Selective Encapsulation of the Polyphenols on Silk Fibroin Nanoparticles: Optimization Approaches

Abstract: The present study proposes a method for designing small bioactive nanoparticles usingsilk fibroin as a carrier to deliver hydrophobic polyphenols. Quercetin and trans-resveratrol, widelydistributed in vegetables and plants, are used here as model compounds with hydrophobic properties.Silk fibroin nanoparticles were prepared by desolvation method and using various concentrations ofethanol solutions. The optimization of the nanoparticle formation was achieved by applying CentralComposite Design (CCD) and the response surface methodology (RSM). The effects of silk fibroinand ethanol solution concentrations together with the pH on the selective encapsulation of phenoliccompounds from a mixture were reported. The obtained results showed that nanoparticles with anaverage particle size of 40 to 105 nm can be prepared. The optimized system for the selective encapsulation of the polyphenols on the silk fibroin substrate was determined to be 60% ethanol solution and1 mg/mL silk fibroin concentration at neutral pH. The selective encapsulation of the polyphenolswas achieved, with the best results being obtained in the case of resveratrol and quercetin andencapsulation of gallic and vanillic acids being rather poor. Thin-layer chromatography confirmedthe selective encapsulation and the loaded silk fibroin nanoparticles exhibited antioxidant activity.