Researchers developed a test chip using graphene, a single carbon atom sheet material. The chip has a trampoline structure with a narrow gap of up to 1 micrometer, formed under a monatomic graphene film, and can specifically capture biomarkers – proteins contained in body fluids, such as blood, urine or saliva, which are released during various diseases. It is reported by Nanoscale Advances.
The biomarker adsorbed by graphene generates a force that deforms graphene into a dome shape. Thus, the group was able to detect the magnitude of the deformation as a color change, using the interference properties of light.
A measuring device for simple and quick examination of the disease is extremely important for accurate diagnosis, verification of therapeutic effects, and the study of relapse and metastasis. If diseases can be investigated using a very small amount of body fluids, such as blood or urine, the physical condition can be easily, quickly, and cheaply controlled.
A methodology for determining the presence or absence of a disease by specifically capturing a biomarker on a flexibly deformable thin film formed using semiconductor microprocessing methods was also investigated. The research team has developed a sensor technology to detect film deformation caused when a marker molecule is adsorbed as color changes. When the film thickness for biomarker adsorption decreases, the sensitivity of this sensing element can be increased.
In a previous study that used suspended graphene in the form of a bridge, however, changes were measured during the physical adsorption of the molecule into suspended graphene, and it was difficult to specifically determine the molecule to be measured. As for the reason for this, it is believed that since modification using antibodies to recognize and specifically bind molecules is usually carried out in solution, the suspended structure of graphene was destroyed during treatment with the solution.
The research team thus created a trampoline structure in which substrate irregularities were coated with graphene sheet in the form of a suspended graphene structure that could withstand solution processing and was capable of modifying graphene with an antibody molecule. The graphene surface was functionalized by an antibody molecule to provide the ability to recognize the molecule, and an ultra-sensitive biosensor that can specifically detect the biomarker was obtained.
A light detection method unique to the research team was used as a method for detecting a biomarker associated with the surface of graphene. In a gap of less than 1 micrometer between suspended graphene and a semiconductor substrate, the color changes depending on the length of the gap under the influence of light. Using this effect, the appearance of a molecule adsorbed on suspended graphene in the test solution was detected by a color change.
According to the biosensing technique developed this time, it is expected that sensitivity per unit area will be improved 2000 times compared to conventional sensors.
In addition to blood tests, the research team also investigated a chemical sensor for odor and chemical detection and believes that the sensor can be applied to a new compact sensor device that contributes to the IoT community. The sensor can be used to detect various biomarkers, as well as to detect viruses by changing probe molecules that modify the surface of graphene.