Scientists at NPL develop new technique for detecting disease biomarkers

Tests to diagnose Alzheimer's disease and cancer at the molecular level are being developed by scientists at the National Physical Laboratory (NPL) in London, who have developed a faster and more precise process to detect proteins associated with disease a new paper reveals.

Identifying disease-related proteins - known as biomarkers - in body fluid such as blood can be a useful medical tool. Much work is being done into discovering prognostic and diagnostic biomarkers for use in targeted treatments.

Biomarkers are often present at very low levels, in amongst many other proteins of different sizes and charges. Condensing a sample down to a concentration where they can be identified has been time-consuming and difficult.

'This new strategy uses a probe to 'fish' for likely proteins, selecting them from a crowded blood sample', said Dr Max Ryadnov, a principle biotechnologist, who co-authored the paper. 'A microgel probe works like a sponge, picking up proteins which have a charge or mass within a certain range'.

Mass spectrometry - an analysis where the molecules are charged and identified from their mass-to-charge ratio - can then be used to see whether or not the biomarker is present in this more select sample.

To test the probe's sensitivity, the team tested it with human growth hormone. This protein is used therapeutically, and is also banned in competitive sports - however it's normally found in blood at around only 100 nanograms per millilitre. The probe could pick it up even at 40 nanograms per millilitre.

Investigating a sample for a biomarker has also been very slow, but the new strategy cuts down the time needed. 'You can do it in a day instead of a few days or even a week', says Dr Ryadnov.

The group at NPL are already working on the next type of probe - one that can detect a specific protein or a shape of the target protein, rather than just ranges of size or charge. They also want to see tests that can quantify levels of a protein, rather than just detecting if it is present or not.

'What we're trying to do is simplify testing', said Ms Paulina Rakowska, research scientist in biotechnology. 'These types of probe would in theory be suitable for different classes of diseases, mainly Alzheimer's and the like, but I also hope they would have applications for cancer'.

The research was published in the Royal Society of Chemistry journal Molecular BioSystems.