Stability investigation of hyaluronic acid based nanoemulsion and its potential as transdermal carrier

In this study, stability of hyaluronic acid (HA) based nanoemulsion was systematically investigated. Factors including zeta potential, pH, crosslinking agents and degree of substitution (DS) were considered to assess their roles in stability. Nanoemulsions prepared from HA-GMS with higher DS showed smaller droplet sizes. In the presence of Ca2+ as a crosslinker, size distribution was improved to be more uniform at the expense of size increases within a controllable range. The optimal amount of Ca2+ usage was determined as 0.05%, which alleviated droplet flocculation and improved morphological qualities as well. Electrostatic, steric, and hydrophobic effects were verified to play crucial roles in emulsion stability. Surfactants strategy was another prerequisite making a key contribution. Encapsulation efficiency (E.E.) study using vitamin E as a model active ingredient proved the eligibility of HA-GMS nanoemulsion exploited as carriers, where the highest E.E. was 93.9 ± 1.4% occurring in sample L6. Fluorescence quenching assay offered evidence of VE encapsulation inside the hydrophobic interior of HA-GMS nanodroplets.