Bone grafts have been predominated used to treat bone defects, delayed union or non-union, and spinal fusion in orthopaedic clinically for a period of time, despite the emergency of synthetic bone graft substitutes. Nevertheless, the integration of allogeneic grafts and synthetic substitutes with host bone was found jeopardized in long-term follow-up studies. Hence, the enhancement of osteointegration of these grafts and substitutes with host bone is considerably important. To address this problem, addition of various growth factors, such as bone morphogenetic proteins (BMPs), parathyroid hormone (PTH) and platelet rich plasma (PRP), into structural allografts and synthetic substitutes have been considered. Although clinical applications of these factors have exhibited good bone formation, their further application was limited due to high cost and potential adverse side effects. Alternatively, bioinorganic ions such as magnesium, strontium and zinc are considered as alternative of osteogenic biological factors. Hence, this paper aims to review the currently available bone grafts and bone substitutes as well as the biological and bio-inorganic factors for the treatments of bone defect.

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Fluorescent magnetic colloidal nanoparticles (FMCNPs) are produced by a two-step, seed emulsifier-free emulsion polymerization in the presence of oleic acid and sodium undecylenate-modified Fe3 O4 nanoparticles (NPs). The Fe3 O4 /poly(St-co-GMA) nanoparticles are first synthesized as the seed and Eu(AA)3 Phen is copolymerized with the remaining St and GMA to form the fluorescent polymer shell in the second step. The uniform core-shell structured FMCNPs with a mean diameter of 120 nm exhibit superparamagnetism with saturation magnetization of 1.92 emu/g. Red luminescence from the FMCNPs is confirmed by the salient fluorescence emission peaks of europium ions at 594 and 619 nm as well as 2-photon confocal scanning laser microscopy. The in vitro cytotoxicity test conducted using the MTT assay shows good cytocompatibility and the T2 relaxivity of the FMCNPs is 353.86 mM(-1) S(-1) suggesting its potential in magnetic resonance imaging (MRI). In vivo MRI studies based on a rat model show significantly enhanced T2 -weighted images of the liver after administration and prussian blue staining of the liver tissue slice reveals accumulation of FMCNPs in the organ. The cytocompatibility, superparamagnetism, and excellent fluorescent properties of FMCNPs make them suitable for biological imaging probes in MRI and optical imaging.

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Novel pyridine‐containing hyperbranched polyimides (HBPIs) were synthesized by using a new triamine 2,4,6‐tris[3‐(4‐aminophenoxy)phenyl]pyridine with prolonged chain segments, ether linkage and meta‐linked units as a BB′2‐like monomer, various commercial aromatic dianhydrides as A2 monomers. Most of the obtained HBPIs were readily soluble in common organic solvents such as N,N‐dimethylformamide, N,N‐dimethylacetamide, N‐methyl‐2‐pyrrolidone, m‐Cresol, and so forth. Meanwhile, they also had good thermal stability with the glass transition temperatures (Tgs) all above 210 °C, the temperature at 10% weight loss of 537.1–574.4 °C in nitrogen atmosphere. Strong and flexible HBPI films were obtained, which had good mechanical properties with tensile strengths of 83.3–95.8 MPa, tensile modulus of 1.82–2.43 GPa and elongations at break of 4.84–6.98%. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2425–2437