteria found on skin relative to controls. Yet, BME
treatments were less effective than aqueous melittin control, in contrast
to well diffusion bioassays performed previously. The results reflect the
strong impact of AMPs and antiseptics on BME structure and dynamics and
the complexity of formulating BMEs for optimal antimicrobial activity.