Deposition, characterization, and in vivo performance of parylene coating on general-purpose silicone for examining potential biocompatible surface modifications

• A complete investigation to identify the characteristics of parylene coatings on general-purpose silicones.
• Microstructures, surface properties and mechanical properties of parylene coatings were examined.
• In vitro (Cell culture, platelet adhesion) tests and animal studies revealed satisfactory biocompatibility.
• An alternative of medical-grade silicones is expected to be obtained.

In this study, a thorough investigation of parylene coatings was conducted, as follows: microstructure (i.e., X-ray diffractometer (XRD) and cold field emission scanning electron microscope (FESEM)), mechanical property (i.e., pencil hardness and cross-cut adhesion test), surface property (i.e., water contact angle measurement, IR, and X-ray photoelectron spectroscopy (XPS)), and biocompatibility tests (i.e., fibroblast cell culture, platelet adhesion, and animal studies). The results revealed that parylene, a crystalline and brittle coating, exhibited satisfactory film adhesion and relative hydrophobicity, thereby contributing to its effective barrier properties. Fibroblast cell culturing on the parylene-deposited specimen demonstrated improved cell proliferation and equivalent to or superior blood compatibility than that of the medical-grade silicone (currently used clinically). In the animal study, parylene coatings exhibited similar subcutaneous inflammatory reactions compared with the medical-grade silicone. Both in vitro and in vivo tests demonstrated the satisfactory biocompatibility of parylene coatings.