Cell-selective zwitterionic parylene with intrinsic antifouling, softness, and conformability†

Abstract

Parylene is one of the most widely used polymers to fabricate flexible bioelectronic devices due to its flexibility, excellent barrier property, and photolithography-compatible fabrication. However, the extensively presented biofouling and the lack of biofunctionalities on the parylene surface prevent the bioelectronic device from constructing intimate coupling with cells/tissues. We herewith fabricated an intrinsically antifouling and soft parylene thin film featuring specific biointeraction, which consists of a bottom layer of pristine parylene and a top layer of 2-bromoisobutyrate functionalized parylene with ligand conjugated zwitterionic polymers. This layer-by-layer structure helps ensure the encapsulation property while allowing for tuning surface function for biomedical applications. This biomimetic parylene thin film presents an excellent barrier property (<10 pA leakage current after 12 weeks of soaking in 37 °C PBS buffer), a three-orders-of-magnitude reduced surface modulus (∼45 kPa), and exceptional mechanical compliance and conformability, all of which are crucial for constructing stable coupling with cells/tissues. Remarkably, the biomimetic parylene demonstrated a highly selective interaction toward PC12/HL-1 cells in the presence of a much higher density of white blood cells, thanks to the construction of specific cell interaction on a biofouling-resistant background. We envision that this biomimetic parylene material would offer bioelectronic devices a controllable interaction with biological systems, allowing seamless integration with cells/tissues and promoting the practical use of bioelectronic devices in real-life situations.