The enzyme alkaline phosphatase (ALP) is added at different concentrations (i.e., 0, 2.5, and 10 mg · ml−1) to oligo(poly(ethylene glycol)fumarate) (OPF) hydrogels. The scaffolds are either incubated in 10 mM calcium glycerophosphate (Ca–GP) solution for 2 weeks or implanted in a rat subcutaneous model for 4 weeks. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and alizarin red staining show a strong ability to form minerals exclusively in ALP-containing hydrogels in vitro. Additionally, the calcium content increases with increasing ALP concentration. Similarly, only ALP-containing hydrogels induce mineralization in vivo. Specifically, small (≈5–20 µm) mineral deposits are observed at the periphery of the hydrogels near the dermis/scaffold interface using Von Kossa and alizarin red staining.
Bongio, M., Nejadnik, M. R., Tahmasebi Birgani, Z., Habibovic, P., Kinard, L. A., Kasper, F. K., ... van den Beucken, J. J. J. P. (2013). In Vitro and In Vivo Enzyme-Mediated Biomineralization of Oligo(poly(ethylene glycol) Fumarate Hydrogels. Macromolecular bioscience, 13(6), 777-788. https://doi.org/10.1002/mabi.201200474