Investigation of Antibacterial Activity and Cell Viability of Ag/Mg and Ag/Zn Co-doped Hydroxyapatite Derived from Natural Limestone

Abstract

Improving the antibacterial activity to avoid infections and keeping the biocompatibility at a safe level of HAp-based materials is highly important for biomedical applications. In this work, we investigate the antibacterial activity of 2.5Ag/2.5Mg co-doped HAp and 2.5Ag/2.5Zn co-doped HAp toward Escherichia coli bacteria. Moreover, their biocompatibility for osteoblastic cells (MC3T3-E1 cells) was also evaluated. The physical properties were characterized with necessary characterization tools such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller. Both 2.5Ag/2.5Mg and 2.5Ag/2.5Zn co-doped HAp consist of hydroxyapatite (HAp) and beta calcium triphosphate (β-TCP) phases. The antibacterial test reveals that 2.5Ag/2.5Mg co-doped HAp or 2.5Ag/2.5Zn co-doped HAp has an outstanding antibacterial activity with a killing rate of 99 ± 1%. More importantly, the cell viability for osteoblast cells with 2.5Ag/2.5Mg and 2.5Ag/2.5Zn co-doped HAp promotes the proliferation much more effectively than 2.5Ag-doped HAp or 5Ag-doped HAp.

Bacterial Inhibition and Osteogenic Potentials of Sr/Zn Co-Doped Nano-Hydroxyapatite-PLGA Composite Scaffold for Bone Tissue Engineering Applications

“…Several previous studies have reported the antimicrobial properties of Zn-nHAp against Staphylococcus aureus and Escherichia coli [ 25 , 57 , 62 , 72 , 73 , 74 ]. Multiple factors could contribute to this bactericidal effect.…”

“…Furthermore, some studies used PLGA to encapsulate antibacterial agents which significantly reduced bacterial growth [ 53 , 54 , 55 ], but this could increase the burden of antibiotic-resistant bacterial species, and also raise the concern of a burst release of the encapsulated antibiotic [ 56 ]. Silver and copper ions (Ag + and Cu 2+ ) have also been extensively studied due to their antimicrobial properties [ 57 ]. Ag + was found to have a high cytotoxic effect compared to Cu 2+ , while Cu 2+ ’s antibacterial effect remained only for a short time frame [ 58 ].…”

Tackling current production of HAp and HAp-driven biomaterials

“…Concerning antimicrobial activity, ions such as fluoride, 72 silver, 92,101,102 zinc, 91,103 magnesium and copper (F − , Ag + , Zn 2+ , Mg 2+ , Cu 2+ , respectively) were revealed to be a valid alternative when combined with HAp.…”

“…Their antibacterial effect is related to its electrostatic interaction with cell membranes resulting in its rupture. 92 Ag + is also highly referred to in the literature of doped HAp. 92,101,102 Sinulingga et al , 106 made two variations of 2.5% Ag + -doped HAp, one with Zn 2+ (2.5%) and another with Mg 2+ (2.5%), 92 in order to try to mitigate the cytotoxic effect found with previously reported 5% Ag + -doped HAp.…”

“…92 Ag + is also highly referred to in the literature of doped HAp. 92,101,102 Sinulingga et al , 106 made two variations of 2.5% Ag + -doped HAp, one with Zn 2+ (2.5%) and another with Mg 2+ (2.5%), 92 in order to try to mitigate the cytotoxic effect found with previously reported 5% Ag + -doped HAp. 106 The presence of Zn 2+ and magnesium enhanced the antimicrobial activity (when compared to the sample with 2.5% Ag + ), since both 2.5 Ag + /2.5 Mg 2+ and 2.5 Ag + /2.5 Zn 2+ killed 99 ± 1% E. coli (similarly to the 5% Ag + HAp), while presenting lower cytotoxicity towards the tested pre-osteoblastic cells.…”