Paua shells inspire bone implant research

Victoria University of Wellington research has brought to life the possibility of creating 3D printed bone-like materials using a biomineralisation process inspired by paua shells.

Dr Mima Kurian, wearing safety glasses and a blue glove, holds up a small piece of shell with a pair of tweezers. She is standing next to a microscope. There is a bench with lab equipment and windows in the background.

Dr Mima Kurian, who graduated last week with a PhD in Chemistry, focused her research on the make-up of paua shells due to their “beautiful” nanostructure.

“The nanostructure of nacre, a component of paua shells, imparts mechanical strength that is comparable to that of natural bone—making it a suitable prospective bone graft material,” says Dr Kurian.

“My research involved developing 3D structures that mimicked the elements of both the nanostructure of nacre and the porous structure of bone, using biopolymers derived from shrimp shells and calcium carbonate.

“I used this biopolymer to 3D print materials which—when combined with calcium carbonate—could potentially replace metal-based bone grafts.”

Dr Kurian’s work was a continuation of the synthetic mineralisation research carried out over the last few years at the University and involved collaboration with the School of Design.

She says her biggest challenge was finding a way to translate the work previously done on 2D systems on to 3D printed biomaterials.

“I was working to 3D print the structures without losing the biocompatible properties of the biopolymer, while also being able to replicate the essential elements of the nacre nanostructure so that would make the final material mechanically strong.

“The biopolymer that I used is not like plastic—it doesn’t necessarily set once it’s printed. That combined with the complexity of replicating bone structures meant little room for error. The final structures that I printed had close to 160 layers.”

A 3D printer was developed for this project and made by the University’s School of Design.

One of Dr Kurian’s biggest considerations was keeping the material as biocompatible as possible for use in the body.

“It is expected that when these 3D materials are implanted in the body a continued natural growth and degradation process occurs, whereby the biopolymer will degrade in the body naturally over time as bone regenerates. These 3D materials are expected to provide support during the healing process and eventually be resorbed into the body, as new bone forms in its place.”

Dr Kurian says her research suggests good potential for making bone grafts out of these materials in the future.

“The structures that I made are very small, and when you consider the size of actual bone implants, they’re huge. The work that I’ve done can be used as a framework for further research.”

Dr Kurian’s PhD research was supervised by Industrial Design programme director Ross Stevens and former Vice-Provost Research Professor Kate McGrath (now at the University of Technology Sydney).

Professor McGrath says: “Materials that more closely replicate the structural complexity of bone, as well as meet the mechanical and cellular demands that the body imposes, have the potential to enhance patient recover and long-term prognosis. The materials produced by Mima during her thesis work capture all of these elements.”