Reduced fibrous capsule formation at nano-engineered silicone surfaces via tantalum ion implantation

Although the design of more biocompatible polymeric implants has been studied for decades, their intended functionality continues to be impaired by the response of the host tissue to foreign bodies at the tissue-implant interface. In particular, the formation and contracture of fibrous capsules prevent the intimate integration of an implant with surrounding tissues, which leads to structural deformation of the implants and persistent discomfort and pain. We report a new surface nano-engineered silicone implant that reduces fibrous capsule formation and improves the biocompatibility of it via sputtering-based plasma immersion ion implantation (S-PIII). This technique can introduce biologically compatible tantalum (Ta) on the silicone surface to produce a Ta-implanted skin layer (<60 nm thick) as well as generate either smooth (Smooth/Ta silicone) or nano-textured (Nano/Ta silicone) surface morphologies. The biologically inert chemical structure and strong hydrophobic surface characteristics of bare silicone are substantially ameliorated after Ta ion implantation. In particular, the Nano/Ta silicone implant's combination of surface nano-texturing as a physical cue and the Ta-implanted layer as a chemical cue was found to be very effective at achieving outstanding hydrophilicity and fibroblast affinity compared to the bare and Smooth/Ta silicone implants. In a mouse in vivo study conducted for 8 weeks, the Nano/Ta silicone implant inhibited fibrous capsule formation and contracture on its surface better than the bare silicone based on an analysis of the number of macrophages, myofibroblast differentiation and activation, collagen density, and thickness of fibrous capsules.