479966 Optimizing the Electrophoretic Deposition of MgO Nanoparticles Onto a Biodegradable Polymer for Antibacterial Properties
Optimizing the Electrophoretic Deposition of MgO Nanoparticles onto a Biodegradable Polymer for Antibacterial Properties
Divya Muthusamy (1), Daniel J. Hickey (1), and Thomas J. Webster (1)
1. Department of Chemical Engineering, Northeastern University, Boston, MA
Magnesium oxide (MgO) nanoparticles are biodegradable, biocompatible, low-cost, and environmentally friendly. Additionally, they have been shown to exhibit strong bactericidal efficacy1. If incorporated into a biomaterial construct, they have the potential to reduce the risk of infection without the use of antibiotics, which bacteria can form resistance to2. Here, for the first time, MgO nanoparticles were electrophoretically deposited onto a biodegradable poly-L-lactic acid (PLLA) scaffold to decrease bacterial colonization by up to 90% compared to the non-treated control. Electrophoretic deposition (EPD) is a commonly used method which uses an electric field to deposit particles suspended in solution onto an electrically conductive surface. In this experiment, MgO nanoparticles were electrophoretically deposited onto PLLA scaffolds from a solution of 2-propanol and dimethylformamide (DMF). The PLLA (a non-conductive material) was attached onto titanium using conductive carbon tape to create a conductive path through the PLLA. This construct then served as the cathode for EPD. The parameters for successful deposition were determined by running the EPD with titanium electrodes at several voltages, ranging from 20V to 150V, and for a duration of 1 minute to 5 minutes. Particle deposition increased with increasing EPD processing time. However, this effect was small compared to the effect of varying the voltage, and 2 minutes was chosen for experimentation. With increasing voltage, the particles were better incorporated into the surface of the polymer, as determined through scanning electron microscopy and a particle adhesion tape test. The scanning electron microscopy images show the consistency of EPD in depositing the particles uniformly in small aggregates throughout the PLLA scaffold. These images also show that nanoparticle structures retained their nano-crystalline form. Importantly, increasing the EPD voltage decreased the adhesion of Staphylococcus aureus, as determined by bacterial plating studies. Additionally, the adhesion of primary human osteoblasts increased on samples prepared with increasing voltages. The results of this study demonstrate that a nano-MgO-PLLA construct can be created via electrophoretic deposition and can be used to inhibit bacterial growth and enhance osteoblast adhesion. Further work is under way to optimize this method and provide biomaterials with inherent antibacterial properties to fight infection in the clinic.
1 Sawai, J., H. Kojima, H. Igarashi, A. Hashimoto, S. Shoji, T. Sawaki, A. Hakoda, E. Kawada, T. Kokugan, and M. Shimizu, Antibacterial Characteristics of Magnesium Oxide Powder, World J Microbiol Biotechnol, 16, pp. 187-94, 2000.
2 Huang, L., D.Q. Li, Y.J. Lin, M. Wei, D.G. Evans, and X. Duan, Controllable Preparation of Nano-MgO and Investigation of Its Bactericidal Properties, Journal of Inorganic Biochemistry, 99, pp. 986-93, 2005.
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