|M.Sc Student||Bachar Michal|
|Subject||Development of B-Casein Nano-Capsules for Oral Delivery|
|Department||Department of Biotechnology and Food Engineering||Supervisor||Professor Dganit Danino|
|Full Thesis text|
β-Casein is an amphiphilic protein that self-organizes above the critical micellar concentration (CMC) into well-defined core-shell micelles. These protein micelles were developed as efficient nanocapsules of drugs for oral delivery applications. The model drug is celecoxib, an anti-inflammatory hydrophobic drug for treatment of rheumatoid arthritis and osteoarthritis and now under investigation as a potent anticancer drug. Entrapment of additional drugs (budesonide and haloperidol) in the protein nanocapsules was effectively achieved, showing the ability of β-casein micelles to encapsulate a variety of drugs. Encapsulation of a considerably high amount of celecoxib - 1:15 mole ratio β-casein:celecoxib, with 5 wt% β-casein - is presented. This encapsulation level is more than 100-fold higher than in other reported β-casein formulations. Moreover, this encapsulation level is high enough to meet the high recommended daily dosage of celecoxib. Direct-imaging cryo-transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) prove that the drug-loaded assemblies are swollen micelles, which maintain the small well-defined micellar structure and morphology of the native β-casein micelles. The protein micelles are shown to swell upon loading with drug, to an extent depending on the amount of drug loaded. Zeta-potential measurements suggest a denser packing of the drug-loaded micelles compared to native β-casein micelles. X-ray diffraction shows an amorphous conformation of celecoxib when encapsulated, which is expected to significantly increase drug absorption in the gastrointestinal tract. It was further demonstrated that the empty and loaded assemblies can be freeze-dried, and upon rehydration, even after 6-months of storage in powder form, they retain their original pre-lyophilized structure, uniform size, and morphology. No cryoprotectant is needed. Such freeze-dried drug-loaded micelles can be used as a dry powder, a great advantage for clinical application.