Engineering natural DNA matrices with halloysite nanotubes to fabricate injectable therapeutic hydrogels for bone regeneration.

Background: Injectable hydrogels are widely used in drug delivery and the repair of irregular tissue defects due to their advantages such as convenient and minimally invasive operation. Although the existing injectable hydrogels have excellent biocompatibility and osteoconduction, they still face clinical challenges such as low osteogenic activity. The key requirements for improved injectable hydrogels as repair materials for non-load bearing bone defects are optimal handling properties, the ability to fill irregular defects and provide osteoinductive stimulation. Methods: We developed an approach to construct injectable hydrogels through a two-step gelation process. In the first step of gelation, the denaturation and rehybridization mechanism of natural biopolymer DNA was utilized to form interconnected structure through hydrogen bonding between complementary base pairs between the DNA strands. In the second step of gelation, the introduction of halloysite nanotubes (HNTs) loaded with osteogenic model drug dexamethasone (Dex) provided additional crosslinking sites through non-covalent interactions with the DNA backbone, including electrostatic interaction and hydrogen bonding interaction. Results: The DNA-based nanocomposite hydrogel material developed in our work can be used as an injectable filling material for the repair of non-load bearing bone defect and can be loaded with osteogenic model drug dexamethasone (Dex) for improved osteoinductivity, promoting new bone regeneration Translational potential of this article: This article highlights the potential of using nanocomposite hydrogels to repair non-load bearing bone defects, which are common injuries in the clinic. This study provides a deeper understanding of how to optimize the properties of hydrogels to regulate cell differentiation and tissue formation.