title: Celecoxib Encapsulation in β-Casein Micelles: Structure, Interactions, and Conformation.
abstract: β-Casein is a 24 kDa natural protein that has an open conformation and almost no folded or secondary structure, and thus is classified as an intrinsically unstructured protein. At neutral pH, β-casein has an amphiphilic character. Therefore, in contrast to most unstructured proteins that remain monomeric in solution, β-casein self-assembles into well-defined core-shell micelles. We recently developed these micelles as potential carriers for oral administration of poorly water-soluble pharmaceuticals, using celecoxib as a model drug. Herein we present deep and precise insight into the physicochemical characteristics of the protein-drug formulation, both in bulk solution and in dry form, emphasizing drug conformation, packing properties and aggregation state. In addition, the formulation is extensively studied in terms of structure and morphology, protein/drug interactions and physical stability. Particularly, NMR measurements indicated strong drug-protein interactions and noncrystalline drug conformation, which is expected to improve drug solubility and bioavailability. Small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cryo-TEM) were combined for nanostructural characterization, proving that drug-protein interactions lead to well-defined spheroidal micelles that become puffier and denser upon drug loading. Dynamice light scattering (DLS), turbidity measurements, and visual observations complemented the analysis for determining formulation structure, interactions, and stability. Additionally, it was shown that the loaded micelles retain their properties through freeze-drying and rehydration, providing long-term physical and chemical stability. Altogether, the formulation seems greatly promising for oral drug delivery.
authors.affiliation: †Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel.
authors.forename: Tanya
authors.initials: T
authors.lastname: Turovsky
authors.affiliation: ‡Department of Chemical Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel.
authors.forename: Rafail
authors.initials: R
authors.lastname: Khalfin
authors.affiliation: §Shulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa 3200003, Israel.
authors.forename: Shifi
authors.initials: S
authors.lastname: Kababya
authors.affiliation: §Shulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa 3200003, Israel.
authors.forename: Asher
authors.initials: A
authors.lastname: Schmidt
authors.affiliation: ∥Laboratory of Membrane and Liposome Research, IMRIC, the Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel.
authors.forename: Yechezkel
authors.initials: Y
authors.lastname: Barenholz
authors.affiliation: †Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel.|⊥Department of Biotechnology and Food Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel.
authors.forename: Dganit
authors.initials: D
authors.lastname: Danino
mesh_terms: D000818:Animals; D002214:Capsules; D002364:Caseins / Q000737:chemistry*; D002417:Cattle; D000068579:Celecoxib / Q000737:chemistry*; D004337:Drug Carriers / Q000737:chemistry*; D005612:Freeze Drying; D008823:Micelles; D008958:Models, Molecular; D011487:Protein Conformation; D055550:Protein Stability
chemical_list: D002214:Capsules; D002364:Caseins; D004337:Drug Carriers; D008823:Micelles; D000068579:Celecoxib