Characterisation and Microbial Activity of Neem Oil Nano-Emulsions Formulated by Phase Inversion Temperature Method

This study has been carried out to prepare neem oil-in-water nano-emulsions stabilized by Brij 30 surfactant using the phase inversion temperature (PIT) method at three different temperatures, i.e., 60, 75 and 80^°C. Compositions of homogenous phase have been identified in the pseudo-ternary phase diagram. Among the total seventeen formulations, three formulations (NB1, NB2 and NB3) have been short-listed and characterized for emulsion size and viscosity. The selected formulations have shown emulsion size of 348-981 nm in diameter. The volume percentage ratio of Brij 30 to neem oil have shown significant effect on the droplet size of nano-emulsions. Formulations having lower concentration of Brij 30 have displayed a smaller emulsion droplet size (348 nm). The NB3 formulation (4% neem oil, 11% Brij 30 and 85% deionized water) has exhibited the highest stability after 60 days of storage. Antimicrobial study has shown that in contrast to raw neem and Ampicillin (synthetic drug), NB1 exhibited best result in terms of minimum inhibition concentration (MIC) reduction by 100% against E-coli, P. aeruginosa, S. aureus and S. pyogenus.