Adsorption of alendronate onto biomimetic apatite nanocrystals to develop drug carrier coating for bone implants

The possibility to develop a bone implant with bioactive aspects and in situ drug-delivery properties, in order to provide local treatment in vivo, is a big challenge. Where conventional surface modifications for bone implants focused on the deposition of ceramic (mostly calcium phosphate, CaP) coatings, current surface engineering approaches attempt to incorporate active features to render bone implant surfaces capable to direct biological performance. Biomimetic apatite nanocrystals (nAp) represent, among the CaPs, an elective material for bone applications and their surface functionalization with drugs allows them to act as a drug-delivery vehicle. Since load-bearing bone implants are increasingly used in patients with compromised health conditions, surface engineering is important to warrant the performance of these implants under such conditions. In view of this, bisphosphonates (BPs) represent a treatment modality for a variety of disorders of bone metabolism associated to bone loss, including Paget's bone disease, osteoporosis, fibrous dysplasia and bone metastases. In this work, we have synthesized and characterized bioinspired nAp and evaluated their functionalization with alendronate. In vitro tests will be used to evaluate the efficacy of the functionalized compound to impede the formation of osteoclasts and to show that alendronate-functionalized nAp can significantly reduce osteoclasteogenesis. Finally, alendronate-functionalized nAp (FnAp) has been deposited on titanium implants via the electrospray deposition technique in order to develop inorganic-organic coatings for bone implants with improved functionality.