Sterilization effects on ultrathin film polymer coatings for silicon‐based implantable medical devices

Abstract Novel biomaterials for medical device applications must be stable throughout all stages of preparation for surgery, including sterilization. There is a paucity of information on the effects of sterilization on sub‐10 nm‐thick polymeric surface coatings suitable for silicon‐based bioartificial organs. This study explores the effect of five standard sterilization methods on three surface coatings applied to silicon: polyethylene glycol (PEG), poly(sulfobetaine methacrylate) (pSBMA), and poly (2‐methacryloyloxyethyl phosphorylcholine) (pMPC). Autoclave, dry heat, hydrogen peroxide (H₂O₂) plasma, ethylene oxide gas (EtO), and electron beam (E‐beam) treated coatings were analyzed to determine possible polymer degradation with sterilization. Poststerilization, there were significant alterations in contact angle, maximum change resulting from H₂O₂ (Δ − 14°), autoclave (Δ + 15°), and dry heat (Δ + 23°) treatments for PEG, pSBMA, and pMPC, respectively. Less than 5% coating thickness change was found with autoclave and EtO on PEG‐silicon, E‐beam on pSBMA‐silicon and EtO treatment on pMPC‐silicon. H₂O₂ treatment resulted in at least 30% decrease in thickness for all coatings. Enzyme‐linked immunosorbent assays showed significant protein adsorption increase for pMPC‐silicon following all sterilization methods. E‐beam on PEG‐silicon and dry‐heat treatment on pSBMA‐silicon exhibited maximum protein adsorption in each coating subset. Overall, the data suggest autoclave and EtO treatments are well‐suited for PEG‐silicon, while E‐beam is best suited for pSBMA‐silicon. pMPC‐silicon was least impacted by EtO treatment. H₂O₂ treatment had a negative effect on all three coatings. These results can be used to determine which surface modifications and sterilization processes to utilize for devices in vivo. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2327–2336, 2018.