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

Abstract

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.

Biodegradable magnesium phosphates in biomedical applications

“…For instance, silver doped MgPs are utilized in tissue engineering to give orthopedic biomaterials antibacterial properties. 69 Sikder et al developed an antibacterial CaP composite cement reinforced with silver doped MgP crystals, in which the incorporation of silver doped MgP significantly enhanced the compressive and flexural strengths of the composite cements, and gave the composite cement effective antibacterial functionalities (>99% bacteria kill) against Escherichia coli . 70 Therefore, the functionalization of nanostructured MgPs will be one of the future research directions.…”

Antibacterial silver (Ag) containing titanium oxynitride (TiOxNy) coatings for inhibiting surgical site infections (SSI)

“…Among them, Ag is outstanding because of the following reasons: 1) it exhibits antibacterial activity against a broad-spectrum of microbes including antibiotic-resistant bacterial strains, 2) it is difficult to mutate Ag-resistant bacterial strains, 3) it is stable in a physiological medium, and 4) it has no toxicity against human cells up to a critical concentrations [6,11,14,15]. Ag has been exploited as an antibacterial agent on orthopedic and dental implants in several notable cases [16][17][18][19]. The antibacterial working of Ag is complex, and various mechanisms have been proposed in the literature over the course of time [20].…”

“…This article is protected by copyright. All rights reserved witness antibacterial effect, especially when Ag + ions are responsible for the effect [6,11,17,18].…”

“…Also, such assay does not help in analyzing the actual antibacterial effect at a cellular level i.e. how Ag have affected the morphology of the bacteria [17,18]. This assay determines the 'contact killing' ability of the coatings.…”

“…All rights reserved Preliminary cytocompatibility test is indeed important to evaluate the biological responses of the biomaterials prior to in vivo assessment [44]. Especially, when certain concentrations of Ag have been proven cytotoxic in pre-osteoblast cells [17]. Figure 8 shows the MTT assay results of the various coatings.…”