Entrapment of Drugs within Metallic Platinum and Their Delivery

Platinum has been a widely used metal for a variety of implanted medical devices, because of its inertness, low corrosion rate, high biocompatibility, high electric conductivity, and good mechanical stability. A highly desirable property still in need to be addressed is the tailoring of drug-delivery ability to that metal. This is needed in order to treat infections due to the process of implanting, to treat postoperation pain, and to prevent blood clotting. Can Pt itself serve as a delivery matrix? A review on metallic implants (Lyndon, J. A.; Boyd, B. J.; Birbilis, N. Metallic implant drug/device combinations for controlled drug release in orthopaedic applications. J. Control. Release 2014, 179, 63-75) proposes that "Metals themselves can be used for delivering pharmaceutics" but adds that "there has been no current research into [that] possibility" despite its advantages. Here we present a solution to that challenge and show a new method of using an inert metal as a 3D matrix from within which entrapped drug molecules are released. This new type of drug-delivery system is fabricated by the methodolodgy of entrapment of molecules within metals, resulting in various drugs@Pt. Specifically the following drugs have been entrapped and released: the pain-killer and platelet-inhibitor nonsteroidal anti-inflammatory drugs (NSAIDs) ibuprofen and naproxen, the antibiotic ciprofloxacin, and the antiseptic chlorhexidine. The delivery profiles of all biocomposites were studied in two forms, powders and pressed discs, showing, in general, fast followed by slow first order release profiles. It is shown that the delivery kinetics can be tailored by changing the entrapment process, by applying different pressures in the disc preparation, and by changing the delivery temperature. The latter was also used to determine the activation energy for the release. Full characterization of the metallic biomaterials is provided, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDAX), thermogravimetric analysis (TGA), and surface area/porosity analysis.