Amine plasma polymers deposited on porous hydroxyapatite artificial bone with bipolar pulsed discharges.

This article focuses on the chemical and physical properties of amine plasma polymers (PPs) deposited by plasma-enhanced chemical vapor deposition (PECVD) on porous hydroxyapatite (HA) and silicon substrates, relevant to artificial bone applications. The study found that approximately 20% of nitrogen atoms in the freshly deposited amine PPs formed primary amines, but this proportion decreased to about 5% after one month of air exposure or sterilization by autoclaving or ethylene oxide gas. The amine PPs penetrated the inner surfaces of interconnected microscopic pores in porous HA, supporting earlier findings that such coatings enhance bone regeneration in porous β-tricalcium phosphate (β-TCP) artificial bones. Molecular dynamics simulations indicated that only about 10% of incident CN radicals retained their nitrile (C≡N) bonds in the deposited films, with energetic ion impacts further reducing nitrile content. The study concludes that while amine PPs are stable and biocompatible coatings for artificial bones, the specific role of primary amines versus other nitrogen functionalities in bone regeneration remains to be clarified.