Porous scaffolds for tissue regeneration are often functionalized with extracellular matrix proteins to enhance surface/cell interactions and tissue regeneration. However, continuous coatings produced by commonly used surface modification strategies may preclude cells from contacting and sensing the chemical and physical cues of the scaffold. Here, it is shown that polydopamine nanoparticles (PDA-NPs) tightly adhere on various scaffolds to form nanostructures, and the coverage can be finely tuned. Furthermore, the PDA-NPs have good affinity to a variety of proteins and peptides. Thus, the PDA-NPs act as an anchor to immobilize signal biomolecules on scaffolds, and consequently promote cell activity and tissue regeneration. -Tricalcium phosphate (TCP) scaffolds decorated with PDA-NPs demonstrate excellent osteoinductivity and bone-regeneration performance due to the protein affinity of PDA-NPs and the intrinsic bioactive characteristics of TCP scaffolds. In summary, PDA-NPs with excellent affinity for protein adhesion represent a versatile platform to modify porous scaffolds while not compromising the biological functions of the scaffolds, and might have potential applications in tissue regeneration.