Carvacrol and astaxanthin co-entrapment in beeswax solid lipid nanoparticles as an efficient nano-system with dual antioxidant and anti-biofilm activities

Carvacrol (Car) and astaxanthin (Asta) are widely used in the food industry as antimicrobial and antioxidant agents. This study investigated simultaneous entrapment of them in beeswax solid lipid nanoparticles (BW.SLNs) in order to increase their biological activities. Constituents of optimized formulation (lecithin (7.31 mg), tween 80 (0.81% v/v), beeswax (25.04 mg), Asta (500 mu g) and Car (5 mg)) were determined by response surface methodology. Car/Asta loaded BW.SLNs (Car/Asta-BW.SLNs) were prepared with size and zeta potential of 58.8 nm and -36 mV, respectively. High entrapment efficacy (EE) for Asta (94.6 +/- 0.72%) and Car (88.5 +/- 1.9%) was achieved. In-vitro release study showed that Car was released into the buffer solution two times more than Asta. Entrapped Car and Asta were more stable under acidic and alkaline conditions. Also, 98.2 and 91.37% of entrapped molecules were intact in BW.SLNs under high oxidative condition. Car/Asta-BW.SLNs (1.5 mg/mL) showed efficiency to remove 92.87 and 84.25% and kill 94.81 and 83.26% of total Pseudomonas aeruginosa and Staphylococcus aureus biofilms cells. In conclusion, simultaneous entrapment of Car and Asta by BW.SLNs is reported for the first time and Car/Asta-BW.SLNs can be applied as an efficient nano-system with dual antioxidant and anti-biofihn functions.