Scientists have developed a prototype ultra-sensitive sensor that would enable doctors to detect the early stages of diseases and viruses with the naked eye, according to research published today in the journal Nature Nanotechnology.
The team, from Imperial College London, report that their visual sensor technology is ten times more sensitive than the current gold standard methods for measuring biomarkers. These indicate the onset of diseases such as prostate cancer and infection by viruses including HIV.
The researchers say their sensor would benefit countries where sophisticated detection equipment is scarce, enabling cheaper and simpler detection and treatments for patients.
In the study, the team tested the effectiveness of the sensor by detecting a biomarker called p24 in blood samples, which indicates HIV infection.
Professor Molly Stevens, from the Departments of Materials and Bioengineering at Imperial College London, says:
"It is vital that patients get periodically tested in order to assess the success of retroviral therapies and check for new cases of infection. Unfortunately, the existing gold standard detection methods can be too expensive to be implemented in parts of the world where resources are scarce. Our approach affords for improved sensitivity, does not require sophisticated instrumentation and it is ten times cheaper, which could allow more tests to be performed for better screening of many diseases."
The researchers in today's study also tested samples for the biomarker called Prostate Specific Antigen (PSA), which is an early indicator for Prostate Cancer. The team say the sensor can also be reconfigured for other viruses and diseases where the specific biomarker is known.
The sensor works by analysing serum, derived from blood, in a disposable container. If the result is positive for p24 or PSA, there is a reaction that generates irregular clumps of nanoparticles, which give off a distinctive blue hue in a solution inside the container. If the results are negative the nanoparticles separate into ball-like shapes, creating a reddish hue. Both reactions can be easily seen by the naked eye.
The team also report that the sensor was so sensitive that it was able to detect minute levels of p24 in samples where patients had low viral loads, which could not be diagnosed using existing tests such as the Enzyme-linked Immunosorbent Assay (ELISA) test and the gold standard nucleic acid based test.
Dr Roberto de la Rica, co-author of the study from the Department of Materials at Imperial College London, adds:
"We have developed a test that we hope will enable previously undetectable HIV infections and indicators of cancer to be picked up, which would mean people could be treated sooner. We also believe that this test could be significantly cheaper to administer, which could pave the way for more widespread use of HIV testing in poorer parts of the world."
The next stage of the research will see the team approaching not-for-profit global health organisations, which could provide strategic direction and funding for manufacturing and distributing the sensor to low income countries.
The research was funded by the Engineering and Physical Sciences Research Council (EPSRC) and by a European Research Council (ERC) starting investigator grant. The study was also supported by a Marie Curie Intra European Fellowship within the 7th European Community Framework Programme.
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Notes to editors:
1. "Plasmonic ELISA for the ultrasensitive detection of disease biomarkers with the naked eye" Nature Nanotechnology, published [insert date] Roberto de la Rica , Molly Stevens 
 Department of Materials, Department of Bioengineering and Institute for Biomedical Engineering, Imperial College London, Exhibition Road, London SW7 2AZ, UK
Download a copy of the paper: https://fileexchange.imperial.ac.uk/files/cb229a60c28/NNANO%202012%20186.pdf
2. About Imperial College London
Consistently rated amongst the world's best universities, Imperial College London is a science-based institution with a reputation for excellence in teaching and research that attracts 14,000 students and 6,000 staff of the highest international quality. Innovative research at the College explores the interface between science, medicine, engineering and business, delivering practical solutions that improve quality of life and the environment - underpinned by a dynamic enterprise culture.
Since its foundation in 1907, Imperial's contributions to society have included the discovery of penicillin, the development of holography and the foundations of fibre optics. This commitment to the application of research for the benefit of all continues today, with current focuses including interdisciplinary collaborations to improve global health, tackle climate change, develop sustainable sources of energy and address security challenges.
In 2007, Imperial College London and Imperial College Healthcare NHS Trust formed the UK's first Academic Health Science Centre. This unique partnership aims to improve the quality of life of patients and populations by taking new discoveries and translating them into new therapies as quickly as possible.
3.About the European Research Council (ERC)
Set up in 2007 by the European Union, the ERC aims to stimulate scientific excellence in Europe by encouraging competition for funding between the very best, creative researchers of any nationality and age based in the EU. Since its launch, it has funded over 3,000 researchers (juniors and seniors) and their frontier research projects, and has become a "benchmark" for the competitiveness of national research systems complementing existing funding schemes at national and European levels. The ERC operates according to a "bottom-up", approach, allowing researchers to identify new opportunities in all fields of research (Physical Sciences and Engineering, Life Sciences and Social Sciences and Humanities). Last year, the European Commission proposed an increase of the funding of the ERC budget from €7.5 billion for 2007-2013 to €13 billion for 2014-2020 under the new research framework programme ('Horizon 2020').