SHIELD: A Spin-Coated Hydrophobic Interface for Extended Low-Fouling Durability

Non-specific protein adsorption compromises the accuracy of biosensor measurements. Although hydrophilic and zwitterionic surface modifications have been proposed as solutions, their practical implementation is hindered by their chemical instability and complex synthesis routes. To address these limitations, we developed a simpler yet effective alternative: a fluorinated copolymer-based hydrophobic coating termed SHIELD. The copolymer was synthesized from 2,2,2-trifluoroethyl methacrylate, which imparts low surface energy and enhances hydrophobicity, and n-butyl acrylate, which confers mechanical flexibility and strong substrate adhesion. The copolymer was uniformly deposited onto diverse substrates through a single-step spin-coating process. The resulting surface exhibited strong antifouling performance in both protein adsorption and cell adhesion assays. Importantly, the coating thickness was precisely tunable by varying the polymer concentration, enabling optimization of antifouling efficacy. These findings demonstrate that the SHIELD coating can be stably and reproducibly applied across a wide range of substrates. Overall, this study presents a robust and facile surface modification strategy with strong potential for antifouling applications in biosensing platforms.