Biodegradable Polymeric Nanocapsules Based on Poly(DL-lactide) for Genistein Topical Delivery: Obtention, Characterization and Skin Permeation Studies

The isoflavone genistein (GEN) is a natural product with potential applications for skin cancer treatment and chemoprevention; however its high lipophilicity and chemical instability limits its clinical use. Therefore, attempts towards protecting GEN against degradation and increasing its penetration in the skin might be a valid approach. In this work, GEN loaded-PLA nanocapsules (GEN-NC) were prepared by interfacial deposition of preformed polymer (nanoprecipitation); physicochemical characterization and stability studies for 90 days were conducted. GEN-NC were incorporated into semi-solid formulations and permeation experiments were carried out using porcine ear skin. GEN-NC optimized formulation presented a mean diameter of 139 +/- 7.31 nm, polydispersity index of 0.128 +/- 0.08, encapsulation efficiency of 89.63 +/- 2.27% and drug loading from 0.6 to 1.4 w/w%. Stability studies demonstrated that nanocapsules did not exhibit aggregation during the 90 days of the assay, however, a drop in encapsulation efficiency was observed in the first 10 days. Permeation experiments demonstrated that a higher amount of GEN reaches deeper layers of the skin and increased penetration was achieved when GEN-NC were incorporated in a semi-solid gel formulation, indicating that GEN-NC might be a promising nanocarrier system for skin delivery of GEN.