Stability of easily hydrolyzable beta-cypermethrin based O/W type drug-loading microemulsion

Abstract

Four surfactants with different counter-ions were synthesized. The effect of their charges, ionic radii, and binding degree on the phase behavior of oil-in-water type drug-loading microemulsion was investigated. Counter ion with smaller ionic hydrated radius, strengthened the hydrophobicity and made the arrangement of micelle interface more compactly. When K⁺ was taken as a counter-ion, the arrangement tightness of interfacial film is highest and water penetration is most difficult. The solubilization location of the oil phase in the microemulsion was determined using pyrene as probe, and the influence law of solvent polarity to the solubilization location of the oil phase was obtained. The oil phase with smaller polarity was more conducive to occupy the inner space of micelle, which means it was beneficial to reduce the contact chance between beta-cypermethrin and osmotic water, thus the hydrolysis of beta-cypermethrin was reduced. For cyclohexanone solvent, the I₁/I₃ value was between 1.03 and 1.09, it indicated that the solubilization location of the oil phase was in a relatively smaller polarity environment. The microemulsion prepared with DBSK and cyclohexanone exhibited the minimum decomposition rate of beta-cypermethrin.

Graphical Abstract

Keywords:

• Beta-cypermethrin
• counter-ions
• drug-loading microemulsion
• micelle
• solubilization

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by The National Natural Science Foundation of China under grant (number 21203114); Science and technology plan of Shandong province colleges and Universities under grant (number J14LC16); and Natural science foundation of Shandong Province under grant (number ZR2017MB018).