3D Printed Dual-Drug Scaffolds

To fabricate the dual-drug-based scaffolds, a drug-loaded scaffold was first prepared by 3D printing, as reported previously [12 (link)]. Briefly, PCL (MW: 45,000; Sigma-Aldrich, St Louis, MO, USA) and cefazolin (CFZ) (Chong Kun Dang pharmaceutical Corp., Seoul, Korea) were mixed at concentrations of 25 mg/mL and 50 mg/mL, respectively, and then ejected using a 3D bioprinting system (Geo Technology, Incheon, Korea) to a 200 μm nozzle (inner diameter) supplied with 800 kPa pressure at a constant speed of 100 mm/min. The resultant cefazolin-loaded scaffolds were cut into 5 mm disks using a punch and immersed in another 12-well plate containing 4% sodium alginate solution (Sigma-Aldrich, St Louis, MO, USA) blended with 9 wt% rifampicin (RFP) (Tokyo Chemical Industry Co., Ltd., Tokyo, Japan), and 100 mM calcium chloride solution (Sigma-Aldrich, St Louis, MO, USA) was added for 30 s at room temperature to encapsulate alginate. The fabrication process of the dual-drug-based scaffold is described in Figure 1A.