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Antibacterial amorphous calcium phosphate nanocomposite with quaternary ammonium salt and silver nanoparticles



Nancy J. Lin, Lei Cheng, Michael D. Weir, Hockin H. Xu, Joseph M. Antonucci, Alison M. Kraigsley, Sheng Lin-Gibson, Xuedong Zhou


Objectives. Calcium and phosphate ion-releasing resin composites are promising for remineralization; however, so far there has been no report on imparting a potent antibacterial capability to these composites. The objectives of this study were to incorporate quaternary ammonium dimethacrylate (QADM) and silver nanoparticles (NanoAg) into amorphous calcium phosphate nanocomposite (NanoACP) for the first time to obtain a strong antibacterial activity. Methods. Bis(2-methacryloyloxy-ethyl) dimethyl-ammonium bromide, the QADM, was synthesized with 2-(N,N-dimethylamino)ethyl methacrylate and 2-bromoethyl methacrylate. NanoAg was synthesized by dissolving Ag 2-ethylhexanoate salt in 2-(tert-butylamino) ethyl methacrylate. Composite disks were inoculated with Streptococcus mutans (S. mutans) and the CFU counts, metabolic activity, and lactic acid production of the biofilms were measured. Results. The flexural strength and modulus of NanoACP+QADM, NanoACP+NanoAg, and NanoACP+QADM+NanoAg matched those of two commercial control composites with no antibacterial property. The NanoACP+QADM+NanoAg composite decreased the CFU counts of S. mutans biofilms adherent on the composite by an order of magnitude, compared to the commercial composites. The metabolic activity and lactic acid production of the biofilms were also greatly reduced on the new nanocomposites. Combining QADM and NanoAg rendered the nanocomposite more strongly-antibacterial than that using either QADM or NanoAg alone. Significance. QADM and NanoAg were incorporated into calcium phosphate composite for the first time. NanoACP+QADM+NanoAg was strongly-antibacterial and greatly reduced the CFU counts, metabolic activity, and acid production of S. mutans biofilms, while possessing mechanical properties similar to commercial composites. The nanocomposite is promising to have the double benefits of remineralization and antibacterial capabilities to inhibit dental caries.
Dental Materials


amorphous calcium phosphate, antibacterial, biofilm, dental composite, dimethacrylate, oral bacteria, polymer, quaternary ammonium compound, silver nanoparticles


Lin, N. , Cheng, L. , Weir, M. , Xu, H. , Antonucci, J. , Kraigsley, A. , Lin-Gibson, S. and Zhou, X. (2012), Antibacterial amorphous calcium phosphate nanocomposite with quaternary ammonium salt and silver nanoparticles, Dental Materials, [online], (Accessed January 18, 2022)
Created February 2, 2012, Updated November 10, 2018