Functionalization of the Polymeric Surface with Bioceramic Nanoparticles via a Novel, Nonthermal Dip Coating Method

Abstract

The only nonthermal method of depositing a bioceramic-based coating on polymeric substrates is by incubation in liquid, e.g., simulated body fluid to form an apatite-like layer. The drawbacks of this method include the long processing time, the production of low scratch resistant coating, and an end product that does not resemble the intended bioceramic composition. Techniques, such as plasma spraying and magnetron sputtering, involving high processing temperature are unsuitable for polymers, e.g., PMMA. Here, we introduce a nonthermal coating method to immobilize hydroxyapatite (HAp) and TiO₂ nanoparticles on PMMA via a simple and fast dip coating method. Cavities that formed on the PMMA, induced by chloroform, appeared to trap the nanoparticles which accumulated to form layers of bioceramic coating only after 60 s. The resulting coating was hydrophilic and highly resistant to delamination. In the context of our research and to address the current clinical need, we demonstrate that the HAp-coated PMMA, which is intended to be used as a visual optic of a corneal prosthetic device, improves its bonding and biointegration with collagen, the main component of a corneal stroma. The HAp-coated PMMA resulted in better adhesion with the collagen than untreated PMMA in artificial tear fluid over 28 days. Human corneal stromal fibroblasts showed better attachment, viability, and proliferation rate on the HAp-coated PMMA than on untreated PMMA. This coating method is an innovative solution to immobilize various bioceramic nanoparticles on polymers and may be used in other biomedical implants.

Keywords: adhesion; bioceramic; biointegration; collagen; cornea; nanoparticles; polymer; surface functionalization.