Liyang Shi

Formation of hierarchical bone-like apatites on silk microfiber templates via biomineralization

Silk microfibers (mSF) are attractive in tissue engineering because of their good plasticity and significant mechanical reinforcement effect. Bone-like apatites coated on the surface of mSF through biomineralization have been rarely reported. In this study, mSF with lengths of 200–300 μm were prepared and used as templates for biomineralization. By immersing in 1.5 times stimulated body fluid (1.5 × SBF), a hierarchical bone-like apatite layer can be formed on the surface of the mSF, which was developed in a time-dependent manner. As basic units, hydroxyapatite (HAp) nanoplates will assembly into microspheres with sophisticated flower-like structures and then, the microspheres gradually aggregated into a complete mineral layer overcovering the mSF. Multiple methods were used to characterize and analyze the organic/inorganic composites, including their morphology, structural and crystallographic properties, as well as the interface between the two different phases. The template effect of the mSF in the biomineralization process was investigated and a possible mechanism was proposed. In addition, cytocompatibility evaluation showed the mineralized silk microfibers (mmSF) tended to achieve better outcomes for cell growth and proliferation. This work provides a facile approach towards the development of mSF/HAp biocomposites, which possess potential applications in bone tissue engineering.

Enzymatic degradation of hyaluronan hydrogels with different capacity for in situ bio‐mineralization

In situ cross‐linked hyaluronan (HA) hydrogels with different capacities for biomineralization were prepared and their enzymatic degradation was monitored. Covalent incorporation of bisphosphonates (BPs) into HA hydrogel results in the increased stiffness of the hydrogel in comparison with the unmodified HA hydrogel of the same cross‐linking density. The rate of enzymatic degradation of HABP hydrogel was significantly lower than the rate of degradation of control HA hydrogel in vitro. This effect is observed only in the presence of calcium ions that strongly bind to the matrix‐anchored BP groups and promote further mineralization of the matrix. The degradation of the hydrogels was followed by noninvasive fluorescence measurements enabled after mild and chemoselective labeling of cross‐linkable HA derivatives with a fluorescent tag.