7 Bio-inspired Inventions That are Transforming Medicine(The gecko tape, Silk circuit, Worm’s glue)

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Inspired by jellyfish, a team at MIT is developing a microchip that uses tiny strands of DNA to grab hold of tumour cells roaming in the bloodstream.

In the past few decades, advances in technology and engineering have made it easier to observe nature and borrow ideas, and bioengineers such as Jeffrey Karp, a leader in bio-inspired medicine and bio-mimetic medicine, are looking towards nature for solutions to scientific problems.

Here, we take a look at 7 bio-inspired inventions.

1. The gecko tape
Geckos are able to scale smooth walls and scamper upside-down across ceilings. They owe their strong grip to millions of microscopic hairs on the bottom of their toes. Each hair's attraction is miniscule, but the total effect is powerful. It is estimated that the setae from the tiny toes of a single gecko, could theoretically carry 250 pounds.

This inspired Jeffrey Karp, a bioengineer at the University of Massachusetts to invent the gecko tape called GeckSkin, his first bioinspired invention. Karp and his group of researchers had created the synthetic material to mimic the properties of gecko feet - a strong adhesive, but when the direction of the setae is changed, the grip is instantly broken. No sticky residues will be left and no tearing or pressure is needed for the removal of the tape. GeckSkin could replace sutures and staples in the hospital, for example, tying together the small intestine during gastric bypass surgery.

2. Silk circuit
Fiorenzo Omenetto, a professor of biomedical engineering at Tufts University, developed a tiny electronic device wrapped in silk that temporarily exists to perform its task, before degrading in just a few weeks. He and his team dissolved and reassembled natural silk crystals into tiny structures to coat silicon circuits and small amounts of magnesium used to conduct electricity.

The silk provides the device with a structure and after a certain period, the crystal structure dissolves along with the silicon and magnesium, making it a biodegradable circuit. It is hoped to be further developed as a way of delivering drugs in precise amounts or stimulating bone healing without having a permanent device in the body. However, it is still a long way from clinical trials.

3. Worm’s glue
Inspired by the sandcastle worm, bioengineering professor Russell Stewart and co-workers from the University of Utah created a liquid adhesive that can be separated from water but still adheres to wet surfaces. This addresses the common problem often encountered in developing bio-inspired medical devices - rejection by the body's immune system.

The glue contains chemical analogs that mimic the worm’s adhesive proteins and properties, using oppositely charged proteins to form a fluid that is denser than water. Currently the team are testing the new adhesives for sealing holes in fetal membranes. If it works, it would allow surgeons to perform advanced fetal surgeries such as cases with spina bifida. Only in preclinical trials, the glue will take years before it could be used in hospitals.

4. Getting a tentacular grip on cancer
Karp also collaborated with other groups, including one at MIT, developing a microchip that uses tiny strands of DNA to grab hold of tumour cells roaming in the bloodstream. They were inspired by jellyfish, which extend their long tentacles to reach for food - regardless of where the food lands.

The microchip is developed to count and sort cancer cells, to determine how well chemotherapy or treatments are working. Doctors will then be able to determine how resistant the tumour is or whether it would appear elsewhere in the body based on the number of cancer cells remaining after chemotherapy.

The microchip also counts cells ten times faster than existing devices. It is currently undergoing laboratory trials on patient tumours.

5. Prolonging the shelf-life of live vaccines
Tardigrades are cousins of arthropods, which can dry out for up to 120 years. A process called anhydrobiosis protects the chemical machinery of the tardigrade - its DNA, RNA and proteins - and upon hydration, gets revived.

Biomatrica, a San Diego company, was inspired by the process and is in the midst of translating the process into protecting live vaccines, eliminating the need for them to be refrigerated - half of vaccines are lost due to handling errors during transportation or treatment.

Biomatrica's chemical barrier "shrink-wraps" the vaccine until it reanimates when water comes into contact.

Nova Laboratories in Leicester, England are also working on similar technology, securing vaccines "in a glassy film made of sugars". This candy coating keeps the virus effective for six months at temperatures up to 45 degrees Celsius, making it particularly useful for vaccinating vulnerable populations in tropical countries.

6. Seaweed sponge to fill gaps
Benefitting from better technology today, David J. Mooney, a research scientist at Harvard University’s Wyss Institute, was able to be inspired by seaweed to develop a new design for a sponge based on the algae's cellular structure.

The properties allow the sponge to shrink to a fraction of its size and be injected into parts of the human body. When it is inside, it re-hydrates and returns to its original size "just like a kitchen sponge," Mooney said. It is built from a polymer derived from the seaweed and is designed to be used to fill space in tissue that has been removed, signalling cells around it to perform some task or even deliver drugs slowly over time.

The sponge is still under development and will take years of testing before it makes it out of the lab.

7. Parasitic staples
Another invention by Karp and his team are microneedle devices inspired by a parasitic worm. It is three times as powerful as conventional surgical staples, but without the risks and side effects perfect for delicate procedures such as skin grafts for burn victims and face transplants and possibly deliver drugs as well.

"Parasites have all sorts of neat tricks that they use to latch onto and colonize hosts," Karp said. The spiny-headed worm lives in fish, attaching to its hosts by sticking its proboscis into the intestinal wall and inflating the appendage's tip, mechanically locking it into place.

The device mimics the worm's proboscis as a tiny array of cone-shaped microneedles with a stiff centre, made of polystyrene and an outer layer tha tis mixed with polyacrylic acid. When a graft covered in the microneedles is inserted into the skin and makes contact with the water in natural tissues, the polyacrylic acid in the tips swell up, providing a mechanical lock with minimal pain and risk of infection. A degradable version is under development.

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