Biosensors Simplify Disease Detection

Finnish researchers at Aalto University have developed a biosensor that enables creation of easy-to-use health tests similar to home pregnancy tests. The plasmonic biosensors are said to be able to detect whether exosomes, cell-derived vesicles present in blood and urine, are diseased - even by the naked eye.

The researchers created a new biosensor by depositing plasmonic metaparticles on a black, physical body that absorbs all incident electromagnetic radiation. A plasmon is a quantum of plasma oscillation and plasmonic materials have been used for making objects invisible in scientific tests as they efficiently reflect and absorb light. Plasmonic materials are based on the effective polarisabilities of metallic nanostructures.

“It is extraordinary that we can detect diseased exosomes by the naked eye. The conventional plasmonic biosensors are able to detect analytes solely at a molecular level. So far, the naked-eye detection of biosamples has been either rarely considered or unsuccessful”, said Professor Mady Elbahri from Aalto University.

Plasmonic dipoles are famous for their strong scattering and absorption. Dr. Shahin Homaeigohar and Moheb Abdealziz from Aalto University explain that the research group has succeeded in demonstrating the as-yet unknown specular reflection and the Brewster effect of ultrafine plasmonic dipoles on a black body host.

“We exploited it as the basis of new design rules to differentiate diseased human serum exosomes from healthy ones in a simple manner with no need to any use specialised equipment”, says Dr. Abdou Elsharawy from the University of Kiel.

The novel approach enables a simple and cost-effective design of a perfect coloured absorber and creation of vivid interference plasmonic colors.

According to Elbahri, there is no need to use sophisticated fabrication and patterning methods. It enables naked-eye environmental and bulk biodetection of samples with a very minor change of molecular polarizability of even 0.001%.

In addition to using discovery in biomedicine, industry may use advanced applications in energy.

The study was published in Advanced Materials.