Tetrahydroxy Diboron-Enabled 3D-Printable Bioactive Hydrogel Scaffolds for Accelerated Repair of Vaginal Defects

Effective repair of vaginal defects, including those associated with Mayer-Rokitansky-Küster-Hauser syndrome, requires biomaterials that combine tissue-mimetic softness, hydration, mechanical resilience, and therapeutic activity. Here, we report a 3D-printable multifunctional hydrogel scaffold enabled by tetrahydroxy diboron (THDB) chemistry for accelerated vaginal defect repair. THDB triggers rapid radical polymerization of 2-hydroxyethyl methacrylate under oxygen-rich conditions, forming a poly(2-hydroxyethyl methacrylate) network strengthened by hydrogen bonding and B─O coordination from multiple boron species. The incorporation of calcium ions (Ca^{2 +}) and N,N'-methylenebisacrylamide further improves mechanical strength and water stability. The resulting hydrogel exhibits tensile strength above 1.0 MPa, compressive stress of ∼2.0 MPa at ∼70% strain, stable cyclic tensile and compressive performance, and long-term aqueous stability with a swelling ratio of ∼160% in phosphate-buffered saline after 30 days. In addition, sustained release of THDB and Ca^{2 +} provides therapeutic bioactivity, including reactive oxygen species scavenging and activation of redox- and metabolism-related signaling pathways. In a standardized rat model of full-thickness vaginal defects, the hydrogel effectively promotes tissue repair, demonstrating its potential as a mechanically robust, swelling-resistant, and bioactive scaffold for vaginal tissue reconstruction.