Search

Bioresorbable composites consist of micro- and nano-sized α-tricalcium phosphate (α-TCP) particles in a poly(D,L-lactic-co-glycolic acid) (PLGA) matrix were compared for their ability to form bone-like apatite in simulated body fluid (SBF). Due to the uniform distribution of α-TCP nanoparticles over the nanocomposite surface, enhanced apatite formation was observed. Compared with microcomposite with the same α-TCP load, this enhanced apatite formation was achieved through faster and more uniform apatite nucleation. In the first stage of apatite formation, the presence of abundant high energy boundaries between α-TCP nanoparticles and PLGA matrix in nanocomposite provided a large number of suitable sites for calcium phosphate (CaP) nucleation. A homogenous distribution fo CaP nuclei formed after days. The resulting apatite crystals grew to form a flake-like apatite layer. In contrast, CaP nucleation was only observed on the micrometre-size α-TCP particles in the microcomposite over the same period. After 14 days, a dense, flake-like apatite was visible covering the surface of nanocomposite, whilst this suface layer was formed only on α-TCP particles of the microcomposite.

Arguably one of the most specialised subtopics in porous materials research is that of tissue engineering scaffolds. The porous architecture of these scaffolds is a key variable in determining biological response. However, techniques for characterising these materials tend to vary widely in the literature. There is a need for a set of transferable and effective methods for architectural characterisation. In this review, four key areas of importance are addressed. First, the definition and interpretation of pore size are considered in relation to fluid transport properties, by analogy with filtration research. Second, the definition of interconnectivity is discussed using insight obtained from cement and concrete research. Third, the issue of data scalability is addressed by consideration of percolation theory, as implemented for the study of geological materials. Finally, emerging techniques such as confocal and multiphoton microscopy are discussed. These methods allow the three-dimensional observation of pore strut arrangement, as well holding great potential for understanding changes in pore architecture under dynamic conditions.