Brigham & Women's Hospital

Thomas S. Thornhill, MD

Thomas S. Thornhill, M.D.

John B. and Buckminster Brown Professor of Orthopaedic Surgery
Harvard medical school

2012-13 Chief's Report | BWH Chief's Report 2012-2013 PDF

Orthopaedic Nanotechnology Research (Anuj Ballare, PhD)


Our laboratory focuses on the following research areas : Polymeric Biomaterials; Implant Tribology, Nanostructured materials for tissue constructs and drug delivery; x-ray and neutron scattering of polymers; Biomechanics of biomaterials and tissue.


Members & Collaborators

  1. 1. Dr. Thomas S. Thornhill, M.D., Dept of Orthopedic Surgery, Brigham & Women’s Hospital, Boston, MA, USA
  2. 2. Professor Robert E. Cohen, Ph.D., Dept of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
  3. 3. Professor Lisa A. Pruitt, Ph.D., Dept of Mechanical Engineering, University of California at Berkeley, Berkeley, CA, USA
  4. 5. Professor Junjie Wu, Durham University, UK
  5. 6. Dr. Alessandro Bistolfi, M.D., Centro Traumatologico Ortopedico, Università di Torino, Turin, Italy
  6. 7. Professor Franziska Groehn, University, Interdisciplinary Center for Molecular Materials, University of Erlangen-Nuremberg, Germany
  7. 8. Dr. Stephen Spiegelberg, Cambridge Polymer Group, Boston, MA
  8. 9. Shi-Shen Yau, Stryker Orthopedics Inc, Mahwah, NJ
  9. 10. Natalie Hope, M.D., Research Fellow, Imperial College, UK
  10. 11. David Zernik, B.S., Research Assistant, Harvard Extension School, Cambridge, MA
  11. 12. Nathan Eberhart, B.S., Research Assistant, Harvard Extension School, Cambridge, MA
  12. 13. Hung Ngo, B.S., Research Assistant, Harvard Extension School, Cambridge, MA
  13. 14. Andrew George, Medical Student, University of Birmingham, UK
  14. 15. Robert Dorfman, Research Assistant, Oxford University, UK.

The goal of this research program is to apply Nanotechnology to formulate high-performance biomaterials for application in orthopedic implants, tissue regeneration and drug delivery. Some of our ongoing projects and capabilities are as follows:


Total Joint Replacements


In this academic year, we have been developing new technologies for highly crosslinked polyethylene, which, while having high wear resistance, has lower mechanical properties compared to uncrosslinked polyethylene. One technology focuses on disentangling polyethylene and then crosslinking it, in order to produce a less tight network of entanglements and crosslinks, thereby making the polymer less brittle, and perhaps more suitable for high stress applications, such as in thin components and knee replacements. Additionally, we have been investigating alternate antioxidants to stabilize irradiated polyethylene against oxidative degradation. We showed that lower molecular weight hindered phenols are more effective in stabilizing polyethylene compared to Vitamin E and Irganox.


We are also currently collaborating with Durham University, University of Oxford and the Massachusetts Institute of Technology, to develop new processes to improve the fusion of polyethylene powder in implant components, which would lead to enhanced mechanical properties compared to state-of-the art polyethylenes, in clinical use today.


Our laboratory is also collaborating with the group of Professor Groehn at the University of Erlangen-Nuremberg to develop radiopacifier nanoparticles encapsulated in a gel, in order to develop bone cements with higher fatigue strength compared to state-of-the-art cements.


We have begun to investigate the morphology and macromolecular characterization of polyether ether ketones, which are finding use in trauma and for spine applications, and are also being investigated for hip replacement prostheses. This study is in collaboration with Stryker Orthopedics Inc and Cambridge Polymer Group.


Nanofiber synthesis


We are currently developing novel methods of synthesis of nanofiber, nanorods and nanofiber meshes. While the most common method is to use electrospinning, we are developing alternate methods that do not involve high voltages, such as spraying, extrusion and template synthesis. Nanofibers of a variety of biocompatible polymers are being studied, both non-degradable as well as degradable polymers. The non-degradable polymer nanofibers will be candidates for sutures while the degradable nanofibers and nanofiber meshes have application as scaffolds in tissue engineering. Incorporation of antiobiotics and other pharmaceutical compounds will enable these high surface area nanostructured materials to be used for drug delivery options as well.


Micro and nanoparticle synthesis


We are using supercritical carbon dioxide based solvent-antisolvent techniques to synthesize mico and nanoparticles of a variety of compounds and polymers for application in total joint replacement prostheses as well as for drug delivery applications. The use of a gas combined with a biocompatible solvent enables microparticles to be fabricated without contacting toxic compounds, thereby making them more attractive for medical applications.


Conference Abstracts and Papers

1. Abreu E, Bellare A “Network parameters of UHMWPE before and after gamma radiation” Trans 9th World Biomaterials Congress, Chengdu, China, 2012
2. Sun DC, Brooks D, Allen M, Lin S, Tsay R, Bellare A “Optimization for Oxidation Resistance, Material Strength and Weight in Highly crosslinked UHMWPE” Trans 9th World Biomaterials Congress, Chengdu, China 2012
3. Fan CE, Halperin J, Bellare A “The Effect of High crystallinity on Tensile Properties of VitamiN E stabilized Irradiated Polyethylene” Trans ORS Vol 38, p45, 2013
4. George A, Ngo H, Bellare A “A method to mitigate the loss in tensile properties of irradiated Vitamin E blended UHMWPE” Trans ORS, p 1056, 2013
5. Sun DC, Lin S, Brooks D, Allen M, Tsay R, Bellare A, Higham P “Evaluation of highly crosslinked UHMWPE by an universal performance index” Trans ORS, p1816, 2013
6. Stamer J, Halperin A, George A, Bellare A “The effect of Vitamin E content on the tensile properties of irradiated Vitamin E blended UHMWPE” Trans ORS, p1826, 2013
7. Ngo H, Hufen J, Walkenhorst R, Bellare A “The efficacy of Vitamin E and a hindered light amine stabilizer in stabilizing UHMWPE from oxidation” Trans Soc Biomaterials, p316, 2013, Boston, MA
8. Bellare A, Le K-P, Yau S-S, Spiegelberg S “Macromolecular and morphological characterization of medical grade PEEK polymers” Ist International PEEK meeting, 2013, Philadelphia, PA
9. Abreu E, Ngo HD, Bellare A “Characterization of network parameters for UHMWPE by plane strain compression” under review, J Mechanical Behavior of Biomedical Materials.
10. Fabio D’Angelo, Ngo HD, Bellare, “Abrasive wear behavior of irradiated UHMWPE containing Vitamin E” under review, J Appl Polym Sci

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