Optimizing stem cell functions and antibacterial properties of TiO2 nanotubes incorporated with ZnO nanoparticles: experiments and modeling

Abstract

Wenwen Liu,1–3 Penglei S Su,2 Arthur Gonzales III,3 Su C Chen,1 Na Wang,1 Jinshu Wang,2 Hongyi Li,2,4 Zhenting Zhang,1Thomas J Webster3,51Laboratory of Biomaterials and Biomechanics, Beijing Key Laboratory of Tooth Regeneration and Function Reconstruction, School of Stomatology, Capital Medical University, 2Photoelectrochemical Research Group, Key Laboratory of Advanced Functional Materials, School of Materials Science and Engineering, Beijing University of Technology, Beijing, People’s Republic of China; 3Chemical Engineering Department, Northeastern University, Boston, MA, USA; 4Guangxi Research Institute of Chemical Industry, Nanning, People’s Republic of China; 5Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah, Saudi ArabiaAbstract: To optimize mesenchymal stem cell differentiation and antibacterial properties of titanium (Ti), nano-sized zinc oxide (ZnO) particles with tunable concentrations were incorporated into TiO2 nanotubes (TNTs) using a facile hydrothermal strategy. It is revealed here for the first time that the TNTs incorporated with ZnO nanoparticles exhibited better biocompatibility compared with pure Ti samples (controls) and that the amount of ZnO (tailored by the concentration of Zn(NO3)2 in the precursor) introduced into TNTs played a crucial role on their osteogenic properties. Not only was the alkaline phosphatase activity improved to about 13.8 U/g protein, but the osterix, collagen-I, and osteocalcin gene expressions was improved from mesenchymal stem cells compared to controls. To further explore the mechanism of TNTs decorated with ZnO on cell functions, a response surface mathematical model was used to optimize the concentration of ZnO incorporation into the Ti nanotubes for stem cell differentiation and antibacterial properties for the first time. Both experimental and modeling results confirmed (R2 values of 0.8873–0.9138 and 0.9596–0.9941, respectively) that Ti incorporated with appropriate concentrations (with an initial concentration of Zn(NO3)2 at 0.015 M) of ZnO can provide exceptional osteogenic properties for stem cell differentiation in bone cells with strong antibacterial effects, properties important for improving dental and orthopedic implant efficacy.Keywords: titanium nanotubes, ZnO nanoparticles, mesenchymal stem cells, antibacterial effect, modeling