Preparation of Citrus reticulata peel nano-encapsulated essential oil and in vitro assessment of its biological properties

Dental caries is the most common biofilm-dependent oral disease. Streptococcus mutans is among the main microorganisms responsible for the development of dental caries. Nano-suspension of Citrus reticulata (tangerine) peel essential oil in 0.5% (v/v) concentration was prepared and its antibacterial effect on S. mutans in planktonic and biofilm forms as well as its cytotoxic and antioxidant effects were assessed and compared with chlorhexidine (CHX). The minimum inhibitory concentration (MIC) of free essential oil, nano-encapsulated essential oil, and CHX was 5.6% (v/v), 0.0005% (v/v), and 0.0002% (w/v), respectively. The percentage of biofilm inhibition by the free essential oil, nano-encapsulated essential oil, and CHX at half-MIC was 67.3%, 24%, and 90.6%, respectively. The nano-encapsulated essential oil had no cytotoxicity and showed significant antioxidant effects in different concentrations. Nano-encapsulation of tangerine peel essential oil significantly enhanced its biological activities in much lower concentrations than the free essential oil (11,000 times diluted). It also showed lower cytotoxicity and higher antibiofilm effects in sub-MICs compared with CHX, indicating the optimal potential of tangerine nano-encapsulated essential oil for incorporation in the composition of organic antibacterial and antioxidant mouth rinses.