Hip and knee implants, made of polyethylene or plastic, need to be replaced approximately every 15 years due to wear and tear. Assistant Professor Ali Miserez and his research team from Nanyang Technological University (NTU), Singapore discovered that the protein structure of beaks of squids could be mimicked to create joint implants for humans. Squid beaks comprise of interlinked chitin fibres, similar to that in insects and crustaceans, as well as concentrated liquid protein solution that diffuses throughout these chitin fibres. The concentrated liquid protein diffuses all the way to the tip of the beak, hardens, and acts as a binder, analogous to superglue hardening when exposed to air.
The beak of the jumbo squid Dosidicus gigas is fascinating; a 200-fold stiffness gradient begins in the hydrated chitin of the soft beak base and gradually increases to maximum stiffness in the dehydrated distal rostrum. The scientists combined RNA-Seq and proteomics to show that the beak contains two protein families. One family consists of chitin-binding proteins (DgCBPs) that physically join chitin chains, whereas the other family comprises highly modular histidine-rich proteins (DgHBPs). DgHBPs play multiple key roles during beak bioprocessing, first by forming concentrated coacervate solutions that diffuse into the DgCBP-chitin scaffold, and second by inducing crosslinking via an abundant GHG sequence motif. These processes generate spatially controlled desolvation, resulting in the impressive bio-mechanical gradient.
While explaining the downside of current joint implants, Prof Miserez shared that, “You have this very stiff material coming into contact with very soft flesh, and you have deep tissue damage.” He believed that implants made with materials resembling squid beaks would prevent tissue damage in patients and prolong the lifespan of implants.
Dr Andrew Dutton, medical director and orthopaedic surgeon of SMG orthopaedic group, also raised his concerns on current cartilage implants, “(Current cartilage implants) are very soft, they can break down, they can loosen and come off, and they may not be well incorporated.”
The NTU scientists aim to create next-generation joint implants using high performance natural resources like chitin from waste seafood, and create the concentrated liquid protein in their laboratory.
Source: The Straits Times.
The original paper can be accessed here.