Nanocomposite Elastomers : An Alternate Route to Developing Bioactive Medical Polymers

Laura Poole-Warren, Katie Styan, Nicole Fong, Brooke Farrugia, Charles Williams, Anne Simmons
Graduate School of Biomedical Engineering , University of New South Wales Sydney, NSW, Australia 2052

Thermoplastic polyurethanes are versatile elastomeric polymers much used for biomedical applications due to their mechanical properties and biological performance. Their application as blood contacting devices ranges from short-term intravenous catheters through to pumping bladders in left ventricular assist devices.

The major disadvantages of any polymer used in these types of applications are that they are susceptible to bacterial colonisation and to thrombus formation. Specifically, some polyurethanes are also susceptible to degradation in vivo. Nanocomposites formed via blending polymer and nanoparticles have potential application as antithrombotic and antibacterial materials. The advantage of nanocomposites over conventional microcomposites presented in the literature mainly relates to improved mechanical properties. However, the high surface area of entrapped nanoparticles and their impact on the barrier properties of polymers are two features that can be exploited to produce a material that can sequester high concentrations of active agent as well as modulate active agent release. Unlike conventional techniques for surface modification, this approach has potential to yield materials that continuously refresh surface expressed active agents via diffusion of molecules out of the polymer matrix.

The objective of this research was to study drug release from polyurethane nanocomposites and to assess the potential for sustained release of bioactive molecules.

These studies suggest that release of low molecular weight compounds from polyurethane elastomers can be modulated via addition of a nanoparticle. The bioactivity of the active agent was retained following processing and release from the system, confirming the potential of this system for applications where bioactive agent release could improve device performance.

Living Free Radical Polymerization as a Tool for Designing Well-Defined Materials for Biomedical Applications

Christopher Barner-Kowollik, Thomas P. Davis, Leonie Barner, Martina H. Stenzel

Centre for Advanced Macromolecular Design, School of Chemical Sciences and Chemical Engineering, The University of New South Wales, NSW 2052, Sydney, Australia

Polymer property design is an integral part of engineering appropriate materials that can be employed in biomedical applications ranging from polymer based drug delivery to polymers for tissue engineering applications. A particularly powerful tool for arriving at variable polymer structures is so-called free radical polymerization. While polymers made via this method are not biodegradable by themselves, they can be biocompatible. During the last decade conventional radical polymerization has been revolutionized with the advent of techniques that can control the polymer microstructure with a high degree of precision (i.e. the molecular weight, polydispersity and architecture). One of the most prominent of these living radical polymerization (LFRP) techniques is the so-called reversible addition fragmentation chain transfer (RAFT) process (1). The paper highlighted how the RAFT process can be employed to synthesize polymers of increasing architectural complexity ranging from block copolymers to multi-block star polymers with a variable number of arms for a great variety of monomers, including those of interest for biomedical applications like vinyl acetate. It also gave selected examples how LFRP can be employed to assemble amphiphilic block copolymer structures for self-assembly into nano-containers for slow release applications, grafting of polymer surfaces and the synthesis of microspheres of variable sizes for the use in diagnostic kits and delivery applications.

Development of Spictra Membrane Oxygenator System: A Historical Perspective

Muraleedharan CV*, Nagesh DS & Bhuvaneshwar GS
Division of Artificial Organs, Biomedical Technology Wing , Sree Chitra Tirunal Institute for Medical Sciences & Technology , Trivandrum – 695012, INDIA

Membrane oxygenators are devices employed during cardiopulmonary bypass for facilitating the functions of lungs. SPICTRA Hollow Fiber Membrane Oxygenator System is a single use gas exchange device with a self contained venous side heat exchanger for regulating blood temperature. A hard shell venous reservoir meant for the storage and filtration of blood is integrated with the oxygenator module to form the membrane oxygenator system. The Spictra Hollow Fiber Oxygenator system is designed to provide low priming volume, efficient gas exchange and heat transfer efficiency, while suitable for a wide range of patient sizes. The system has been evaluated qualified based on the International Standards ISO 7199: Cardiovascular Implants and Artificial Organs - Blood Gas Exchangers (Oxygenators).

The various phases of design, development and technology transfer of this product which took almost a decade of effort was discussed in the presentation.

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