Collagen piezoelectricity
Collagen is the most abundant protein in the human body and as one of the principal building blocks of tissues, plays a dominant role in the functioning of tendon, ligament, bone, cartilage, skin, heart and blood vessels. As such, its function is central to materials-based strategies for regenerative medicine, as well as providing a biomimetic target for high-performance, multifunctional fibre-based materials in applications outside of biomedicine. The defining feature of collagen is an elegant structural motif in which three parallel polypeptide strands coil with a one-residue stagger to form a right-handed triple helix, known as tropocollagen. Tropocollagen is unstable at body temperature, driving its formation into supertwisted, right-handed microfibrils with molecules packed in a quasi-hexagonal lattice. This leads to a spiral-like structure within the mature collagen fibril, with interdigitated microfibrils forming a networked, nanoscale rope.
The complex hierarchical structure within a collagen fibril provides interesting mechanical and electrical properties, and the basis for interactions with other tissue components. This allows collagen to modulate tissue structure and therefore function. Through organisation and interactions on the nanometre to micrometre scales, collagen can work effectively in a wide variety of tissue configurations to provide exceptional mechanical performance, tuned to specialised applications. The piezoelectric nature of collagen-rich tissues has been known for some time yet the role of collagen piezoelectricity in the body has remained elusive.
We are exploring the role of collagen piezoelectricity in signalling, and in modulating the mechanical functioning and interactions of collagen structures. Combining scanning probe and nonlinear optical microscopy with numerical modelling, we are developing new insights into biological function and the physical processes in disease. The structure-property-function relationships described in this work also provide opportunities for translation to functional materials development for the wider biomaterials and engineering fields.
