Evaluation of Biosourced Alkyd Nanoemulsions as Drug Carriers

Abstract

Novel oil-in-water (O/W) nanoemulsions were formulated using short, medium, and long oil length alkyds synthesized from palm kernel oil by a two-stage alcoholysis-polyesterification reaction. Alkyd/surfactant/water ternary phase diagrams identified a composition of 1% alkyd, 9% Tween 80, and 90% water where spontaneous production of nanoemulsions occurred. The pH, droplet size, and zeta potential of all formulations were in the range of 6.4–6.6, 11–14 nm, and −6 mV to −8 mV, respectively. Rheological studies showed that the nanoemulsions displayed non-Newtonian shear thinning behavior at low shear rates up to 20 s−1with conversion to Newtonian behavior above this shear rate. All nanoemulsions were found to be stable against phase separation on storage at 4°C and 25°C for three months. Short oil length alkyd nanoemulsions exhibited significantly higher stability compared with medium and long oil length alkyd nanoemulsions, as demonstrated by an absence of phase separation and only minor changes of droplet size on storage at an elevated temperature of 45°C for 3 months. The drug carrying capacity and storage stability of the nanoemulsions were assessed using phenytoin. The entrapment efficiency of alkyd nanoemulsions was in excess of 90% and loss of phenytoin content was restricted to less than 4% during storage of the nanoemulsions for three months at 4°C, 25°C, and 45°C. Taken together, these findings indicate that nanoemulsions prepared from palm kernel oil-based alkyds offer potential as nanocarriers for drug delivery applications.