Scientists from Imperial College London and the University of Vigo have developed a super-sensitive biosensor to detect a disease even before the symptoms appear.

According to the researchers, standard biosensors used today can only detect presence of biological markers or "biomarkers" if its concentration in a given sample is high. This new sensor can detect the presence of biomarkers even in very low concentrations.

"It is vital to detect diseases at an early stage if we want people to have the best possible outcomes - diseases are usually easier to treat at this stage, and early diagnosis can give us the chance to halt a disease before symptoms worsen. However, for many diseases, using current technology to look for early signs of disease can be like finding the proverbial needle in a haystack. Our new test can actually find that needle," said Molly Stevens from the Departments of Materials and Bioengineering at Imperial College London, lead author of the study.

The researchers said that their new sensor can detect biomarkers of prostate cancer called Prostate Specific Antigen (PSA). They added that this sensor can be modified to test the presence of other biomarkers as well.

"We only looked at the biomarker for one disease in this study, but we're confident that the test can be adapted to identify many other diseases at an early stage," said Stevens.

This biosensor contains gold stars of nanoscopic size. These stars have antibodies attached on them that latch to PSA in the blood (if present). An enzyme, glucose oxidase present in the secondary antibody that recognizes PSA creates a distinctive silver coating on the stars which can be detected by using optical microscopes. The silver coating appears more distinctively if the concentration of biomarkers is low in the blood sample.

The study is published in the journal Nature Materials.