Silver (Ag) doped magnesium phosphate microplatelets as next-generation antibacterial orthopedic biomaterials

This article reports for the first time our successful result in the synthesis of antibacterial single-phase newberyite (NB, MgHPO₄ .3H₂ O), an important magnesium phosphate (MgP) bioceramic. The prime novelty lies in the fact that we explore novel MgPs as next-generation orthopedic biomaterials as opposed to conventional calcium phosphates (CaP). While NB has already shown great promise, unlike its competitor struvite (ST, MgNH₄ PO₄ .6H₂ O), NB is not intrinsically antibacterial. Given the havoc created by surgical site infections (SSI) in orthopedics, it would be worthwhile to explore if antibacterial NB can be synthesized cost-effectively. To accomplish that central goal, we used silver ion (Ag⁺ ) containing precursor solutions and exposed those to microwave irradiation. This action resulted in the rapid synthesis of NB microplatelets. Besides, three other specific objectives are addressed. First, Ag-doping was optimized to preserve the single-phase nature for sustained dopant release. Second, Ag⁺ release kinetics against common infection causing bacterial strains was analyzed. Finally, we inspected for any harmful effect of Ag-doped NB on MC3T3 preosteoblasts. Interestingly, the single-phase nature of NB microplatelets can be retained until 2 wt % Ag-doping and they exhibit good antibacterial and cytocompatible properties. Even though 3 wt % Ag-doped compositions (composites) were 100% antibacterial; they were cytotoxic.