Decreased Staphylococcus aureus and increased osteoblast density on nanostructured electrophoretic-deposited hydroxyapatite on titanium without the use of pharmaceuticals

Abstract

Dennis Mathew,1 Garima Bhardwaj,1,2 Qi Wang,3 Linlin Sun,3 Batur Ercan,3 Manisavagam Geetha,1 Thomas J Webster3,4 1Department of Biomedical Engineering, VIT University, Vellore, Tamil Nadu, India; 2Centre for Biomaterials Science and Technology, School of Mechanical and Building Sciences, VIT University, Vellore, Tamil Nadu, India; 3Department of Chemical Engineering and Program in Bioengineering, Northeastern University, Boston, MA, USA; 4Center of Excellence for Advanced Materials Research, University of King Abdulaziz, Jeddah, Saudi Arabia Background: Plasma-spray deposition of hydroxyapatite on titanium (Ti) has proven to be a suboptimal solution to improve orthopedic-implant success rates, as demonstrated by the increasing number of orthopedic revision surgeries due to infection, implant loosening, and a myriad of other reasons. This could be in part due to the high heat involved during plasma-spray deposition, which significantly increases hydroxyapatite crystal growth into the nonbiologically inspired micron regime. There has been a push to create nanotopographies on implant surfaces to mimic the physiological nanostructure of native bone and, thus, improve osteoblast (bone-forming cell) functions and inhibit bacteria functions. Among the several techniques that have been adopted to develop nanocoatings, electrophoretic deposition (EPD) is an attractive, versatile, and effective material-processing technique. Objective: The in vitro study reported here aimed to determine for the first time bacteria responses to hydroxyapatite coated on Ti via EPD. Results: There were six and three times more osteoblasts on the electrophoretic-deposited hydroxyapatite on Ti compared with Ti (control) and plasma-spray-deposited hydroxyapatite on Ti after 5 days of culture, respectively. Impressively, there were 2.9 and 31.7 times less Staphylococcus aureus on electrophoretic-deposited hydroxyapatite on Ti compared with Ti (control) and plasma-spray-deposited hydroxyapatite on Ti after 18 hours of culture, respectively. Conclusion: Compared with uncoated Ti and plasma-sprayed hydroxyapatite coated on Ti, the results provided significant promise for the use of EPD to improve bone-cell density and be used as an antibacterial coating without resorting to the use of antibiotics. Keywords: bacteria, nanotechnology, electrophoretic deposition, inhibition