Scientists at ETH Zurich have invented a hydrogel implant that mimics the body's natural bone healing process. Composed mostly of water, the material can be precisely shaped using lasers to create detailed structures resembling bone tissue. This innovation aims to offer a better alternative to traditional grafts and metal implants.
When bones suffer severe fractures or require tumor removal, surgeons typically use autografts from the patient's own body or rigid metal and ceramic implants. Autografts demand extra surgery, prolonging recovery and risks, while metal implants, being stiffer than natural bone, can loosen over time.
To address these issues, Xiao-Hua Qin, Professor of Biomaterials Engineering at ETH Zurich, and his team, including ETH Professor Ralph Müller, have developed a hydrogel that integrates biology into the repair process. "For proper healing, it is vital that biology is incorporated into the repair process," Qin stated.
The hydrogel, which is 97 percent water and 3 percent biocompatible polymer, replicates the initial soft, permeable stage of bone healing after injury. It forms a temporary scaffold similar to the hematoma that allows immune and repair cells to enter and deliver nutrients, eventually transforming into solid bone.
Two specialized molecules enable control: one links polymer chains, and the other solidifies the material upon light exposure. Wanwan Qiu, a former doctoral student, designed the linking molecule, noting, "It enables rapid structuring of hydrogels in the sub-micrometer range."
Using laser pulses, the team prints structures as fine as 500 nanometres at speeds up to 400 millimetres per second—a world record. They have recreated bone's trabecular lattice and nanoscale tunnels, with a dice-sized bone containing 74 kilometres of such channels.
Laboratory tests demonstrate biocompatibility, as bone-forming cells readily infiltrate the hydrogel and produce collagen. The base material is patented, and the researchers plan animal studies with the AO Research Institute Davos to assess in vivo performance. The work appears in Advanced Materials.
