Antiresorption implant coatings based on calcium alendronate and octacalcium phosphate deposited by matrix assisted pulsed laser evaporation.

The integration of an implant material with bone tissue depends on the chemistry and physics of theimplant surface. In this study we applied matrix assisted pulsed laser evaporation (MAPLE) in order tosynthesize calcium alendronate monohydrate (a bisphosphonate obtained by calcium sequestration fromoctacalcium phosphate by alendronate) and calcium alendronate monohydrate/octacalcium phosphatecomposite thin films on titanium substrates. Octacalcium phosphate coatings were prepared as refer-ence material. The powders, which were synthesized in aqueous medium, were suspended in deionisedwater, frozen at liquid nitrogen temperature and used as targets for MAPLE experiments. The transferwas conducted with a KrF* excimer laser source ( = 248 nm, FWHM≤ 25 ns) in mild conditions of temper-ature and pressure. XRD, FTIR and SEM analyses confirmed that the coatings contain the same crystallinephases as the as-prepared powder samples. Osteoblast derived from stem cells and osteoclast derivedfrom monocytes of osteoporotic subjects were co-cultured on the coatings up to 14 days. Osteoclastdisplayed significantly reduced proliferation and differentiation in the presence of calcium alendronatemonohydrate, pointing to a clear role of the coatings containing this bisphosphonate on inhibiting exces-sive bone resorption. At variance, osteoblast production of alkaline phosphatase and type I pro-collagenwere promoted by the presence of bisphosphonate, which also decreased the production of interleukin6. The positive influence towards osteoblast differentiation was even more enhanced in the compositecoatings, thanks to the presence of octacalcium phosphate.