Move Over, Mammography, There’s a New Biosensor in Town

Mammography is currently the gold standard technique for detecting breast cancer; however, radiation exposure coupled with low sensitivity and specificity leave a gaping hole in the diagnostic landscape. Recognizing this need, a team of researchers have developed a prototype biosensor to challenge current diagnostic standards for one of the most common types of cancer – and one of the leading causes of cancer-related deaths – in women (1).

“In this scenario, we focused on the detection of a certain microRNA (miR-99a-5p) in plasma,” says Ramón Martínez-Máñez, an author on the study. “In fact, several authors have evidenced the relevance of circulating miRNAs in plasma as minimally invasive biomarkers for the prognosis and diagnosis of different types of cancers, including breast cancer. Nowadays, the detection of circulating miRNAs is mainly assessed in laboratories through quantitative real-time PCR, which is a time-consuming and complex technique.”

How does the biosensor work? Martínez-Máñez says, “The biosensor is based in nanoporous anodic alumina. This alumina contains quite a large amount of nanopores of about 20–30 nm. The pores are loaded with a dye (rhodamine B) and capped with an oligonucleotide that blocks cargo release. In the presence of miR-99a-5p, the capping oligonucleotide recognizes the miR-99a-5p sequence and displaces – allowing the release of the encapsulated dye, which is easily detected with a fluorimeter.”

Though there is still a long way to go before pathologists will see the biosensor in routine practice – it is currently being validated with a large number of samples by the team – Martínez-Máñez highlights the impact it will have when the time does come. He says, “The concept of detecting circulating biomarkers in blood samples is related to the concept of liquid biopsy that aims to use a simple, noninvasive analysis for disease diagnosis. To be able to detect such biomarkers in fluids can help pathologists detect a tumor in its earliest stages, more easily control the efficacy of a certain treatment, and quickly detect relapses.”