08 August 2023

Optical biochip created to rapidly detect signs of cancer, toxins and viruses

Researchers have developed a metasurface designed to detect a large number of different molecules.

Engineers from Stanford University have developed a sensitive tiny silicon biochip that can detect a large number of different molecules. The technology would be suitable for medical tests, including clinical analysis and searching for cancer markers or signs of various viral and bacterial infections.

The principle of the technology is based on the method of optical detection of molecules using a metasurface consisting of small silicon blocks. Each such array is a rectangular parallelepiped with blocks 500 nm high, 600 nm long and 160 nm wide.

The silicon blocks focus near-infrared light on their top surface thanks to subwavelength nanoantennas. This allows a basic optical microscope to measure the wavelength shift of the light coming from each silicon block, which varies depending on the molecules on them.

To test the accuracy of the method, the researchers attached 22-nucleotide-long fragments of a single-stranded gene to silicon boxes and immersed the array in a buffer solution. When complementary DNA strands were introduced into the solution, they immediately attached to the bound strands, shifting the wavelength of light from each parallelepiped.

Most sensors for genetic tests are based on monitoring the absorption or emission of light by target molecules designed to bind to a target gene. But these methods use polymerase chain reaction to make many copies before trying to identify it. This increases the cost and time of testing. Sensitive metasurfaces, on the other hand, can detect even a small number of molecules.

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