A Difunctional Regeneration Scaffold for Knee Repair based on Aptamer-Directed Cell Recruitment

An aptamer-functionalized bilayer scaffold (denoted as aptamer-bilayer scaffold) was introduced to achieve successful knee repair. GO as nanoscale filler is crosslinked into a sodium alginate (SA)-based network containing KGN to create a GO-SA gel for cartilage regeneration. Meanwhile, a 3D grapheme oxide-based biomineral framework (3D-GBF) is designed for bone regeneration. The bilayer scaffold is then assembled from the GO-SA gel and 3D-GBF. Finally, MSC-specific aptamers are immobilized on the bilayer scaffold. The aptamer-gel has a well-defined and interconnected 3D porous network with pore diameters of hundreds of micrometers, which is favorable for cell migration, cell proliferation, and ECM deposition. No characteristic peak of GO at 10.6° was observed in the X-ray diffraction (XRD) pattern of the aptamer-gel. The addition of 0.03% and 0.06% GO resulted in significant increases in compressive stress. However, the compressive stress of the aptamer-gel began to decrease when the amount of GO increased to 0.09%. These results indicate that a certain amount of GO can increase the compressive stress, whereas excess GO leads to reduced compressive stress. Due to its recruitment of MSCs and its other outstanding properties, the bilayer design has been demonstrated to be a potential scaffold for knee repair and worthy of further investigation toward clinical application.