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R&D Profile: Drug-eluting Anodized Titanium Orthopedic Implants: T. Webster, Brown University

The average functional lifetime of orthopedic implants has been estimated to be less than 15 years. Few studies have focused on creating an orthopedic implant with multi-functional drug release to inhibit infection and wound inflammation events while increasing new bone formation.
Thomas J. Webster

R&D Overview Courtesy of Thomas Webster, Associate Professor, Division of Engineering, Brown University.

Dr. Webster is a featured speaker at next month’s NSTI Nanotech conference, and will also lead the one-day workshop Biomaterials and Nanotechnology for Tissue Engineering Sunday, June 1.

In previous studies, titania nanotube arrays fabricated via anodization in dilute hydrofluoric acid were shown to increase bone growth compared to currently implanted titanium. In this study, these tubular structures were further utilized as novel prolonged-release drug delivery system. For this purpose, antibiotic drugs (penicillin and streptomycin) and an anti-inflammation drug (dexamethasone) were loaded into these nanotubular structures by either physical adsorption or electrochemical deposition. To mediate interactions between drug molecules and nanotube walls, anodized titanium nanotubes were modified by silanization to possess amine or methyl groups on their surface instead of OH groups. Results showed increased hydrophobicity of chemically modified titania nanotubes as well as improved drug loading efficiency on the more hydrophobic samples. These drug loaded substrates were soaked in phosphate buffered solution in a simulated body environment to determine drug release behavior. Buffer solution was collected and replaced every day. The eluted drug amounts were measured spectroscopically. Results showed prolonged drug releasing behavior from chemically modified nanotubes compared to conventional titanium substrates. In this manner, this study advances currently used titanium to possess drug release behavior which can improve orthopedic implant efficacy.


Nanotubes Under High Magnification, Courtesy of T. Webster, Brown University

Since we have already demonstrated the in vitro efficacy of these anodized nanotubular contructs for releasing drugs (anti-bacterial, anti-inflammatory, and pro-bone growing) and promoting new bone growth, we are planning to conduct in vivo verification. Currently, we are planning to conduct animal studies in which currently implant materials are modified via anodization to possess such novel nanotubular structures to both release drugs and promote new bone growth.

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