Disease diagnosis in minutes

Researchers have developed a biosensor that uses antibodies to detect molecules in the body’s fluids, so often indicative of disease.

The Leeds University team claim the device could test for cancer and multiple sclerosis in 15 minutes. As well as being quick, the technology could be used to better inform GPs prior to hospital referrals.

The technology was developed through a European collaboration of researchers and commercial partners in a €2.7m (£2m) project called ELISHA (Electro-Immunointerfaces and Surface Nanobiotechnology: A Heterodoxical Approach).

At present the technology is the size of a shoebox, but the team believes it could be developed into a wireless debit card terminal-sized device, into which different sensor chips could be inserted depending on the disease being tested for.

‘The test is faster and cheaper than current methods and doesn’t require a laboratory,’ said project co-ordinator Dr Paul Millner, a biological sciences professor at Leeds. ‘So even a small hospital or clinic could have a machine and test for a particular marker [of a biological disease].’

Many biosensor technologies employ a technique called ELISA (Enzyme-Linked ImmunoSorbent Assay) a laboratory method used to detect the presence of antigens (foreign substance that stimulate the production of antibodies) or antibodies in biological samples. But the process is time-consuming and requires highly-trained staff.

The team believes biosensors based on antibodies are more versatile and that a sensor could be designed to detect almost any molecule.

The biosensor is based on the way immune cells recognise and stop the spread of invading viruses by producing attack molecules called antibodies. Immune cells learn to produce a new type of antibody for each new virus.

Millner said the ability to manipulate this recognition system allows them to create specially-tailored biosensors. An antibody could be created, he said, by immunising an animal such as a sheep for a specific disease such as TB. ‘You would then draw blood from the sheep and extract the antibodies,’ said Millner.

The antibodies would then be attached to an electrode surface on a microchip using a special chemical process. The biosensor could then be used to test the contents of a person’s bodily fluid, which could be blood, urine — or spinal fluid in the case of suspected MS.

If the antibody detected an antigen it would bind to it. Millner explained that this action effectively changes the electrical current from the sensor. The change in current is proportional to the amount of substance present. ‘The more antigen in your sample, the more binds, and the bigger the signal,’ he said. ‘The testing machine would then calibrate this information and tell a clinician the concentration of antigen in a sample.’

So far the biosensors have been shown to detect analytes (substances being measured) including biomarkers present in prostate and ovarian cancer, stroke, heart disease and fungal infections. The team also believes the biosensors could test for TB and HIV.

Millner said his group also sees uses for its device in environmental applications, such as testing for herbicides or pesticides in water and antibiotics in milk.

A spin-out, ELISHA Systems, has been set up by ELISHA manager Dr Tim Gibson and commercial partners Uniscan Instruments and Technology Translatorsto commercialise the technology.

Siobhan Wagner