Sustained Release Geraniol Nanoparticles Inhibit Human Axillary Odor-Causing Bacteria

Abstract

Human axillary odor is formed when the skin secretions come into contact with the microflora residing on the skin. The interplay between skin bacteria led to microbial conversion of odorless apocrine sweat into odorous organic acid compounds. Geraniol exhibited significant antimicrobial activity against several human axillary odor-causing bacteria; however, the usage in antiperspirants was limited due to its high volatility. In this study, geraniol nanoparticle was synthesized using dextran as encapsulant to improve its release sustainability. The antimicrobial efficiency of the nanoparticles was also tested on human axillary odor-producing bacteria. The particle size of geraniol nanoparticles ranged from 70 to 110 nm, with an average size of 88 nm while the encapsulation efficiency was 69.24%. The release of geraniol was slow and gradual throughout the experimental period, with no burst release effect. Geraniol was totally entrapped into the interior structure of polymer matrix, and 81.28% of geraniol was released from the nanoparticles in 48 h. The release was plateau on 96 h, following the first order of kinetic. On disk diffusion assay, 6 out of 8 test bacteria were susceptible to geraniol nanoparticles. The inhibitory activity was broad spectrum, as it inhibited both Gram-positive and Gram-negative bacteria. Based on kill curve analysis of Staphylococcus hominis, the bacterial killing capability of geraniol nanoparticles was concentration-dependent. At minimal bactericidal concentration, 99.9% of growth reduction was observed relative to control. In conclusion, an efficient nanoparticle-based geraniol drug delivery system was successfully developed using dextran as encapsulant. The well-regulated drug delivery system enables sustainable release of geraniol to meet the application requirements.