Changing Regulations are Increasing Rubber Compounders’ Workloads

Bye bye, bacteria.
 
Scientists have developed a promising new weapon in the war against hospital-acquired infections. UCLA specialists are fine-tuning an anti-microbial barrier they created for implantable medical devices using zwitterionic material and ultraviolet light. Zwitterionic substances are comprised of molecules that possess an equal amount of cationic and anionic groups, thereby rendering them electrically neutral.
 
The UCLA team built the barrier by depositing a thin layer of zwitterionic material to a device surface and then bonding it to the underlying substrate through UV light irradiation. Early clin- ical results are encouraging—laboratory testing shows the surface treatment reduces biofilm growth by more than 80% and in some cases up to 93%, depending on the bacterial strain.
 
“The modified surfaces exhibited robust resistance against microorganisms and proteins, which is precisely what we sought to achieve,” Richard Kaner, a UCLA Dr. Myung Ki Hong professor of Materials Innovation, and senior research author, told the university’s news service earlier this year. “The surfaces greatly reduced or even prevented biofilm formation. Our early clinical results have been outstanding.”
 
Those results are based on 16 long-term urinary catheter users who switched to silicone devices containing the zwitterionic surface treatment. The modified catheter is the first product made by SILQ Technologies Corp., a UCLA spinout company Kaner founded out of his lab in April 2020. The catheter has been cleared for use by the U.S. Food and Drug Administration.
 
Materials science is key to medtech innovation. New and improved manufacturing materials have led to advancements such as bioprinting, skin-friendly adhesives, shape memory plastics, bioactive glass (orthopedic repair), and bioresorbable stents.
 
MPO’s materials feature examines the latest trends and challenges in medtech materials science, as well as the factors driving innovation in this field. John Tranquilli, materials manager at Lancaster, N.Y.-based Apple Rubber, was among the experts interviewed for this story; his full input is provided in the following Q&A:
 
Michael Barbella: What are the latest trends in medical device materials? What factors are driving these trends?
John Tranquilli: Changing regulations requires more work for rubber compounders in the medical device market. With the implementation of the European Union Medical Device Regulations EU/2017/745 (EU MDR), making sure chemicals listed as carcinogenic, mutagenic, or toxic to reproduction (CMR) are known and reported. There are a few chemicals such as polycyclic aromatic hydrocarbons (PAH), mostly found in carbon black, phthalates plasticizers, certain peroxides, and some antioxidants found in the CMR list. These ingredients are commonly used in rubber compounding. With proper substitutions, these can be eliminated to help assure regulatory approvals. Companies require more assurance of rubber materials passing toxicology testing before medical applications. Materials need to be tested to USP Class VI or ISO 10993 protocols to assure final parts will not affect the comprehensive testing of final devices.  
 
Barbella: What factors are driving innovation in medical device materials science?
Tranquilli: New rubber materials to replace commonly used medical compounds like medical grade silicone. Materials are required to give better abrasion resistance, less friction, and better gas permeability. EPDM- and FKM-based materials are showing growing acceptance and an alternative. Proper compounding is required to assure new compounds will pass all medical regulations. 
 
Barbella: What material challenges are associated with medical device miniaturization and how can these challenges be overcome?
Tranquilli: We have seen many final parts size reductions over the years. Companies require smaller and smaller finished pieces. With proper part design and tool build, these can be met. Over the years,we have replaced older CNC machining centers with higher speed and higher precision CNC centers. This allows us to build molds with small parts to higher precision. 
 
Barbella: How have materials suppliers managed the supply chain challenges prompted by the pandemic, and what lessons (changes) might they implement going forward to avoid future problems/issues?
Tranquilli: Depending on the material, most suppliers have materials on allocations. You can only purchase what was purchased in the previous years, if you can even get it. Some materials are not even meeting allocations. This hurts any new production requirements since all current material is used for current orders, so material can’t be procured for new production. The Just In Time supply is being thrown out the window. Higher safety stock levels are needed to assure production since consistent material shipments might not happen with COVID-19 supply challenges. This is an opportunity for the medical industry to develop better procedures on second sourcing material. For example, only one compound will be tested for application. So when supply disruptions like COVID-19 happen, material changes are not allowed, so production is shut down. Approving multiple materials in the final design will help assure production during supply disruptions. Or, companies need to have efficient procedures to support new material during supply shutdowns. 
 
Barbella: In what ways has the COVID-19 pandemic spurred medical materials innovation, if at all?
Tranquilli: COVID-19 spurred quicker final device approval schedules. Materials that had testing already completed were needed to be used to speed regulatory approval. Lower friction materials or part design required for low force fill application. Reactant compatibility was needed for multiple testing platforms. Materials that can run high volume with low mould fouling and good mold release are preferred for the high volume COVID applications.
 
Barbella: How can materials help improve and/or achieve medical device sustainability?
Tranquilli: New base polymers and plasticizers are using sustainable inputs. As more rubber compounds become eco-friendly and sustainable while moving away from fossil fuel inputs. This will improve medical device sustainability. 
 
Barbella: Please discuss an instance (example) of an innovative material solution your company came up with to meet a challenging customer request.
Tranquilli: A customer needed a more chemical resistance, higher modulus rubber compound for sanitary gaskets compared to using silicone. We developed a new high fluorine FKM 75 durometer black compound for the application. This compound uses a high fluorine peroxide-cured FKM polymer. This gives high chemical resistance and better steam resistance. Using different carbon black gave the compound higher modulus then standard compounds for better seal gap protrusion resistance. This compound did pass FDA USP Class VI for pharmaceutical uses. 
 
Barbella: How will medical materials science evolve over the next five years?
Tranquilli: As automotive moves to EV cars that require less rubber parts, I think more research will be done for rubber in medical devices. This will benefit the medical industry with better polymers that work for more medical applications and improve performance.