Fig. 1

Synthesis of silica-collagen xerogels (sicXer) and bortezomib-releasing silica-collagen xerogels (boXer) as well as collagen- and bortezomib-release kinetics. A. Schematic view. A1 Suspensions of bovine collagen w/wo bortezomib and silica formed a hydrogel by a sol–gel process. After drying, a mesoporous xerogel resulted. A2 Bortezomib-binding within xerogels during the sol–gel manufacturing process, i.e., before the gel was finally formed. B. Photographical image of sicXer-iaf (left panel; 250–710 µm) and sicXer (right panel; < 125 µm). Bortezomib addition did not alter the visual impression (not shown). C. Scanning electron microscopic images of C1 monolitic xerogels powdered to different granular sizes. C2 Irradiation after formation (sicXer-iaf) or C3 before formation (sicXer) can be used to impact on the form and distribution of collagen fibrils (white colored arrows) in the silica matrix. D. In vitro degradation of xerogel granules. Release of collagen from both sicXer-iaf and sicXer granules of different size into cell culture medium. Particle size and preparation method, i.e., irradiation before or after formation, determine in vitro collagen release from silica-collagen xerogels. E. In vitro bortezomib-release. Cumulative release of bortezomib from boXer-100 and boXer-500 as measured by UPLC-MS/MS related to the amount of incorporated bortezomib