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Highly-sensitive optical biosensor may be able to detect cancer in early stages

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A team of researchers from Case Western University (OH, USA) has developed an optical biosensor using nanostructured metamaterials, which is 1 million times more sensitive than currently available sensors. The new biosensor could be utilized in early cancer detection, as well as to monitor treatment and resistance.

The research, published recently in Nature Materials, describes the biosensor as a ‘molecular sieve’, able to detect single protein molecules produced by circulating tumor cells in a dilute solution. Tumor cells express proteins of approximately 500 Daltons, a molecular mass too small to be detected by current systems, meaning diagnostic tests may give a false result.

The new biosensor has been demonstrated to detect 244 Dalton protein molecules, which means the device could be crucial in early diagnoses, not only for cancer but potential for other diseases as well.

Current biosensors are limited in their detection of small molecules due to their use of lightwaves as a detection means, which limits detection range to molecules of approximately half a micron in diameter or more. This problem was overcome by utilizing nanotechnology, and coupling these tools to a microfluidic channel with a multilayer metamaterials sensor surface.

Researchers also had to overcome the unlikelihood of molecules in a dilute solution landing on the sensor surface due to their floating in Brownian motion. The microfluidic channel restricts the molecules’ movement and drives them in to the sensing area on the metamaterial surface.

The engineered multilayer metamaterial used within the sensor is extremely sensitive. When a small molecule lands on its surface, this causes a local modification, causing a shift in reflected light. The light will shift by varying amounts according to the size of the molecule.

At present, the biosensor is able to quantify the size of a molecule, but it is hoped that the highly sensitive sensor can be developed to identify specific molecules, including cancer type-specific biomarkers, by their light shifts. This technology could then be employed as an early detection system, which could prove particularly useful in pancreatic and bowel cancer diagnosis, for example.

Nima Sharifi, co-leader of the Genitourinary Cancer Program for the Case Comprehensive Cancer Center (OH, USA), commented: “This new sensing technology may help us not only to detect cancers, but what subset of cancer, what’s driving its growth and spread and what it’s sensitive to. The sensor, for example, may help us determine markers of aggressive prostate cancers, which require treatments, or indolent forms that don’t.”

The research team is now working with other oncology specialists to test the device, with the hope of bringing it to clinical use.

Sources: Sreekanth K, Alapan Y, El Kabbash M et al. Extreme sensitivity biosensing platform based on hyperbolic metamaterials. Nature Materials. DOI: 10.1038/nmat4609 (2016); Case Western Reserve University press release

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