Polymer-coated 3D printed antibacterial tricalcium phosphate scaffolds under static and dynamic osteoblast culture

Craniomaxillofacial bone defects complicated by implant-associated infection require scaffolds that combine structural support, localized therapeutic delivery, and antibacterial function. Polymer coatings can modify scaffold-drug interactions and surface wettability but controlling cumulative drug release and early burst behavior simultaneously remains challenging with a single coating layer. Here, silver-doped 3D-printed tricalcium phosphate (Ag-TCP) scaffolds were modified with a sequential polydopamine (PD) - polycaprolactone (PCL) coating to regulate vitamin D₃ (VD₃) delivery and determine whether coating-mediated osteogenic effects persist under static and dynamic culture conditions. PD increased surface hydrophilicity and raised cumulative VD₃ release from approximately 18% to 25% over 35 days but also increased early burst release. Addition of a 1 wt% PCL overlayer reduced the initial burst by 1.3-fold while maintaining sustained release behavior. In static osteoblast culture, PD-PCL-coated scaffolds increased cell viability by 2.5-fold by day 11 and elevated alkaline phosphatase activity by 1.3-fold compared with uncoated Ag-TCP. Under dynamic recirculating culture, the coated scaffolds maintained enhanced osteoblast viability, producing a 2-fold increase compared with uncoated Ag-TCP. These findings demonstrate that sequential PD-PCL coatings provide a tunable strategy for controlled VD₃ delivery from 3D-printed Ag-TCP scaffolds while supporting improved osteoblast response across static and fluid-dynamic culture environments.