Protein-repellent Nanocomposite With Remineralization Capabilities and Rechargeable Calcium Phosphate Ions

Objectives: The incorporation of nanoparticles of amorphous calcium phosphate (NACP) and 2-methacryloyloxyethyl phosphorylcholine (MPC) into composite showed improved caries-inhibition, remineralization, and protein-repellent effects. There has been no report on the rechargeability of nanocomposite containing NACP-MPC. Our objectives were to develop rechargeable NACP-MPC composite, and investigate the effects of MPC and NACP on mechanical properties, protein-repellency, antibacterial effects, calcium (Ca) and phosphate (P) ion release and rechargeability.
Methods: Nanocomposites were synthesized with 0 (control), 1.5%, and 3% of MPC by mass. MPC, NACP (20%) and glass particles (50%) were mixed into pyromellitic glycerol dimethacrylate and ethoxylated bisphenol A dimethacrylate. Mechanical properties were measured in three-point flexure. Protein adsorption onto the composites was measured by a micro bicinchoninic acid method. A human saliva microcosm model was used to grow biofilms. Colony-forming units (CFU), live/dead, metabolic activity, and lactic acid were determined. Ca and P release, recharge and re-release were measured.
Results: Nanocomposites with 1.5% MPC (70.67±4.5) and 3% MPC (71.2±7.8) had flexural strength in MPa similar to those without MPC (72.3±10.2) and the commercial control (70.2±9.3). The incorporation of MPC reduced protein adsorption (p<0.05). MPC groups inhibited biofilm metabolic activity, lactic acid and CFU, compared to controls (p<0.05). Experimental control, 1.5% MPC and 3% MPC showed high Ca ion release in mmol/L of (3.85±0.04), (4.06±0.02), and (4.30±0.03), and P ions (1.15±0.01), (1.26±0.01), and (1.34±0.01), respectively, at 70 days (p>0.1). After the 3rd recharge cycle, Ca release was (0.82±0.01) for control, (0.78±0.01) for 1.5% MPC and (0.78±0.01) for 3% MPC, and P ions were (0.25±0.001), (0.24±0.001), and (0.26±0.001), respectively (p>0.1).
Conclusions: Addition of MPC into nanocomposite achieved protein-repellent and antibacterial capabilities without compromising the mechanical properties, ion release, and rechargeability. All nanocomposites had high and durable Ca and P re-release which did not decrease with increasing the number of recharge cycles.