Structural and probing dynamics of Brij-35-based microemulsion for fluoroquinolone antibiotics

In this study, an oil-in-water microemulsion (µE) formulation was developed using clove oil/Brij-35/isopropanol/water to solubilize fluoroquinolone (FLQ) antibiotics, namely, Ciprofloxacin (CF), Levofloxacin (LF), and Moxifloxacin (MF). Through the mapping of pseudo-ternary phase diagram, optimum µE containing clove oil (18%) and water (26%) were established, maintaining the Brij-35/isopropanol ratio (1:1) to upheld the appropriate amount of FLQ, i.e., CF (3.8 wt. %), LF (5.2 wt. %), and MF (4.2 wt. %). Through optical microscopy and electrical conductivity, the structural transformation of as-formulated µE was analyzed. The peak-to-peak correlation of the FTIR study shows that FLQ have good compatibility with µE excipients, while the DLS results show monomodal size distribution of microdroplets. Similarly, FLQ fluorescence detection perceives the interface environment of the colloidal domain. In addition, the agar well diffusion method was used to evaluate the antibacterial potential of the formulated FLQ-loaded µEs, indicating the enhanced antibacterial activity against all bacterial strains. Graphical abstract