(536c) A Nanotextured Drug-Eluting Coating for Biomedical Implants

Rebecca Chase, Dr. Judit Puskas

The University of Akron, Department of Chemical and Biomolecular Engineering

May 1, 2012

The objective of the work is to develop, characterize, and optimize a drug eluting coating for use in biomedical applications such as implant texturing and coatings based on a highly biocompatible and biostable polymer.

A novel, layered design model for biomedical implant coatings is proposed which will combine a controlled drug eluting capability with nano- or micro- texturing for improved tissue interaction.  The primary materials of interest for the proposed coating are the linear and hyperbranched versions of the block co-polymer, poly (styrene-isobutylene-styrene), SIBS and Arbomatrix, respectively.  SIBS and Arbomatrix are elastomeric polymers that have been previously demonstrated as being bioinert and have tunable mechanical properties similar to those of silicon rubber.  These properties make them an ideal candidate for implant coatings, soft tissue repair/replacement, and tissue scaffolds.  When combined with the electrospinning technologies, a hydrophobic surface can be obtained which promotes cell adhesion while the low permeability of the thin polymer coating ensures a slow and prolonged drug release profile.

The coating design of the proposed work will consist of three layers.  The base for the coating will be made of Arbomatrix or carbon black composite from the hyperbranched Arbomatrix block co-polymer. This layer will function as either an implant shell or as the interfacing layer of the coating with an implant structure.  The second layer will be biocompatible nanofibers used for drug adsorption and/or encapsulation and release and to improve implant/tissue interaction.  This layer will be produced via electrospinning.  A bioactive compound such as Taxol can be adsorbed to the surface of the fibers.  The third layer will be a thin coating deposited evenly over the fibers in order to provide a bioinert layer of uniform thickness but maintain the topology of the underlying nanofiber surface.  SIBS or Arbomatrix will be used for this bio-interfacial layer.  Coating options include spin coating or electrospraying a thin layer on the biocompatible nanofiber mat.  This will be among the first examples of a continuous coating over electrospun fiber surfaces.

Some factors will be studied around the fiber mat including, the drug adsorption effects of the fiber mat.  Parameters that can affect or control this are the morphology of the fibers such as diameter and surface roughness.