Endless possibilities? What in situ cure silicones can offer medical devices
Benny David, PhD., director of business development, NuSil, talks to Med-Tech Innovation News about the new possibilities that in situ cure silicones can offer medical devices.
What types of applications use medical-grade silicone, and why is it appealing for use in implantable medical devices?
Medical-grade silicones have a long and proven track record of use in healthcare applications. Every day across the globe, this biomaterial is used in everything from soft silicone adhesives used in wound care products to components in medical devices implanted in the human body. Today, silicone can be found in applications such as cardiovascular pacemakers, cochlear implants, drug delivery devices, joint replacements and intraocular lenses. Silicone is appealing in medical devices due to the material’s polymer stability. They are also chemically inert, biocompatible, and easy to clean and sterilise. Silicone formulations are highly customisable, enabling them to be tuned to the critical needs of a variety of applications.
What possibilities do in situ cure silicones offer for implantable medical devices?
In situ curing silicones bring personalised medicine to implantable devices. Normally, these devices are formed, cured and sterilised outside the body before the implantation procedure. NuSil’s patented dispensing system provides an alternative to surgical implantation by allowing uncured, pre-sterilised silicone to be delivered directly into the body, precisely where the device is needed. The silicone forms into the shape of the implant site — rather than a one-size-fits-all approach with standard implant shapes. Once delivered, the silicone cures in situ at body temperature.
The result is a “real-time” implant that creates opportunities for novel customised therapies that require less invasive implantation procedures. It offers application potential for cardiovascular, neurological, urological and ophthalmic aesthetic implants. For example, in situ-cured silicones could be leveraged in a custom device for bone and vertebral repair.
What challenges did you face in developing this technology?
The challenge was to find a way to package both the uncured silicone and sterilisation chemistry in a safe, all-in-one delivery system. The solution is a pre-filled, dual cartridge dispensing technology. Each cartridge contains a gas-permeable plunger seal that allows an ethylene oxide (EtO) sterilant gas to permeate the seal and sterilise uncured silicone inside the barrel. The silicone is then delivered directly to the point where the implant is needed.
How are in situ cure silicones developed?
An extremely versatile material, silicone’s chemical make-up can be fine-tuned to match specific material properties, including durometer, elasticity and fatigue resistance. We collaborate closely with customers to ensure the in situ-cured silicone meets their requirements and functions as intended. For example, hardness can be precisely defined in a silicone device intended to provide orthopaedic support; likewise, an in situ-cured silicone implant used to cushion a joint can be formulated for a specific level of softness.
Is this technology specifically for long-term implants?
Yes, NuSil’s in situ cure technology is for long-term implant devices (more than 29 days). Like all of our medical-grade silicones, the silicone is formulated, manufactured and purified to meet the strictest regulatory requirements. We maintain more than 700 Master Files (MAFs) with the U.S. Food and Drug Administration and can provide the relevant regulatory support needed to help smooth the path to commercialisation.
What benefits do you feel NuSil offers that otherwise wouldn’t be available?
For more than 40 years, we’ve helped move innovation and discovery forward. Whether we’re developing silicones for medical devices or for spacecraft roving Mars, we bring innovation and manufacturing expertise to every project. NuSil can supply off-the-shelf medical-grade silicones as well as custom formulations that meet precise process and device performance requirements. Our team understands how to move a silicone component or device from design to full-scale manufacturing.
What further advances do you envisage in this particular area?
We expect to continue to see in situ cure technology enabling novel therapies that hadn’t been possible without this innovation in applications that could include orthopaedics, cardiovascular, aesthetic or neurological therapies. For example, recent advances in the field of sustained release drug delivery are incorporating long term implants that leverage in situ cure technology.