Finding a plasma copolymerization fit that is “just right” using pentane and acrylic acid precursors

Plasma-enhanced chemical vapor deposition is a versatile technology to control interactions at the biomaterial/biological environment interface. Plasma copolymerization is a related strategy that utilizes a mixed feedgas of two or more plasma precursors, whereby conformal coating surface properties can be controlled by simply varying the feedgas composition. This study reports a previously unexplored combination of plasma precursors—pentane and acrylic acid—to deposit coatings with tunable chemistry and wettability on silk fibroin constructs. Five pentane/acrylic acid feedgas compositions were utilized, ranging from 100%, 75%, 50%, 25%, to 0% pentane by pressure. Plasma-deposited coating properties were evaluated through water contact angle goniometry and x-ray photoelectron spectroscopy. Coating static water contact angle values were tunable between >90° and <55° depending on the feedgas composition. Plasma diagnostics and density functional theory were used to evaluate plasma precursor fragmentation. This library of plasma-modified silk-based materials can be used to design biomaterial surfaces that are “just right” for the intended biomedical setting.