Three-dimensional plasma micro–nanotextured cyclo-olefin-polymer surfaces for biomolecule immobilization and environmentally stable superhydrophobic and superoleophobic behavior

• Micro–nanotexturing of COP is done using plasma etching.
• Chemically stable and high binding surfaces are demonstrated.
• Alternatively, environmentally stable superoleophobic COP surfaces are fabricated.
• COP functional surfaces with localized high binding/antifouling patterns.

Cyclo-olefin polymer (COP) surfaces are micro–nanotextured using O2 plasma chemistry in one-step process. These surfaces subsequently display multiple functionality, (A) they are stable in time (i.e. non ageing), functional, high surface area, substrates suitable for biomolecule binding, after thermal annealing in order to induce accelerated hydrophobic recovery while preserving the chemical functionality created by the plasma. (B) Alternatively, they are robust and environmentally stable superhydrophobic and superoleophobic surfaces, after mechanical stabilization via wetting–drying and gas-phase coating with a perfluoroctyltrichlorosilane monolayer (PFOTS) or plasma deposited Teflon-like polymer layer. The plasma treated, micro–nanotextured surfaces used for biomolecule binding exhibit remarkable retention of the initially immobilized biomolecule compared to untreated COP surfaces (up to 75%), after washing with aggressive washing solutions (sodium dodecyl sulfate), while showing excellent intensity, uniformity and sensitivity. The superoleophobic COP material surfaces exhibit very high static contact angles (SCA >150°) and very low hysteresis (CAH <10°), for a wide range of liquids from water (surface tension: 72.8 mN/m) to hexadecane (surface tension: 27 mN/m). In addition, these superhydrophobic and superoleophobic surfaces exhibit excellent stability against environmental ageing after 60 continuous cycles of exposure to various harsh environmental conditions (heat, moisture, UV irradiation) in a controlled environment. Finally, the two presented functionalities are combined for the first time on the same COP substrate, creating localized rough hydrophilic and antifouling patterns that exhibit spatially selective biomolecule immobilization inside a microfluidic device.

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