Graphene sheets allow for very-low-cost diagnostic devices

March 20, 2017

A new, very-low-cost diagnostic method. Mild heating of graphene oxide sheets makes it possible to bond particular compounds (blue, orange, purple) to the sheets’ surface, a new study shows. These compounds in turn select and bond with specific molecules of interest, including DNA and proteins, or even whole cells. In this image, the treated graphene oxide on the right has oxygen molecules (red) clustered together, making it nearly twice as efficient at capturing cells (green) as the material on the left. (credit:  the researchers)


A single cell can contain a wealth of information about the health of an individual. The new system could ultimately lead to a variety of simple devices that could perform a variety of sensitive diagnostic tests, even in places far from typical medical facilities, for cancer screening or treatment follow-up, for example.

How to capture DNA, proteins, or even whole cells for analysis

The material (graphene oxide, or GO) used in this research is an oxidized version of the two-dimensional form of pure carbon known as graphene. The key to the new process is heating the graphene oxide at relatively mild temperatures.

This low-temperature annealing, as it is known, makes it possible to bond particular compounds to the material’s surface that can be used to capture molecules of diagnostic interest.

Schematic showing oxygen clustering, resulting in improved ability to recognize foreign molecules (credit: Neelkanth M. Bardhan et al./ACS Nano)

The heating process changes the material’s surface properties, causing oxygen atoms to cluster together, leaving spaces of bare graphene between them. This leaves room to attach other chemicals to the surface, which can be used to select and bond with specific molecules of interest, including DNA and proteins, or even whole cells. Once captured, those molecules or cells can then be subjected to a variety of tests.*




They did this by enzymatically coating the treated graphene oxide surface with peptides called “nanobodies” — subunits of antibodies, which can be cheaply and easily produced in large quantities in bioreactors and are highly selective for particular biomolecules.**

The new process allows for rapid capture and assessment of cells or biomolecules within about 10 minutes and without the need for refrigeration of samples or incubators for precise temperature control. And the whole system is compatible with existing large-scale manufacturing methods.

The researchers believe many different tests could be incorporated on a single device, all of which could be placed on a small glass slide like those used for microscopy. The basic processing method could also make possible a wide variety of other applications, including solar cells and light-emitting devices.


“Efficiency is especially important if you’re trying to detect a rare event,” Belcher says. “The goal of this was to show a high efficiency of capture.” The next step after this basic proof of concept, she says, is to try to make a working detector for a specific disease model.

The work was supported by the Army Research Office Institute for Collaborative Biotechnologies and MIT’s Tata Center and Solar Frontiers Center.

* Other researchers have been trying to develop diagnostic systems using a graphene oxide substrate to capture specific cells or molecules, but these approaches used just the raw, untreated material. Despite a decade of research, other attempts to improve such devices’ efficiency have relied on external modifications, such as surface patterning through lithographic fabrication techniques, or adding microfluidic channels, which add to the cost and complexity. Those methods for treating graphene oxide for this purpose require high-temperature treatments or the use of harsh chemicals; the new system, which the group has patented, requires no chemical pretreatment and an annealing temperature of just 50 to 80 degrees Celsius (122 to 176 F).


Abstract of Enhanced Cell Capture on Functionalized Graphene Oxide Nanosheets through Oxygen Clustering
