Transdermal BQ-788/EA@ZnO quantum dots as targeting and smart tyrosinase inhibitors in melanocytes

Tyrosinase inhibitors could effectively limit the activity of tyrosinase in melanocytes to reduce the excessive synthesis and deposition of melanin. However, low skin permeability and lacking in targeting greatly restricted their application. Herein, ZnO quantum dots were synthesized by gel-sol method and grafted with BQ-788, which have been employed as transdermal and targeting carrier to delivery ellagic acid to melanocytes. Ellagic acid loaded ZnO quantum dots with the size distribution of around 9 nm could targetedly bind to melanocytes and enter the melanocytes by endocytosis within 1 h. The ellagic acid release behavior was controlled by the decreasing of pH via the rapid dissolution of ZnO. When the concentration of BQ-788/EA@ZnO was 12.5 μg/mL, the inhibition rate on tyrosinase activity and melanin deposition were up to 44.23 ± 4.97% and 37.50 ± 5.23%, respectively. In view of their good biocompatibility, they were of great potential in clinically external application for tyrosinase inhibition.