A new, cheaper test that diagnoses cancer or HIV in an instant could help tackle disease early in developing countries, UK researchers have said.

Researchers from Imperial College London have developed nano particles that change the colour of a blood serum sample to show if bio markers for the HIV virus or prostate cancer are present.

The nano particles will turn the sample blue if tiny amounts of a prostate cancer bio marker called Prostate Specific Antigen or an HIV marker called p24 are detected. If they are not present, the sample will turn red.

The breakthrough, published in the journal Nature Nanotechnology, means diagnoses can be made without expensive lab equipment, the researchers said.

“Current strategies for ultrasensitive detection often require sophisticated instruments that may not be available in laboratories with fewer resources,” the study said.

“Here, we circumvent this problem by introducing a signal generation mechanism for biosensing that enables the detection of a few molecules of analyte with the naked eye.”

Biosensors expert Nico Voelcker, Professor of Chemistry and Materials Science at the University of South Australia, said the finding was very significant.

“It’s certainly a breakthrough,” said Prof Voelcker, who was not involved in the research.

“A lot of research groups have attempted to come up with a simple mechanism to detect a disease marker that doesn’t rely on much more than the unaided eye.”

Prof Voelcker likened it to a pregnancy test that gives a reliable diagnosis without expensive kit or complicated steps.

“And in the case of HIV, the earlier you can detect it, the better the outcome,” he said.