Preparation and characterization of silver-doped, zinc-doped, and silver-zinc co-doped β-tricalcium phosphate/barium titanate/collagen composite scaffolds

To overcome the disadvantage of lacking antibacterial properties for beta-tricalcium phosphate (β-TCP), the Ag, Zn, or Ag/Zn-doped powders were synthesized using spray pyrolysis. Afterward, by adding barium titanate (BT) and collagen (COL), a freeze-drying method was applied to prepare pure β-TCP/BT/COL and metal (Ag, Zn, or Ag/Zn)-doped β-TCP/BT/COL composite scaffolds. In this study, the morphologies, phase compositions, porosities, mechanical properties, antibacterial properties, and cell viabilities of composite scaffolds were characterized by X-ray diffraction, scanning electron microscopy, mercury porosimeter, universal testing machine, antibacterial test, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, respectively. Among these scaffolds, unlike the single metal-doped β-TCP scaffolds (e.g., Ag-doped β-TCP/BT/COL scaffolds or Zn-doped β-TCP/BT/COL scaffolds), the Ag/Zn co-doped β-TCP/BT/COL scaffolds offer the excellent antibacterial properties of ∼99.65 % against Escherichia coli and exhibit the superior cell viability of ∼94.59 % against MC3T3-E1 cells. Additionally, the Ag/Zn co-doped scaffolds showed enhanced compressive strength and maintained an interconnected porous architecture favorable for osteointegration. These results suggest that co-doping with Ag and Zn not only imparts strong antibacterial activity but also improves the biological and mechanical performance of the scaffolds. Therefore, the Ag/Zn co-doped β-TCP/BT/COL scaffold presents a promising multi-functional material for future applications in bone tissue engineering.