Incorporating collagen in shape-memory hydrogels for injectable tissue scaffolds

Shape-memory hydrogels (SMHs) have the potential for widespread use in drug delivery systems, soft robotics, biosensors, and actuators. They also can be used as injectable scaffolds to restore and heal major tissue defects. If a scaffold can be inserted into the body and then stimulated (via hydration, temperature, or light) to regain its shape, it could be used for minimally invasive surgical procedures.

Collagen has the potential to be an important component in these hydrogels as one of the main structural proteins in tissues and organs. However, studies on collagen typically focus on its biological advantages rather than its biophysical properties such as shape recovery.

Lee and Kim fabricated a new collagen-based SMH by combining two different techniques to create SMHs. The first is a Cryo-gel that is poured into a mold and cooled to form ice crystals before being immersed into a cross-linker to maintain its structure. The second is a fibrous gel (F-gel) that leverages the self-assembly characteristics of collagen. It was synthesized by fibroblastic cells and then crosslinked.

The Cryo-gel recovered its initial shape quickly. In contrast, the F-gel better supported cell adhesion and growth. The team implemented a dual-crosslinking strategy to combine these benefits into a single SMH.

“By these methods, we can fabricate a microporous scaffold with a roughened and partially fibrous structure,” said author GeunHyung Kim. “This could provide an actual platform for delivery systems of various growth factors or drugs. Future work will be directed toward various preclinical applications of the SMHs as injectable scaffolds.

The team hopes these preparation methods will be broadly used in various tissue engineering and clinical applications.

Source: “Collagen-based shape-memory biocomposites,” by JiUn Lee and GeunHyung Kim, Applied Physics Reviews (2022). The article can be accessed at https://doi.org/10.1063/5.0084794 .