Novel microemulsions formulated from sodium N-Lauroyl sarcosinate as nanocarrier for encapsulation of α-Tocopherol

Abstract

Oil-in-water (o/w) microemulsions (MEs) are gaining increasing attention as nanocarriers for the encapsulation and delivery of hydrophobic bioactive molecules which has huge applications in cosmetic, pharmacological, food and beverage industries. However, the major challenge is to formulate these MEs from biodegradable and biocompatible components in low concentration to form stable formulations. In the current work, physiochemical characterization of blank and α-tocopherol loaded o/w MEs formulated using the biodegradable amino-acid based sodium N-lauroyl sarcosinate (SNLS) as surfactant was performed. These MEs were utilized as potential nanocarriers to solubilize and encapsulate an antioxidant α-tocopherol. The utilization of o/w MEs increased the solubility of α-tocopherol from 0.1% in 10% SNLS solution to 0.2% and 0.8% in MEs without and with cosurfactant respectively. The effect of cosurfactant, concentration of Smix (SNLS:butanol = 1:1) and oil was evaluated using conductivity, viscosity studies and encapsulation efficiency to select the optimum composition for encapsulation. The Z-average size of blank MEs without and with cosurfactant was 304 nm and 199 nm respectively with low PDI and negative zeta potential values determine the enhanced stability of these MEs. The HRTEM images revealed the spherical shape of o/w MEs with darker oily core and were utilized to study the effect of cosurfactant and encapsulation of α-tocopherol on the size and morphology of o/w ME droplets. Further, FTIR studies showed the molecular interactions in α-tocopherol and in the optimized ME. In addition to this, the in-vitro antioxidant study of α-tocopherol loaded MEs was determined by the DPPH free radical scavenging activity and the IC50 value was 9 mg/mL for the optimized ME containing 0.5% α-tocopherol. The contact angle studies revealed excellent wetting and spreading ability of MEs on the hydrophobic surface. Thus, SNLS based o/w MEs could be utilized as potential nanocarriers for the encapsulation and delivery of α-tocopherol.