New graphene dialysis membrane could be 'amazing' for seriously ill patients

A new filtering process using the versatile 2D material graphene could have “amazing” possibilities for people with serious diseases, an expert has said.

Engineers at MIT have made a functional dialysis membrane from a sheet of the material, a single layer of carbon atoms linked together in a hexagonal lattice. The dialysis process filters molecules out of a solution, such as removing waste products from the blood of patients with kidney disease.

The graphene dialysis membrane is much thinner than existing examples, which are normally made of cellulose or synthetic polymers, with a thickness of 1nm compared to the previous thinnest 20nm. As a result, the graphene can filter molecules out of solutions 10 times faster, said the MIT department of mechanical engineering team led by Piran Kidambi.

The increased efficiency could “make a serious difference to patients, particularly those who are suffering from blood illnesses or kidney disease,” said Helen Meese, head of healthcare at the Institution of Mechanical Engineers. “Going into hospital for long periods of time can be time-consuming and painful, and can affect people quite severely if they are having to go two or three times a week for dialysis.”

Quicker filtering and increased portability with graphene membranes could let patients stay at home or visit their GP surgery rather than hospital, she added, saving costs and possibly helping patients recover faster.

The new membrane could have many other uses, said the MIT team, including purifying drugs for pharmaceutical companies and isolating molecules during medical diagnosis of patients. Current membranes work slowly because they are relatively thick, the engineers said, with molecules travelling through “winding paths” to the diluted solution.

“Because graphene is so thin, diffusion across it will be extremely fast,” Kidambi said. “A molecule doesn’t have to do this tedious job of going through all these tortuous pores in a thick membrane before exiting the other side. Moving graphene into this regime of biological separation is very exciting.”

The team filtered a variety of molecules with diameters between 0.66nm and 4nm out of solutions with their 1cm² membrane. The graphene was customised to “selectively sieve” the molecules, with oxygen plasma used to make holes of different sizes.

The engineers plan to make the membrane bigger, and to create more “tailored” pores to allow more molecules through, something which would cause problems for the super-strong, thin and conductive material in other applications.

“What’s exciting is, what’s not great for the electronics field is actually perfect in this field,” Kidambi said. “In electronics, you want to minimize defects. Here you want to make defects of the right size.”

The study was published in Advanced Materials.