Advances in Medical Device Materials Part 1

Advances in Medical Device Materials. Part 1: Polycarbonate Resins

In Preclinical by Amarjit Luniwal

Polycarbonate resins are being used to create promising and versatile new high-performance materials that can be tailored to meet multiple needs:

  • Optical clarity and colorability
  • Durability/impact resistance
  • Ductility for rigorous use
  • High heat resistance
  • Low water absorption
  • Dimensional stability
  • UV light/gamma radiation resistance
  • High flow and enhanced release
  • Flame retardant properties
  • Sterilizable
  • Chemical resistance
  • Biocompatibility (ISO 10993-1, USP Class VI)
  • Ultrasonic weldable/bondable
  • Food compliant

Various physical attributes of polycarbonate resins, including high heat resistance, impact resistance, and optical clarity, are due to interactions such as van der Waals’, pi-stacking, and electronic interactions between constituent functional moieties (i.e., phenyl and carbonate groups). Polycarbonate resins offer strength, which helps reduce device failures, and glass-like clarity, which provides optimal visibility. Their high heat and radiation resistance means they can be sterilized using most of the major sterilization methods (e.g., gamma and electron-beam irradiation, ethylene oxide, and steam autoclave).

Their ease of processing also adds to the utility of these materials because it allows them to be transformed into various shapes and sizes. In addition to standard injection molding, extrusion and blow molding are used to transform polycarbonate resins into film, sheet, and tubing of varying thickness.

All of these important characteristics make polycarbonate resins extremely versatile. They are widely used in the manufacturing of several critical use medical devices, including renal dialysis filters, cardiac surgery products, surgical instruments, IV connection components, high-pressure syringes, glucose meters, insulin pens, device handles and housings, neonatal incubators, and drug delivery devices.

Newer products include polycarbonate resins and blends developed by Bayer MaterialScience, one of which is their Makroblend® M525. This polymer alloy is made up of polycarbonate and polyester co-polymers; the polyester component imparts desired flexibility and higher chemical resistance to the relatively rigid and less chemically resistant polycarbonate component. This blend, designed for use in wearable medical devices, is claimed to provide resistance to various chemicals found in body lotions and meets the requirements for biocompatibility (ISO 10993-5 and ISO 10993-10).

Additionally, M525 is claimed to be resistant to various disinfectants such as isopropyl alcohol, betadine, bleach, and 3% hydrogen peroxide.Makroblend® EL4000 is another example of a polycarbonate/polyester blend from Bayer MaterialScience. This blend is composed of polycarbonate and polybutylene terephthalate and is claimed to be resistant to 2% glutaraldehyde in addition to the disinfectants mentioned above. These resistance profiles are useful features when it comes to sterilizing equipment to prevent the spread of hospital-acquired infections.

The benefits of polycarbonates have made them more cost-effective than traditional materials. Caltorque Medical Products, for example, has developed a line of instruments with handles made of Bayer MaterialScience’s Makrolon® polycarbonate resin, which is a change from the previous stainless steel and silicon instruments.

Research into the characteristics of novel materials and of biological systems provide valuable insights into how to optimize medical device design and performance. Newer materials are being produced that offer specific and customizable qualities that can be manipulated to address the relevant needs. Choosing materials with characteristics best suited for the required applications can improve overall device performance and maintain patient safety, while also reducing production costs. NAMSA has the resources and expertise to assist you in the development and testing of devices that take advantage of what these new materials have to offer.

Next Steps

Resources

ASTM International. Standard Specification for Polycarbonate Resin for Medical Applications. Active Standard ASTM F997. Available at:http://www.astm.org/Standards/F997.htm.

Chaubaroux C, Perrin-Schmitt F, Senger B, et al. Cell alignment driven by mechanically induced collagen fiber alignment in collagen/alginate coatings. Tissue Eng Part C Methods. 2015 Mar 17 [Epub ahead of print].

ISO Standards 11.100.20: Biological evaluation of medical devices [Standards catalog]. Available at:http://www.iso.org/iso/home/store/catalogue_ics/catalogue_ics_browse.htm?ICS1=11&ICS2=100&ICS3=20&.

Makroblend® (PC+PBT; PC+PET blend) product description. Bayer MaterialScience AG. Available at:http://www.plastics.bayer.com/en/Products/Makroblend.aspx.

Makrolon® (polycarbonate) [product information]. Bayer MaterialScience AG. Available at:http://www.sheffieldplastics.com/makrolon_family.cfm.

Authors:

Amarjit Luniwal received a M.S. degree in pharmaceutical sciences from the State Technical University, M.P., India. He received a Ph.D. in Synthetic Medicinal Chemistry from the University of Toledo (advisor Prof. Paul Erhardt) and carried out postdoctoral research in the field of biochemistry from the University of Toledo. Since 2012 he has been at NAMSA and currently works as a Principal Chemist with primary focus on structural identification of unknowns using high resolution mass spectrometry data, and ISO 10993-18 based material characterization testing.