Catherine P. Barnes

Electrospun polydioxanone–elastin blends: potential for bioresorbable vascular grafts*

An electrospun cardiovascular graft composed of polydioxanone (PDO) and elastin has been designed and fabricated with mechanical properties to more closely match those of native arterial tissue, while remaining conducive to tissue regeneration. PDO was chosen to provide mechanical integrity to the prosthetic, while elastin provides elasticity and bioactivity (to promote regeneration in vitro/in situ). It is the elastic nature of elastin that dominates the low-strain mechanical response of the vessel to blood flow and prevents pulsatile energy from being dissipated as heat. Uniaxial tensile and suture retention tests were performed on the electrospun grafts to demonstrate the similarities of the mechanical properties between the grafts and native vessel. Dynamic compliance measurements produced values that ranged from 1.2 to 5.6%/100 mmHg for a set of three different mean arterial pressures. Results showed the 50:50 ratio to closely mimic the compliance of native femoral artery, while grafts that contained less elastin exceeded the suture retention strength of native vessel. Preliminary cell culture studies showed the elastin-containing grafts to be bioactive as cells migrated through their full thickness within 7 days, but failed to migrate into pure PDO scaffolds. Electrospinning of the PDO and elastin-blended composite into a conduit for use as a small diameter vascular graft has extreme potential and warrants further investigation as it thus far compares favorably to native vessel.

Biomedical Nanoscience: Electrospinning Basic Concepts, Applications, and Classroom Demonstration

Electrospinning is an old polymer processing technique that has recently been rediscovered. It allows for the easy creation of nano- to micro-fibers that can be collected to form a non-woven structure, which can then be used to fabricate novel structures for various applications including tissue engineering scaffolds, clothing, drug delivery vehicles, and filtration media. Current research in our laboratories is focused on the processing of synthetic and biological polymers to create materials with tailored properties and functions for tissue engineering scaffolds and various other medical applications. This technology is revolutionizing the biomaterials and nanotechnology fields and has prompted us to incorporate its history, basic concepts, and applications into diverse courses such as Biomaterials, Tissue Engineering, Polymers in Medicine, and Senior Design in Chemical and Biomedical Engineering. This Innovation of the Curriculum is timely and crucial for multiple reasons. There is a need for a systematic approach to course structure that ties historical concepts to new materials and processes and, ultimately, to practical applications. Combining this lecture organization with active learning in the forms of open discussions and hands-on experiments/demonstrations will enhance learning outcomes (including retention and critical thinking) at all levels of education. At the undergraduate and graduate levels in the courses mentioned, discussions of electrospinning can create a classroom atmosphere of creative thinking, and an actual demonstration of nanomaterial fabrication can serve as a visual aid to the students. More importantly, this curriculum innovation can be used at the high school level to demonstrate nanotechnology and its applications to medicine, which will aid in sparking the interest of future generations of tissue engineers, biomaterial scientists, nanotechnologists, and scientists and engineers in general.