High‐Performance Thiol–Ene Composites Unveil a New Era of Adhesives Suited for Bone Repair

Abstract

The use of adhesives for fracture fixation can revolutionize the surgical procedures toward more personalized bone repairs. However, there are still no commercially available adhesive solutions mainly due to the lack of biocompatibility, poor adhesive strength, or inadequate fixation protocols. Here, a surgically realizable adhesive system capitalizing on visible light thiol-ene coupling chemistry is presented. The adhesives are carefully designed and formulated from a novel class of chemical constituents influenced by dental resin composites and self-etch primers. Validation of the adhesive strength is conducted on wet bone substrates and accomplished via fiber-reinforced adhesive patch (FRAP) methodology. The results unravel, for the first time, on the promise of a thiol-ene adhesive with an unprecedented shear bond strength of 9.0 MPa and that surpasses, by 55%, the commercially available acrylate dental adhesive system Clearfil SE Bond of 5.8 MPa. Preclinical validation of FRAPs on rat femur fracture models details good adhesion to the bone throughout the healing process, and are found biocompatible not giving rise to any inflammatory response. Remarkably, the FRAPs are found to withstand loads up to 70 N for 1000 cycles on porcine metacarpal fractures outperforming clinically used K-wires and match metal plates and screw implants.

Bioinspired Mineral–Organic Bone Adhesives for Stable Fracture Fixation and Accelerated Bone Regeneration

“…To examine the ability of SF@TA@HA to repair ruptured bone tissues in vivo, an assessment of fixation rigidity was performed using the cracked rat femur bone as a fracture model ( Figure A) . After fixation for 8 weeks in vivo, the rat femur treated by SF@TA@HA displayed a fracture resistance similar to that of the normal non‐fractured rat femur (Figure B), which is crucial for the proper load‐bearing function of regenerated bone tissue.…”

“…In Vivo Fracture Fixation Evaluation : Female Wistar rats (200–250 g) were used for in vivo experiments. A study was performed, where 12 rats had surgery of which eight had femur fracture and four had intact femur . The rats with fractured femur divided into two groups, four rats for which the femur was stabilized with SF@TA@HA and four rats for which the femur was untreated.…”

A biomechanical test model for evaluating osseous and osteochondral tissue adhesives

“…Calcified tissue adhesives have also been evaluated in whole tissues, ex vivo and in vivo, by: tensile fracture testing in canine knees, where fibrin glue was compared to Kirschner wire fixation in vivo [13]; peel testing of human periosteum fixated with a glutaraldehyde modified serum based adhesive, compared to untreated periosteum [30]; bending fracture testing of a gelatin based adhesive, compared to untreated fractures, in a murine tibial fracture model, in vivo [31]; multi-modal testing of a polymeric adhesive in a porcine femoral fracture model, ex vivo [32]; three-point bending testing in a porcine metacarpal fracture model, compared with Kirschner wire fixation, ex vivo, and peel testing on rat femoral tissue, in vivo, using a novel click-chemistry adhesive [14].…”

Bioactive Pore‐Forming Bone Adhesives Facilitating Cell Ingrowth for Fracture Healing

“…Replacing traditional invasive materials (e.g., steel plates, screws, and pins) with adhesives for bone fracture fixation and repair may revolutionize orthopedic surgeries. [1][2][3][4][5] Instant strong fixation is essential in the treatment, which remains a challenge to most of the available biomedical glues. [6][7][8][9][10][11] Cyanoacrylates (CA) are one class of the few adhesives that can provide both biocompatibility and adhesion strength to meet such criteria.…”

“…Replacing traditional invasive materials (e.g., steel plates, screws, and pins) with adhesives for bone fracture fixation and repair may revolutionize orthopedic surgeries . Instant strong fixation is essential in the treatment, which remains a challenge to most of the available biomedical glues .…”