Hydrothermally converted coralline hydroxyapatite (HAp) particles loaded with medically active substances were used to develop polylactic acid (PLA) thin film composites for slow drug delivery systems. The effects of HAp particles within PLA matrix on the gentamicin (GM) release and release kinetics were studied. The gentamicin release kinetics seemed to follow Power law Korsmeyer Peppas model with mainly diffusional process with a number of different drug transport mechanisms. Statistical analysis shows very significant difference on the release of gentamicin between GM containing PLA (PLAGM) and GM containing HAp microspheres within PLA matrix (PLAHApGM) devices, which PLAHApGM displays lower release rates. The use of HAp particles improved drug stabilization and higher drug encapsulation efficiency of the carrier. HAp is also the source of Ca²⁺ for the regeneration and repair of diseased bone tissue. The release profiles, exhibited a steady state release rate with significant antimicrobial activity against Staphylococcus aureus (S. aureus) (SH1000) even at high concentration of bacteria. The devices also indicated significant ability to control the growth of bacterial even after four weeks of drug release. Clinical release profiles can be easily tuned from drug-HAp physicochemical interactions and degradation kinetics of polymer matrix. The developed systems could be applied to prevent microbial adhesion to medical implant surfaces and to treat infections mainly caused by S. aureus in surgery.

A vital ingredient for engineering bone tissue, in the culture dish, is the use of recombinant matrix and growth proteins to help accelerate the growth of cultivated tissues into clinically acceptable quantities. The skeletal organic matrices of calcifying marine invertebrates are an untouched potential source of such growth inducing proteins. They have the advantage of being ready-made and retain the native state of the original protein. Striking evidence shows that skeleton building bone morphogenic protein-2/4 (BMP) and transforming growth factor beta (TGF-β) exist within various marine invertebrates such as, corals. Best practice mariculture and the latest innovations in long-term marine invertebrate cell cultivation can be implemented to ensure that these proteins are produced sustainably and supplied continuously. This also guarantees that coral reef habitats are not damaged during the collection of specimens. Potential proteins for bone repair, either extracted from the skeleton or derived from cultivated tissues, can be identified, evaluated and retrieved using chromatography, cell assays and proteomic methods. Due to the current evidence for bone matrix protein analogues in marine invertebrates, together with the methods established for their production and retrieval there is a genuine prospect that they can be used to regenerate living bone for potential clinical use.

Musculoskeletal disorders in the elderly have significantly increased due to the increase in an ageing population. The treatment of these diseases necessitates surgical procedures, including total joint replacements such as hip and knee joints. Over the years a number of treatment options have been specifically established which are either permanent or use temporary natural materials such as marine skeletons that possess unique architectural structure and chemical composition for the repair and regeneration of bone tissue. This review paper will give an overview of presently used materials and marine structures for hard tissue repair and regeneration, drugs of marine origin and other marine products which show potential for musculoskeletal treatment.

Foraminifera carbonate exoskeleton was hydrothermally converted to biocompatible and biodegradable zinc-tricalcium phosphate (Zn-TCP) as an alternative biomimetic material for bone fracture repair. Zn-TCP samples implanted in a rat tibial defect model for eight weeks were compared with unfilled defect and beta-tricalcium phosphate showing accelerated bone regeneration compared with the control groups, with statistically significant bone mineral density and bone mineral content growth. CT images of the defect showed restoration of cancellous bone in Zn-TCP and only minimal growth in control group. Histological slices reveal bone in-growth within the pores and porous chamber of the material detailing good bone-material integration with the presence of blood vessels. These results exhibit the future potential of biomimetic Zn-TCP as bone grafts for bone fracture repair.

While one of the major clinical and scientific challenges in the management of implant-related infections and post-operative 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 Ca²⁺ and phosphate PO₄²⁻ 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.