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It is important to synthesize materials to recapitulate critical functions of biological systems for a variety of applications such as tissue engineering and regenerative medicine. The purpose of this study was to synthesize a chimeric hydrogel as a promising extracellular matrix (ECM) mimic using gelatin, a nucleic acid aptamer and polyethylene glycol (PEG). This hydrogel had a macroporous structure that was highly permeable for fast molecular transport. Despite its high permeability, it could strongly sequester and sustainably release growth factors with high bioactivity. Notably, growth factors retained in the hydrogel could maintain ~50% bioactivity during a 14-day release test. It also provided cells with effective binding sites, which led to high efficiency of cell loading into the macroporous hydrogel matrix. When cells and growth factors were co-loaded into the chimeric hydrogel, living cells could still be observed by day 14 in a static serum-reduced culture condition. Thus, this chimeric aptamer-gelatin hydrogel constitutes a promising biomolecular ECM mimic for loading cells and growth factors.

Surfaces functionalized with affinity ligands have been widely studied for applications such as biological separations and cell regulation. While individual ligands can be directly conjugated onto a surface, it is often important to conjugate polyvalent ligands onto the surface to enhance ligand display. This study was aimed at exploring a method for surface functionalization via polymerization of affinity ligands, which was achieved through ligand hybridization with DNA polymers protruding from the surface. The surface with polyvalent ligands was evaluated via aptamer-mediated cell binding. The results show that this surface bound target cells more effectively than a surface directly functionalized with individual ligands in situations with either equal amounts of ligand display or equal amounts of surface reaction sites. Therefore, this study has demonstrated a new strategy for surface functionalization to enhance ligand display and cell binding. This strategy may find broad applications in settings where surface area is limited or the surface of a material does not possess sufficient reaction sites.