Fig. 1. Schematic illustration of the processing steps in (a) machining and (b) molding methodology [15] for fabricating Mg cannulated stents.

Fig. 2. Morphology of the cannulated Mg stents. (a) Macroscopic photos in side view; (b) Macroscopic photos in cross-sectional view (left: machining; right: molding).

Fig. 3. Microstructure of cannulated Mg stents fabricated by machining and molding before degradation: (a) XRD spectra, (b) Reconstructed micro CT images showing porosity.

Fig. 4. SEM scanning of Mg stents fabricated by molding and machining processes magnifying at (a) 80 times, (b) 200 times and (c) 3000 times.

Fig. 5. EDS mapping of cannulated Mg stents fabricated by (a) machining and (b) molding in cross-sectional view magnifying at 1000 times.

Fig. 6. Microhardness distribution across depth from the surface for Mg stent prepared by molding and machining processes.

Fig. 7. Changes in (a) weight loss rate, accumulated concentration of (b) Mg, (c) Ca and (d) P ion release of the machining and molding with paraffin-filling as well as their respective non-filling counterparts in SBF solution at 37 °C.

Fig. 8. Potentiodynamic polarization curves of the machining and molding with paraffin-filling as well as their respective non-filling counterparts in (a) SBF and (b) αMEM solution at 37 ℃.

Fig. 9. Surface SEM scanning of Mg stents fabricated by molding and machining processes after soaked in SBF solution and magnified at (a) 80 times, (b) 200 times and (c) 3000 times, respectively.

Fig. 10. EDS mapping of cannulated Mg stents fabricated by (a) machining for 90 days and (b) molding for 7 days after soaked in SBF solution from surface view magnifying at 3000 times.

Fig. 11. Cross sectional SEM scanning of Mg stents fabricated by molding and machining processes after soaked in SBF solution and magnified at (a) 80 times, (b) 200 times and (c) 3000 times, respectively.

Fig. 12. EDS mapping of cannulated Mg stents fabricated by (a) machining for 90 days and (b) molding for 7 days after soaked in SBF solution from cross-sectional view magnifying at 1000 times.

Fig. 13. Hemolysis ratio of the machining and molding with paraffin-filling as well as their respective non-filling counterparts. The upper dashed line denotes the hemolysis value of 5.0% according to the ISO 10993-4.

Fig. 14. Two cell models for evaluating cytotoxicity effect of the machining and molding with paraffin-filling as well as their respective non-filling counterparts: (a) in vitro cytotoxicity test showing osteoblast cultured with primary and 8 times-diluted Mg extracts, (b) in vitro live/dead staining showing osteoblast cultured under the exposure of Transwell insert with the presence of Mg disks.

Fig. 15. Migration assay of osteoblasts under direct culture with Mg disks to mimic in vivo application (Red dotted line: the interface between implants and osteoblasts at initial stage; White arrow: implants located region).

Fig. 16. Schematic diagram of the formation of the apatite deposition layer and degradation process on cannulated Mg stents fabricated by (a) machining and (b) molding, respectively.