Durable Zwitterionic Coatings: Dramatic Reduction of Implant-Induced Inflammation and Fibrosis

Project Summary/Abstract: Polydimethylsiloxane (PDMS), also known as silastic, is commonly used for medical implants. Despite advantages over earlier elastomers and plastics, PDMS surfaces elicit a significant foreign body response (FBR). This response, triggered by adhesion of non-specific proteins, leads to a thick fibrotic capsule post-implantation, impacting the functionality, safety, and longevity of various medical devices. For neurostimulators such as cochlear implants (CIs), this fibrotic tissue increases the impedance of the nerve - tissue interface and has other deleterious effects, e.g., reduced hearing quality in the case of CIs. Similarly, in stents, catheters, and tubes, the FBR can permanently damage tissue, narrow passageways, and restrict flow rates. A notable example is endotracheal (ET) tubes, which commonly induce subglottic stenosis in long-term intubated patients, leading to life-long complications. Moreover, PDMS-based implanted biomaterials are prone to bacterial biofilm formation, presenting a significant risk for infections. Hospital-acquired infections associated with implanted devices incur ~30 billion dollars annually in healthcare costs in the U.S. alone. To address these challenges, surface modifications to enhance the biocompatibility of PDMS have been a significant focus of research. While impressive antifouling properties have been realized in a variety of coatings—and particularly those based on zwitterionic polymers—these coatings have yet to be incorporated in commercial biomedical devices due to weak grafting to the PDMS surface, inadequate mechanical durability, and complex processing steps that aren’t easily transferable to existing manufacturing processes. Our company, ZwiCoat Materials Innovations (ZCMI), has developed the first ever ultra-low-fouling thin film coating that forms a permanent, covalent bond with PDMS surfaces in a simple one-step process. This patented technology combines several properties crucial for commercial viability: strong covalent bonding to PDMS, high lubricity, mechanical durability, and exceptional antifouling capabilities—all achieved through a straightforward, single-step photoinitiated reaction that can be integrated with existing manufacturing protocols. This SBIR project aims to establish the technical merit and feasibility of applying our innovative coating to two existing medical implants, CI electrode arrays and ET tubes—both of which would benefit from greatly reduced fibrosis and are representative of large classes of biomedical devices. The project aims to develop efficient coating technologies, validate coating durability, while confirming their robust antifouling properties on these devices. Phase I success is expected to enable industry partnerships and pave the way for regulatory approval. Concurrently, targeted interviews with hospitals, physicians, patients, and industry leaders will be conducted to inform and refine subsequent Phase II work as well as our commercialization strategy. This approach will position ZCMI to revolutionize the current paradigm wherein fibrosis and moderate infection rates are viewed as inevitable consequences of implanted medical devices, thereby establishing a new standard for patient safety and device efficacy.