Engineering of new durable cross-linked poly(styryl bisphosphonate) thin coatings onto polypropylene films for biomedical applications

Bone tissue engineering uses biocompatible biomaterials to stimulate bone regeneration. Bone has two major components, organic collagen fibers and inorganic hydroxyapatite (HAP) which makes up about 60 percent of bone. Bisphosphonates (BPs) are compounds which are used clinically for bone disorders because of their high affinity for calcium ions. Previously, we reported on the synthesis of cross-linked poly(styryl bisphosphonate) nanoparticles (poly(StBP) NPs) which demonstrated a strong affinity for calcium ions. Here, we describe the use of these NPs for the synthesis of new durable cross-linked poly(StBP) thin coatings on corona-treated polypropylene films by means of a simple method of UV-curing. To produce the coatings, poly(StBP) NPs were mixed with the cross-linking monomer poly(ethylene glycol) dimethacrylate and a photo-initiator, spread on the PP films using a Mayer rod, and then UV-cured. The coatings were characterized using XPS, AFM, FIB, and water contact angle goniometry. Wettability, durability, and optical properties of the coatings were also studied. It was found that HAP flower-like crystals grew on the surface of the coated films but not on the control films, indicating that the poly(StBP) coating may be a good candidate for use in bone tissue engineering.