Resveratrol-loaded solid lipid nanoparticles versus nanostructured lipid carriers: evaluation of antioxidant potential for dermal applications

Background: Excessive generation of radical oxygen species (ROS) is a contributor to skin pathologies. Resveratrol (RSV) is a potent antioxidant. Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) can ensure close contact and increase the amount of drug absorbed into the skin. In this study, RSV was loaded into SLN and NLC for dermal applications. Methods: Nanoparticles were prepared by high shear homogenization using Compritol 888ATO, Myglyol, Poloxamer188, and Tween80. Particle size (PS), polydispersity index (PI), zeta potential (ZP), drug entrapment efficiency (EE), and production yield were determined. Differential scanning calorimetry (DSC) analysis and morphological transmission electron microscopy (TEM) examination were conducted. RSV concentration was optimized with cytotoxicity studies, and net intracellular accumulation of ROS was monitored with cytofluorimetry. The amount of RSV was determined from different layers of rat abdominal skin. Results: PS of uniform RSV-SLN and RSV-NLC were determined as 287.2 nm +/- 5.1 and 110.5 nm +/- 1.3, respectively. ZP was -15.3 mV +/- 0.4 and -13.8 mV +/- 0.1 in the same order. The drug EE was 18% higher in NLC systems. TEM studies showed that the drug in the shell model was relevant for SLN, and that the melting point of the lipid in NLC was slightly lower. Concentrations below 50 mu M were determined as suitable RSV concentrations for both SLN and NLC in cell culture studies. RSV-NLC showed less fluorescence, indicating less ROS production in cytofluorometric studies. Ex vivo skin studies revealed that NLC are more efficient in carrying RSV to the epidermis. Conclusion: This study suggests that both of the lipid nanoparticles had antioxidant properties at a concentration of 50 mu M. When the two systems were compared, NLC penetrated deeper into the skin. RSV-loaded NLC with smaller PS and higher drug loading appears to be superior to SLN for dermal applications.