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Allografts are commonly used as an alternative to autografts for bone defect repair, but in some instances suffer from reduced host incorporation that can lead to complications 5 and 10 years post-implantation. We have previously demonstrated that using a thin polymeric coating along the outer surfaces of cortical bone can improve the biofunctionality of devitalized bone allografts by permitting the upload and delivery of growth factors from the thin coating. Here, we expand on our previous work to develop a methodology to coat porous trabecular allografts with a similar polymer coating with careful attention to maintaining an open pore network within the allograft and establishing the effect of varying the polymer solution viscosity on coating extent and thickness. Results indicate that varying the polymer solution viscosity by changing the polymer to solvent ratio used to coat the samples allows for variations in coating thickness and extent of surface area coverage, each perhaps allowing for greater control over growth factor loading and release concentration and kinetics. Further, we develop a dynamic coating method that produces a continuous and consistent coating throughout the pore structure vs. the previously used static method that resulted in a discontinuous coating throughout the pore network. The work demonstrated here provides important techniques for varying the payload of polymer-coated, factor-loaded trabecular allografts which would provide another tool to the orthopedic surgeon when healing large-scale defects with trabecular allograft. Large scale bone defects are traditionally treated with either autografts or allografts. Allografts suffer from poor incorporation in part due to the processing undertaken to render them safe to transplant from one individual to another. We sought to add back some of the biological functionality that is removed in this processing by loading growth factors into a very thin polymeric coating that we apply to the surface of the allograft. Our results indicate a thin, continuous polymeric coating throughout the trabecular allograft, with the amount of this coating varying as we vary the concentration of this polymer solution prior to coating. Future studies will evaluate the ability of this varied concentration of polymer coating to permit the delivery of varying amounts of growth factors, imparting a greater degree of control over the amount of growth factor delivered from the coated allografts.

This manuscript focuses on bone repair/regeneration using tissue engineering strategies, and highlights nanobiotechnology developments leading to novel nanocomposite systems. About 6.5 million fractures occur annually in USA, and about 550,000 of these individual cases required the application of a bone graft. Autogenous and allogenous bone have been most widely used for bone graft based therapies; however, there are significant problems such as donor shortage and risk of infection. Alternatives using synthetic and natural biomaterials have been developed, and some are commercially available for clinical applications requiring bone grafts. However, it remains a great challenge to design an ideal synthetic graft that very closely mimics the bone tissue structurally, and can modulate the desired function in osteoblast and progenitor cell populations. Nanobiomaterials, specifically nanocomposites composed of hydroxyapatite (HA) and/or collagen are extremely promising graft substitutes. The biocomposites can be fabricated to mimic the material composition of native bone tissue, and additionally, when using nano-HA (reduced grain size), one mimics the structural arrangement of native bone. A good understanding of bone biology and structure is critical to development of bone mimicking graft substitutes. HA and collagen exhibit excellent osteoconductive properties which can further modulate the regenerative/healing process following fracture injury. Combining with other polymeric biomaterials will reinforce the mechanical properties thus making the novel nano-HA based composites comparable to human bone. We report on recent studies using nanocomposites that have been fabricated as particles and nanofibers for regeneration of segmental bone defects. The research in nanocomposites, highlight a pivotal role in the future development of an ideal orthopaedic implant device, however further significant advancements are necessary to achieve clinical use.

The need and the growing interest in polymers as biomaterials have led to the synthesis of new polymers with a variety of physico-chemical properties. Biomedical application of such materials not only depends on their physical properties but also on biocompatibility and biodegradability. Polyphosphazenes are a family of ‘hybrid inorganic–organic polymers’ with inorganic elements in the backbone and organic side-groups. The polyphosphazenes constitute a family of greatly diverse performance materials with a broad spectrum of properties. The present review focuses on the biodegradable polyphosphazenes, their biocompatibility, and degradation behavior both in vitro and in vivo. This review also covers the use of biodegradable polyphosphazenes as controlled release devices.

Novel copolymers of poly(aniline-co-m-chloroaniline)-doped dodecylbenzenesulphonic acid (DBSA) with embedded silver nanoparticles were synthesised using the in situ chemical oxidative method. The structural properties of the copolymers were characterised using the UV-VIS and FTIR spectroscopic methods. The crystalline nature of the copolymer was demonstrated by way of the X-ray diffraction (XRD) pattern. Scanning electron microscopy (SEM) revealed the presence of particle agglomerates measuring 50 nm to 100 nm on the surface of the nanocomposites. The electrical conductivity of the copolymer was dependent on the monomer composition and was found to be in the range of 10−2 S cm−1 to 10−6 S cm−1 with an increasing chloroaniline content and exhibiting improved solubility.