Protein-repellent and antibacterial functions of a calcium phosphate rechargeable nanocomposite

Xianju Xie; Lin Wang; Dan Xing; Dwayne D Arola; Michael D Weir; Yuxing Bai; Hockin H K Xu

doi:10.1016/j.jdent.2016.06.003

Protein-repellent and antibacterial functions of a calcium phosphate rechargeable nanocomposite

J Dent. 2016 Sep:52:15-22. doi: 10.1016/j.jdent.2016.06.003. Epub 2016 Jun 17.

Authors

Xianju Xie¹, Lin Wang², Dan Xing³, Dwayne D Arola⁴, Michael D Weir⁵, Yuxing Bai⁶, Hockin H K Xu⁷

Affiliations

¹ Department of Orthodontics, School of Stomatology, Capital Medical University, Beijing, China; Biomaterials & Tissue Engineering Division, Department of Endodontics, Periodontics and Prosthodontics, University of Maryland Dental School, Baltimore, MD 21201, USA.
² Biomaterials & Tissue Engineering Division, Department of Endodontics, Periodontics and Prosthodontics, University of Maryland Dental School, Baltimore, MD 21201, USA; VIP Integrated Department, Stomatological Hospital of Jilin University, Changchun, China.
³ Biomaterials & Tissue Engineering Division, Department of Endodontics, Periodontics and Prosthodontics, University of Maryland Dental School, Baltimore, MD 21201, USA; Department of Dentistry, China Rehabilitation Research Center, Beijing, China.
⁴ Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195, USA.
⁵ Biomaterials & Tissue Engineering Division, Department of Endodontics, Periodontics and Prosthodontics, University of Maryland Dental School, Baltimore, MD 21201, USA.
⁶ Department of Orthodontics, School of Stomatology, Capital Medical University, Beijing, China. Electronic address: byuxing@263.net.
⁷ Biomaterials & Tissue Engineering Division, Department of Endodontics, Periodontics and Prosthodontics, University of Maryland Dental School, Baltimore, MD 21201, USA; Center for Stem Cell Biology & Regenerative Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Mechanical Engineering, University of Maryland, Baltimore County, MD 21250, USA. Electronic address: hxu@umaryland.edu.

PMID: 27327110
DOI: 10.1016/j.jdent.2016.06.003

Abstract

Objectives: We recently developed a new rechargeable composite with nanoparticles of amorphous calcium phosphate (NACP) having long-term calcium (Ca) and phosphate (P) ion release; however, this composite was not antibacterial. The objectives of this study were to: (1) incorporate dimethylaminohexadecyl methacrylate (DMAHDM) and 2-methacryloyloxyethyl phosphorylcholine (MPC) into rechargeable NACP composite, and (2) investigate mechanical properties, protein adsorption and biofilm response of composite, and the pH of biofilm medium.

Methods: MPC, DMAHDM and NACP were mixed into a resin of ethoxylated bisphenol A dimethacrylate (EBPADMA) and pyromellitic glycerol dimethacrylate (PMGDM). Protein adsorption was measured using a micro bicinchoninic acid method. A human saliva microcosm biofilm model was used to grow biofilms on composites. Colony-forming units (CFU), live/dead assay, metabolic activity, and biofilm culture medium pH were determined. The tests used n=6.

Results: The composite with 3% MPC had protein adsorption an order of magnitude less than that of a commercial composite (p<0.05). Control composites were fully covered by live bacteria. Live bacteria were reduced via MPC; 3% MPC+3% DMAHDM had the least live bacteria (p<0.05). The composite with 3% MPC+3% DMAHDM inhibited biofilm growth and viability, reducing biofilm CFU by 3 log compared to commercial control composite (p<0.05), while having a flexural strength similar to that of the commercial composite (p>0.1). The composite containing 3% MPC+3% DMAHDM with biofilm culture maintained a pH above 6.5, while the commercial composite had a cariogenic pH of 4.2 in biofilm culture medium.

Conclusions: The new protein-repellent and antibacterial NACP rechargeable composite substantially reduced biofilm growth, yielding a much higher pH than a commercial composite.

Clinical significance: This novel bioactive nanocomposite is promising to protect tooth structures from biofilm acids and caries. The method of using NACP, MPC and DMAHDM may be applicable to other dental materials to reduce plaque buildup and secondary caries.

Keywords: Antibacterial; Calcium phosphate nanoparticles; Dental caries inhibition; Dental composite; Human saliva microcosm biofilm; Protein repellent.

MeSH terms

Anti-Bacterial Agents
Biofilms
Calcium Phosphates
Humans
Methacrylates
Nanocomposites*
Phosphorylcholine / analogs & derivatives

Substances

Anti-Bacterial Agents
Calcium Phosphates
Methacrylates
Phosphorylcholine
2-methacryloyloxyethyl phosphorylcholine