A mussel-bioinspired coating strategy to licence PCL osteoinductive activity for repairing bone defects

3,4-Dihydroxyphenylalanine (DOPA) is believed to play an essential role in the solidification and adhesion of liquid mussel adhesives; this thin polymer layer very tightly adheres to the surface of scaffolds, making it stable enough to prevent it from being peeled off. Fascinatingly, the deposition of DOPA on various types of surfaces via the self-polymerization of DOPA under alkaline conditions is a simple approach for creating biomimetic coatings. In this study, DOPA derivatives were used as monomers to form primary coatings on polycaprolactone (PCL) surfaces. After that, a second chemical crosslinking method was utilized to graft alendronate (AL) on the DOPA coatings via genipin (GP) crosslinking (D-PCL@AL). X-ray photoelectron spectroscopy, Fourier transform infrared reflection and scanning electron microscopy analyses indicated that AL was distributed homogeneously on the surface of PCL. This new organic–inorganic hybridized coating could support EMSC growth and osteogenic differentiation. Additionally, animal studies were also performed to verify the function of D-PCL@AL in promoting osteogenesis. The method is simple, cheap and highly efficient, which makes it very convenient to apply on a large scale.