Preparation and characterization of silk fibroin based materials loaded with natural compounds

Abstract

In this study, it was aimed to increase solubility of flavonoids via inclusion complexation. Silk was also selected as carrier material. Firstly we have prepared cyclodextrin inclusion complexes with rutin via co-precipitation method. Stability constant of Beta-cyclodextrin complex was calculated as 262 M-1. Aqueous solubility of rutin was increased with inclusion complex of Beta-Cyclodextrin. Effect of temperature on aqueous solubility of free rutin, and its complex were studied. Also solubility energies are calculated. Characterization of cyclodextrin complexes were conducted with the help of UV-visible spectroscopy, X-Ray Diffractometry, Differential Scanning Calorimetry, Thermal Gravimetric Analysis, Fourier Transform Infrared spectroscopy and Scanning Electron Microscobe techniques. Characterization results supported formation of inclusion complexes which were compatible with the previous literature studies. Before release tests, dissolution profile of rutin, physical mixture and inclusion complex was observed at 37.C and in PBS; results show that addition of cyclodextrin has an increasing effect on solubility rate and amount. Then silk fibroin based films were prepared and used as carriers for natural compounds. After loading flavonoids and complexes into silk fibroin based films, release tests were done at 37 .C in neutral pH conditions for 24 hours. Most of the Rutin .independent from the form, whether free or complexed- released from Silk Fibroin films within the first 5 hours (burst release occurs) and the rest of it released slowly within 24 hours. Electron microscobe analyses showed that films have a homogenous and dense morphology. Consequently, silk fibroin is useful to load natural compounds into silk fibroin films in order to modify their release period within physiological conditions.