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Calcium phosphate materials can be produced using a number of wet methods that are based on hydrothermal or co-precipitation methods that might use acidic or basic chemical environments. In our previously published works, we have investigated calcium phosphates such as monetite, hydroxyapatite, and whitlockite which were successfully produced by mechano-chemical methods and/or hydrothermal treatments from a range of marine shells and corals which were obtained from the Great Barrier Reef. The aim of the current work was to analyze and compare the mechanisms of conversion of one hard coral species and one calcified algae species from the Great Barrier Reef.

Ion substitution Human stem cells Bone biomaterial Calcium phosphate Dicalcium phosphate dihydrate, DCPD (CaHP0 4 •2H 2 O), brushite, is an important calcium phosphate compound encountered in mineralized tissues and used in medicine, especially in bone cernent for mulations. However, the use of DCPD as direct implantable biomaterial has not received dedicated attention. In addition, the possibility to dope DCPD with biologically active ions to modulate its per formances was not systematically explored. We have investigated in depth the doping of DCPD with Mg 2+ , sr2 + , Zn 2+ , Cu 2+ , and Ag + ions. Clear modifications in terms of chemical composition, particl e size, pore distribution, crystal morphology, and affinity for water were pointed out. Then, the samples were cultured with human adipose derived stem cells to explore cytotoxicity and proliferation. Various be haviors were noticed dependent on the incorporated metal ions. Such DCPD compounds associated with bioactive metal ions, and particularly Ag + and Zn 2+ , appear promising as a new family of reactive ma terials for use, as such or in combination, in bone related applications.

The biodegradable and biocompatible antibiotic containing thin film composites are very appropriate biomaterials as coating materials for dental implants because of their adjustable drug loading and release rates for the prevention of implant related infections. Coralline hydroxyapatite (HAp) was loaded with gentamicin antibiotics and combined with a biodegradable polylactic acid (PLA) to form thin film composites. PLA-HAp, PLA-Gentamicin (GM) and PLA-HAp-GM composites were produced, and their dissolution studies were carried out in phosphate buffered saline under SINK conditions. It was observed that the coatings could be efficiently applied to titanium dental implants and the drug release rates can be efficiently controlled.

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While one of the major clinical and scientific challenges in the management of implant-related infections and postoperative complications after surgery is the application of new techniques, a new approach is pertinent in the design of medical implants to reduce bacterial infections. We have designed and tested antibiotic-containing biocomposite thin films of polylactic acid (PLA), and coralline-derived hydroxyapatite (HAp) as controlled drug delivery systems for the treatment of dental, orthopaedic and neural implant-related post-operative infections. These films can be applied to complicated designs of dental, miniaturized neural devices, cochlear or total hip replacement (THR) implants by spray or dip-coating techniques. Current results reveal that the devices could release antibiotic in a controlled manner to prevent significantly bacterial growth and biofilm production. Hydroxyapatite within the composites controls the release rate and also supplies minerals, such as calcium Ca 2+ and phosphate PO 4 2− ions, which are essential minerals for bone tissue regeneration. It is concluded from the physical, mechanical and biological properties that these coatings and devices could easily be utilized in a wide range of biomedical applications.

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