Gadolinium chelate MRI RANK-RANKL-OPG anodic oxidation antibacterial activity antibacterial properties biointegration biomaterials fabrication bone regeneration cell sheet cornea endothelial cells dental enamel regeneration dental implant dental stem cells drug delivery epithelial-mesenchymal interactions graphene lysophosphatidic acid magnetic nanoparticles medicine mimetic peptide nanofibers nanomaterials nanotechnology odontogenic cells osteoclastogenesis photocatalytic activity protein regeneration silk fibroin