title: Ion-substituted calcium phosphate coatings deposited by plasma-assisted techniques: A review.
abstract: One of the main critical aspects behind the failure or success of an implant resides in its ability to fast bond with the surrounding bone. To boost osseointegration, the ideal implant material should exhibit composition and structure similar to those of biological apatite. To this aim, the most common approach is to coat the implant surface with a coating of hydroxyapatite (HA), resembling the main component of mineralized tissues. However, bone apatite is a non-stoichiometric, multi-substituted poorly-crystalline apatite, containing significant amounts of foreign ions, with high biological relevance. Ion-substituted HAs can be deposited by so called "wet methods", which are however poorly reproducible and hardly industrially feasible; at the same time bioactive coatings realized by plasma assisted method, interesting for industrial applications, are generally made of stoichiometric (i.e. un-substituted) HA. In this work, the literature concerning plasma-assisted deposition methods used to deposit ion-substituted HA was reviewed and the last advances in this field discussed. The ions taken into exam are those present in mineralized tissues and possibly having biological relevance. Notably, literature about this topic is scarce, especially relating to in vivo animal and clinical trials; further on, available studies evaluate the performance of substituted coatings from different points of view (mechanical properties, bone growth, coating dissolution, etc.) which hinders a proper evaluation of the real efficacy of ion-doped HA in promoting bone regeneration, compared to stoichiometric HA. Moreover, results obtained for plasma sprayed coatings (which is the only method currently employed for deposition at the industrial scale) were collected and compared to those of novel plasma-assisted techniques, that are expected to overcome its limitations. Data so far available on the topic were discussed to highlight advantages, limitations and possible perspectives of these procedures.
authors.affiliation: Department of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, via Terracini 28, Bologna 40131, Italy.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Graziani
authors.affiliation: Rizzoli Orthopaedic Institute, NanoBiotechnology Laboratory (NaBi), Research Innovation and Technology Department (RIT), via di Barbiano 1/10, Bologna 40136, Italy. Electronic address: m.bianchi@biomec.ior.it.
authors.forename: Michele
authors.initials: M
authors.lastname: Bianchi
authors.affiliation: Department of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, via Terracini 28, Bologna 40131, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Sassoni
authors.affiliation: Rizzoli Orthopaedic Institute, NanoBiotechnology Laboratory (NaBi), Research Innovation and Technology Department (RIT), via di Barbiano 1/10, Bologna 40136, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Russo
authors.affiliation: Rizzoli Orthopaedic Institute, NanoBiotechnology Laboratory (NaBi), Research Innovation and Technology Department (RIT), via di Barbiano 1/10, Bologna 40136, Italy.
authors.forename: Maurilio
authors.initials: M
authors.lastname: Marcacci
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry; D001861:Bone Regeneration; D002130:Calcium Phosphates / Q000737:chemistry*; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry; D006801:Humans; D007834:Lasers; D058626:Plasma Gases / Q000737:chemistry; D019736:Prostheses and Implants
chemical_list: D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; D058626:Plasma Gases; D017886:Durapatite
keywords: Biomimetic coating; Bone; Hydroxyapatite; Joint replacement; Osseointegration; Plasma deposition