Light Triggered Self-Assembly of Collagen Type I for Additive Manufacturing of Cell Scaffolds

Researcher: Akash Dhawan

Chronic wounds are wounds that have not progressed through the normal healing cascade and are indefinitely experiencing inflammation, primarily due to an underlying condition such as diabetes or peripheral arterial disease. Collagen is the main structural protein of the body, making up most of the dry weight of many organs like skin and bone. It is a fibrillar protein that is soluble in acidic solutions (pH < 3) and forms an insoluble fiber when neutralized. Collagen hydrogels provide a scaffold for cells and can help progress chronic wounds toward full healing. However, these gels are difficult to use in wounds with complicated shapes. In this case, we may be able to use additive manufacturing, commonly known as 3D printing, to create a personalized medicine approach to these wounds. Thus, architected collagen cell scaffolds may be the next stage in chronic wound treatment.

There are currently two methods for additively manufacturing collagen hydrogels, extrusion and vat polymerization. In extrusion, the collagen construct is made layer by layer by pushing an acidic collagen solution through a nozzle into a neutralizing bath. However, this method is slow and the viscosity of high concentration collagen solutions makes it difficult to use small gauge nozzles for high resolution printing. In vat polymerization, the collagen is modified with acrylate groups. With the addition of a photo-initiator and light irradiation, the solution can be crosslinked into an acrylate polymer using free-radical polymerization. However, acrylate groups can be cytotoxic and the acrylate polymer does not have the same microstructure as fibrillar collagen, which is important for cell and protein interactions.

We are developing a method for triggering collagen self-assembly by using light to create local pH changes in acidic collagen solutions. In this way, we may be able to achieve collagen constructs with the fibrillar microstructure that we get from extrusion and the speed and resolution of vat polymerization.