Researchers at Massachusetts Institute of Technology (MIT) have devised a hydrogel-based substance which imitates the structure of a lobster’s underbelly.

The paper, “Strong fatigue-resistant nanofibrous hydrogels inspired by lobster underbelly.”, suggests that the nanofibrous hydrogel-based material has the potential strength and stretch to be used to replace robust tissues such as tendons, ligaments and cartilage.

Shaoting Lin, a postdoctoral associate at MIT’s department of mechanical engineering explained,

‘For a hydrogel material to be a load-bearing artificial tissue, both strength and deformability are required. Our material design could achieve these two properties.’

Hydrogels are gelatin-like materials consisting mainly of water and cross-linked polymers found in both plants and animals. A lobster’s underbelly – the toughest known hydrogel in nature – is a distinct multi-layered structure with aligned chitin nanofibres in each layer which is highly durable and resistant to tearing. This means that the underbelly is lined with a thin, elastic, and translucent membrane that is stretchy, flexible, and remarkably tough.

Nanofibrous hydrogels are already seen in engineering applications,

“Owing to the merits of high porosity, high water content, and biocompatibility, nanofibrous hydrogels have been explored in diverse applications, including tissue regeneration, ionic skin, haemostatic dressings, cartilage repair, imperceptible textile sensors, printable electrodes for flexible implants, tissue adhesives, and small-scale bio-robots,” say the report’s authors.

The process starts with a fibre production technique known as electrospinning which extracts ultrathin threads out of polymer solutions using electric charges. Though electrospinning is a common method for fabricating nanofibrous hydrogels, they tend to be fragile and weak.

The MIT team’s method spins nanofibers from a polymer solution using high-voltage charges to form a flat film of nanofibers, each measuring about 800 nm. By placing the nanofibre film in a temperature and humidity chamber, the individual fibres are bound together as an interconnected web which is then incubated at a high temperature to solidify the individual nanofibers, strengthening the material even more.

After further stretch-testing, the team calculated that the nanofibrous films were 50 times more resistant to fatigue than the conventional nanofibrous hydrogels.
As the chitin in the protective membrane of a lobster’s underbelly has a layered, rotating configuration known as a bouligand structure, which augments its strength and ability to stretch, the researchers wanted to see if they could reproduce this membrane structure using their fatigue-resistant, synthetic films.

In fact, stretch tests showed that the material was able to stretch repeatedly without wear and tear, and its remarkable properties of strength and flexibility suggests that the application of the technology as tissue replacement may well be possible.