Scientists in Britain say they have developed a super-sensitive test using nanoparticles to spot markers for cancer or the virus that can lead to Aids in blood serum that can be verified using the naked eye.
As it does not need sophisticated equipment to conduct, the test-tube technique should be cheap and simple, making it a boon for disease detection in poor countries, the team wrote in Nature Nanotechnology.
Researchers from Imperial College London used the technology to scan for molecules of p24, a marker for HIV infection, and prostate-specific antigen protein or PSA, an early indicator of prostate cancer.
Their method is used to analyse serum, a light-yellow fluid that is extracted from blood by a centrifuge and is commonly used in health tests.
"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 a container," the team said.
"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."
Nanoparticles are microscopic clusters of atoms sized between one and 100 nanometres (a billionth of a metre), that are seen as a promising field of research for their potential in delivering medicines, for example.
The team said their visual sensor technology was 10 times more sensitive than existing standard methods for measuring p24 and PSA biomarkers - molecules that can indicate the presence of disease.
The new method is also 90 per cent cheaper.