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, MgHPO4.3H2O), 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, MgNH4PO4.6H2O), 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.